Filter Choice

[jif001]

Had a good old rummage around but haven’t found an answer to this so here goes...

40 years after life got in the way of astronomy, and after 35 years of employment, I’m now in the happy position of being able return to a great hobby and to kit myself out with proper stuff, my aim being ultimately mono imaging with filters. I have a scope (Altair Astro StarwaveAscent 102ED) and Mount (EQ5 Pro GOTO) and currently use it with a Nikon D7200. The next step is a mono camera and filters, but which filters to buy? This isn’t a question about Ha, Hb, Oiii, Sii, but about the merits of 1.25” vs 2”  

It seem logical that the larger aperture of a 2” filter would be better, but is that the case? Would an all-2” setup be significantly better than an all 1.25” setup? Does it warrant the extra cost?

[old_eyes]

Choose your camera first. The chip size will tehn tell you whether you need 2" or 1.25". Unless the camera chip needs 2" you would be wasting your money. So for example, the ASI1600MM Pro has a 4/3 chip with lots of resolution. That matches well with 1.25". A full frame camera like the Atik 1100 will need bigger filters. Your supplier should be able to advise filter size for a given scope, camera, filter-sheel combination.

[jif001]

Thanks for the response. There’s more to this than I thought. Having been enlightened by it I googled ‘chip size vs filter size’ and it led me right back here to this useful thread: