@@JoesAstrophoto thanks Joe, waiting for the OAG to arrive from Stateside, I live in UK and certain items just aren’t available for weeks & months. So glad you are putting tutorials out about the EDGE HD8… it’s a new area for me, only ever owned refractors.
Great tutorial on back-focus Joe. I am resetting my EdgeHD 11" on the newly repaired CGEM mount and plan to use my Celestron OAG ... so this is very helpful.
Thanks so much Russell, I'm glad it was helpful! When I first got my Edge 8, I had the hardest time trying to find information on backfocus and the different configurations.
@@JoesAstrophoto thanks Joe 👏 I can't wait to start using it, gotta grab a few things first 🤩 Planning on Moon photography over the light Swedish summer before some Deep Sky this autumn! I just love this hobby 😊👍
scrambling around in the box of adapters to come up with the correct combination to meet the needs... I got myself a couple of the Baader varilock adapters which are adjustable for tinkering.
Thanks Dave! Those varilocks are really cool and so very helpful. I have so many connectors I just never seem to have a problem finding one that is the perfect fit most of the time.
I got the OAG today, and it is missing the Prism, but it was enough to calculate my Train I have asi2600 17.5mm so removed everything and attached the OAG right to the filter wheel and ended up at 106, calculate in speed of light slowing down going through a Ha filter and I should be at 105 exactly. Thank you very much for the video seeing your gear helped much.
Well done Joe. Great job showing many of the different configurations and also mentioning that the filterwheel and filter drawer are the same size. I just connected the ASI2600MC to my Canon Lens and and was a little concerned since Canon lenses require 44mm of backspace and 2600 is set at 17.5 mm rather than the 6.5mm for the 1600. It ended up being no issue because 11mm spacer - Cheers
Thanks Kurt! That's good to know about the Canon lens as well because I've been thinking about getting those step down rings you have and trying out that astromechanics connector later this summer for some widefield.
Nicely done Joe! Well explained, back focus can be a pain, I had a problem originally with my Esprit and reducer/Flatner! Sorted it out in the end and I don’t have a filter wheel or oag! Clear skies Joe
Joe great video, i am still having problems with HD8 to achieve focus, your video verifies my right amount of focus space was right. However, I run out of focus travel in focuser knob, currently i am working with Celestron to see what type of solution they give me. Weather here in San Diego is rainy so i cannot try without the electronic focuser to see if i manually can get in focus. If You have any suggestion I will highly appreciate. I believe the focal length of the telescope is not right or something like primary mirror spacing not right. Thank you in advanced.
Thanks Juan! I’ve never run across that issue before. If you have the correct back focus and you are properly collimated, then there should be a lot of room on either side of the focus travel. Feel free to email me with your imaging train details and I can see go over them to see if I can think of anything. Also make sure your mirror lock is loosened. Hopefully Celestron can help and you don’t have a faulty scope.
Great video, Joe. Thanks so much. In the diagram you have denoting that the distance to the guide cam sensor and main camera sensor have to be the same, I'm not sure that where you have the furthest distance to the guide cam sensor is right. I think from what the ZWO site depicts, the 174mm Mini's sensor is 8.5 mm from the front edge of the guide cam. But, I could be wrong. Perhaps you drew this only as an illustration, or am I wrong about the position of the CMOS sensor's position on the 174MM mini? So, I'm curious about how you positioned the 174MM mini to get an approximate position. (My Edge HD 8 will be arriving in a few days and I'm trying to educate myself about all the pitfalls before it gets here. Seeing some of the troubles people have getting this scope set up for imaging is making me nervous!)
Thanks Greg! I just drew it as an illustration, sorry for any confusion. The easiest way for me, is to get a decent approximation at first by just looking at the PHD2 screen, then I get the scope in focus first. I do an autofocus with the Lum filter. Once I'm happy with that, I just slowly adjust the guide camera until I like what I see. It doesn't have to be dead on perfect, just as close as you can get it.
Very good video Joe, well explained and worth bookmarking to save me time scrounging around endless piles of adapters and manuals. Would be good if you can follow up with the 174mm setup, I've been playing catch 22 trying to find the optimal position for mine to really make use the larger sensor, it either vignettes too much or I can only use about 60% of the 174's sensor.
Thanks BBP! I never had an issue with the 174 vignetting. I just use my calipers and estimate the distance, from there I just loosen the set screws enough to make fine adjustments up or down and the focus ring on the OAG. I’ve read that you will get vignette with the 174 if using one of the older ZWO OAGs or a similar brand with the smaller prism. If using the Celestron or new larger prism ZWO OAG, you shouldn’t have issues. Feel free to email me and I’ll do my best to help you out (email in about tab of the channel)
I appreciate your time to make this video, I just ordered my Edge HD 800, I noticed when you measure the distance from prism that the sensor is much further forward in the camera than in the photo, Did I miss understand not only am I moving to a SC Tube I'm also diving in to OAG and trying to learn as much as possible.
Thanks Dudley and congrats on your new scope! My overlay on the guiding camera may have been a little long, but it was more for a visual aid to help get a picture of have equal distance between the guide camera and the imaging camera. It’s just a rough starting point. The best way to go is to get a solid focus on your imaging camera first. Then adjust the guiding camera to an acceptable focus afterwards. Hope that helps and sorry for any confusion.
Thanks John! You will get a slight vignette with the reducer and the 2600 but it calibrates out with flats. May want to consider a 9.25 as the image circle with the reducer is larger if the vignette will be an issue. I prefer to use the 4/3 sensor of the 294 in bin2 mode with my EdgeHD 8 with the reducer myself.
Very informative video, thank you. This is a must see if you own this gear. I have the same parts except that I have the moonlite low profile focuser which greatly complicates things with reaching back focus. I must say I love the Celestron OAG but man it's bulky. Again, awesome content!
Thanks so much Joel! I’m guessing you can’t use the Celestron OAG with your moonlight focuser due to running out of backspace, but you get to lock the mirrors and probably have a much easier time with autofocus as well. You’re right, it takes up the majority of space in the system by far.
I have the 2600MM and filterwheel on my GT81. The EdgeHD 8 has the ASI294MC Pro. Or should I say "had", because I have sent the 294 back to the shop for repairs (video on that will follow). What do you think Joe (perhaps you've seen my "Lord Of The Rigs" video), should I bolt my 2600MM directly to the filterwheel, or should I keep using the rotator that you see me use in the video?
Hey Martin, I haven't seen your latest video, but will go watch it now. I need to set my notifications for all the channels I follow as I wait for the little blue dots to show up to tell if there is a new video and sometimes they don't show up. In theory, the closer your sensor is to your filters, the less vignette you should have, but if you don't have any vignette with it screwed on, I don't think bolting it on will make a whole lot of difference anyway.
I am new in this hobby and your video is great. could you be so kind and let me know what SCT adapter do you use? I have the same set up but can not find 25 mm adapter.thanks krzy
Thanks K! All my SCT adapters came with the Celestron OAG. If you have a different OAG, you may need to order some adapters to make it work. If you have the Celestron OAG, it should be in your box that the OAG came with. Hope that helps!
Hi Joe… still waiting for First Light with my EDGE HD 8” here in UK (weather has been terrible for Astro for weeks now😐) I have a question about using the 2600mm Pro with this scope. I currently have it as main camera and a 174mm in the Celestron OAG focussed up and ready to image. I’ve used exactly your image train giving 106.3mm with the main camera tilt plate installed. I have an option to take off the tilt plate and put in a 4mm spacer to bring the backfocus down to 105.3mm (I can’t remove the 2mm ring as I’m using a 2” EFW and it has to be there)… Have you found much difference between using a backfocus of 106.3mm and 105.3mm❓ The reason I ask is because with my image train at 106.3mm it’s a straight swap back to my Esprit 100ed which shares this camera. I suppose I’m asking how tolerant the 8” EDGE is to being away from exact backfocus. Thanks for your time👍🏻
Thanks Olly! I don’t think you’ll have a problem at 106, but of course you’ll have to test. You are going to have a little vignette with the 2600 and reducer, but flats should take care of it. That being said, if you end up cropping a bit, then any very slight back focus issues may not matter.
