I'm have done some wide-field astrophotography on a tripod and planning to try piggybacking over my telescope (manual tracking, low focal length).
I use a Pentax MX with the stock focussing screen (matte+microprism+split) and the lenses I got are a 28, 50, 135 and 75-300mm in focal length.
Locking forward the next local star party I was thinking of getting something to assist focusing. Options available here are a small bahtinov mask or a 90 degree viewfinder with 1x and 2~3x magnification. Both are somewhat more expensive than I think they should be.
So the questions are:
- At those focal lengths, can I get significative improvement over just using the viewfinder?
- It's even possible to use a Bahtinov mask on a SLR or the viewfinder is too dark/small to even see the diffraction spikes?
- Are there any other focus assistance that you guys could recommend?
Thanks in advance for any suggestions,