85 f1.8 backfocusing on my 5D classic

Started Jun 2, 2011 | Discussions
sergesret Regular Member • Posts: 141
85 f1.8 backfocusing on my 5D classic

Got a new 85 f1.8 and I'm finding that it is consistently backfocusing on my 5D classic. The farther away, the worse the backfocus. Shooting subjects almost at infinity puts the whole image out of focus. I sent the lens back to Canon and they did a calibration but there is no change.

I have a couple of film bodies, an EOS3 and an EOS10s and I ran some tests with these, side by side with the 5D. I also simultaneously tested my 100 2.8, 24-105L and 70-200L4IS set as close to 85 as possible. The 85 did OK on the film bodies for the most part. Maybe one misfire on the old 10s. Nasty backfocus on the 5D. The rest of the lenses did great as they always have.

So it seems, that for some reason, the 5D and the 85f1.8 just don't play well together. I know it's often suggested to send the camera and lens in together but wouldn't that throw off the 5D for all the other lenses? Or is there something they can do for the autofocus of a specific lens/body combination?

I'm going to see if I can ask a couple of friends at work if I can try the lens on their digital bodies to test if the problem is really just the specific combination of my body and lens, which it looks like it is. If that's the case I'll likely keep the lens to use with the 5DmkIII when that comes out. Or I might sell it off. If it doesn't work with the other digital bodies then that would be something to further pursue with Canon.

Curious if you folks have any thoughts of suggestions.
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fras23 Regular Member • Posts: 147
Re: 85 f1.8 backfocusing on my 5D classic

when you send the body in with the lens they calibrate the lens to the body, it shouldn't make a difference to your other lenses.

Scales USA Veteran Member • Posts: 3,121
Re: 85 f1.8 backfocusing on my 5D classic

With a wide aperture lens, even a tiny amount of mis focus by the body is noticible, where with a f/2.8 or f/4 lens, the tiny misfocus can be lost in depth of field. If it gets a lot sharper at f/2.8 or f/4, that is something to consider.

The 85mm f/1.8 is not incompatible with any of the bodies. If you can, try a different lens.

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KevinRA Regular Member • Posts: 374
Re: 85 f1.8 backfocusing on my 5D classic

Hi

The 85mm 1.8 should work fine- I have this combo (5D classic) and it is very good. DOF is tiny at f/1.8.

Have you done any tripod tests- to see if it is a constant fron-back focus - the standard newspaper 45 degree test for example?

How does the 85mm compare accuracy-wise at the same aperture as your slower lenses? Trying the lens out on another full frame digital body is a good idea. Of course later bodies also have micro adjust.....

The 85 1.8 should be great on a 5D classic- sharp corners even at f/1.8- and the big pixels are forgiving of the lens's only downside - purple fringing. I like my 85 on 12MP full frame - not so keen unless stopped down with the tiny pixels on 15MP crop....

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idigi Regular Member • Posts: 244
Re: 85 f1.8 backfocusing on my 5D classic

I had to microadjust 85 1.8 on 50D to +5 to nail the focus.

Lucian_C Contributing Member • Posts: 550
Re: 85 f1.8 backfocusing on my 30D

I have the same on my 30D. I tried another 2 copies from my friends and they too backfocus.

I tried my 85/1.8 on a Rebel and boy, that lens is sharp. So my 30D has a problem.

That is why my next body MUST have focus adjustment.

Lucian

OP sergesret Regular Member • Posts: 141
Re: 85 f1.8 backfocusing on my 5D classic

I ran a full battery of tests, including a shot of ruler from a tripod much like your newspaper suggestion. The other tests included shooting an old pool chem bucket with printing on it on my lawn and next to hedge so I could visually gauge how the focus was falling at various distances. All done on a tripod with a shutter release I also did a specific real world test where I took the lens and camera to work on a day we were having a company wide event. It's a large campus with interesting architecture and I shot over a hundred pictures at all distances. Every last one obviously backfocused. The most striking is a shot of a palm tree crown from a high balcony with a small power plant maybe a fifty yards behind. Palm tree dead center, out of focus, wall surrounding the power plant with a sign, beautifully in focus. Before I sent the lens to Canon for adjustment the first time I used it for was for a headshot session for a friend of mine. I tried it at 2.8 and 4 and trying to focus on her eyes I consistently got her ears in focus. Switched to using my 70-200F4 which was bang on.
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OP sergesret Regular Member • Posts: 141
Re: 85 f1.8 backfocusing on my 5D classic

I'm definitely mindful of the thin DOF of this lens at 1.8. It was my primary reason for getting it.