@@JoesAstrophoto Hi Joe, thanks for getting back, much appreciated… I read further in your comments after posting this question that filters need to be taken into account… I’m on Optolong 3nm which are 2mm thick so I reckon 106.3mm must be pretty much spot on… I’m hoping the 2600mm Pro will give me good results, otherwise I’ll be heading down the Astrophotography Cash Rabbit Hole again 😱
@@JoesAstrophoto Hi Joe… First Light with EDGE HD8 using your backfocus was a spectacular success with the 2600mm Pro, no vignetting… probably because I’m using 48mm tubes throughout. Guiding at 0.3-0.4 with the Celestron OAG and 174mm Mini… So happy… Ha images of PacMan were so nice, thanks again 👍🏻
Hi Chris, I'm really liking them a lot! I can't say enough good things about them so far. At half the price of Astrodon and Chroma, they are amazing for the money. I have been mostly using LRGB though, I'm switching camera with scope tomorrow and starting to test on nebulae again with narrowband so I'll have more data soon, but so far so good!
@@chriscausseaux4793 None that I can really see. I think it will depend on your scope though. For example with my reducer on the EdgeHD 8, I'll get some but it's because of the image circle being too small form the reducer and not the filters. When I'm not using the reducer I don't have any vignette at all, but that's at f10 as well. I'm not sure if faster systems will show any or not.
Hi Ron, I do not get any vignette with that combination. The only reason to get larger filters with the 294 is if you plan on upgrading to a larger sensor in the future. I’m not sure why you are being told you need 2” filters as even my 2600 works just fine with 36mm filters. Hope that helps.
@@JoesAstrophoto A certain vendor told me I must go with 2". Didn't make sense to me with what Astronomy Tools was calculating and your experience confirms it! Thanks for your great videos!
Hey Joe... you didn't include the change in back focus because of the filters you've got in there. You need to add 0.33mm of back focus for every 1mm of filter glass thickness. So, with my 3mm thick Chroma filters, I need to add 1mm of back focus distance. In other words, in my setup of 8" EdgeHD with the 0.7x reducer, I need 106mm of back focus. Second, unless your 174MM Mini is much different than mine, the sensor is not where you drew the graphic to :). You're absolutely right, about the need for both the guide camera sensor and the main imaging camera sensor to be equidistant from the OAG pick off prism.
Thanks Jonny, you are absolutely correct. I just didn’t add them in because it doesn’t really affect my setup, but I should’ve talked about it. I’m also assuming that most people have 1mm shim rings to add if they find they need to add that extra little bit but I forgot to mention that as well. My drawing was just a visualization to get the point across. I wasn’t going for dead on balls accurate of where the sensor is, but thanks for noticing lol :P
@@JoesAstrophoto PERFECT! Thank you so much for the response. I've been wanting a set up like this for a while and just took the plunge and ordered it all at once. lol However, as all things astrophotography, before it gets here, I have to get another mount. I'm currently using the iOptron GEM28, 26lbs would be pushing that mount too far I believe. I'm torn between the AM5 and iOptron CEM40 for this setup.
Hi Joe. What are your guide stars looking like with the reducer on? I just switched from imaging at F/10 to using the reducer and my guide stars went from round to UFO shaped. Just wondering if the backfocus distance is affecting it. The stars in the main camera image are fairly round at the edges, but I just find the guiding better on a round star rather than an elongated one. Cheers, Jason
Thanks Jason! My stars are round in either configuration. I will only get the UFO stars in my guiding camera when I'm not equally distanced between my imaging and guiding cameras or I'm out of collimation on the SCT.
Hi Joe. Do you have a Pegasus 54mm Male to 42 mm Male adapter between the 11.55 medium spacer and the Filter wheel? That adds about 1.8mm and my net result is closer 107 mm end to end(instead of 105mm). I have a ZWO 294 and 0.7 reducer. Also the SCT Adapter is 32 mm but 6 mm is taken off this when you screw it in, so I have about 26 mm for the SCT adapter. I have not been able to get great focus yet. Not sure if this is why???
Hi Jim, I was using the adapter that came with the camera, it’s 2mm I believe. I don’t think 107mm should cause you much issues. I’ve ran it out as far as 108mm with no issues. I would check collimation. I’ve noticed that when focusing out to do collimation it’s correct. I’ve tried focusing in to collimate and that causes me problems. I hope that makes sense and helps.
Thanks Joe. I have a question though. I was under the impression that the backfocus of the Edge HD SCTs with the 0.7 reducer require a backfocus of 146mm? Isn’t the 105mm backfocus requirement for the regular NON Edge Celestron SCTs using the 0.63 reducer? Please correct me if I’m wrong?
Thanks Osama! You are not wrong for the EdgeHD 9.25, 11, and 14. they use the same backspacing with and without the reducer of 146.05mm. The EdgeHD 8 is the odd scope out of the bunch with a backspacing of 133.35mm without the reducer and 105mm with the reducer. Hope that helps.
@@JoesAstrophoto thanks Joe. Yes, got it. Just for sake of completion, do you know what the backfocus is for the 0.63 reducer on the non Edge SCTs? Is it also 105?
The 8" EdgeHD with the 0.7x reducer has a 105mm back focus requirement. Edit: appears Joe sent his response as I was typing mine. Sorry for the redundant post!
The .63 reducer is not compatible with the Edge 8, it's for the c8 because it has a corrector built in. If you use it, you will over correct the star field. I don't know the backspacing on .63 with normal c8 either, sorry.
I think so Glenn. I have not used one myself, but I know people who have and they really like the larger prism and that’s why I got the Celestron because at the time it was the only one with a large prism. If you go that route, you’ll need to add some other spacers though, because it is shorter in length than the Celestron.
Joe , ok now I am confused , I always had a problem with back focus (like everyone else) .... This is what was told to me... If you do not use a reducer or flattener you dont have to worry about back focus , so now I dont worry.....
Hey Steve, not sure who told you that, but I'm sorry to say you were told wrong. Check out this link, it's Celestron's white paper on the EdgeHD. It clearly states on page 13 that the optimal back focus of the EdgeHD 800 is 133.35mm at f/10. Hope that helps out. s3.amazonaws.com/celestron-site-support-files/support_files/edgehd_whitepaper_final.pdf
Oh, I thought your Edge was an 11”! I think the Edge HD 8” + 0.7 reducer is similar to non edge Celestron SCTs in requiring only 105mm backfocus. It’s the 11” Edge HD that needs 146mm, not the Edge 8!
Joe, you are making some of the best videos on UA-cam. Your detailed explanations are a great help. Thanks so much.
Wow Marvin, thanks so much for the kind words! I’m glad they are being helpful.
Edge HD 800, Celestron OAG, 2” EFW and 2600mm Pro is my new build in progress so I can’t thank you enough for doing this Joe… excellent 😀👍🏻⭐️⭐️⭐️⭐️⭐️
Congrats on your new setup Olly!
@@JoesAstrophoto thanks Joe, waiting for the OAG to arrive from Stateside, I live in UK and certain items just aren’t available for weeks & months. So glad you are putting tutorials out about the EDGE HD8… it’s a new area for me, only ever owned refractors.
Excellent presentation Joe and very timely since I just received my EdgeHD 8. Much appreciated. 👍
Thanks Bill, much appreciated! Congrats on the new scope, I’ll have to check out your video on it.
Nice workflow Joe!
Thanks Avanteesh! Much appreciated!
Great video Joe, explained and demonstrated really well.
Thank you Glenn!
Great tutorial on back-focus Joe. I am resetting my EdgeHD 11" on the newly repaired CGEM mount and plan to use my Celestron OAG ... so this is very helpful.
Thanks so much Pat! I’m glad you got your mounts repaired as well. Looking forward to seeing your work with them.
Brilliant video mate, very clear and really helpful. I am sure loads of people will find this useful! Thanks for putting it together 👍
Thanks so much Russell, I'm glad it was helpful! When I first got my Edge 8, I had the hardest time trying to find information on backfocus and the different configurations.
