Hello! Concerning your last question - I've just published a video (reviewed and fact checked by an optical engineer, and using optics simulation software) that can shed light on this. As I commented in a previous video, your diagram effectively shows light rays from a single on axis point (for instance from a star at center of FoV) that gets focused at the center of the field of view, so it can't be used to show any inversion of the image (a sensor in focus is placed exactly where the light rays cross). To show an inversion (or for that matter the forming of a focused image beyond a single dot on-axis), you'd need to add the light rays from a second star. I do that in the video, and while I don't specifically call out the inversion, you can see that for an off axis star above the center star, its image on the sensor is formed below the center star. With the light rays from both stars pictured, you can indeed see the light rays cross each other throughout the light path rather than all at a specific point. Hope this helps!
I'm rather familiar on the functioning of the Schmidt Cassegrain telescope (owning a Meade 10" LX200R) and have seen a few pictorial descriptions of them. This was very well presented, uniquely with the description of the secondary mirror acting as a Barlow. Great video!
Nice diagram and explanation of the optical design. My first telescope in 2018 was a vintage C8 from 1978. Definitely an excellent optical design, and I would certainly prefer it over an imaging Newtonian any day of the week. I also like how the corrector plate protects the primary mirror. Loved my C8, but eventually picked up a refractor (SW Esprit 100ED) because I grew weary of downtime any time I had to collimate in-between nights of inclement weather. Back then I didn't even have plate solving or auto-focus setup at all (just remote operation) so that also meant a lot of wasted crisp winter nights during weekdays. I'm having a good time imaging star clusters, and nebulae, but at some point I'd like to get another SCT since I kind-of chipped the edge of the secondary mirror during collimation. Speaking of which, I have taken apart that C8. If I find time to pop-off the corrector plate again, I'll be sure to take measurements. I might try to salvage the secondary mirror by covering the outer circumference with something dark but I'm not in a rush to do that. Bottom line, I do miss using an SCT at times. Visually, the Esprit actually does really well with planets. For imaging planets with any semblance resolution by way of angular-size, hands-down it goes to the C8.
It sounds like your C8 from the 70s had to be collimated a lot. Is that right? Celestron has upgraded the C8 design a lot over the years. I wonder if that was a problem with the original models. Please let me know if you ever take measurements of the interior distance between the primary and secondary mirrors.
I've had two refractors and like them both. I just never miss a chance to laugh about that myth that "real astrophotographers use refractors". That was pushed so hard a few years back, and the myth still makes its rounds though I think less so these days.
SCTs are definitely nice, compact and light. I can see the appeal of a refractor for its' ease of use and widefield photography but for everything else you need aperture, not to mention the chromatic aberration issues on anything but the most expensive ones that mirror telescopes don't have. I'd still argue you can't beat a Newtonian in terms of performance per dollar even if they are a bit finicky.
I gave a lot of thought to getting a Newtonian but there is so much pollen and spores in the air where I live in the backwoods of Canada. A closed design just makes more sense in my area. Otherwise, I would definitely have a Newt for wide field imaging.
@@SKYST0RY IT will take A LOT of dirt to affect your views on a Newtonian mirror. I mean significantly more than you think. And even in the worst case scenario, Newtonian mirror cleaning is a breeze.
My newtonian lives outside 24/7 in Northern Nevada (under a cover when not in use). We have plenty of dust that's for sure. But 2 years and counting... Still haven't felt the need to clean my mirror.
I own a 80 mm refractor, a 8“ f/5 newtonian and a 6“ classic cassegrain. Every telescope has strength and weaknesses. Since I changed the spider vanes against a cnc machined spider it has much cleaner diffraction spikes and collimation is much more stable. It is in my roll of roof observatory and only needs collimation every couple of months. The refractor is nice but if I could I‘d rather exchange it for a faster newtonian of the same focal length for imaging. The cassegrain on the other hand is a f/12 system and very nice for planetary work. I also tried imaging M42 once and it felt pretty nice but having a bigger and faster newtonian it can‘t quite compete.
I would love to be able to use a Newt but the woods where I live are too dusty. Hazes of pollen in the summer and spores in all but winter. A closed system telescope is much easier to keep clean. I like my 81 mm refractor and use it for wide field, but like you, I would definitely trade it for a Newt-like telescope if I could fine one that was a closed system. I know the RASA is an alternative, but I am not fond of the design.
The telescope design the pros are using is the RC (Ritchey-Chrétien) that has no glass plate in the front which makes it possible to make them very big. The corrections are build into the mirror design itself. They are also made in sizes for us deadlies :)
The RC scopes do have glass in the front. For the ones I’ve seen, that front glass element is just curved, so that they can do first surface mirror on the backside of that glass, and not have a separate physical component to provide the secondary mirror function. See en.wikipedia.org/wiki/Ritchey%E2%80%93Chr%C3%A9tien_telescope for more information.
Now, many larger RCTs have a spider like you would see in a Newtonian, to hold the secondary mirror. But smaller RCTs actually use a single piece of curved glass on the front.
@@shubinternet I think you are talking about the Maksutov-Cassegrain type. The glass element mentioned in the article is placed close to the focus point, so in the back of the scope near the camera.
With no experience with the RC scope, I can't make any meaningful comment on it other than I stick with closed designs because it is so dewy around here. And during the warm months, there is so much dust and spores. Keeping the optical system closed makes for faster cleaning.
Finally, someone else who agrees the refractor is definitely not the king ESPECIALLY for imaging. You cannot defy the laws of physics - larger aperture = more resolving power and light gathering, regardless of focal ratio. Btw, I have both a Celestron SCT and a Meade SCT - the Meade is definitely a nicer built instrument, but visually they're really really similar. I just want to mention, I have a newtonian as my primary deep sky imaging rig outside and have done for over a year and the collimation is still bang on. Collimation with newtonian telescopes is hugely depends on the construction. A CNC spider setup and good focuser is 95% of the issue with most newtonians. Really good video explaining the optics, presentation was fantastic.
I'd love to get a Newtonian to replace the refractor I use for wide field imaging, but with all the pollen and spore dust here in the backwoods, it's best to stick with closed system telescopes in these parts. I wish there was a Newt with a glass plate in front.
@@SKYST0RY I have the same issue, but use a newt anyway! I'm surrounded by fields and countryside, loads of pollen. You just have to make sure things are covered and you clean the primary mirror every few years. That said, you can always get a Mak-Newt. they're not common, but Skywatcher make the 190MN that is pretty solid. They have a corrector plate at the front like a Mak but with the mirror setup as a newt. No diffraction spikes from a spider and coma free optics :)
Nice video. In newons, cassegrains, refractors, the images of celestial objects don't invert on its way to focal point. It forms at the focal-point. And the secondary do the same as a barlow, but you did mention that.
SCTs when transported from place to place sometimes need just a bit of fine collimation to get really decent images. It isn't difficult to do that (often, when using stars for collimation, is easier to do than with a Newtonian), but it often has to be done. Some of the bad press the SCT often gets on higher power views may be due to the fact that some users may neglect doing that last bit of collimation alignment.
You're probably right. Some of the bad press is also legacy, I think, dating from days when guiding was more of a challenge. A decent mount these days, and a calibrated guiding app, give adequate guiding.
*Old* Meade scopes are nice. I have an old Meade 4500 that actually has a parabolic primary. Long length(F8) 4.5 scopes have since gone to sphericals; I found a newer Meade 4505 for $50 that I got for my nephew and was covered in plastic hardware and had highly disappointing image quality. You can definitely tell the difference in the primaries.
Your graphic explaining the function of an SCT was excellent for me. So, am I thinking right that a reducer / corrector for an SCT acts to narrow the beam of photons and concentrate the brightness -- thus lower "magnification" but yielding a brighter f stop for the same scope?
I really enjoyed this video. I have a NexStar 8SE as well (that appears to be what you have as a base). I have used it purely for optical observations. I got a Seestar S50 a few months back and it has really ignited an interest in Astrophotography for me. My next step is to get a used DSLR and a TRing and try some imaging with the stock 8SE Alt-Az mount. Don't know if I can afford a guided EQ mount quite yet :-) Any advice you have for me would be extremely cool. Thanks for helping this n00b out!
With the rising popularity of harmonic mounts, you can get a good equatorial mount at good prices these days. If you are not travelling and can leave it out, it's a good option. I heartily recommend the Sky-Watcher EQ6R. It has a great reputation and I get great results from it. I recommend you get a dedicated astro camera instead of a DSLR or mirrorless camera. I know the cheap pricing of a used camera can be tempting, but you will get far better results with a dedicated astro cam. The Player One Ares-C has a good pixel size match for the C8, or its counterpart from ZWO, the ASI533. One thing to bear in mind is ZWO is more user friendly, but Player One has legendarily good customer service.
@SKYST0RY I found mine on fb marketplace for a ludicrously low price, but it was completely dismantled, and many of the threaded bolt holes had been stripped. I spent the better part of a month getting the optics sorted out and screw holes properly rethreaded. Definitely worth it.
To my knowledge, very similarly. If memory serves, the main difference is they have a differently designed corrector plate, though the sub-aperture model has a concave secondary mirror.
I plan on buying a used C8 from Celestron around Christmas time and putting it on my AVX, but I got to looking and I think i’m going to go for the EdgeHD version of the C8, but i’ll have to sell my only wide field telescope, my EvoStar 72ED to get it. What do you think about this choice? I do have a few concerns about the EdgeHD and SCT’s in general. 1. Am I going to have any vignetting problems? I’m going to be using my Nikon D5300 but later upgrading to a dedicated astronomy camera. 2. Is focus going to drift when I slew and with temperature change? 3. Is dew going to be a big problem? Living here in Michigan, it can get pretty dewy and frosty. And 4. Is tracking and guiding going to be a problem with my AVX and could I upgrade to an OAG to solve that?
One thing to be aware of with the Edge is the optics seem to suffer more from the dew ring which is really essential if you live in a dewy area. I get only very slight dew ring abberations on the standard model. Warm nights are also very subject to dew here, so I have developed a three stage dew management technique that works 100% of the time. You can see the method here: ua-cam.com/video/93O6sN2KqAQ/v-deo.html 1. WIth a very large sensor you may get vignetting. I avoid large sensors to leave plenty of room for the OAG and to avoid the alignment problems that also come with large sensors. If you get vignetting, it can be corrected out with modern tools or you can just crop it. 2. Focus changes with all telescopes with temperature change. You will need an electronic focuser. I am using the Celestron EF on my C8, and it works flawlessly. 4. I have never used the AVX. Celestron mounts don't have a good reputation, sadly. Okay, but not great. I have my C8 mounted on a Sky-Watcher EQ6R which works great. On a night of good seeing, I can get guiding to 0.5.
Hi, brodymk45. I have the EdgeHD 800 on an AM5 mount guided by the Celestron OAG / ASI174 and imaging on an ASI2600MC-P. EAF focuser and ASIair Plus, too. With only four or five imaging sessions, it has proved to be fun and is producing some great images. I am waiting (along with the rest of the world) for the Celestron 0.70X reducer to come back in stock so I can try that combo, too. I found I had to adjust guide settings and guide cam exposures to get best results, but that is part of the adventure.
Cliff, I'm about to do first collimation on the EdgeHD 800 with an OAG and planning to use an AstroZap artificial star. Skies are hating me right now. Any specific thoughts regarding collimation with an artificial star? Is the angle at which the SCT rests critical? Bob
In my limited experience with collimating SCTs (limited because my present SCT is mounted in an observatory permanently, never gets moved so has never needed collimation), only collimate an SCT if you need it. If you start to see the stars going into oblong donuts when put a bit out of focus. A slight miscollimation is fine; don't get focused on making it utterly perfect. But SCTs are very stable reflectors. If not moved, they are unlikely to need much in the way of collimation, based on my own experience. Mine has been sitting on the mount a year now in the heat of summer and extreme cold of winter and the collimation looks as good as when I first put it there.
Schmidt are ok! I prefer my Mewlon = CDK. Pointing all that glass at the sky has consequences and is a little old fashioned.🙂 In light path optical correction is the way to go. Still it is the person using the tool rather than the tool itself that matters.
First he demotes Pixinsight. Now he promotes the SCT! Cliff is surely in line to be burned in Salem!!! Or in that even more ancient colony "Cloudy Nights". ;-) Just kidding. Thanks, Cliff.
I have a 190/1000 Maksutov-Newtonian. Jack-of-all-trades-master-of-none. I use it for Jupiter and Saturn (with a 3x Barlow) just as well as for M31, M42 and many other popular deep sky objects. The first and foremost condition to meet on behalf of any astrophotography task is not the telescope, but the mount. Beginners wine about which telescope they should buy. Veterans smirk and point to their mount.
It's all built around the mount, to be sure. Professional photographers soon learn technique is far more important than gear and leave the gear chase behind and focus on their methods. I saw a great video recently where a guy bought the cheapest, junkiest 4K camera he could find and filmed a very popular video with it to see if anyone would notice a difference between that video and his far more expensive camera. No one commented on any observable quality difference. Quality mostly is about technique, so long as one has a good mount and good sky. Fortunately, we're entering an age where good mounts are becoming very accessible, though, unfortunately, good skies are becoming rare.
Hello! Concerning your last question - I've just published a video (reviewed and fact checked by an optical engineer, and using optics simulation software) that can shed light on this.
As I commented in a previous video, your diagram effectively shows light rays from a single on axis point (for instance from a star at center of FoV) that gets focused at the center of the field of view, so it can't be used to show any inversion of the image (a sensor in focus is placed exactly where the light rays cross).
To show an inversion (or for that matter the forming of a focused image beyond a single dot on-axis), you'd need to add the light rays from a second star. I do that in the video, and while I don't specifically call out the inversion, you can see that for an off axis star above the center star, its image on the sensor is formed below the center star.
With the light rays from both stars pictured, you can indeed see the light rays cross each other throughout the light path rather than all at a specific point.
Hope this helps!
Weldone mate!
Forget the cosmos . . . You are the REAL STAR!
Many blessings dear friend,
Annika
🔮🍹🔭
Thank you, Annika.
I'm rather familiar on the functioning of the Schmidt Cassegrain telescope (owning a Meade 10" LX200R) and have seen a few pictorial descriptions of them. This was very well presented, uniquely with the description of the secondary mirror acting as a Barlow. Great video!
The Meade 10" was what I was considering for the second observatory. Such a shame the company went under.
Nice diagram and explanation of the optical design.
My first telescope in 2018 was a vintage C8 from 1978. Definitely an excellent optical design, and I would certainly prefer it over an imaging Newtonian any day of the week. I also like how the corrector plate protects the primary mirror. Loved my C8, but eventually picked up a refractor (SW Esprit 100ED) because I grew weary of downtime any time I had to collimate in-between nights of inclement weather. Back then I didn't even have plate solving or auto-focus setup at all (just remote operation) so that also meant a lot of wasted crisp winter nights during weekdays.
I'm having a good time imaging star clusters, and nebulae, but at some point I'd like to get another SCT since I kind-of chipped the edge of the secondary mirror during collimation. Speaking of which, I have taken apart that C8. If I find time to pop-off the corrector plate again, I'll be sure to take measurements. I might try to salvage the secondary mirror by covering the outer circumference with something dark but I'm not in a rush to do that.
Bottom line, I do miss using an SCT at times. Visually, the Esprit actually does really well with planets. For imaging planets with any semblance resolution by way of angular-size, hands-down it goes to the C8.
It sounds like your C8 from the 70s had to be collimated a lot. Is that right? Celestron has upgraded the C8 design a lot over the years. I wonder if that was a problem with the original models. Please let me know if you ever take measurements of the interior distance between the primary and secondary mirrors.
I love my Schmidt Cassegrain, but I do still love my refractor. :)
I've had two refractors and like them both. I just never miss a chance to laugh about that myth that "real astrophotographers use refractors". That was pushed so hard a few years back, and the myth still makes its rounds though I think less so these days.
