...just how SHARP a good achromat can be when using a good green filter.
Last night I was tweaking my Istar 6" F10 achromat via star testing thru my green Baader solar filter. I had dialed in the scope to the point where I was getting really good, round intra/extra focal diffraction patterns, and a tight round airy disk with a very dim & uniform first ring. Very nice. Then I decided to turn my attention to the Moon.
Oh my goodness. I was INCREDIBLY sharp. But green of course and I have to say I really did not mind the green at all, not even a second thought, as the image was soooo sharp. The view of Saturn was a knock out as well.
No CA at all!! ;-)
I did something similar decades ago with an old Jaegers 6" F10 and was amazed then too but I had forgotten over the years just how sharp a really good achromat can be in green light.
Jeff
Last night I was tweaking my Istar 6" F10 achromat via star testing thru my green Baader solar filter. I had dialed in the scope to the point where I was getting really good, round intra/extra focal diffraction patterns, and a tight round airy disk with a very dim & uniform first ring. Very nice. Then I decided to turn my attention to the Moon.
Oh my goodness. I was INCREDIBLY sharp. But green of course and I have to say I really did not mind the green at all, not even a second thought, as the image was soooo sharp. The view of Saturn was a knock out as well.
No CA at all!! ;-)
I did something similar decades ago with an old Jaegers 6" F10 and was amazed then too but I had forgotten over the years just how sharp a really good achromat can be in green light.
Jeff
"Don't sweat the petty things and don't pet the sweaty things" 8O
