My Patreon: www.patreon.com/cuivlazygeek Here is an EXCELLENT explainer by Dale Ghent, one of the NINA developers: daleghent.com/2020/08/understanding-camera-offset My videos on gain, etc: ua-cam.com/video/GKXkM_FbFgg/v-deo.html and ua-cam.com/video/SYQ1i4k62eI/v-deo.html Amazon affiliate: amzn.to/3hTB5Ne Agena affiliate: bit.ly/3Om0hNG High Point Scientific affiliate: bit.ly/3lReu8R All-Star Telescope affiliate: bit.ly/3SCgVbV Dwarf 2 Smart Telescope: bit.ly/3SyChXu Seestar S50: tinyurl.com/3n62hpzx
Two problems with making a video on 25th December are the fact that for at least 364 days of the year, people will be watching on the wrong day for you to greet them as you did. And of course countless millions of people don't celebrate the day. Nonetheless, thank-you for your thoughts and for the video. 🙂👍
That histogram would be more useful if it could be switched to a logarithmic wavelength display. That would spread the low end for you, if the software has that facility,
Great video Cuiv. When I started this hobby back in 2021, I searched for answers to the mysterious offset, it seemed no one wanted to talk about it or if they did it was "yeah just set it at 50". I finally figured it out on my own, after much trial and error, this video will help many newcomers to the hobby.
The issue is not explaining it, as that is relatively easy. It is just most novices have far better things to worry about messing with. That and devices like the ASIAIR do not let you adjust it.
What I have learned is that you should always make sure your histogram is as far away from the left side of the histogram as possible to prevent clipping since what we image is so faint. Because this is a linear RAW image that will be stretched later, don't worry about the peak being too far to the right as long as it does not exceed the 1/3 of the histogram as we can fix this with the histogram stretch in post processing. Already messed up and imaged at zero offset? Don't throw those frames away, you can add a pedestal when you integrate. Yes you lost data but you can still process your image. And yes whatever you change whether it be the gain, offset, temperature, and even the USB limit (yes that can cause issues too like banding!) take new calibration frames. Thanks for making this important video Cuiv and Happy Holidays!
Cuiv, most logical and rational method I have seen for setting offset. Nice one mate. One other small point is that yet again NINA gives us astrophotographers all the tools we need.
Thank you for going over this in detail! I just set mine to 50 and just ran with it, now I need to go in and do the same exercise and figure out my optimal settings. Very helpful explanations.
This video is a good opportunity to again say thank you for your commitment to astrophotography and to your viewers. Your explanations make sometimes complicated topics understandable, and your sense of humor makes your channel a welcome place to be. Merry Christmas Cuiv.
I was absolutely setting my offset wrong. Thank you very much for explaining how it actually works! Now to retake all my master-darks in preparation for the next clear night....
I breathed a sigh of relief after checking some old bias files. With a gain of 120 and an offset of 50 on my ASI294MC pro, it appears that I've been doing it right, more or less. Thanks for the clear explaination of what offset is all about.
@@CuivTheLazyGeek I should mention that I don't take biases everytime I shoot. In fact, I just subtract off the bias value when I do my stacking in SIRL--supposedly less noise added to the result.
@@richardshagam8608 having a bias library you keep reusing is fine, I do the same :) But what do you mean by "you just subtract off the bias value when you do your stacking"?
As a fellow geek, I like how you deep dive and dig into these details that most others overlook without giving it a second thought. You are one of the few youtubers finding truly original tips!
Finally someone answers my question on Offset. I have seen it on NINA, in the sequencer, and never knew where to set it, or what to set it too. I have the OGMA AP26CC camera now, which I think is the same as the Topek ?? that you have, with the Sony 571 chip. I love the camera, but this will really help me get the maximum performance from it. Thank you very much for making this video. I really love NINA as well, but wish I knew how to use it better. Thanks for this, and many of your other videos...all very helpful. Mark
Another great video, thanks! I've been taking short exposures that are long enough to swamp the read noise and usually used a 500 ADU offset but lost the offset setting. I collected many nights of images at 0 offset and had clipped badly which really impacted the processed image quality. It is important to set the offset high enough that there is minimal clipping.
I did mine last year in SharpCap and ended up with a value of 6 on my ASI585, but the offset only ranges from 0-200 on this camera. I thought I'd give it a shot with this method just now and I think it was pretty close, but I'll probably bump it up by a whole digit to 7. I found that the numbers change a lot if I loop my images in NINA though; for me at 1*e-5s it goes like: 0(x1), 40(x2) , (0(x1), (160(x1), (128(x3), (0(x1)... And at 7 everything is just a little bit higher, I still hit a few 0s, but less frequently. I found the SharpCap method to be a bit "hacky", and I was never quite sure if it was correct, but I think I like this NINA method a bit better because you get to see the real numbers, plus it's additional confirmation that I was in the right ballpark. I think the default in the ZWO driver for my camera was originally 25, which was far too high!
Very helpful, now at least I have some method behind my setting. I just read somewhere it should be set at 70 and I had no idea why. Going to try this method before next session. Thank you!
Merry Christmas Cuiv! Back in the long, long ago there was an article from Dr. Craig Stark (original author of PHD Guiding) that described the process for CCD cameras. When I got into CMOS cameras I read Dr. Q's article (QHYCCD) that described the same process you go over here. I basically read his article and followed the same process you highlight here. It does help to optimize your dynamic range which helps minimize frustration in imaging from Bortle 9 zones like I am in near Dallas, Texas, USA. One of these days I need to take my daughter to Tokyo so she can meet her Japanese relatives.
Very useful video. Thank you. I must admit I've always gone with the "ask someone else" method of getting the gain value for my camera, so this will allow me to correct that mistake!
Merry Christmas, Cuiv, and thanks for another great video. Interesting to see how different manufacturers using the same sensors, apply their firmware/electronics differently. In your Touptec camera, apparently 1 offset equals 1 ADU. For QHY this is 16 ADU, and for ZWO this is 40 ADU. So correct offset values between cameras differ a lot. Also, the Touptec apparently can report a ‘0’ value, whereas QHY and ZWO cameras report ‘1’ as the minimum value, or ‘4’ if it is a 14-bit camera.
