Focusing issues going from a 50D to 5D Mark III

tommyboy · Mar 27, 2012

I think it has to do with going from an aps-c size sensor to a full frame on the 5D. I've heard the DOF on the full frame model is significantly shallower than same aperture on smaller APS-C sensor.

JacquesV · Apr 1, 2012

JClishe said:
My 5D3 arrived on Friday (guess I need to change my signature) and I shot about 400 shots with it in the studio over the weekend. I noticed that I have a higher percentage of missed focus shots than I'm used to with my 50D, particularly at wider apertures (4.0 - 5.6 or so). This is my first time using a full frame camera, is this likely a situation of the DoF being thinner on FF versus my 50D's sensor, and I just need to pay more attention to my focus point? I'm wondering if I was simply able to get away with being a little "sloppy" with focusing on the 50D and I need to untrain bad habits? I have some boudior shots where the model was laying on her back looking up at me and at F/4 her forehead is sharp and her eyes are soft. Based on my distance to the model, F/4 wasn't typically that shallow on my 50D so I suspect this is user error but I'm still curious what others think about moving from crop to FF and how that affects focusing.

Hi, I just posted this on canon rumors as well and I think you will find it help full as there is a thread for this topic there too.The mark iii seems to have a serious default focusing problem. You will notice this all the time when shooting wide open, especially with big lenses used open like a 200 f/2 or 400 f/2.8. Each lens will need to be micro adjusted (5 tab on AF menu) it is a tedious procedure but the only way to get sharp photos when shooting open. I really hope Canon brings out a software update to fix this ridiculous problem. Below I list my findings I'll start doing the micro adjustment tomorrow

50 f/1.2 front focus, 200 f/2 front focus, 70-200 f/2.8 ii @ 70 spot on @ 200 front focus, 400 f2.8 ii back focus allot!* not nice so every lens is different and with every doubler the trouble doubles*

hukim0531 · Apr 1, 2012

JClishe said:
My 5D3 arrived on Friday (guess I need to change my signature) and I shot about 400 shots with it in the studio over the weekend. I noticed that I have a higher percentage of missed focus shots than I'm used to with my 50D, particularly at wider apertures (4.0 - 5.6 or so). This is my first time using a full frame camera, is this likely a situation of the DoF being thinner on FF versus my 50D's sensor, and I just need to pay more attention to my focus point? I'm wondering if I was simply able to get away with being a little "sloppy" with focusing on the 50D and I need to untrain bad habits? I have some boudior shots where the model was laying on her back looking up at me and at F/4 her forehead is sharp and her eyes are soft. Based on my distance to the model, F/4 wasn't typically that shallow on my 50D so I suspect this is user error but I'm still curious what others think about moving from crop to FF and how that affects focusing.

I would put your 5D3 through a series of focus test with the lenses you have at your disposal. It's not just lens that can have focus problem. If all of your lenses are consistently showing either back or front focus, you know your camera will need to go back for calibration.

fokker · Apr 1, 2012

OP, you may want to put a NWS warning on those shots. I didn't mind though :drool:

KmH · Apr 1, 2012

It wouldn't be the first time Canon shipped a new high end model with auto focus and other problems - Canon says EOS-1D Mark III AF issues fixed, now leave us alone -- Engadget

JClishe · Apr 1, 2012

To be honest the point of my post was more a question about whether greater focus point precision is generally required when moving up to full frame from a crop body. I do plan on doing some focus tests with my lenses, but my suspicion is this is user error. Actually I'd prefer to call it a "learning curve".

mcap1972 · Apr 2, 2012

Try micro-adjustment - it should help if the lens is the problem.

JacquesV · Apr 2, 2012

Thanks, I had most of my kit at my dealer today, where we carried out some more precise testing on a proper setup. The only lens that was spot on was the 85 prime. All others (f2.8 or wider) had some front or back focusing, with erratic results. When we moved the test rig outside to natural light we had different results. In the end we contacted canon who will now be helping us to resolve the problem. I'm so glad that I'm dealing with a reputable retailer, they are great

Remember this is on a brand new 5D iii.

idratherplaytennis · Apr 19, 2012

I made a similar jump, in going from a 20D cropped to the 5DIII as well, and noticed the same thing you seem to be noticing (I think... I couldn't see the photos that everyone seems to be jealous of

) but from other posts via canonrumors forums etc, I've found that it probably is error on my part, shooting with a far narrower dof than I am used to as well. On the few shots I got of my dog, where it is spot on with her eyes, the reflection is intense, but I (along with some other forum members) felt the shots were too wide open. Case in point being one shot where her head was just slightly tilted, shooting at f/4 and one eye was in focus, the other just soft and ever so slightly out. Then the shots that I miss, tend to be due to her movement or focus hitting something else which was very intense in the one area but not the rest.

Definitely going to be practicing this a lot and shooting far less wide open than I used to (on close up objects/dogs etc). Had no idea that the crop affected the DOF as much as it really does when you go to a FF. On the upside, I'm no longer afraid to stop it down as much thanks to the obscene jump in IQ at high ISO's, shooting something and viewing it at anything above what was acceptable to me on my 20D at basicall 100-4 or 800, and going into the 1000's?? I literally think I "bwahahaa-ed" out loud >