Quote:
Originally Posted by JA
Hi Paul,
Did you try both of the lenses you listed? I suspect the full frame EF lens might be better, but you never know. Did you try stopping down the lenses to reduce coma or did you use them wide open? Stopping down one or two stops should make a considerable difference (improvement) in coma, sharpness and most other aberrations.
Otherwise a Sigma Art 35mm f1.4 or 50mm f1.4 are very sharp and have low coma. The 40mm even lower, but it's heavy and expensive and you need to find a way to operate the aperture with these lenses when not used on a DSLR.
Best
JA
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Quote:
Originally Posted by Leo.G
I have no idea with Canon lenses and required operation (JA knows a lot more than I do about this stuff) but I do know with my little CMOS camera I can use some of my older Nikon lenses with full manual operation which are still suitable for my Nikon. I don't even know if I'd have any old Canon lenses but if you're using an adapter for the 183MC you really don't have to limit yourself to Canon lenses, a different adaptor for Nikon mount or possibly (I don't own a ZWO camera so I'm guessing) like my player one Neptune which has a standard M42 mount thread (or M48, I forget) which will should a standard old Pentax/Practica/other M42 lens screw mounts and many of the older lenses are available used for reasonable prices in good condition (I always check Salvation Army and St Vinnies if I'm passing and pick up some surprising camera stuff for a donation. The pawn shops are worth taking a peek in too if passing.
HOWEVER, buying dedicated to suit your Canon DSLR when not doing Astro is a smart financial choice if buying new lenses (sorry, I know I'm stating the obvious but I like my collection of old lenses and have a range of different brands and focal length/apertures to play with (I also collect old cameras)).
Sorry, obviously not JA but just happened to be here in this thread.
If you are using an f2.8 lens you could try stopping it down from the widest aperture to a narrower aperture, f3.3/f4.5/f5.6/f8.....
Stopping a lens down gives better depth of field (more depth (a larger focal area instead of like a portrait where only the face is in focus).
I know a few of my larger f1.4/f2.8 lenses are much better stopped down. If you can't take longer subs due to less light coming in through the smaller aperture (depending on guiding) more subs of the same time period is a good substitution.
https://en.wikipedia.org/wiki/Stopping_down
There's a lot of good information available with benefits and drawbacks online. |
Thanks Leo and JA for your valued information... Understanding the term "Stopping Down" and JA I will try the full frame lens, I did use them wide open at its highest possible f value so I will try the full frame as you suggested...