Thanks a lot for this explanation! For my Touptek-based Omegon VeTec 751C and based on your video I found an interesting relationship between the gain and offset. No matter which gain I use, taking the same value for the offset - 8% works great (gain 100, offset 92; gain 316, offset 291; gain 2500, offset 2300). Though, I know that i.e. the gain of the ZWO cameras is calculated differenty, so this will probably not work for any camera
I love the work you do and your contribution to AP. I have a RASA11 and I am worried about doing a "tilt correction". Please consider a review of this factor and how to do the procedure.
Thanks Steve! Tilt is one of those things I have never had success with - and imo unless someone is using full frame and a Tak, it may not be worth the effort... Right now I'm definitely not qualified to make such a video unfortunately!
I remember this one time when I was trying to apply my calibration frames to my light frames with different offset values. I kept on getting error warnings from Siril , Astap or any other preprocessing software. I could not understand why until I figured that I was working with different offset values. Lesson learned after many hours of frustration. I wish I had my hands on this video back a few years from now! lol
Happy Christmas Cuiv. Good explanation of this setting. I have been leaving the offset on my mono and OSC cameras at default settings as the images seem to be ok. Will try adjusting the offset the next time I get a clear night ( have only had three in the last two months )
Merry Christmas. A real present for us. I’ve watched a lot of videos and read a lot of literature and this has not come up before. Thanks for this, looks like an important setting usually overlooked.
Thank you Cuiv, it's good to have this valuable nugget of information. It's been ages now watching rain drops UK running down my windows. clear skies are rare as rocking horse poo💩💩.. So applying tips etc has now become more interesting than taking the light frames!!! 😂😂 Happy day & new year, thank you for all you do.. Atb Tom dull wet UK....
Well Cuiv, if there was no way to prove you were the Lazy geek before or even convince some of us, this has done it! I did wonder why my astronomy photos didn’t have any stars.
I was told by experienced astro photographer that it needs to stay ( gain ) at factory level which is 48, so now you presenting the new ( it isn't new, is it ) idea about offset. I'll get it tested for sure, thanks.
I forgot to ad that my camera is Altair 269C, I will test it anyway, I love your work and getting your tips and tricks implemented into my circumstances. @@CuivTheLazyGeek
Hi there Geek. I recently bought the Altair Astro version (AA26C) and use Indi/Ekos + altair driver. My understanding is that when taking short exposure darks (BIAS frame) the histogram should not get cut off on the left. I think I saw this on a Sharpcap forum. In Indi oontrols my camera settings are Conversion Gain = High. High Full Well Mode = off. Low Noise Mode = off. Gain=100, Offset=50, exp=.001. The histogram using indi looks fine. Peak at 50, drops to zero below 25 and above 75. In NINA I get the Ultra Mode option same as you which up to now I had set to off. 12000 clipped pixels is microscopic compared to 24Million pixel on the sensor (5 parts in ten thousand). Not sure this makes that much difference for this camera, but great that you explain how to measure things. Should I be using Ultra Mode (NINA) / Low Noise Mode (indi) ? Confusing camera.
This was a very helpful video - thanks! There was one aspect that initially confused me, however. Clearly simply adding a constant uniformly to an entire set of data cannot increase the amount of information; it simply resets the zero point. I'm guessing then that what is really happening is that the camera performs some kind of internal mapping from the raw data to the stored data, and the offset is applied to the _raw_ data before that mapping, so that pixels with low counts don't get mapped to zero, i.e. clipped. Applying it to the stored data would not help in that way.
Cheeky! Thank you for this info! I just got a ASI585MC PRO and was not getting enough light at 252 gain and even 120 sec. NINA has a default offset of 125. I didn’t know what it was and how to set it. Too bad it’s 10 degree Fahrenheit at night.
Nice video, and well done. Yes, everything in the video is correct. I've given the same advice to people before when they asked how to adjust the camera offset. But this is the first video I've seen on the topic (at least that I've seen). Thanks Cuiv. This video should prove quite useful to a lot of people.
Merry Christmas! Yes, a lot of people afraid to use a high offset, somehow the loss of dynamic range scares people I guess, but seeing images from people their loss of DR is more contributed to incorrect processing and I'm guilty of that too. I would say on average; without careful image editing; people ruin their DR in their image by cutting as much as many thousands of ADU steps, compared to a few hundreds that a higher offset would do. The loss of DR with the offset just irrelevant and minuscule, compared to wrong image editing habits. I just follow how ZWO set it in Asiair, (offset 75 for zwo cameras) and seeing how that's like almost halfway up on the offset scale, I imitate it to do similar with my non-zwo cameras and I am perfectly fine losing a few hundred or even a 1000 DR steps due to high offset. Otherwise Pixinsight will report me that it had to do a "huge pedestal" correction when processing and that lets me know that I did use the wrong offset.
Merry Christmas to you and yours, and thank you for being such a wonderfully enthusiastic lazy geek. May clear skies follow you to wherever you may roam.
Super informative video Quiv, very understandable explained, thank you for all those great videos you made during the past years. Wishing you and your family happy holidays
Interesting. Would like to see what the master lights look like at various offsets and how one setting might produce a better end result over the others. In PixInsight, you can set a minimum pedestal value during WBPP, which I'm not sure yields the same outcome.
Good post! It would be interesting to statistically compare images of a bright source, a glowing nebula, with offsets of double or triple the 151 and see if there is any deterioration of image quality. Dynamic range is important, but I don't see how sacrificing even up to 1% of dynamic range would make any difference in the final image quality. If you are clipping the brightest stars, it shouldn't matter since most people end up reducing the number of stars and their brightness in the final image.
Merry Christmas. An excellent video as offset seems to be quite a mysterious topic out on the net and on the forums with a whole range of settings being offered without any real explanation as to why that number was settled on. Your video gives a nice explanation of how to calculate it with meaning. Thanks again and wishing you a great 2024 (hope we see some more paragliding videos too).
Thanks for pointing this out. Was always eager to fiddle with the offset. However when counting pixels with the minimum ADU I'm thinking now about dead pixels of the sensors falsifying statistics and so even higher offsets might be feasible 🤔 but I don't know at the end the offset just makes a small difference with regard to whole dynamic range I guess
Great video, thanks! I'm trying to get this right on my Altair 269C TEC, the range is a lot smaller 0-462 and NINA set the default to 16. Setting it higher, the Mean and Median go far too off and the difference is more than 1000, so it might have to do that it is a dual mode camera, or just a driver thing. Maybe I'll give SharpCap calibration a test, to see what values it shows. Love your channel and I can see how Japan has formed your kindness! ありがとう ございます
Thanks, Cuiv now I know how to check the offset. My ZWO ASI2600MC Duo default offset is also 50 but this gives the histogram Mean and Median values near 500. For any offset the Mean and Median histogram values near 10X the offset. UPDATE Looking at the fits header, NINA is added 50 as the offset not the 500 being added my ZWO.