Thank you so much for this video Joe 👏Got my EdgeHD 800 yesterday! Super useful 👍
Thanks Scott, I'm glad it's helpful and congrats on the new scope!
@@JoesAstrophoto thanks Joe 👏 I can't wait to start using it, gotta grab a few things first 🤩 Planning on Moon photography over the light Swedish summer before some Deep Sky this autumn! I just love this hobby 😊👍
The joys of back focus!
scrambling around in the box of adapters to come up with the correct combination to meet the needs... I got myself a couple of the Baader varilock adapters which are adjustable for tinkering.
Thanks Dave! Those varilocks are really cool and so very helpful. I have so many connectors I just never seem to have a problem finding one that is the perfect fit most of the time.
Excellent video Joe. So useful to see an OAG setup up close with all the measurements provided as setting up OAGs can be a nightmare to work out.
Thanks so much Logan, much appreciated!
I got the OAG today, and it is missing the Prism, but it was enough to calculate my Train I have asi2600 17.5mm so removed everything and attached the OAG right to the filter wheel and ended up at 106, calculate in speed of light slowing down going through a Ha filter and I should be at 105 exactly. Thank you very much for the video seeing your gear helped much.
Thanks Dudley! Sorry to hear about the OAG issues though.
Best explanation, thank you!
Thank you, glad it was helpful!
Well done Joe. Great job showing many of the different configurations and also mentioning that the filterwheel and filter drawer are the same size. I just connected the ASI2600MC to my Canon Lens and and was a little concerned since Canon lenses require 44mm of backspace and 2600 is set at 17.5 mm rather than the 6.5mm for the 1600. It ended up being no issue because 11mm spacer - Cheers
Thanks Kurt! That's good to know about the Canon lens as well because I've been thinking about getting those step down rings you have and trying out that astromechanics connector later this summer for some widefield.
Great video and very useful info.
Thanks Jason!
Nicely done Joe! Well explained, back focus can be a pain, I had a problem originally with my Esprit and reducer/Flatner! Sorted it out in the end and I don’t have a filter wheel or oag!
Clear skies Joe
Thank you Simon! It took a long time to make that with all the annotations, so I appreciate it.
Joe great video, i am still having problems with HD8 to achieve focus, your video verifies my right amount of focus space was right. However, I run out of focus travel in focuser knob, currently i am working with Celestron to see what type of solution they give me. Weather here in San Diego is rainy so i cannot try without the electronic focuser to see if i manually can get in focus. If You have any suggestion I will highly appreciate. I believe the focal length of the telescope is not right or something like primary mirror spacing not right.
Thank you in advanced.
Thanks Juan! I’ve never run across that issue before. If you have the correct back focus and you are properly collimated, then there should be a lot of room on either side of the focus travel. Feel free to email me with your imaging train details and I can see go over them to see if I can think of anything. Also make sure your mirror lock is loosened. Hopefully Celestron can help and you don’t have a faulty scope.
Great video Joe. Very helpful :)
Thanks so much James!
Great video, Joe. Thanks so much. In the diagram you have denoting that the distance to the guide cam sensor and main camera sensor have to be the same, I'm not sure that where you have the furthest distance to the guide cam sensor is right. I think from what the ZWO site depicts, the 174mm Mini's sensor is 8.5 mm from the front edge of the guide cam. But, I could be wrong. Perhaps you drew this only as an illustration, or am I wrong about the position of the CMOS sensor's position on the 174MM mini? So, I'm curious about how you positioned the 174MM mini to get an approximate position. (My Edge HD 8 will be arriving in a few days and I'm trying to educate myself about all the pitfalls before it gets here. Seeing some of the troubles people have getting this scope set up for imaging is making me nervous!)
Thanks Greg! I just drew it as an illustration, sorry for any confusion. The easiest way for me, is to get a decent approximation at first by just looking at the PHD2 screen, then I get the scope in focus first. I do an autofocus with the Lum filter. Once I'm happy with that, I just slowly adjust the guide camera until I like what I see. It doesn't have to be dead on perfect, just as close as you can get it.
