10-21-2020 12:08 AM - edited 10-21-2020 12:24 AM
I recently purchased a Canon 15-85 for my Canon T7i and noticed that some of my photos taken with this lens were awfully blurry on the left side of the image as compared to the right, and I have no idea why. Anyone have any ideas? Is there any in-camera solution I could try, or is it a defect with the lens? An example photo is shown below.
Taken at 1/800, f/8 at ISO200.
10-21-2020 05:42 AM
This is a sign of a decentred lens, nothing you can do with it apart from return it for repair or preferably a replacement.
10-21-2020 10:40 AM
I don't know or think anything is wrong. Most lower priced plastic zoom lenses have some FL range where part of the image may get soft. Also barrel distortion can affect sharpness it too. Returning it may get you another that displays the same thing.
10-21-2020 10:53 AM
You seem to have this problem a lot:
I knew I had seen that bus before.
BTW, the real test for testing for lens de-centering is the newspaper test:
10-21-2020 11:21 AM
"BTW, the real test for testing for lens de-centering is the newspaper test:
Great idea! Love it.
10-21-2020 11:23 AM
Yes, I originally had that 18-135 and unfortunately a few months ago just after the pandemic started, I damaged it beyond repair. So I purchased this lens to use as my main walk around lens. Thanks though, I will definetely try the newspaper test when I get home to see what the results are.
10-21-2020 11:32 AM
Make sure you don't confuse it with barrel distortion. These types of lenses are prone to at least some degree of distortion. And, that can not be corrected in the lens but can be edited in post by software like PS.
If a lens like the 15-85mil gets bumped or dropped even a little it can decenter its optics.
10-21-2020 11:57 AM
I agree with KV, you need to shoot a photo with a flat plane focal object across the width of the frame to see whether the lens has an issue.
The EF 400 f2.8 is the most expensive lens I own and I am confident it is in great optical shape but this photo shows the results when eye catching subjects are at radically different distances from the plane of the image sensor with a shallow depth of field. I suspect if you shot a scene like this one with your lens you would also find sharply focused grass across the width of the frame.
10-21-2020 12:45 PM - edited 10-21-2020 12:47 PM
Agree. Here's another example of that.
85mm, f2.8, 1/200, ISO 4000
Subjects in middle of photo. f2.8 foreground and background are blurred.
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10-21-2020 12:54 PM
I don't think there is anything wrong with the original sample shot. Nothing, at all. It is a consumer lens.
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