Hi @CuivTheLazyGeek. First sorry for my English… 🇫🇷 your offset at the end still appears too low, you didn't take in account, that bias (also dark) will be substracted from your light, which means your light histogram will be shifted back to the the left. I have the same camera, after researches and tests, I set my offset to 768 and activate the high full well mode. I double checked under SiriL , which has a much better histogram than Nina, and got something comparable to zwo cameras with their default offset under asiair. In addition, I kept an older version of the risingcam driver and SDK (February 22) cause the next ones are buggy with short exposure and they made flat frames unusable. Greetings from France
Thanks for the feedback! The ZWO cameras afaik use offset 50 (which is really 500 ADU). For the light frames, I think PixInsight can add a Pedestal prior to bias calibration, so the issue you mention isn't hit, I will need to check though!
@@CuivTheLazyGeek yes I know for zwo cam, I compared histogram from zwo cam with zwo offset and try to reach the same histogram with the risingcam. I had good results for the few times I could try (very long bad weather for me) Anyway thanks for your reply, hope to see the following of your investigation soon, in order to improve my settings 😉
Finding the correct offset was always a thing for old-school QHY CCD cameras before finding the correct gain - something lost in the mists of time I guess. From my understanding set it once and never touch it again - I check offset/gain values every couple of years and they haven't moved.
Cuiv, Interesting Video. However, I have an issue. The video seems to be a some what comparison between the ZWO-ASI2600mm and the Touptek/RisingCam 2600mono camera as they both use the following sensor: SONY IMX571 CMOS. Accordingly, they supplied information on the specifications of the camera, for the vendor to select functions that they wish to pass on to the consumer. It appears that ZWO seem to have gone out of their way to make it easier for the consumer in calculating the optimum gain and offset, known as 'Unity Gain'. Also allowing the user to have the ability to select a manual option and set values of their choosing. All good so far. So here is my issue. You have a Touptek camera and set your 'Gain' to 100 (101),'Offset' to be 151. Using the short Bias exposure to calculate values for the 'Min (0)' and 'Max (65536)' Pixel values. I don't see a problem with this, other than the values you have defined as correct for your camera. It appears to me that you are using the ZWO 'Unity Gain 100' as the starting point gain for the Touptek camera. I know the Touptek Min gain is 100, which is just a coincidence compared to the ZWO 100 optimum gain. So my point is this. Taking that ZWO has calculated the 'Unity Gain' correctly, and we can probably assume they have, and we need a comparison of the two, as Touptek, as I know, does not supply a unity gain value, then the following formula would need to be applied. The ZWO has a gain value of 0 to 450. The Touptek has a gain value of 100 to 10,000. Note: Values under 100 cannot be selected. So, if one needs to take a direct comparison between the two cameras to find the gain for the Touptek, the following calculation would need to apply. Touptek's max gain is 10,000. We would divide this with ZWO's max gain of 450. This would give a value of 22.2222. We would multiply 22.222 by ZWO's Unity Gain of 100, and would give a value of 2222. This value would be equivalent to the ZWO Unity Gain of 100. So the unity gain for the Touptek would be 2222. Formula: 10000/450=22.2222 22.2222x100=2222 Touptek max Offset is 7936. We would divide this with ZWO's max Offset 240. This would give a value of 33.06. We would multiply 33.06 by ZWO's Unity Offset of 75, and would give a value of 2479. This value would be equivalent to the ZWO Unity Offset of 75. So the unity offset for the Touptek would be 2479. Formula: 7936/240=33.06 33.06x75=2479 UNITY GAIN ZWO GAIN 0 100 450 Touptek GAIN 100 2222 10000 UNITY OFFSET ZWO Offset 0 75 240 Touptek 0 2479 7936 I have ignored LCG, HCG etc. as we are only finding a comparison unity between the ZWO and Touptek. I have always used the above gain at 120s for my Touptek/RisingCam camera as I found 100 did not work too well even with the above activated. I am not all that concerned about a few black pixels or over bright ones, as this depends on the target anyway. I am in a high bortle zone 7 and getting worse. So what is your opinion? Is it that we have been used to values of ZWO and think these values also apply to all other cameras, such as Touptek. ------------
Great tutorial as always. Question. I may have missed this but you said you dont use dark frames anymore. Do you have a video, you can share, showing why?
Dude... this video, and your channel as a whole, is SO informative and straightforward. I sincerely appreciate your demonstration of each step you take and what it all means and why you do different things. One question I have... you mentioned that you don't use dark frames any more. Can I ask why? I am new to astrophotography, but I thought dark frames were essential to getting the best images?
I followed this method on my ASI6200MC and determined the optimal offset is 15 at gain 0. My minimum pixel value on bias frames is 9 at those settings.
Aha… now the offset might be why my images looks pixelated when doing background extraction in Pixinsight. As some pixels turn absolutely black. 😮 Will experiment with the offset and hopefully get some clear whether to test in 2024.
Thanks for the tutorial !. So you set the offset high enough to avoid zeroes. Makes sense. Curious what then happens to the repeatability of pixels in dark frames and if that 'image' helps to characterize/process images. Is there a test object to help set gain also ?
I measure the sky brightness around my target with Sharpcaps smart histogram brain function. Assuming you have previously performed a sensor analysis ( only need to perform this once) Sharpcap with work out your offset, optimal gain, sub length, exposure etc. I mean how easy was that?
Thanks for this video. I'm also using an IMX 571 camera (QHY 268C). As you said the behavior will depend on the read mode and gain, but will the values be dependent on sensor temp too?