SCTs are definitely nice, compact and light. I can see the appeal of a refractor for its' ease of use and widefield photography but for everything else you need aperture, not to mention the chromatic aberration issues on anything but the most expensive ones that mirror telescopes don't have. I'd still argue you can't beat a Newtonian in terms of performance per dollar even if they are a bit finicky.
I gave a lot of thought to getting a Newtonian but there is so much pollen and spores in the air where I live in the backwoods of Canada. A closed design just makes more sense in my area. Otherwise, I would definitely have a Newt for wide field imaging.
@@SKYST0RYit never even crossed my mind that pollen can impact the image quality, darn
@@SKYST0RY IT will take A LOT of dirt to affect your views on a Newtonian mirror. I mean significantly more than you think. And even in the worst case scenario, Newtonian mirror cleaning is a breeze.
My newtonian lives outside 24/7 in Northern Nevada (under a cover when not in use). We have plenty of dust that's for sure. But 2 years and counting... Still haven't felt the need to clean my mirror.
I had a meade etx125 for 20 years with perfect collimation. I moved to a celestron 6 sct with hyperstar and f6.3 reducer options. It's amazing!
I own a 80 mm refractor, a 8“ f/5 newtonian and a 6“ classic cassegrain. Every telescope has strength and weaknesses.
Since I changed the spider vanes against a cnc machined spider it has much cleaner diffraction spikes and collimation is much more stable. It is in my roll of roof observatory and only needs collimation every couple of months.
The refractor is nice but if I could I‘d rather exchange it for a faster newtonian of the same focal length for imaging.
The cassegrain on the other hand is a f/12 system and very nice for planetary work. I also tried imaging M42 once and it felt pretty nice but having a bigger and faster newtonian it can‘t quite compete.
I would love to be able to use a Newt but the woods where I live are too dusty. Hazes of pollen in the summer and spores in all but winter. A closed system telescope is much easier to keep clean. I like my 81 mm refractor and use it for wide field, but like you, I would definitely trade it for a Newt-like telescope if I could fine one that was a closed system. I know the RASA is an alternative, but I am not fond of the design.
The telescope design the pros are using is the RC (Ritchey-Chrétien) that has no glass plate in the front which makes it possible to make them very big. The corrections are build into the mirror design itself. They are also made in sizes for us deadlies :)
The RC scopes do have glass in the front. For the ones I’ve seen, that front glass element is just curved, so that they can do first surface mirror on the backside of that glass, and not have a separate physical component to provide the secondary mirror function. See en.wikipedia.org/wiki/Ritchey%E2%80%93Chr%C3%A9tien_telescope for more information.
Now, many larger RCTs have a spider like you would see in a Newtonian, to hold the secondary mirror. But smaller RCTs actually use a single piece of curved glass on the front.
@@shubinternet
I think you are talking about the Maksutov-Cassegrain type.
The glass element mentioned in the article is placed close to the focus point, so in the back of the scope near the camera.
With no experience with the RC scope, I can't make any meaningful comment on it other than I stick with closed designs because it is so dewy around here. And during the warm months, there is so much dust and spores. Keeping the optical system closed makes for faster cleaning.
Finally, someone else who agrees the refractor is definitely not the king ESPECIALLY for imaging. You cannot defy the laws of physics - larger aperture = more resolving power and light gathering, regardless of focal ratio. Btw, I have both a Celestron SCT and a Meade SCT - the Meade is definitely a nicer built instrument, but visually they're really really similar.
I just want to mention, I have a newtonian as my primary deep sky imaging rig outside and have done for over a year and the collimation is still bang on. Collimation with newtonian telescopes is hugely depends on the construction. A CNC spider setup and good focuser is 95% of the issue with most newtonians. Really good video explaining the optics, presentation was fantastic.
I'd love to get a Newtonian to replace the refractor I use for wide field imaging, but with all the pollen and spore dust here in the backwoods, it's best to stick with closed system telescopes in these parts. I wish there was a Newt with a glass plate in front.
@@SKYST0RY I have the same issue, but use a newt anyway! I'm surrounded by fields and countryside, loads of pollen. You just have to make sure things are covered and you clean the primary mirror every few years.
That said, you can always get a Mak-Newt. they're not common, but Skywatcher make the 190MN that is pretty solid. They have a corrector plate at the front like a Mak but with the mirror setup as a newt. No diffraction spikes from a spider and coma free optics :)
Nice video. In newons, cassegrains, refractors, the images of celestial objects don't invert on its way to focal point. It forms at the focal-point. And the secondary do the same as a barlow, but you did mention that.
SCTs when transported from place to place sometimes need just a bit of fine collimation to get really decent images. It isn't difficult to do that (often, when using stars for collimation, is easier to do than with a Newtonian), but it often has to be done. Some of the bad press the SCT often gets on higher power views may be due to the fact that some users may neglect doing that last bit of collimation alignment.
You're probably right. Some of the bad press is also legacy, I think, dating from days when guiding was more of a challenge. A decent mount these days, and a calibrated guiding app, give adequate guiding.
*Old* Meade scopes are nice. I have an old Meade 4500 that actually has a parabolic primary. Long length(F8) 4.5 scopes have since gone to sphericals; I found a newer Meade 4505 for $50 that I got for my nephew and was covered in plastic hardware and had highly disappointing image quality. You can definitely tell the difference in the primaries.
Top Gun -
Maverick "I was inverted"
"at what ranger?"
Maverick, "about 2 meters"
Maybe he was talking about SCT's
Top Gun - an astrophotographers reference guide :)
Your graphic explaining the function of an SCT was excellent for me. So, am I thinking right that a reducer / corrector for an SCT acts to narrow the beam of photons and concentrate the brightness -- thus lower "magnification" but yielding a brighter f stop for the same scope?
That's exactly correct. I did a video not long ago about what reducers do if you want to view it: ua-cam.com/video/aqBF1-RcoqY/v-deo.html
I really enjoyed this video. I have a NexStar 8SE as well (that appears to be what you have as a base). I have used it purely for optical observations. I got a Seestar S50 a few months back and it has really ignited an interest in Astrophotography for me. My next step is to get a used DSLR and a TRing and try some imaging with the stock 8SE Alt-Az mount. Don't know if I can afford a guided EQ mount quite yet :-) Any advice you have for me would be extremely cool. Thanks for helping this n00b out!
With the rising popularity of harmonic mounts, you can get a good equatorial mount at good prices these days. If you are not travelling and can leave it out, it's a good option. I heartily recommend the Sky-Watcher EQ6R. It has a great reputation and I get great results from it. I recommend you get a dedicated astro camera instead of a DSLR or mirrorless camera. I know the cheap pricing of a used camera can be tempting, but you will get far better results with a dedicated astro cam. The Player One Ares-C has a good pixel size match for the C8, or its counterpart from ZWO, the ASI533. One thing to bear in mind is ZWO is more user friendly, but Player One has legendarily good customer service.
every type of telescope has its pro and cons, there is not a single type that is the king.
Very true.
My c11 is so versatile! The only reason I'd want a refractor is to guide an SCT.
A C11 is probably what I am going to get for the next observatory. Bit of a dream telescope for me, really.
@SKYST0RY I found mine on fb marketplace for a ludicrously low price, but it was completely dismantled, and many of the threaded bolt holes had been stripped. I spent the better part of a month getting the optics sorted out and screw holes properly rethreaded. Definitely worth it.
Very informative, thank you. Does a Maksutov-Cassegrain telescope operate in a similar way?
To my knowledge, very similarly. If memory serves, the main difference is they have a differently designed corrector plate, though the sub-aperture model has a concave secondary mirror.
I plan on buying a used C8 from Celestron around Christmas time and putting it on my AVX, but I got to looking and I think i’m going to go for the EdgeHD version of the C8, but i’ll have to sell my only wide field telescope, my EvoStar 72ED to get it. What do you think about this choice?
I do have a few concerns about the EdgeHD and SCT’s in general.
1. Am I going to have any vignetting problems? I’m going to be using my Nikon D5300 but later upgrading to a dedicated astronomy camera.
2. Is focus going to drift when I slew and with temperature change?
3. Is dew going to be a big problem? Living here in Michigan, it can get pretty dewy and frosty.
And 4. Is tracking and guiding going to be a problem with my AVX and could I upgrade to an OAG to solve that?
One thing to be aware of with the Edge is the optics seem to suffer more from the dew ring which is really essential if you live in a dewy area. I get only very slight dew ring abberations on the standard model. Warm nights are also very subject to dew here, so I have developed a three stage dew management technique that works 100% of the time. You can see the method here: ua-cam.com/video/93O6sN2KqAQ/v-deo.html
1. WIth a very large sensor you may get vignetting. I avoid large sensors to leave plenty of room for the OAG and to avoid the alignment problems that also come with large sensors. If you get vignetting, it can be corrected out with modern tools or you can just crop it.
2. Focus changes with all telescopes with temperature change. You will need an electronic focuser. I am using the Celestron EF on my C8, and it works flawlessly.
4. I have never used the AVX. Celestron mounts don't have a good reputation, sadly. Okay, but not great. I have my C8 mounted on a Sky-Watcher EQ6R which works great. On a night of good seeing, I can get guiding to 0.5.
Hi, brodymk45. I have the EdgeHD 800 on an AM5 mount guided by the Celestron OAG / ASI174 and imaging on an ASI2600MC-P. EAF focuser and ASIair Plus, too. With only four or five imaging sessions, it has proved to be fun and is producing some great images. I am waiting (along with the rest of the world) for the Celestron 0.70X reducer to come back in stock so I can try that combo, too. I found I had to adjust guide settings and guide cam exposures to get best results, but that is part of the adventure.
Cliff, I'm about to do first collimation on the EdgeHD 800 with an OAG and planning to use an AstroZap artificial star. Skies are hating me right now. Any specific thoughts regarding collimation with an artificial star? Is the angle at which the SCT rests critical? Bob
In my limited experience with collimating SCTs (limited because my present SCT is mounted in an observatory permanently, never gets moved so has never needed collimation), only collimate an SCT if you need it. If you start to see the stars going into oblong donuts when put a bit out of focus. A slight miscollimation is fine; don't get focused on making it utterly perfect. But SCTs are very stable reflectors. If not moved, they are unlikely to need much in the way of collimation, based on my own experience. Mine has been sitting on the mount a year now in the heat of summer and extreme cold of winter and the collimation looks as good as when I first put it there.
@@SKYST0RY Many Thanks.
Schmidt are ok! I prefer my Mewlon = CDK. Pointing all that glass at the sky has consequences and is a little old fashioned.🙂 In light path optical correction is the way to go. Still it is the person using the tool rather than the tool itself that matters.
Very true. Profiency of technique is the most important variable.
First he demotes Pixinsight. Now he promotes the SCT! Cliff is surely in line to be burned in Salem!!! Or in that even more ancient colony "Cloudy Nights". ;-) Just kidding. Thanks, Cliff.
I think it was on CN that I read the refractor was "king of telescopes". LOL
Dynamax also made an Fork mounted 8 inch SCT Dynamax 8, but it was a much poorer design than Meade and Celestron and soon it went extinct.
I'd never even heard of that one.
I only know of it because it was in ads in Astronomy magazine from the beginning of the eighties I subscribed to.
I have a 190/1000 Maksutov-Newtonian. Jack-of-all-trades-master-of-none. I use it for Jupiter and Saturn (with a 3x Barlow) just as well as for M31, M42 and many other popular deep sky objects.
The first and foremost condition to meet on behalf of any astrophotography task is not the telescope, but the mount. Beginners wine about which telescope they should buy. Veterans smirk and point to their mount.
It's all built around the mount, to be sure. Professional photographers soon learn technique is far more important than gear and leave the gear chase behind and focus on their methods. I saw a great video recently where a guy bought the cheapest, junkiest 4K camera he could find and filmed a very popular video with it to see if anyone would notice a difference between that video and his far more expensive camera. No one commented on any observable quality difference. Quality mostly is about technique, so long as one has a good mount and good sky. Fortunately, we're entering an age where good mounts are becoming very accessible, though, unfortunately, good skies are becoming rare.