Bandpass shift overlooked on clip in when using lenses? [Deep Sky] Acquisition techniques · AstRobert · ... · 2 · 62 · 0

Hi,

currently i was trying to get a bit into widefield again, but since I spent a lot of time reading into narrowband and how fast scopes benefit less and less (often starting from faster than f4) when filters get tighter, I wonder how this topic was overlooked when e.g. Clip-In filters are used which are perfect for using a fast high quality prime lens with your apsc…

I am planing to use a really sharp 100mm F2.8 lens but also the classic Samyang 135mm f2 are all in the "fast range" of e.g. hyperstar, where everyone would tell you too look out for bandshift issues. But seemingly its not a topic with lenses as there are not "fast" alternatives of clip ins.

So when i plan to use an l-enhance together with an f2 or f2.8 lens… is this actually useless since I will shift my lines (especially Ha as the filter is rather narrow there) out of the band?
Or am i missing something?

And yes yes I know one can and would probably stop down a bit but, thats not the point of fast, sharp prime lenses, is it? ;-)

Cheers, Robert

Even with a narrow bandpass it might not apply. Camera lenses are very complicated compared to telescopes. It's quite possible that the angle of the light cone is as steep as the F number suggests.