The first time I used the lens was to do some portraiture and I stopped down to 2.8, then 4.0. Frustrated I switched to my 70-200F4 set to about 85 and bam!: pretty much perfect. Certainly night and day with the 85. The 85 should work fine with the 5D and I tested it with my EOS3 and EOS10s film bodies and those performed OK, though not quite perfectly. As I mentioned, I did run tests using the other 3 lenses I have that can do 85 or 100 and those were fine. I also have tons of real world shots racked up with this camera (had it since 2006) and these lenses and I'm pretty happy with the results. When I get back from vacation later this month I'm going to see if I can get 15min with a 5Dmk2 and a T2i that a couple of my comrades at work own.

I guess at this point my question is can Canon fix my 5D/85mm combo without throwing the rest of my kit out of whack and at least one poster believes so.

Scales USA wrote:

With a wide aperture lens, even a tiny amount of mis focus by the body is noticible, where with a f/2.8 or f/4 lens, the tiny misfocus can be lost in depth of field. If it gets a lot sharper at f/2.8 or f/4, that is something to consider.

The 85mm f/1.8 is not incompatible with any of the bodies. If you can, try a different lens.

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OP sergesret Regular Member • Posts: 141
Re: 85 f1.8 backfocusing on my 30D

Yeah, agree with you there. Waiting for the 5DmkIII to come out so I can upgrade and have that feature. (I know the 5DmkII has it but I just felt overall, for my case, it wasn't a worthwhile upgrade at the time.)

Lucian_C wrote:

I have the same on my 30D. I tried another 2 copies from my friends and they too backfocus.

I tried my 85/1.8 on a Rebel and boy, that lens is sharp. So my 30D has a problem.

That is why my next body MUST have focus adjustment.

Lucian

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MysticX Regular Member • Posts: 465
Re: 85 f1.8 backfocusing on my 5D classic

sergesret wrote:

So it seems, that for some reason, the 5D and the 85f1.8 just don't play well together. I know it's often suggested to send the camera and lens in together but wouldn't that throw off the 5D for all the other lenses? Or is there something they can do for the autofocus of a specific lens/body combination?

I'm going to see if I can ask a couple of friends at work if I can try the lens on their digital bodies to test if the problem is really just the specific combination of my body and lens, which it looks like it is.

Well, I happen to have the 85mm and it works just perfectly on my 5D mk1 body.

At least in the portrait distance range, it's reliable, never tried it for infinity focus.

But the truth is I don't use it much more open than f/5.6 so I can't tell you 100% percent sure.

It just works for me and the kind of photography I use it for.

I remember I used it once at f/1.8 for a wedding, maybe I'll try find the pictures.
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OP sergesret Regular Member • Posts: 141
Re: 85 f1.8 backfocusing on my 5D classic

Well, holy cow! I just got my 5D body back from Canon, along with the 85mm and it is freaking beautiful. Now I'm seeing the results I was expecting from this lens. Lovely thin depth of field right were I asked the camera to put it. This is going to be fun!

Still have to check the body against my other lenses but I'm sure they'll be fine, given that the body was tweaked to Canon's standard reference first. My hat's off to Canon Irvine. They calibrated my 5 year old, way out of warranty body gratis as a courtesy along with the in warranty lens. Yay!
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Scales USA Veteran Member • Posts: 3,121
Re: 85 f1.8 backfocusing on my 5D classic

Yes, contrary to some comments, they calibrate the lens and the body separately, not to each other, which would mean they would not work on other bodies / lenses.

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