Hi Cuiv! I've got an ASI6200MM that I use with an ASIAIR Plus (just replaced my old ASIAIR Pro with the Plus). Of course , you can't adjust the offset in the ASIAIR. I noticed on some data I just took that I had a lot of dead pixels on my Oiii and Sii Masters. Should I shoot new Darks and Flats...I use a library...since I got a new ASIAIR, or should I use a Pedestal in WBPP?? If I need to use a Pedestal, what value would you recommend?? Thanks! Tom
If your biases have no dark pixels you're fine :) the ASIAIR automatically sets offset to a good value for the camera. If you see dark pixels in your stack but not in the bias frames then this was likely caused by bias or dark subtraction. You can use a pedestal but you will need to test and see how high it needs to be for you! By the way if you take your darks/bias with the camera attached to the scope, always take them in a dark room!
Hey Cuiv, first of all Merry Christmas!!🎄 and thank you for all your great contents and advice. Perfect timing, just last night I was searching for this topic and then you came to the rescue 😀.
Merry Christmas. I just bought the same camera you have and was in doubt as to how the gain and offset values should be set. Thank you for the clarification 😊🎅
Not looking forward to trying to balance offset and gain against sub lengths and filling well capacity. Is there a way to do this in just nina? Do you have a video how to? :) Ive watched you video on optimum exposure times, ill watch it again ;)
And like you say in your video, be aware to always calibrate using the same offsets. Once you start experimenting with offset, a mistake is easily made. Therefore in WBPP in PixInsight, I always have Offset on as a grouping parameter. It has saved my bacon more than once…
Hi Cuiv! Great and informative video👍 I've just tried this metod with my asi533mc-p, at -10 C degrees, gain 100 and I've got the offset of 7 to be about right(with minimun of 80 and mean of 230). But is it okay that the calculated offset is so low for this type of sensor ?
Not all cameras calculate the offset the same. My ASI2600mm used a default of 50 and that gives a mean bias of 500 ADU. I have it reduced to 30 and that gives 300 ADU.
The issue I see is the histogram values are near 10X the offset value. ZWO may be doing things different, but it looks like be a software bug. I can set my offset to 18 and have zero dark pixels but then the histogram Mean and Median values are near 180. For now, I am leaving it at 50 since the histogram Min value 323 (2x).@@davidkennedy3050
Maybe a daft question, but where does one set the pedestal for the ToupCam camera? I use the ToupSky app when I image, rather than Nina - I find it easier to use than Nina, but I can't find a pedestal setting on the ToupCam programme. It does allow me to set the Black Point, which I suppose is a type of pedestal. Is that what should use?
Hi Cuiv! As always, thank you for all your useful tips! What would you do with an ASI294 MC-Pro and it's problems with inconsistent low exposure shots? Is this method viable to understand the correct offset or should I go up to 2+ seconds shots? Regards!
@@CuivTheLazyGeek thank you for the response! I've already tried both "bias" timings and "darkflat" timings and the difference is almost negligable for this test. To be sure I've used 3 seconds exposures and got a final value for my offset of 4 (in ZWO terms). The default value for the "unity gain" in the drivers is usually 6, so I'm surprised! I've always used 30 offset and I wil ltry with 4 my next session! Thank you again Cuiv!
So for my IMX571 and IMX585 cameras I basically use the following with the sensor cooled to -10C - 1s long bias frames (1s is pretty much the same as 0.0001s at that temperature) - 1-2s flat frames I use this to calibrate all my frames regardless of length and I don't bother with dark frames.
My Patreon: www.patreon.com/cuivlazygeek
Here is an EXCELLENT explainer by Dale Ghent, one of the NINA developers: daleghent.com/2020/08/understanding-camera-offset
My videos on gain, etc: ua-cam.com/video/GKXkM_FbFgg/v-deo.html and ua-cam.com/video/SYQ1i4k62eI/v-deo.html
Amazon affiliate: amzn.to/3hTB5Ne
Agena affiliate: bit.ly/3Om0hNG
High Point Scientific affiliate: bit.ly/3lReu8R
All-Star Telescope affiliate: bit.ly/3SCgVbV
Dwarf 2 Smart Telescope: bit.ly/3SyChXu
Seestar S50: tinyurl.com/3n62hpzx
Two problems with making a video on 25th December are the fact that for at least 364 days of the year, people will be watching on the wrong day for you to greet them as you did. And of course countless millions of people don't celebrate the day.
Nonetheless, thank-you for your thoughts and for the video. 🙂👍
That histogram would be more useful if it could be switched to a logarithmic wavelength display. That would spread the low end for you, if the software has that facility,
Great video Cuiv. When I started this hobby back in 2021, I searched for answers to the mysterious offset, it seemed no one wanted to talk about it or if they did it was "yeah just set it at 50". I finally figured it out on my own, after much trial and error, this video will help many newcomers to the hobby.
Thanks William, thanks for your support, and Merry Christmas!
The issue is not explaining it, as that is relatively easy. It is just most novices have far better things to worry about messing with. That and devices like the ASIAIR do not let you adjust it.
What I have learned is that you should always make sure your histogram is as far away from the left side of the histogram as possible to prevent clipping since what we image is so faint. Because this is a linear RAW image that will be stretched later, don't worry about the peak being too far to the right as long as it does not exceed the 1/3 of the histogram as we can fix this with the histogram stretch in post processing. Already messed up and imaged at zero offset? Don't throw those frames away, you can add a pedestal when you integrate. Yes you lost data but you can still process your image. And yes whatever you change whether it be the gain, offset, temperature, and even the USB limit (yes that can cause issues too like banding!) take new calibration frames. Thanks for making this important video Cuiv and Happy Holidays!
Cuiv, most logical and rational method I have seen for setting offset. Nice one mate. One other small point is that yet again NINA gives us astrophotographers all the tools we need.
NINA is awesome :)
Thank you for going over this in detail! I just set mine to 50 and just ran with it, now I need to go in and do the same exercise and figure out my optimal settings. Very helpful explanations.
Glad it was helpful!
This video is a good opportunity to again say thank you for your commitment to astrophotography and to your viewers. Your explanations make sometimes complicated topics understandable, and your sense of humor makes your channel a welcome place to be. Merry Christmas Cuiv.
I appreciate that! Thank you! And (belated) merry Christmas!
I was absolutely setting my offset wrong. Thank you very much for explaining how it actually works!
Now to retake all my master-darks in preparation for the next clear night....
Hope that next clear night comes soon!
I breathed a sigh of relief after checking some old bias files. With a gain of 120 and an offset of 50 on my ASI294MC pro, it appears that I've been doing it right, more or less. Thanks for the clear explaination of what offset is all about.
Great to know!
@@CuivTheLazyGeek I should mention that I don't take biases everytime I shoot. In fact, I just subtract off the bias value when I do my stacking in SIRL--supposedly less noise added to the result.
@@richardshagam8608 having a bias library you keep reusing is fine, I do the same :)
But what do you mean by "you just subtract off the bias value when you do your stacking"?
As a fellow geek, I like how you deep dive and dig into these details that most others overlook without giving it a second thought. You are one of the few youtubers finding truly original tips!
Much appreciated! Thank you!
Cuiv! I hope your well. I’ve been watching your videos for over 4 years and still one of my favorite channels. Happy new year!
Finally someone answers my question on Offset. I have seen it on NINA, in the sequencer, and never knew where to set it, or what to set it too. I have the OGMA AP26CC camera now, which I think is the same as the Topek ?? that you have, with the Sony 571 chip. I love the camera, but this will really help me get the maximum performance from it. Thank you very much for making this video. I really love NINA as well, but wish I knew how to use it better. Thanks for this, and many of your other videos...all very helpful. Mark
Glad this is helpful Mark!
Thanks!
Wow thanks for the support! Merry Christmas!
At last!!! Someone who explained it so good!! Thank you Cuiv!
Another great video, thanks! I've been taking short exposures that are long enough to swamp the read noise and usually used a 500 ADU offset but lost the offset setting. I collected many nights of images at 0 offset and had clipped badly which really impacted the processed image quality. It is important to set the offset high enough that there is minimal clipping.
Sorry to hear about those suboptimal nights due to the offset!
I did mine last year in SharpCap and ended up with a value of 6 on my ASI585, but the offset only ranges from 0-200 on this camera. I thought I'd give it a shot with this method just now and I think it was pretty close, but I'll probably bump it up by a whole digit to 7.
I found that the numbers change a lot if I loop my images in NINA though; for me at 1*e-5s it goes like: 0(x1), 40(x2) , (0(x1), (160(x1), (128(x3), (0(x1)...
And at 7 everything is just a little bit higher, I still hit a few 0s, but less frequently.
I found the SharpCap method to be a bit "hacky", and I was never quite sure if it was correct, but I think I like this NINA method a bit better because you get to see the real numbers, plus it's additional confirmation that I was in the right ballpark.
I think the default in the ZWO driver for my camera was originally 25, which was far too high!
Very helpful, now at least I have some method behind my setting. I just read somewhere it should be set at 70 and I had no idea why. Going to try this method before next session. Thank you!
For ZWO, 50 or 70 both should work fine (they actually mean 500 and 700 ADUs in the ZWO world apparently)
Merry Christmas Cuiv!
Back in the long, long ago there was an article from Dr. Craig Stark (original author of PHD Guiding) that described the process for CCD cameras. When I got into CMOS cameras I read Dr. Q's article (QHYCCD) that described the same process you go over here. I basically read his article and followed the same process you highlight here. It does help to optimize your dynamic range which helps minimize frustration in imaging from Bortle 9 zones like I am in near Dallas, Texas, USA. One of these days I need to take my daughter to Tokyo so she can meet her Japanese relatives.
Good to know Dr Q describes the same method! And yes you need to bring your daughter to Toyko! ;)
Very useful video. Thank you. I must admit I've always gone with the "ask someone else" method of getting the gain value for my camera, so this will allow me to correct that mistake!
Merry Christmas, Cuiv, and thanks for another great video. Interesting to see how different manufacturers using the same sensors, apply their firmware/electronics differently. In your Touptec camera, apparently 1 offset equals 1 ADU. For QHY this is 16 ADU, and for ZWO this is 40 ADU. So correct offset values between cameras differ a lot. Also, the Touptec apparently can report a ‘0’ value, whereas QHY and ZWO cameras report ‘1’ as the minimum value, or ‘4’ if it is a 14-bit camera.
Thanks a lot for this explanation! For my Touptek-based Omegon VeTec 751C and based on your video I found an interesting relationship between the gain and offset. No matter which gain I use, taking the same value for the offset - 8% works great (gain 100, offset 92; gain 316, offset 291; gain 2500, offset 2300). Though, I know that i.e. the gain of the ZWO cameras is calculated differenty, so this will probably not work for any camera
I love the work you do and your contribution to AP. I have a RASA11 and I am worried about doing a "tilt correction". Please consider a review of this factor and how to do the procedure.
Thanks Steve! Tilt is one of those things I have never had success with - and imo unless someone is using full frame and a Tak, it may not be worth the effort... Right now I'm definitely not qualified to make such a video unfortunately!
I remember this one time when I was trying to apply my calibration frames to my light frames with different offset values. I kept on getting error warnings from Siril , Astap or any other preprocessing software. I could not understand why until I figured that I was working with different offset values. Lesson learned after many hours of frustration. I wish I had my hands on this video back a few years from now! lol
Thanks Cuiv, finally a simple explanation along with a demonstration of contrast setting!
Happy Christmas Cuiv. Good explanation of this setting. I have been leaving the offset on my mono and OSC cameras at default settings as the images seem to be ok. Will try adjusting the offset the next time I get a clear night ( have only had three in the last two months )
Happy holidays! Have fun adjusting the offset!
I was just questioning what offset I should be using a few days ago. Thanks for the help Cuiv
No problem 👍
Merry Christmas. A real present for us. I’ve watched a lot of videos and read a lot of literature and this has not come up before. Thanks for this, looks like an important setting usually overlooked.
Thanks, and Merry Christmas!
Thank you Cuiv, it's good to have this valuable nugget of information. It's been ages now watching rain drops UK running down my windows. clear skies are rare as rocking horse poo💩💩.. So applying tips etc has now become more interesting than taking the light frames!!! 😂😂 Happy day & new year, thank you for all you do.. Atb Tom dull wet UK....
Hope you get clear skies soon!
Well Cuiv, if there was no way to prove you were the Lazy geek before or even convince some of us, this has done it! I did wonder why my astronomy photos didn’t have any stars.
Very helpful. A project for one day this week. Seasons greeting to you and your family.
I don’t know which is worse , you posting a video on Christmas morning or me watching it ! LOL . Merry Christmas Cuiv .
They're both fine haha 😂
I was told by experienced astro photographer that it needs to stay ( gain ) at factory level which is 48, so now you presenting the new ( it isn't new, is it ) idea about offset. I'll get it tested for sure, thanks.
