This is terrific! Thanks so much for all the hard work you must have put into this. If I'm understanding correctly, I will need to have taken some subframes of a target prior to using this calculator, correct? I wonder (but I have no idea how!) if it's possible to make the app entirely predictive, i.e., predictions about sub exposures before ever imaging a target, by using an actual skyglow value for a particular site as measured by an SQM meter or a light pollution map. Thank you once again for this calculator! Much appreciated.
Thank you! I wonder too if it could be automated. Thinking about it though it would be a pretty big task. You'd need to know aperture size, f-ratio, pixel size, brightness of the target... If I had enough data though with those variables, maybe I could do something like a statistical model to get a rough estimate! :)
Hi! I'm really happy to have found this channel-it’s helped me gain a fresh understanding of SNR and how to calculate the related data. I do have a couple of questions, though: 1.When calculating the GSO+SkyGlow and SkyGlow background, is there any specific requirement for the exposure time of the light frame? For instance, does it need to match the dark signal exposure or the main exposure duration? 2.If I want to see how different exposure times impact the number of subframes needed for the same SNR, should I actually take light frames at various exposure lengths, or can I just adjust the 'mult. exposure by _ time' setting? Thanks so much for making such an awesome and helpful video!
Thanks for the comment! To answer your questions: 1) The DSO+Skyglow and SkyGlow numbers should come from a light frame that has the same duration as the dark frame. And the exposure duration is what you put in for sub-exposure time. (Let me know if I misunderstood the question!) 2) You can get a theoretical estimate for the different exposure times with the "mult. exposure by _time" slider. I'm not 100% sure how accurate it is (I think it should get you in the right ballpark). You could also get a real measurement by putting in the numbers for the longer/shorter exposure time.
Extremely useful, thank you! The app shows me that to double my SNR, I need to do at least 4x the number of 5min subs I was doing! Now I know... :) PS - could you perhaps issue another Discord invite, the one below has expired. Keep up the great work!
Hi, thanks so much for making this app and explaining it so clearly! I tried it with my OSC + narrowband filter setup but I was running into trouble. I was wondering if any of the fields require special treatment if using an OSC camera and/or narrowband filters? Or perhaps if the app is just meant for mono?
@@deepskydetail Thanks. Handy tool for sure. My input numbers for my PlayerOne Poseidon-M and subs(measured with PixInsight's statistic process) were just so much lower i wasn't 100% sure I was using it properly (ha filter, DSO signal: 267, skyglow 151, 161 dark signal, 159 bias) but after putting everything in and my measured sensor info from sharp cap analysis it does seem to add up to fairly close to the SNRs i end up with from the number of frames I have.
What if you have something like a SeeStar S50, which doesn’t take some of those types of calibration frames? Where would we find this kind of information?
Tried out the app but something doesn't make sense. Just to try it out I used your default values with 15s exposure. The result was 1429 subs for 5.95 hours. Then I changed it to 30s and got 1429 (teh same) subs for 11.91 hours! All other inputs remained the same.
If you change the exposure time to 30s, the app will think your sub exposures are 30s long and will adjust things accordingly (5.95 x 2 = 11.9). To test a different sub-exposure time, you need to either input data from another sub frame that is 30 seconds long and use a comma (15, 30 in the sub exposure length box), or you can try the theoretical estimate using the slider called "Mult. exposure by __ times:"
I could tell this right after one frame is captured. If nothing is seen on initial frame, but there should be something there, then integration on this filter is 16+ hours.
Discord invite link: discord.gg/rXmvTT5P
This is terrific! Thanks so much for all the hard work you must have put into this. If I'm understanding correctly, I will need to have taken some subframes of a target prior to using this calculator, correct? I wonder (but I have no idea how!) if it's possible to make the app entirely predictive, i.e., predictions about sub exposures before ever imaging a target, by using an actual skyglow value for a particular site as measured by an SQM meter or a light pollution map. Thank you once again for this calculator! Much appreciated.
Thank you! I wonder too if it could be automated. Thinking about it though it would be a pretty big task. You'd need to know aperture size, f-ratio, pixel size, brightness of the target... If I had enough data though with those variables, maybe I could do something like a statistical model to get a rough estimate! :)
Hi! I'm really happy to have found this channel-it’s helped me gain a fresh understanding of SNR and how to calculate the related data. I do have a couple of questions, though:
1.When calculating the GSO+SkyGlow and SkyGlow background, is there any specific requirement for the exposure time of the light frame? For instance, does it need to match the dark signal exposure or the main exposure duration?
2.If I want to see how different exposure times impact the number of subframes needed for the same SNR, should I actually take light frames at various exposure lengths, or can I just adjust the 'mult. exposure by _ time' setting?
Thanks so much for making such an awesome and helpful video!
Thanks for the comment! To answer your questions:
1) The DSO+Skyglow and SkyGlow numbers should come from a light frame that has the same duration as the dark frame. And the exposure duration is what you put in for sub-exposure time. (Let me know if I misunderstood the question!)
2) You can get a theoretical estimate for the different exposure times with the "mult. exposure by _time" slider. I'm not 100% sure how accurate it is (I think it should get you in the right ballpark). You could also get a real measurement by putting in the numbers for the longer/shorter exposure time.
Extremely useful, thank you! The app shows me that to double my SNR, I need to do at least 4x the number of 5min subs I was doing! Now I know... :)
PS - could you perhaps issue another Discord invite, the one below has expired.
Keep up the great work!
Hi! Thanks for the comment! I'm glad the app works. Here is an invite link: discord.gg/zngSPdVG
Let me know if the link works.
@@deepskydetail worked 100%, thank you!
Hi, thanks so much for making this app and explaining it so clearly! I tried it with my OSC + narrowband filter setup but I was running into trouble. I was wondering if any of the fields require special treatment if using an OSC camera and/or narrowband filters? Or perhaps if the app is just meant for mono?
You can use it for OSC cameras too. I would just use the average brightness of the RGB channels (however you want to do it).
Nicely done original and update - thank you!
Thank you too!
Great enhancement Mark!
Thanks, Doug!
You help the community so much
Thank you! :)
Sorry if I missed it. Are these SNR values in db? I know the SNR scripts for PixInsight provide 2 numbers, one being larger and one being decibel.
Good question. They're in raw SNR, not decibels. :)
@@deepskydetail Thanks. Handy tool for sure. My input numbers for my PlayerOne Poseidon-M and subs(measured with PixInsight's statistic process) were just so much lower i wasn't 100% sure I was using it properly (ha filter, DSO signal: 267, skyglow 151, 161 dark signal, 159 bias) but after putting everything in and my measured sensor info from sharp cap analysis it does seem to add up to fairly close to the SNRs i end up with from the number of frames I have.
Thanks for the info! It's good to know things line up between the two tools :)
What if you have something like a SeeStar S50, which doesn’t take some of those types of calibration frames? Where would we find this kind of information?
I'm not 100% sure. Does the s50 calibrate the light frames automatically with dark and bias?
@@deepskydetail The seestar just takes dark frames and then calibrates the light frames for you as it live stacks
great updates friend!! Many thanks
Thank you!! :)
this begs the question, what is the SNR to aim for
You can check out this video I made on it :)
ua-cam.com/video/eRKk3lNyXO8/v-deo.html
Tried out the app but something doesn't make sense. Just to try it out I used your default values with 15s exposure. The result was 1429 subs for 5.95 hours. Then I changed it to 30s and got 1429 (teh same) subs for 11.91 hours! All other inputs remained the same.
If you change the exposure time to 30s, the app will think your sub exposures are 30s long and will adjust things accordingly (5.95 x 2 = 11.9). To test a different sub-exposure time, you need to either input data from another sub frame that is 30 seconds long and use a comma (15, 30 in the sub exposure length box), or you can try the theoretical estimate using the slider called "Mult. exposure by __ times:"
@@deepskydetail I'll try that!
I could tell this right after one frame is captured. If nothing is seen on initial frame, but there should be something there, then integration on this filter is 16+ hours.
Why dont you just use Sharpcaps brain function smart histogram? It measures the sky background etc.
Is the smart histogram part of the free version of sharpcap? Or the pro version?
@@deepskydetail Pro version £12 a year lol