I'm about to embark on an interesting idea I had for my C6-RGT. As of now, it actually doesnt have too much chromatic aberration, albeit it is still noticible. A good collimation definitely helps.
At any rate, per the definition of chromatic aberration basically the lens doesnt focus light near the blue wavelength (and some red) to the same point as other wavelengths, which is why u see blue edges.
NOW, this being the case... using RGB filters with achromats should not be too much of a big deal. Why?? After switching color filters you'll refocus each time. Even when using a stiletto u can easily get the same framing of your shot simply by using index marks on your camera. If you're worried about rack and pinion focuser image shift, just make a note of whether your focuser is in perfect alignment as you're slewing in or out (assuming you've collimated your focuser and taken note of whether u were slewing in or out at perfect collimation).
Assuming u pinpoint each color with a ronchi screen and take precautions with camera placement and image shift you should be able to get the clearest, brightest, most contrasty images in any scope of that comparable aperture save an APO. As well, using film with RGB cuts way down on reciprocity failure, meaning u can use higher grain films without too much consideration for this. Lastly, with drum scans or even quality home-scanning technology u'll still be ahead of the DSLR game when u go to post processing as good quality home-scanners are still way ahead of DSLR. Amd of your frames are not exactly the same of course u can align it post-processing digitally.
Note: one could conceive using this same technique photographing in the Sulfur, mercury, Ha, etc. wavelengths too.
So, given all the money u'll save using an achromat and a simple 35mm with a ronchi or varimagni it's way worth it. If you dont want to invest in a filter wheel u could always purchase the filters only and simply place them in the image plane. Since u'll have to reset your camera anyways this isnt a big deal.
At any rate, per the definition of chromatic aberration basically the lens doesnt focus light near the blue wavelength (and some red) to the same point as other wavelengths, which is why u see blue edges.
NOW, this being the case... using RGB filters with achromats should not be too much of a big deal. Why?? After switching color filters you'll refocus each time. Even when using a stiletto u can easily get the same framing of your shot simply by using index marks on your camera. If you're worried about rack and pinion focuser image shift, just make a note of whether your focuser is in perfect alignment as you're slewing in or out (assuming you've collimated your focuser and taken note of whether u were slewing in or out at perfect collimation).
Assuming u pinpoint each color with a ronchi screen and take precautions with camera placement and image shift you should be able to get the clearest, brightest, most contrasty images in any scope of that comparable aperture save an APO. As well, using film with RGB cuts way down on reciprocity failure, meaning u can use higher grain films without too much consideration for this. Lastly, with drum scans or even quality home-scanning technology u'll still be ahead of the DSLR game when u go to post processing as good quality home-scanners are still way ahead of DSLR. Amd of your frames are not exactly the same of course u can align it post-processing digitally.
Note: one could conceive using this same technique photographing in the Sulfur, mercury, Ha, etc. wavelengths too.
So, given all the money u'll save using an achromat and a simple 35mm with a ronchi or varimagni it's way worth it. If you dont want to invest in a filter wheel u could always purchase the filters only and simply place them in the image plane. Since u'll have to reset your camera anyways this isnt a big deal.
