7D AF issues - with samples

Started Oct 22, 2009 | Discussions thread
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Carbonman Regular Member • Posts: 349
7D AF issues - with samples

Premptive statement - I'm not a troll. I shoot a 1DsMk2, 1DMk2N, 2-20ds and a crap load of "L" glass. Yeah I know, my bodies are old, but they're great. My wife uses one of the 20Ds as her daily shooter. I know how to use cameras in manual mode with manual AF point selections, etc, etc. This about a 7D being used as a daily camera by someone who just wants to pick it up and shoot beautiful pictures (like the 20D does on the little "green box").

I purchased a 7D kit with the 18-135 IS lens for my wife a couple weeks ago as an upgrade to the 20D she's been shooting for nearly five years. I took off for a three day tour (Minnesota's Boundary Waters) with several family members. She was clicking away happily taking group shots and general snaps (using the freindly green box mode) as we were loading canoes and gear.

On my return the first words from her mouth were, "What am I doing wrong?" She had loaded the pictures onto the computer and about 80% of them were soft / out of focus (or in her words, "fuzzy").

I took the camera and started shooting with it (on auto) and had the same results - basically soft pictures. My first thought was bad lens so I popped on my 24-70 2.8L and my 85 1.2 II. Same deal. I spent a little more time with the camera and decided to exchange it. Fortunately for me, someone had reserved a kit and never picked it up so I got a new one on the spot.

I noticed the same issue with the new camera - soft pictures so I decided to do a little more digging figuring there can't be two bad copies of this camera. I had checked micro adjust on the first kit and did the same with this one - both were spot on.

What I have come up with after a couple of hours is in the automatic AF selection mode (green box default), even if the points the camera selects are over the shooting subject, focus is hit or miss. I then used the zone AF (nine points in a cluster in "P"), and the results were much better. Single point AF is also much more reliable. I have included a series of identical shots (as identical as I could get of a squirrely eight year old). The first four pictures are using the "green box" mode of the camera - automatic AF point selection. The second four are using the "P" mode with the Zone AF. The last four are in "P" with the center AF point only. I also incoluded two snaps from the first body which are typical of what I'm seeing in auto.

All pictures were at ISO 400, 100mm, IS on, f5.6 (camera automatically selects these items - except focal length and IS).

The results, in my opinion, are as follow:
Auto - 1 excellent, 2 ok, 1 poor
Zone - 2 excellent, 2 ok
Single - 3 excellent, 1 ok

I understand the sample pool is quite low and I will work on expanding this, but it is totally consistent with what my wife is experiencing with her shots.

Automatic 1

Automatic 2

Automatic 3

Automatic 4

Zone 1

Zone 2

Zone 3

Zone 4

Single 1 - AF point on corner of left eye

Single 2 - AF point on corner of left eye

Single 3 - AF point on corner of left eye

Single 4 - AF point on corner of left eye

Two other samples from my wifes snaps:

Initial conclusion - it's not an issue with the sensor or lens. This camera can make stunning pictures. The issue seems to be unreliable autofocus using the automatic point selection. Both other modes appear to offer very good reliability. Since the AF points are tecnhically the same it must be the an issue with how the software calculates the AF distance or how the points are averaged to calculate focus.

I'll do more extensive samples and post the results over the next day to show hit/miss percentages in the different modes. I'd appreciate any suggestions or test ideas to help sort this issue.

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Flame alert: I wear Ztex underwear so if you flame me, not only don't I care, but you can't toast what matters.

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