Ed Camera Lens vs. Non ED Camera Lens

[FOOTPRINT]

Hi All,
Back again after loosing the Manage Attachments bit for a while, all O.K. now thanks to MOJO & others assistance, I though this might be an interesting example of the difference between ED and non-ED Camera Lenses, took both Pix on the same night, same Camera (Canon EOS300D modded) . just changed lenses, The First Lens was an 135mm F 2.8 (non ED), the other a Nikon 70-300 Zoom ED Lens set at 135mm and at F 4, exposure time for the Non ED Lens was 2 Mins. and I gave the Nikon 3 Mins. (could have been longer) Non Ed Lens was 15 Exp. , Nikon was 9 Exp., both DF removed, and guided, The Pentax could have been stopped down a notch or two maybe with better results, but the sharpness of the Ed Lens is noted by comparison to the non Ed Lens where the colours dont converge as well.


cheers.....Jim

[Garyh]

Hi Jim,
Interesting comparison there.The stars a much tighter in the Nikon yet on the very bright stars there is still some CA. Was the Nikon lense at 70mm and what F ratio is it. I find with the old takamar lenses if you stop them down a few stops it makes a lot of difference. I had a look at a pic of the same area I have taken with a old 50mm f/1.4 stopped down to f/3.5 and the stars would be as tight and as well corrected as the ED lense. My other pentax lenses are much the same except when you get to the longer focal lenghts they start to fall behind.....I would like to see the comparison with your pentax stopped down and compared again..
Cheers Gary....

[FOOTPRINT]

Hi Gary, I made some errors in my post, and have corrected them, got ahead of myself as I have been trying out a lot of different Camera Lenses, Yes I will try stopping down the non-ED Lens see how it goes, I am amaized at the good colour on M42 Etc. with the Non-ED lens, If stopping down a notch or two sharpens things up, It makes you wonder about the additional cost of ED Camera Lenses for Astrophotography.cheers....Jim

[Kal (Andrew)]

Can you stop the non-ED down to F4? You would expect 40% more CA in the non-ED based just on the differing focal ratios, so it is a bit hard to compare the two objectively.