@@JoesAstrophoto Great! Thanks so much, Joe, and thanks for all the helpful videos. We appreciate the hard work you put in to helping us out!
Very good video Joe, well explained and worth bookmarking to save me time scrounging around endless piles of adapters and manuals. Would be good if you can follow up with the 174mm setup, I've been playing catch 22 trying to find the optimal position for mine to really make use the larger sensor, it either vignettes too much or I can only use about 60% of the 174's sensor.
Thanks BBP! I never had an issue with the 174 vignetting. I just use my calipers and estimate the distance, from there I just loosen the set screws enough to make fine adjustments up or down and the focus ring on the OAG. I’ve read that you will get vignette with the 174 if using one of the older ZWO OAGs or a similar brand with the smaller prism. If using the Celestron or new larger prism ZWO OAG, you shouldn’t have issues. Feel free to email me and I’ll do my best to help you out (email in about tab of the channel)
I appreciate your time to make this video, I just ordered my Edge HD 800, I noticed when you measure the distance from prism that the sensor is much further forward in the camera than in the photo, Did I miss understand not only am I moving to a SC Tube I'm also diving in to OAG and trying to learn as much as possible.
Thanks Dudley and congrats on your new scope! My overlay on the guiding camera may have been a little long, but it was more for a visual aid to help get a picture of have equal distance between the guide camera and the imaging camera. It’s just a rough starting point. The best way to go is to get a solid focus on your imaging camera first. Then adjust the guiding camera to an acceptable focus afterwards. Hope that helps and sorry for any confusion.
Hey Joe, great video! Looking to maybe get an EdgeHD 8 myself so I’m curious, how’s the imaging circle with the 0.7x reducer with the 2600MM?
Thanks John! You will get a slight vignette with the reducer and the 2600 but it calibrates out with flats. May want to consider a 9.25 as the image circle with the reducer is larger if the vignette will be an issue. I prefer to use the 4/3 sensor of the 294 in bin2 mode with my EdgeHD 8 with the reducer myself.
Thanks Joe, much appreciated feedback!
Very informative video, thank you. This is a must see if you own this gear. I have the same parts except that I have the moonlite low profile focuser which greatly complicates things with reaching back focus. I must say I love the Celestron OAG but man it's bulky. Again, awesome content!
Thanks so much Joel! I’m guessing you can’t use the Celestron OAG with your moonlight focuser due to running out of backspace, but you get to lock the mirrors and probably have a much easier time with autofocus as well. You’re right, it takes up the majority of space in the system by far.
Can you fit a linear focuser into the imaging chain?
Hi Lubo, it is possible, but not with the Celestron OAG. You’d have to use a much smaller OAG, like the older ZWO OAG.
I have the 2600MM and filterwheel on my GT81. The EdgeHD 8 has the ASI294MC Pro. Or should I say "had", because I have sent the 294 back to the shop for repairs (video on that will follow).
What do you think Joe (perhaps you've seen my "Lord Of The Rigs" video), should I bolt my 2600MM directly to the filterwheel, or should I keep using the rotator that you see me use in the video?
Hey Martin, I haven't seen your latest video, but will go watch it now. I need to set my notifications for all the channels I follow as I wait for the little blue dots to show up to tell if there is a new video and sometimes they don't show up. In theory, the closer your sensor is to your filters, the less vignette you should have, but if you don't have any vignette with it screwed on, I don't think bolting it on will make a whole lot of difference anyway.
I am new in this hobby and your video is great. could you be so kind and let me know what SCT adapter do you use? I have the same set up but can not find 25 mm adapter.thanks krzy
Thanks K! All my SCT adapters came with the Celestron OAG. If you have a different OAG, you may need to order some adapters to make it work. If you have the Celestron OAG, it should be in your box that the OAG came with. Hope that helps!
