85/1.8 AF hit rate

So I've noticed that the hit rate on my 85/1.8 has been getting worse while my other prime lenses continue to perform brilliantly including my 30/1.4, 50/1.4, 100L and 135L. Even the 30 and 50 which aren't famous for being consistent but mine are. The problem is worst when in lower light when I would use this lens anyhow. Still no problems with other lenses in the same lighting. The other crazy thing is that when I put the 85/1.8 on a tripod in good light to shoot a high contrast test subject, I see no reason to use any AFMA which is set at 0. It's as sharp as a live view shot. Has anyone seen a similar problem, did you send it in to Canon for adjustment and what did it cost?

Thanks

Are you doing your focus test at the same distances that you are having your focus issues at? If you are testing at near MFD and the the focus problems are at a much greater distance that could be the problem. Sigma's dock allows for testing at four different focus distances for just this reason. I have no doubt that at times even Canon lenses could probably do with the same level of adjustability.

Alan

Yep, same portrait distance where I am seeing issues.

All I have to add is that just 10 minutes ago i was relying to a thread about how much better faster and more consistent the AF of the 85mm is compared to the 50mm 1.4!

So you certainly do have a problem somewhere.

All I can suggest is that you try it on the tripod with multiple AF attempts, defocusing between shots, and actually look at the hit rate. If that is OK then I would try it on a tripod under the same lighting conditions as you are using for the actual shoots, and preferably with a human like subject that won't move. Once you have some reliable figures for hit rate you will know if you have a problem lens, and if so exactly what to tell the service center if you choose to send it in.

I come from an engineering background, and really only thorough systematic testing of both the good lenses, and the suspect lens will help in this situation. Also having hard figures will allow you to asses if the repair has been carried out successfully. If you do not have reproducible test results of your own, don't expect service to find anything wrong.

Alan

CyberDyneSystems wrote in post #17831577
All I have to add is that just 10 minutes ago i was relying to a thread about how much better faster and more consistent the AF of the 85mm is compared to the 50mm 1.4!

So you certainly do have a problem somewhere.

I am very impressed with my 50/1.4s AF. I just wish it was sharper from 1.4-1.8. 2.0 gets pretty sharp.

BigAl007 wrote in post #17831582
All I can suggest is that you try it on the tripod with multiple AF attempts, defocusing between shots, and actually look at the hit rate. If that is OK then I would try it on a tripod under the same lighting conditions as you are using for the actual shoots, and preferably with a human like subject that won't move. Once you have some reliable figures for hit rate you will know if you have a problem lens, and if so exactly what to tell the service center if you choose to send it in.

I come from an engineering background, and really only thorough systematic testing of both the good lenses, and the suspect lens will help in this situation. Also having hard figures will allow you to asses if the repair has been carried out successfully. If you do not have reproducible test results of your own, don't expect service to find anything wrong.

Alan

It's just hard to reproduce but I'll try the tripod with a stuffed animal or something after the kids go to sleep in the problematic light to see what the hit rate is then. I would say tonight while doing portraits, it was probably only 50%, While the other glass was well over 90%. It tends to front focus when it misses. Crazy how in a three shot burst, one is badly front focused, another is not bad for a 4x6" but soft at larger print sizes, then the third is right on tack sharp. FYI shutter was max synch 1/250" for these with on camera bounce flash.

my 85 is fantastic. its focus speed is extremely fast and it locks in low light no problem. Mine has a -18 Microadjust to it. But I will say this is my 3rd 85 I have owned and they all needed a good amount of microadjust. Id say on my 1D3 I have like a 90% keeper rate with it

All of my fast primes suffer, to varying degrees, in lousy or fluorescent light. From worst to best, I'd rate them: 50 1.4, 85 1.8, 28 1.8, and 135L. I don't use my 100 macro for anything but macro. I thought it had something to do with color temperature or something. All of them work fine in good light.

mine has been getting less use lately but I think it is still my most consistent with the 70-200 right behind.

I had the same problem. I finally got fed up and sold the 85 1.8.

Do not know what camera are you using, but mine had very similar problem when was connected to 7d and my friend has same issue with this combo. MA did not help either. On 5dIII 85/1.8 was better, but sold it to get 100/2. 135/2 and 85/1.2 are way better.

Mine is just excellent, even in bad light. I have no issues with it at all.

I am using a 1200d, 60d and a 5d. I have no focus issues, no front or back focusing.

Not sure what kind of shooting you do, but to me, real world performance is far more important than testing. Generally if I'm seeing a problem, I check camera settings, my technique and then mf adjustment.
I use my 85 for basketball pretty often, and it's about as fast and sharp as any other lens I use (70-200 f2.8, 300mm f2.8 and 17-55 f2.8). I've had good focus success with it in gyms with light levels as low as 8000 ISO. It also works well for corporate meetings and events which are usually in florescent lighting.
Good luck with your issue.

I'm using it on a 7D so that is interesting. I also have the 350D, but the AF there is crap on any fast lens so I don't know what that would help with troubleshooting.

I am mostly using it for fairly stationary portraits and grab shots. I was using it for indoor swimming and stage/theater performance shots but when I got my 135L with the more reach, I started using that for those shots since.

So still no one has sent it in to Canon for a similar issue?