Lens testing - Canon

Rudesing

Rudesing

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Name
Ruth
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I have been using two lenses in a studio set up with my Canon 50D. Mainly I use the 24-105L, but with larger families I've tried the 17-55, but wasn't getting the quality of shots with the 17-55.

Did a test tonight, using the same settings at the same focal length, the 17-55 is not as sharp. I've used the 17-55 outside (at weddings etc) and always thought it has been really sharp.

Is there any technical reason why it wouldn't be as good as the 24-105 generally or in a studio setting?

1) 24-105
24-1051.jpg


2) 17-55
17-55.jpg


I know it's not an 'L' lens, but would that result in this big a difference?
Any advice appreciated, many thanks :thumbs:
 
Why has the guy got his arms crossed in pic 2? Seems stupid not to have both pics the same if u want to compare?
 
yeah thought that myself. should be two identical shots. But if youre having issues with sharpness being poor you may have a poor copy of the lens as the 17-55 is uber sharp
 
The last thing you want to photograph if testing a lens is something that can move.

You need to get as much the same as possible, first, stick the camera on a tripod, light the image with either ambient light or a fixed (manual flash exposure) select the same focusing point on whatever you are shooting, have both apertures the same and then check your shots.

It may well be that the 24-105L is focusing correctly but the 17-55 may need a little focus adjustment as it may be slightly front or back focusing. Bt you'll never know until you take out as many variables as possible first.
 
I would say you need to test the 17-55 wide open at 17mm and then at 55mm, it could require calibration?
 
Thanks all for the quick responses. Will get onto it.

Edit: by 'it' I mean a proper test with a non moving subject!
Oops, wrong username!
 
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On a 'proper' test I'm not seeing any difference:

This is tripod mounted:
1) 24-105 @24
24-105at24.jpg


2) 17-55 @ 24
17-55at24.jpg


Confused myself now! As the above 'person test' is the standard result I get when I do a studio shoot with the 17-55. The shots appear grainy and not as sharp as with the 24-105.
 
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The focus is closer to the camera on the 17-55 shot. Might be the camera focussed different because the scene was different, but it could be that the AF needs fine tuning.


Try using the AF microadjust on the 50D (there are plenty of guides on t'internet), and if that doesn't solve it (sometimes doesn't with zooms lenses if the focus characteristic is different at different focal lengths), get it off to canon to be properly calibrated.
 
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