For ZWO that offset may indeed be good enough :)
I forgot to ad that my camera is Altair 269C, I will test it anyway, I love your work and getting your tips and tricks implemented into my circumstances. @@CuivTheLazyGeek
Great video, very informative. I use Sharpcap and I will go back and take a look at the offset. Happy New Year!
Cheers Rick!
Hi there Geek. I recently bought the Altair Astro version (AA26C) and use Indi/Ekos + altair driver. My understanding is that when taking short exposure darks (BIAS frame) the histogram should not get cut off on the left. I think I saw this on a Sharpcap forum.
In Indi oontrols my camera settings are Conversion Gain = High. High Full Well Mode = off. Low Noise Mode = off. Gain=100, Offset=50, exp=.001.
The histogram using indi looks fine. Peak at 50, drops to zero below 25 and above 75.
In NINA I get the Ultra Mode option same as you which up to now I had set to off.
12000 clipped pixels is microscopic compared to 24Million pixel on the sensor (5 parts in ten thousand).
Not sure this makes that much difference for this camera, but great that you explain how to measure things.
Should I be using Ultra Mode (NINA) / Low Noise Mode (indi) ? Confusing camera.
This was a very helpful video - thanks! There was one aspect that initially confused me, however. Clearly simply adding a constant uniformly to an entire set of data cannot increase the amount of information; it simply resets the zero point. I'm guessing then that what is really happening is that the camera performs some kind of internal mapping from the raw data to the stored data, and the offset is applied to the _raw_ data before that mapping, so that pixels with low counts don't get mapped to zero, i.e. clipped. Applying it to the stored data would not help in that way.
While I understood what it was doing, I never knew where to set it.
Thanks!
Merry Christmas / Happy New Year.
Glad I could help!
Cheeky! Thank you for this info! I just got a ASI585MC PRO and was not getting enough light at 252 gain and even 120 sec. NINA has a default offset of 125. I didn’t know what it was and how to set it. Too bad it’s 10 degree Fahrenheit at night.
Another great video Cuiv and one that is sorely needed in the astroimaging community! Happy Holidays and Clear Skies in 2024!
Happy holidays!
Merry Christmas Quiv! You’ve solved yet another mystery setting for me - so invaluable - many thanks!
Happy holidays! Glad to help!
Nice video, and well done. Yes, everything in the video is correct. I've given the same advice to people before when they asked how to adjust the camera offset. But this is the first video I've seen on the topic (at least that I've seen). Thanks Cuiv. This video should prove quite useful to a lot of people.
Thanks Mark!
This is a nice Christmas present! Thanks for helping me understand the offset! 🎄😁👍✨🎶
Happy to help! And Merry Christmas!
Merry Christmas! Yes, a lot of people afraid to use a high offset, somehow the loss of dynamic range scares people I guess, but seeing images from people their loss of DR is more contributed to incorrect processing and I'm guilty of that too. I would say on average; without careful image editing; people ruin their DR in their image by cutting as much as many thousands of ADU steps, compared to a few hundreds that a higher offset would do. The loss of DR with the offset just irrelevant and minuscule, compared to wrong image editing habits. I just follow how ZWO set it in Asiair, (offset 75 for zwo cameras) and seeing how that's like almost halfway up on the offset scale, I imitate it to do similar with my non-zwo cameras and I am perfectly fine losing a few hundred or even a 1000 DR steps due to high offset. Otherwise Pixinsight will report me that it had to do a "huge pedestal" correction when processing and that lets me know that I did use the wrong offset.
So many light bulb moments in this video. Thank you so much.
Now how do you remove clouds from your imaging 😁
TO remove clouds, you can join my Patreon, guaranteed to work!(not) :D
Great video! I guess it is time to go through all of my cameras and check this in NINA.
Thanks, that is a really useful nugget on a function I never truly understood.
Big thanks, the clip helped me a lot with my Christmas gift, a cooled Touptek with the IMX 585 chip.
Super glad this is helpful! What gain and offset did you end up at? And thanks for your support!
@@CuivTheLazyGeek I was quite astonished. At gain 100 I ended up with an offset of 192 in LCG and 426 in HCG. Sorry for the late answer, Cuiv.
Merry Christmas to you and yours, and thank you for being such a wonderfully enthusiastic lazy geek. May clear skies follow you to wherever you may roam.
Same to you!
Thank you Cuiv! I had heard of offset and pedestal, but didn't know what to do. Happy New Year!
Happy new year!
Merry Christmas Cuiv! Thank you for all the great information you share with us!
Happy holidays!
Super informative video Quiv, very understandable explained, thank you for all those great videos you made during the past years.
Wishing you and your family happy holidays
Great video Cuiv helps a lot on this aspect of imaging .
Merry Christmas Cuiv! - I've learned alot from you over the year. Thanks for doing what you do!
Happy holidays!
Merry Christmas Cuiv
Thank you for this
Hope you get some r&r don’t bun out!
Best wishes
Thanks Bryan, merry Christmas to you too!
Interesting. Would like to see what the master lights look like at various offsets and how one setting might produce a better end result over the others. In PixInsight, you can set a minimum pedestal value during WBPP, which I'm not sure yields the same outcome.
Good post! It would be interesting to statistically compare images of a bright source, a glowing nebula, with offsets of double or triple the 151 and see if there is any deterioration of image quality. Dynamic range is important, but I don't see how sacrificing even up to 1% of dynamic range would make any difference in the final image quality. If you are clipping the brightest stars, it shouldn't matter since most people end up reducing the number of stars and their brightness in the final image.
Very helpful. I'm new in this hobby and saw many videos on these topics. But the offset was a miracle. Thanks so much.
Glad it was helpful!
Merry Christmas. An excellent video as offset seems to be quite a mysterious topic out on the net and on the forums with a whole range of settings being offered without any real explanation as to why that number was settled on. Your video gives a nice explanation of how to calculate it with meaning. Thanks again and wishing you a great 2024 (hope we see some more paragliding videos too).
Glad it is helpful! Merry Christmas!
Thanks for pointing this out. Was always eager to fiddle with the offset. However when counting pixels with the minimum ADU I'm thinking now about dead pixels of the sensors falsifying statistics and so even higher offsets might be feasible 🤔 but I don't know at the end the offset just makes a small difference with regard to whole dynamic range I guess
Exactly, very small diff in dynamic range
Great video, thanks! I'm trying to get this right on my Altair 269C TEC, the range is a lot smaller 0-462 and NINA set the default to 16. Setting it higher, the Mean and Median go far too off and the difference is more than 1000, so it might have to do that it is a dual mode camera, or just a driver thing. Maybe I'll give SharpCap calibration a test, to see what values it shows.
Love your channel and I can see how Japan has formed your kindness! ありがとう ございます
Thanks, Cuiv now I know how to check the offset. My ZWO ASI2600MC Duo default offset is also 50 but this gives the histogram Mean and Median values near 500. For any offset the Mean and Median histogram values near 10X the offset.
UPDATE Looking at the fits header, NINA is added 50 as the offset not the 500 being added my ZWO.
Yep seems this is how ZWO have defined their offset!
Hi @CuivTheLazyGeek. First sorry for my English… 🇫🇷 your offset at the end still appears too low, you didn't take in account, that bias (also dark) will be substracted from your light, which means your light histogram will be shifted back to the the left. I have the same camera, after researches and tests, I set my offset to 768 and activate the high full well mode. I double checked under SiriL , which has a much better histogram than Nina, and got something comparable to zwo cameras with their default offset under asiair. In addition, I kept an older version of the risingcam driver and SDK (February 22) cause the next ones are buggy with short exposure and they made flat frames unusable. Greetings from France
Thanks for the feedback! The ZWO cameras afaik use offset 50 (which is really 500 ADU). For the light frames, I think PixInsight can add a Pedestal prior to bias calibration, so the issue you mention isn't hit, I will need to check though!
@@CuivTheLazyGeek yes I know for zwo cam, I compared histogram from zwo cam with zwo offset and try to reach the same histogram with the risingcam. I had good results for the few times I could try (very long bad weather for me)
Anyway thanks for your reply, hope to see the following of your investigation soon, in order to improve my settings 😉
Finding the correct offset was always a thing for old-school QHY CCD cameras before finding the correct gain - something lost in the mists of time I guess. From my understanding set it once and never touch it again - I check offset/gain values every couple of years and they haven't moved.
Excellent video and content Cuiv, appreciate the time and information. Cheers!
Tanhsk a lot for the simple explaination Cuiv !
Very helpful! Thanks Cuiv, I’ll admit I did not fully understand this before.
Glad it's helpful!
Cuiv,
Interesting Video. However, I have an issue.
The video seems to be a some what comparison between the ZWO-ASI2600mm and the Touptek/RisingCam 2600mono camera as they both use the following sensor: SONY IMX571 CMOS.
Accordingly, they supplied information on the specifications of the camera, for the vendor to select functions that they wish to pass on to the consumer.
It appears that ZWO seem to have gone out of their way to make it easier for the consumer in calculating the optimum gain and offset, known as 'Unity Gain'.
Also allowing the user to have the ability to select a manual option and set values of their choosing.
All good so far.
So here is my issue. You have a Touptek camera and set your 'Gain' to 100 (101),'Offset' to be 151. Using the short Bias exposure to calculate values for the 'Min (0)' and 'Max (65536)' Pixel values.
I don't see a problem with this, other than the values you have defined as correct for your camera. It appears to me that you are using the ZWO 'Unity Gain 100' as the starting point gain for the Touptek camera.
I know the Touptek Min gain is 100, which is just a coincidence compared to the ZWO 100 optimum gain.
So my point is this.
Taking that ZWO has calculated the 'Unity Gain' correctly, and we can probably assume they have, and we need a comparison of the two, as Touptek, as I know, does not supply a unity gain value, then the following
formula would need to be applied.
The ZWO has a gain value of 0 to 450. The Touptek has a gain value of 100 to 10,000. Note: Values under 100 cannot be selected.
So, if one needs to take a direct comparison between the two cameras to find the gain for the Touptek, the following calculation would need to apply.
Touptek's max gain is 10,000. We would divide this with ZWO's max gain of 450. This would give a value of 22.2222. We would multiply 22.222 by ZWO's Unity Gain of 100, and would give a value of 2222.
This value would be equivalent to the ZWO Unity Gain of 100. So the unity gain for the Touptek would be 2222.
Formula:
10000/450=22.2222
22.2222x100=2222
Touptek max Offset is 7936. We would divide this with ZWO's max Offset 240. This would give a value of 33.06. We would multiply 33.06 by ZWO's Unity Offset of 75, and would give a value of 2479.
This value would be equivalent to the ZWO Unity Offset of 75. So the unity offset for the Touptek would be 2479.
Formula:
7936/240=33.06
33.06x75=2479
UNITY GAIN
ZWO
GAIN 0 100 450
Touptek
GAIN 100 2222 10000
UNITY OFFSET
ZWO
Offset 0 75 240
Touptek 0 2479 7936
I have ignored LCG, HCG etc. as we are only finding a comparison unity between the ZWO and Touptek.
I have always used the above gain at 120s for my Touptek/RisingCam camera as I found 100 did not work too well even with the above activated.
I am not all that concerned about a few black pixels or over bright ones, as this depends on the target anyway.
I am in a high bortle zone 7 and getting worse.
So what is your opinion? Is it that we have been used to values of ZWO and think these values also apply to all other cameras, such as Touptek.
------------
Merry Christmas, Cuiv! Thank you for your videos!
Merry Christmas!
How hard would it be for manufacturers to put a black line on the outside of the camera to mark the front of sensor ?
That would just be too convenient!
Wonderful. Thank you so much🙏😘
Does it mean,that I I set the perfect off set, than I don't have to run a cosmetic correction for cold pixels?
Great tutorial as always. Question. I may have missed this but you said you dont use dark frames anymore. Do you have a video, you can share, showing why?
Dude... this video, and your channel as a whole, is SO informative and straightforward. I sincerely appreciate your demonstration of each step you take and what it all means and why you do different things. One question I have... you mentioned that you don't use dark frames any more. Can I ask why? I am new to astrophotography, but I thought dark frames were essential to getting the best images?
ZWO recommends a gain of 0 for my ASI6200MC when shooting DSO's. I can set my offset now to double that and pull out my clipped levels.
I followed this method on my ASI6200MC and determined the optimal offset is 15 at gain 0. My minimum pixel value on bias frames is 9 at those settings.
"...slightly better images at no cost..."😅 oh Cuiv you say the funniest things.
