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I am interested to know what your idea of a good telescope for astrophotography might be. I’ve been writing about this topic and wanted to get some additional thoughts from those on this forum who have experience in astrophotography. This could start a nice conversation about what to look for when upgrading.
Here are my own thoughts about a good telescope for astrophotography:
https://astroimagery.com/equipment/telescopes/best-telescope-for-astrophotography/
Do you agree with what I have written? Any additional points I have missed?
One thing in my mind is how important is the size of the aperture for astrophotography. I use a 5-inch Celestron SLT at the moment and have done it for three years. It does OK but I wonder if a much bigger scope (how big is best?) would cut down the imaging time or the fine details I can get. I realize there are so many factors involved here such as the Bortle level (mine is 5), the camera (ZWO 533MCPRO), the Telescope focal length of 650mm, F5 focal ratio, and so on…
Look forward to your replies and if useful I will add them to my post.
Karl Perera
Astrophotographer, Teacher and Author
https://astroimagery.comIt does OK but I wonder if a much bigger scope (how big is best?)
How much do you want to spend?
A fully kitted out 4-metre telescope will produce some very fine images but is likely beyond your budget.
Your question as phrased is essentially unanswerable.
Do you agree with what I have written? Any additional points I have missed?
When you describe reflectors you state that one mirror is flat. This true, by and large, only for Newtonians and other folded optical path designs. My scope is a sort of Cassegrain but, to be fair, it does contain a flat just before the camera or eyepiece assembly.
I find it amusing that you have a Celestron NexStar 5 SLT which is a Schmidt-Cassegrain I believe. It also has a flat for ease of uses near the zenith.
It is difficult to know where to start. The website is riddled with misleading nonsense. For example here
https://astroimagery.com/equipment/telescopes/best-telescope-for-astrophotography/#research-what-telescope-would-you-recommend-for-astrophotography
in positions 2 and 7 here you have a Dobsonian mounted scopes which are not suitable for astrophotography and the description does not match the scope.I apologise if I am wrong but the main purpose of this website appears to make money not to inform.
Robin
It is difficult to choose an ideal telescope as it depends on so many factors. I think you may be considering Deep Sky imaging, which has similar requirements to variable star photometry and comet imaging. While planetary imaging has different needs.
I would say good quality optics of a variety of designs can produce excellent deep sky images. If you want top quality results, then put quality before aperture within your budget.
A key point is ensuring you have a good quality mount that can robustly support the telescope and track well, or receive guider commands to correct for tracking errors. With smaller telescopes, such as small short focus refractors, you can get away with a much smaller and cheaper mount. As you go to larger telescopes and longer focal lengths, the cost of the mount will go up dramatically.
It is also important to have a focuser that can support the camera, as well as any filters or an off-axis guide camera if used.
For starting out with imaging I would recomend a short focus refractor. However, something like an 8-inch SCT on a sturdy mount is a great all round telescope. With available accessories that can be used for both deep sky and planetary imaging.in positions 2 and 7 here you have a Dobsonian mounted scopes which are not suitable for astrophotography
While planetary imaging has different needs.
Indeed.
Martin Lewis takes some absolutely superb planetary images with his Dobsonian mounted telescopes. The rings of Uranus and surface detail on each of Ganymede, Mercury, and Venus are among some of his achievements.
Martin Lewis takes some absolutely superb planetary images with his Dobsonian mounted telescopes. The rings of Uranus and surface detail on each of Ganymede, Mercury, and Venus are among some of his achievements.
But the list is supposed to be the best telescopes for astrophotography. I doubt if you polled astrophotographers (planetary or deep sky) they they would put this scope as the second best for astrophotography (or for that matter the one placed top of the list.)
Does someone get a payment if you click though to amazon on these links ?
Robin: I agree with you almost but not quite completely.
Part of my problem is that I do not have a good definition of the term “astrophotography” other than it appears to place pretty pictures much higher than their scientific value.
Is planetary imaging “astrophotography”? I don’t know. Neither do I know whether alt-az mounted DSLRs are used for “astrophotography” but they can certainly take pretty pictures, as well as take images which when analysed yield good science.
Indeed the question as posed is unanswerable.
Telescopes are used to take images in two basic ways (not counting spectroscopy):
1. To image faint objects
2. To image fine detail
(3. Some combination of these)Aperture allows you to resolve detail, but focal length allows you to image the resolved detail with a detector. Aperture also allows you to image faint stars, but the imaging of faint extended objects depends inversely on focal ratio. Width of field, with a given detector, depends inversely on focal length. If you wish to image the combination of faint stars, faint extended objects, and detail, you require a large aperture at a low focal ratio. If you wish to image wide fields you need a short focal length, but unless you have a large aperture and hence a low focal ratio as well, your detection of faint objects and your resolution will be limited. But there is a limit to how low focal ratio can go without optical problems, so for the widest fields, very small telescopes are needed, which are limited in both resolution and limiting magnitude.
This is all before one gets into considerations of mounts and drives.
So what is ‘a good telescope for astrophotography’ depends on what exactly you are trying to achieve.
David: The Vera Rubin telescope has both an enormous aperture (8.4m) and a very low focal ratio ( f/1.23). Its field of view exceeds my 0.4m f/6.5 scope about 20-fold and its collecting area about 200-fold (call it a limiting magnitude about 5 magnitudes fainter than mine).
But this is an exceptional case and your post applies to almost all telescopes and certainly all amateur telescopes.
Once more: the question comes back to: what is your budget?
Until we get sensible answers to this question, and to the one about intended use, the original question is indeed unanswerable.
Karl: what is your budget and what do you want to image?
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