Hi Joe… still waiting for First Light with my EDGE HD 8” here in UK (weather has been terrible for Astro for weeks now😐) I have a question about using the 2600mm Pro with this scope. I currently have it as main camera and a 174mm in the Celestron OAG focussed up and ready to image. I’ve used exactly your image train giving 106.3mm with the main camera tilt plate installed. I have an option to take off the tilt plate and put in a 4mm spacer to bring the backfocus down to 105.3mm (I can’t remove the 2mm ring as I’m using a 2” EFW and it has to be there)…
Have you found much difference between using a backfocus of 106.3mm and 105.3mm❓ The reason I ask is because with my image train at 106.3mm it’s a straight swap back to my Esprit 100ed which shares this camera. I suppose I’m asking how tolerant the 8” EDGE is to being away from exact backfocus.
Thanks for your time👍🏻
Thanks Olly! I don’t think you’ll have a problem at 106, but of course you’ll have to test. You are going to have a little vignette with the 2600 and reducer, but flats should take care of it. That being said, if you end up cropping a bit, then any very slight back focus issues may not matter.
@@JoesAstrophoto Hi Joe, thanks for getting back, much appreciated… I read further in your comments after posting this question that filters need to be taken into account… I’m on Optolong 3nm which are 2mm thick so I reckon 106.3mm must be pretty much spot on… I’m hoping the 2600mm Pro will give me good results, otherwise I’ll be heading down the Astrophotography Cash Rabbit Hole again 😱
@@JoesAstrophoto Hi Joe… First Light with EDGE HD8 using your backfocus was a spectacular success with the 2600mm Pro, no vignetting… probably because I’m using 48mm tubes throughout. Guiding at 0.3-0.4 with the Celestron OAG and 174mm Mini… So happy… Ha images of PacMan were so nice, thanks again 👍🏻
@@olly7248 That's awesome Olly! Happy it worked out.
Curious, how’s the 36mm Antlia filters working with the 2600mm?
Hi Chris, I'm really liking them a lot! I can't say enough good things about them so far. At half the price of Astrodon and Chroma, they are amazing for the money. I have been mostly using LRGB though, I'm switching camera with scope tomorrow and starting to test on nebulae again with narrowband so I'll have more data soon, but so far so good!
@@JoesAstrophoto Any vignette experienced with the 2600 using the 36mm filters?
@@chriscausseaux4793 None that I can really see. I think it will depend on your scope though. For example with my reducer on the EdgeHD 8, I'll get some but it's because of the image circle being too small form the reducer and not the filters. When I'm not using the reducer I don't have any vignette at all, but that's at f10 as well. I'm not sure if faster systems will show any or not.
Joe, do you get any vignetting with the Edge8, Asi294 and your 1.25” filter wheel? Im being told to go with a 2” if I buy one.
Hi Ron, I do not get any vignette with that combination. The only reason to get larger filters with the 294 is if you plan on upgrading to a larger sensor in the future. I’m not sure why you are being told you need 2” filters as even my 2600 works just fine with 36mm filters. Hope that helps.
@@JoesAstrophoto A certain vendor told me I must go with 2". Didn't make sense to me with what Astronomy Tools was calculating and your experience confirms it! Thanks for your great videos!
Hey Joe... you didn't include the change in back focus because of the filters you've got in there. You need to add 0.33mm of back focus for every 1mm of filter glass thickness. So, with my 3mm thick Chroma filters, I need to add 1mm of back focus distance. In other words, in my setup of 8" EdgeHD with the 0.7x reducer, I need 106mm of back focus. Second, unless your 174MM Mini is much different than mine, the sensor is not where you drew the graphic to :). You're absolutely right, about the need for both the guide camera sensor and the main imaging camera sensor to be equidistant from the OAG pick off prism.
Thanks Jonny, you are absolutely correct. I just didn’t add them in because it doesn’t really affect my setup, but I should’ve talked about it. I’m also assuming that most people have 1mm shim rings to add if they find they need to add that extra little bit but I forgot to mention that as well. My drawing was just a visualization to get the point across. I wasn’t going for dead on balls accurate of where the sensor is, but thanks for noticing lol :P
I would love to know the total weight of this set up. (excluding the mount). I have almost the exact setup ordered.
Hi Terry, my setup comes in around 26lbs with everything including my little counter weight for DEC balancing.
