RF 28-70mm soft left edge or normal performance?

mvert wrote:

I would like to hear comments form someone owning R5 and RF28-70mm about left edge performance of my lens. Following full resolution image is taken at 28mm, f2. How does this compare to you lens?

28mm, f2, Focus Center of the image, left edge seems much worse than right.

Here is also 28mm, f4 version. Soft left edge might be easier to spot on this one.

28mm, f4, Focus Center of the image, left edge seems much worse than right.

Did also some close distance testing inside. Left is also here pretty bad compared to right side. Siemens stars are crops from the extreme corners. Focused camera center of the lens and took picture (ibis off) and set lens to manual focus. Moved camera on tripod head (without moving tripod) so that I could set Siemens star in the each corner and took picture and combined all in this image.

Test setup 5 images from tripod, focus center.

Some more picture can be seen on: https://mve.kuvat.fi/kuvat/Testikuvia/

Site might be slow outside Finland.

I have two of them and one of them was like this also. I sent it in to Canon, long story short, they adjusted it a little and it is somewhat better.

Based on what I have seen I think it is pretty apparent that this is probably within Canon's specifications for the lens although they may replace it if you complain to them.

Here is the thing, as tempting as it is to use this for landscapes, they must see it as a portrait lens first and foremost otherwise they wouldn't be putting so many out with these problems.

And I should mention I had two other 28-70's that were similar. They just would not get sharp at at the edges, but one of them was particularly bad at infinity. No matter what f-stop the left 1/3rd of the frame at 28mm looked wrong. It also didn't focus properly and would hunt a lot, which I only realized once I had received a replacement. The lens should be very reliable with focusing even when using eye detect AF.

I wish my current lens was also perfect, sadly it is not. And the annoying thing is it was only at 28mm, every other focal length was near perfect. But, because I shoot groups of people frequently I decided to send it in. The fixes they applied were OK. It was odd because it was razor sharp on most of the frame, but then the right edge just degraded to pure mush. Somehow they were able to even it out a bit. Sometimes I think about sending it in again but having gone through 4 of the lenses in total and currently having 2, I think I have realized the futility of pursuing it further.

I only say this to help save you the headache, it might be best to just try another lens unless you just really love the 28-70. It took over 3 months of back and forth emails and mailing lenses before I got where I am at and it still isn't *perfect*.

For portraits it is still amazing though...

I also messed around with it using an extension tube: