I have began to dabble in astrophotography, after being a visual observer for 50+ years. Its quite a learning curve, which has not been helped by my history of preferring simple, non-goto altz mounts.
I use a Canon M50 mirrorless camera at the prime focus of an Orion 80mm F6 Triplett on an old EQ5 mount. I am finding distortion at the edges of my images and have tried to minimize this by using square (1:1) images for keepsake images. However, even so, I have progressed to the stage where I can see that this is ruining my images. I think that I need a field flattener.
However, I am only learning with the 80mm and hope to progress to using one of my larger scopes for astrophotography, so I do not want to buy things that I will not use in a longer timeframe.
I am pondering my options and this is where I need some help.
Will it help if I move from prime-focus to using a low powered EP with a large field?
Or perhaps I am better of trying one of my larger scopes and working upon my learning curve with that? If so, if seeking a sharper field, is it better to have a longer F ratio, or just a longer actual focal length?
To be more specific, I have a Tak 100 F7.4 fluorite, a Vixen ED115mm F7.7 and a Vixen 140SS F5.7 Achromatic. The Vixen 140mm is often referred to as having a flat field, which is good, but it is the heaviest, which is bad for both the mount and me. However, as my skills improve, I aim to buy a more suitable mount. I also have a 100mm ED F11, but suspect that will be beyond my current ability to track effectively.
So will any of the above scopes improve the image quality of my edges, without having to buy a flatteners?