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Old 21-03-2010, 09:05 PM
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Canon 100mm F2.8 FD lens test

Finally I had the opportunity tonight to test this lens, modified to fit on EOS 3 weeks ago but somehow I never had time to take couple of test images. Tonight, I did it just before clouds rolled in (they are even visible on part of the image as lighter background).
The standard 100% crops from 15x stack are attached below (from DSS TIFF file, image was enhanced in DPP in terms of contrast and LP removal).
15x15sec, ISO1600, @F4.

The lens is very sharp in the centre, but still mildly suffers from lateral CA at corners. For $150 (and a bit of tinkering), it is a very good deal, methinks
It is close in performance to JJJ's Tamron 90mm F2.8 (but not as good, CA is more visible on Canon - it is similar to 200mm with internal iris).

I will try to see in the next couple of evenings how it performs @F5.6, and if CA can be reduced by use of external aperture (which I expect to be the case)..
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Last edited by bojan; 24-03-2010 at 09:40 AM.
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  #2  
Old 21-03-2010, 09:11 PM
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I'll follow your lead and see if I can improve the performance of my lens too.

Last edited by jjjnettie; 21-03-2010 at 09:29 PM.
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Old 21-03-2010, 09:24 PM
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BTW, your lens is better re CA (at corners.. in the centre they behave very similar)
Also, on corners taken with Tamron, the hint of blue is visible, while on Canon, it is red that comes out (assuming in both cases the focussing was done in the centre of the frame)

Last edited by bojan; 22-03-2010 at 08:16 AM.
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Old 21-03-2010, 09:36 PM
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Looking forward to getting the best out of this lens. Adjusting focus feels different compared to the other lenses I have. There isn't as much resistance (though it's not sloppy at all) and I have to physically watch the little window on the lens to see how far I've corrected.
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Old 21-03-2010, 09:43 PM
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For the focus, I adjusted the focus stop such that I just have to rotate the focus ring all the way to the end (focus stop is accessible after removal of front retaining rings with special tool with rubber pads).
So for me, focus is easy :-)
But then again, this is a good old, all metal manual lens (very rarely if ever used, judging by its condition) and I like to improve things (sometimes I manage to destroy them in the process.. not too often recently :-))

Last edited by bojan; 22-03-2010 at 07:42 AM.
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Old 21-03-2010, 09:57 PM
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Hey, so long as you learn from your mistakes. That's what it's all about.
Once these clouds clear, I'll be able to spend more time working with the lens. It won't be long before its use becomes second nature.
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Old 22-03-2010, 09:59 PM
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Tonight I did some more tests with this lens, at f5.6.
Also, I tried the external aperture.
The results (crops from corners) are attached.
While CA is much better at f5.6 with internal iris, it is still barely visible.
However, with external aperture (17mm dia, which makes F5.6) it is gone.. only to be replaced by coma. So, all I can say is this lens is pretty well optimised for what it is...
While I am not particularly happy with that amount of CA with internal iris, I discovered that I can get rid of it almost completely with software
Gimp has plugin that deals with this nuisance.
It is sort of cheating.. but I will have to live with it, it seems.

All in all, good lens!
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Last edited by bojan; 23-03-2010 at 07:45 AM.
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Old 22-03-2010, 10:41 PM
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A very good study in camera optics Bojan.
I hope to get my $5.50 135mm 2.8 this week.
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