Friday, September 23, 2011

Disaster (Nearly) Averted, Quasi-Resurrection of the Nifty Fifty

After the initial mourning period regarding the dropping and breaking of my EF 50mm f/1.8 II lens, I consulted the elves at about what might be done. I was instructed to get epoxy glue to reset the back-most element group (below) which had become dislodged and lost some of the brads that held it in place.

[Note: Cyanoacrylate glue should be avoided; it has poor shock resistance and gives off a vapour which condenses on the lens elements."]

This morning, I began the rather quick process of gluing and reattaching the displaced element, and reinstalling the back cover the lens, which just snaps in place. That being done, it was time for the real test, taking photos.

I was immediately encouraged that the focusing ring moved smoothly throughout the focal range and that the autofocus worked.

So with good initial results, I then set up the camera on a tripod in front of a brick wall, so I could make sure all the elements were still properly aligned after the impact of the 5-foot fall that caused the damage. They were not.

They four photos below will serve to indicate the problem the lens now has.

Full Photo @ f/1.8 :: Notice the sharp center and the deteriorating focus as you move toward the corners
100% Crop of the Top Left corner @ f/1.8
I then tested the lens at full stop increments from f/1.8 to f/22, the lens' smallest aperture. As the depth of field increased with the smaller apertures, everything in the frame began to come into focus. By f/11, everything was more-or-less as it should have been.

Full Photo @ f/22 :: Notice everything in the frame is equally sharp
100% Crop of the Top Left @ f/22
Of course, only being able to use the lens at f/11 or smaller completely defeats the benefits of the lightweight, wide aperture 50mm f/1.8. It looks as though the Nifty Fifty will have to be replaced, either with the same lens or the Canon EF 50mm f/2.5 Macro Lens, so if anyone's looking to donate to a worthy cause, I can give you the necessary information.

Update: I have been told that the above photos at f/1.8 are what one should expect from this lens with the aperture wide open. And since the lack of corner sharpness is even throughout each of the corners, then the lens is not likely out of alignment.

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