As has been pointed out by Jazz, yes the scope is important but your mount should just as much be influencing your scope choice to keep it within realistic weight, stability, and reliable tracking limits for astrophotography.
Just because an AM5 can cope with up to 20lbs it doesn't mean its good for decent astrophotography up to 20lbs. Whatever configuration you use it has to be absolutely rock solid, stable, and track well. In the absence of real test data the old rule of thumb for astrophotography was to assume loading it to half the manufacturer’s advertised payload. I would say if your mount choice is fixed for now, be really realistic about what is achievable with that mount and don't get swayed by marketing which significantly increases the weight loading (e.g. aperture fever).
I followed a similar astrophotography route to you and had exactly the same ambitions. I started around 25 years ago. I still have the same 617mm APO refractor, but I have been through 3 mounts in that time. I was very very reluctant to change mounts and these decisions were not taken lightly at all (option of absolute last resort) and were delayed as long as practical by putting the system on weight loss programs, but it still ended up at 3.
The more you add on the extras for your future ambitions, the weight just keeps going up bit by bit, even when being as frugal and weight-thoughtful as possible. I honestly thought my EM-11 (second mount) would see me through for life but then moved from DSLRs to true astro cameras. Then for convenience and cold nights you find you want a mini pc for remote camera operation, then the electronic focuser to stop wobbling and remote operation, then the camera for the finderscope/guidescope, then the more rigid extension rings/tubes to get the camera(s) in focus and to stop the optical system bending, then bigger/longer dovetails, etc, etc, etc. It all really adds up. Suddenly you wonder why you no longer get nice images out of your nice astro setup, and it can take a long time to work out the cause. The mount has gone past its optimum loading for astrophotography. I could easily have stayed with my EM-11 for visual astronomy but for astrophotography I had to move to an EM-200 (luckily a good second-hand one became available) for what is a pretty small 4" scope with those extra bits and bigger dovetails on it, and its still a very simple setup compared with many people's.
Also worth thinking about if you mean 'sharp' or if you mean 'detail'. Detail will only come with a larger aperture (assuming your local atmosphere can cope with it) which also means significantly higher weight, and for refractors, significantly higher cost. What people think of as 'sharp' is often about the scope's optical quality and, as has been said above, in most cases it means investing in a true high-quality scope. If on a fixed budget, have a serious think, is it 'detail' or 'sharpness' you want. For your use cases I would personally always favour investment in a higher quality 'sharper' scope that immediately gives you that image pop and ‘wow’ factor, than a larger poorer quality scope which gives more ‘detail’.
With regards to the telescope shortlist, some of the WIllian Optics FLT (fluorite glass) range are within your financial reach, e.g. FLT-91.
If you are keeping the AM5 mount for a long time and want really 'wow' images, another option is to invest in very 'sharp' highest quality smaller aperture scopes. This is because it can always be re-purposed later as a finderscope/gudescope/portable scope later if your ambitions move towards to a larger scope (on a larger mount) later. The smaller, very high quality, Takahashi scopes are within your price range and focal length. I find the 'sharper' photos of big things (Andromeda, M45, North America Nebule, etc) are far more 'wow' from my well-made smaller Takahashi scope (60mm aperture) than my larger (more detailed) fluorite Taiwanese 4" scope (which is by no means a poor-quality scope either).
Also consider trying the astro object simulators (e.g. astronomy.tools) for your objects of interest with your scope/camera combos; it might shorten your list more. You may struggle to fit the full extent of bigger objects (e.g. M31) at the upper end of your focal length range. Possibly just about with the full-frame sensor on your DSLR, but are you prepared to pay the cost of the full-frame sensor astro camera when you start upgrading (bare minimum of 3000 EUR at today's prices).
Hope this helps
Edited by alanajones, 10 August 2024 - 03:12 AM.
