85 f1.8 back focus

I just picked up the Canon 85f1.8 and was bummed out. It back-focused by about 3/8" or more. I even got the effect using 2 batteries on a table top, and with a test target. The problem was obvious. My Canon 35f2 was right on. I used a tripod, level, and electronic cable release. I shot a number of exposures at f1.8 and even took one shot at f2.

I sent it back to Amazon for replacement. I'd like sharp images where I focus.

How common is this problem? Have many people had this experience?
My camera has no micro-adjustment. It is an XS.

No problems with my 85. Are you doing focus-recompose?

How far away was the target ?

the 85mm has a 3 foot minimum focus distance while the 35mm has a 10 inch MFD. Did you adjust your test for that when interchanging lenses?

Also the battery test can be flawed, did you take any real world pictures?

As to your question, there are bad copies of all lenses out there. Pretty rare to hear of a duff 85mm, though.

Hope you did not tell Amazon the reason to return was that it does not do batteries well. I'll bet on user error.

I used more than 1 distance, including a near focus and a bit further away. I checked the angle of the lens to be sure it was close to 45 degrees. I also made sure to take some of the photos with a cable release.
I also checked by photographing real objects - same story. The amount of back focus was identical to the test chart.
Amazon was good and has already sent out a replacement. My copy was dropped off this morning at UPS.
This one is not user error - I checked repeatedly. I told Amazon that the lens was not focusing properly - it wasn't. I first noticed the problems in photos of real objects, and that was why I did the formal and informal tests. I don't routinely test every lens. For example, I was fine with the photos I get from my Sigma 50f2.8, and saw no reason to test it.
This lens just wasn't working properly at f1.8 and f2.
I hope that the next one works well.

Enjoy your replacement lens. I doubt there are too many bad ones, so you should have better luck the next time.

artyH wrote in post #9137551
I used more than 1 distance, including a near focus and a bit further away. I checked the angle of the lens to be sure it was close to 45 degrees. I also made sure to take some of the photos with a cable release.
I also checked by photographing real objects - same story. The amount of back focus was identical to the test chart.
Amazon was good and has already sent out a replacement. My copy was dropped off this morning at UPS.
This one is not user error - I checked repeatedly. I told Amazon that the lens was not focusing properly - it wasn't. I first noticed the problems in photos of real objects, and that was why I did the formal and informal tests. I don't routinely test every lens. For example, I was fine with the photos I get from my Sigma 50f2.8, and saw no reason to test it.
This lens just wasn't working properly at f1.8 and f2.
I hope that the next one works well.

It's probably just a fluke...bad one of the bunch...I'm willing to bet your next one will be fine

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I sure hope so. I'll let everyone know how it turns out. The replacement should be in later in the week.

jrscls wrote in post #9139184
Enjoy your replacement lens. I doubt there are too many bad ones, so you should have better luck the next time.

I bought one used and it's perfect on my 5D2 without microadjustment.

The replacement seems OK. I took a few informal photos and a couple of photos of a focus chart at f1.8 and f2. It is satisfactory at the point labelled "focus here" - I'll do some more test photos later.
Amazon was very good about this exchange. The original copy was not sharp at the point of focus - but about 3/8" or 1/2" in back.