@@JoesAstrophoto PERFECT! Thank you so much for the response. I've been wanting a set up like this for a while and just took the plunge and ordered it all at once. lol However, as all things astrophotography, before it gets here, I have to get another mount. I'm currently using the iOptron GEM28, 26lbs would be pushing that mount too far I believe. I'm torn between the AM5 and iOptron CEM40 for this setup.
Hi Joe. What are your guide stars looking like with the reducer on? I just switched from imaging at F/10 to using the reducer and my guide stars went from round to UFO shaped. Just wondering if the backfocus distance is affecting it. The stars in the main camera image are fairly round at the edges, but I just find the guiding better on a round star rather than an elongated one.
Cheers,
Jason
Thanks Jason! My stars are round in either configuration. I will only get the UFO stars in my guiding camera when I'm not equally distanced between my imaging and guiding cameras or I'm out of collimation on the SCT.
@@JoesAstrophoto thanks for the info. Good to have a baseline. Cheers.
Hi Joe. Do you have a Pegasus 54mm Male to 42 mm Male adapter between the 11.55 medium spacer and the Filter wheel? That adds about 1.8mm and my net result is closer 107 mm end to end(instead of 105mm). I have a ZWO 294 and 0.7 reducer. Also the SCT Adapter is 32 mm but 6 mm is taken off this when you screw it in, so I have about 26 mm for the SCT adapter. I have not been able to get great focus yet. Not sure if this is why???
Hi Jim, I was using the adapter that came with the camera, it’s 2mm I believe. I don’t think 107mm should cause you much issues. I’ve ran it out as far as 108mm with no issues. I would check collimation. I’ve noticed that when focusing out to do collimation it’s correct. I’ve tried focusing in to collimate and that causes me problems. I hope that makes sense and helps.
@@JoesAstrophoto Thanks. I ran out of time to try collimation. I'll give that a try next clear night!
Thanks Joe.
I have a question though.
I was under the impression that the backfocus of the Edge HD SCTs with the 0.7 reducer require a backfocus of 146mm?
Isn’t the 105mm backfocus requirement for the regular NON Edge Celestron SCTs using the 0.63 reducer?
Please correct me if I’m wrong?
Thanks Osama! You are not wrong for the EdgeHD 9.25, 11, and 14. they use the same backspacing with and without the reducer of 146.05mm. The EdgeHD 8 is the odd scope out of the bunch with a backspacing of 133.35mm without the reducer and 105mm with the reducer. Hope that helps.
@@JoesAstrophoto thanks Joe. Yes, got it.
Just for sake of completion, do you know what the backfocus is for the 0.63 reducer on the non Edge SCTs? Is it also 105?
The 8" EdgeHD with the 0.7x reducer has a 105mm back focus requirement.
Edit: appears Joe sent his response as I was typing mine. Sorry for the redundant post!
The .63 reducer is not compatible with the Edge 8, it's for the c8 because it has a corrector built in. If you use it, you will over correct the star field. I don't know the backspacing on .63 with normal c8 either, sorry.
Is the ZWO-OAG-L a good option?
I think so Glenn. I have not used one myself, but I know people who have and they really like the larger prism and that’s why I got the Celestron because at the time it was the only one with a large prism. If you go that route, you’ll need to add some other spacers though, because it is shorter in length than the Celestron.
Joe , ok now I am confused , I always had a problem with back focus (like everyone else) .... This is what was told to me... If you do not use a reducer or flattener you dont have to worry about back focus , so now I dont worry.....
Hey Steve, not sure who told you that, but I'm sorry to say you were told wrong. Check out this link, it's Celestron's white paper on the EdgeHD. It clearly states on page 13 that the optimal back focus of the EdgeHD 800 is 133.35mm at f/10. Hope that helps out. s3.amazonaws.com/celestron-site-support-files/support_files/edgehd_whitepaper_final.pdf
Oh, I thought your Edge was an 11”!
I think the Edge HD 8” + 0.7 reducer is similar to non edge Celestron SCTs in requiring only 105mm backfocus.
It’s the 11” Edge HD that needs 146mm, not the Edge 8!
Hahaha I was just replying when you were. I wish I had an 11 or even a 14 right about now with galaxy season upon us!