Aha… now the offset might be why my images looks pixelated when doing background extraction in Pixinsight. As some pixels turn absolutely black. 😮
Will experiment with the offset and hopefully get some clear whether to test in 2024.
But what does this mean for ASIAir users who do not have the option to adjust offset?
Awsome OFFSET explanation video! Thanks!
So helpful Cuiv. This was exactly what I needed right now. Thanks
Glad it helped!
Thanks for the tutorial !. So you set the offset high enough to avoid zeroes. Makes sense. Curious what then happens to the repeatability of pixels in dark frames and if that 'image' helps to characterize/process images. Is there a test object to help set gain also ?
thank you for this - how do I check the offset while using everything in the ZWO Eco System ? ASI Air , ASI 294MM Pro, etc.
Apparently not possible in the ASIAir, but ZWO sets a good offset value in the first place so you should be fine
I measure the sky brightness around my target with Sharpcaps smart histogram brain function. Assuming you have previously performed a sensor analysis ( only need to perform this once) Sharpcap with work out your offset, optimal gain, sub length, exposure etc. I mean how easy was that?
Super cool!
Here’s your comment you cheeky monkey! I always learn so much from you, and I truly appreciate your hard work.
Haha thank you!
Thanks for this video. I'm also using an IMX 571 camera (QHY 268C). As you said the behavior will depend on the read mode and gain, but will the values be dependent on sensor temp too?
In theory it shouldn't depend on temp, but if you use different temps, better to check!
Hi Cuiv!
I've got an ASI6200MM that I use with an ASIAIR Plus (just replaced my old ASIAIR Pro with the Plus). Of course , you can't adjust the offset in the ASIAIR. I noticed on some data I just took that I had a lot of dead pixels on my Oiii and Sii Masters. Should I shoot new Darks and Flats...I use a library...since I got a new ASIAIR, or should I use a Pedestal in WBPP?? If I need to use a Pedestal, what value would you recommend??
Thanks!
Tom
If your biases have no dark pixels you're fine :) the ASIAIR automatically sets offset to a good value for the camera. If you see dark pixels in your stack but not in the bias frames then this was likely caused by bias or dark subtraction.
You can use a pedestal but you will need to test and see how high it needs to be for you!
By the way if you take your darks/bias with the camera attached to the scope, always take them in a dark room!
Thanks Cuiv!@@CuivTheLazyGeek
Excellent information. Love your videos, I learn something everytime I watch
Awesome, thank you!
Can you do like a test with some nerrowband filters?
Hey Cuiv, first of all Merry Christmas!!🎄 and thank you for all your great contents and advice. Perfect timing, just last night I was searching for this topic and then you came to the rescue 😀.
Glad to help!
Merry Christmas! Thank you so much for sharing your knowledge. ❤
Happy holidays!
Merry Christmas. I just bought the same camera you have and was in doubt as to how the gain and offset values should be set. Thank you for the clarification 😊🎅
Happy holidays! And glad to help :)
Thanks for the very useful present! Merry Christmas Cuiv!
My pleasure! Happy Holidays!
Not looking forward to trying to balance offset and gain against sub lengths and filling well capacity. Is there a way to do this in just nina? Do you have a video how to? :) Ive watched you video on optimum exposure times, ill watch it again ;)
Merry Christmas, thank you for all your great videos. Clear Skys
Happy holidays!
For Asi Air users, there seems to be no offset options - what do we do beyond making sure the histrogram is separated on the left?
And like you say in your video, be aware to always calibrate using the same offsets. Once you start experimenting with offset, a mistake is easily made. Therefore in WBPP in PixInsight, I always have Offset on as a grouping parameter. It has saved my bacon more than once…
Hi Cuiv! Great and informative video👍
I've just tried this metod with my asi533mc-p, at -10 C degrees, gain 100 and I've got the offset of 7 to be about right(with minimun of 80 and mean of 230). But is it okay that the calculated offset is so low for this type of sensor ?
Thank you Mr Lazy Geek and JOYEUX NOËL !!!
Joyeux Noël !
Not all cameras calculate the offset the same. My ASI2600mm used a default of 50 and that gives a mean bias of 500 ADU. I have it reduced to 30 and that gives 300 ADU.
Same with my ZWO ASI2600MC Duo. I sent an email to ZWO. This may be a driver issue.
@@bobbryant4410 There is no issue. Just use a Bias just like Cuiv did to see what ADU the offset gives you.
Interesting! Makes sense though! Thanks for letting us know
The issue I see is the histogram values are near 10X the offset value. ZWO may be doing things different, but it looks like be a software bug. I can set my offset to 18 and have zero dark pixels but then the histogram Mean and Median values are near 180. For now, I am leaving it at 50 since the histogram Min value 323 (2x).@@davidkennedy3050
Maybe a daft question, but where does one set the pedestal for the ToupCam camera? I use the ToupSky app when I image, rather than Nina - I find it easier to use than Nina, but I can't find a pedestal setting on the ToupCam programme. It does allow me to set the Black Point, which I suppose is a type of pedestal. Is that what should use?
I haven't used ToupSky, sorry...
@@CuivTheLazyGeek Many thanks.
Happy Christmas Cuiv and thanks as always:)
Happy holidays!
Amazing Esoteric Info, Cuiv! You are the bomb!
Hi Cuiv! As always, thank you for all your useful tips!
What would you do with an ASI294 MC-Pro and it's problems with inconsistent low exposure shots? Is this method viable to understand the correct offset or should I go up to 2+ seconds shots?
Regards!
Good point! While cooling to -10C or -15C, take a 3s exposure, it will be equivalent to a bias frame!
@@CuivTheLazyGeek thank you for the response! I've already tried both "bias" timings and "darkflat" timings and the difference is almost negligable for this test. To be sure I've used 3 seconds exposures and got a final value for my offset of 4 (in ZWO terms). The default value for the "unity gain" in the drivers is usually 6, so I'm surprised!
I've always used 30 offset and I wil ltry with 4 my next session! Thank you again Cuiv!
Hi , which is work for a 0.001s exposure time is also right for 300s ?
So for my IMX571 and IMX585 cameras I basically use the following with the sensor cooled to -10C
- 1s long bias frames (1s is pretty much the same as 0.0001s at that temperature)
- 1-2s flat frames
I use this to calibrate all my frames regardless of length and I don't bother with dark frames.