5D vs xxD autofocus test

I am thinking about upgrading to 5D. But before spending $1K+ I would want to make sure it's worth it. Has any one compared 5D's AF with that of xx/xxxD? I'm more interested in one shot, center AF, fairly static object.

Reason I'm asking is I'm not very happy with xxxD's AF. I've done such a test: use tripod, mirror lock up,remote,center AF, etc, and 85mm@F2 to shoot a bottle/battery with small letters on them (that you can barely read from the photo). Each time I would manually de-focus the lens and then let it auto focus. I took the exact same shots 10 times, and only 50% are tack sharp. This way, I can rule out it's a lens problem. It has something to do with AF system's error rate. I find that the 50% tack sharp rate not impressive. Is the 5D a lot better? Has any one done similar testing on xxxD vs xxD vs 5D?

EDIT: the reason I do this test is because I found many of my real world shots slightly out of focus. And this test seems to confirm with my real world experience.

I can't speak for the 40D or the 50D or any xxxD, but I have experience with the 5D and 30D. Although the 30D is a good body, the 5Ds AF was enhanced for center point AF and does seem to be improved in my experience, although I didn't do in-depth AF testing.

The one issue that people have had with the AF of the 5D is that it doesn't have precision AF points outside of the center, which can cause some suffering in low light, but from what I gather the bulk of users are quite pleased with the cross-type and grouped AF assist center points.

Thanks, Tony. Anyone know of a published review? I often run into situation that the "best shots" out of a bunch is slightly out of focus, and I'm not very happy about that.

I'd be shocked if the 50D AF wasn't at least slightly better than 5D given the ages of the cameras, Digic IV and the ability to micro-adjust your lenses. If I recall from other threads people thought 40D was about equal or slightly better for AF vs. 5D and 50D should be an improvement on that.

lungdoc wrote in post #6726138
I'd be shocked if the 50D AF wasn't at least slightly better than 5D given the ages of the cameras, Digic IV and the ability to micro-adjust your lenses. If I recall from other threads people thought 40D was about equal or slightly better for AF vs. 5D and 50D should be an improvement on that.

I haven't had 5D or even 40D for very long to test, so what I say is purely guess/rumor. But I think some camera or not doing as good a job because Canon didn't want it to, not because Canon don't have the ability to. It's all because of the tiering model Canon enforces. I've heard from many source that some of the old film cameras have better/as good AF unit than many of current DSLRs.

The major complaint I have with my pair of 5Ds is the AF. The center focus point is pretty good, but when shooting portraits at wide apertures, focus-recompose makes the part of the photo you want in focus, out of focus. So you really need to use the outer points, and I find the outer points on my 5Dd to be very innacurate. When shooting at f2 or faster, I typically take a few shots to make sure one is in focus.

One of my 5D's is in the shop, so I picked up a 40D for my wedding last weekend. The AF on the 40F seemed much better than that of my 5D and the off center points were very accurate. I shot a lot with the 85 f1.2 @ f1.2 and my keeper rate was significantly higher than when I've shot the 85 f1.2 wide open in similar lighting in the past.

Just my experiences, others might be different.

dr_who,
I have both the 5D and the 40D and to me the 40D AF is much better! All focus points on the 40D is much better then my 5D AF points (including the 5D center focus point) in low light focusing. All 40D focus points are Cross-Type where the 5D are not (except the center point).
However the 5D does have 6 hidden focus points around the center which do give it good tracking of moving subjects in good light.

When my 5D was my main camera I rarely used AF but with my 40D I rarely use MF

My experience has been the center AF point on the 5D is just as good as the center point on my 40D. The outside focus points of the 40D are better. This is saying something, because the 40D's AF is light years better than the rebel lines'. That being said, if spot on and accurate auto-focus is your largest concern/decision point, I would recommend a 1D series body. The auto-focus on a 1D classic even, obliterates the AF of both the 5D and 40D

I had a 5D (sold to fund the 5Dii) and own a 40D. The 40D's outer points are better in low light, but the 5D's center is better in any light. Also the 5Ds AI servo tracks better when using the center.

If you ONLY care about center AF, one shot, and a static object the 5D is amazing. It's the most accurate canon body I've had in terms of keepers. Sometimes it's a tad slow in low light locking on, but it always achieves a lock and nails it. It's outer points are the only issue I've found, and it's a similar issue with a 40D in similar light.

thanks for all your input. Looks like 5D and 40D are pretty close with each's own advantage in turn of AF. Hemm, looks like 40D might fit me better since it's 1/2 the price of 5D.

I've found exactly the opposite. When I am shooting low light things the 5D is far superior. With the 40D it hunts and hunts.

This just happened to me this weekend.

jacobsen1 wrote in post #6727282
I had a 5D (sold to fund the 5Dii) and own a 40D. The 40D's outer points are better in low light, but the 5D's center is better in any light. Also the 5Ds AI servo tracks better when using the center.

If you ONLY care about center AF, one shot, and a static object the 5D is amazing. It's the most accurate canon body I've had in terms of keepers. Sometimes it's a tad slow in low light locking on, but it always achieves a lock and nails it. It's outer points are the only issue I've found, and it's a similar issue with a 40D in similar light.

Pretty much the exact words I would say.
I would only add that the 5D also tracks with center point better than my 20/30/40D ever did.
Only thing I would change is it being "slow". While its not as fast as my MkIII, it focuses faster in low light than my XXD bodies did.

I don't have any real proof, but I just got my 50D the other night and it's AF compared to the XTi's was like an epic battle between Chuck Norris(XTi) and Bruce Campbell(50D).

The Chin won, hands down!


Seriously. I put my nifty fifty on the 50D and it breathed a whole new life into that lens. I never realized how great that lens COULD be in AF until 2 nights ago!!!

AdamLewis wrote in post #6727547
Only thing I would change is it being "slow".

yeah, that's relative for sure. I wouldn't have said that until I had a kid... Now, in low light, with him moving, I'd bet I could challenge a 1 series at times. I'm certainly not going to complain about the 5D's AF, it's perfect for what that body is designed for IMHO.

Also, as for the 40Ds outer points. Yes they work better in low light... BUT! They still hunt and sometimes giveup. I've basically abandoned outer points all together in low light. I sold my 1 series before I had a kid, so I can't say if that's even good enough, but I will say with a 40D or 5D I just go for the center AF point and make it work. Otherwise the cameras either NEVER acheive lock, or do it just before he moves so I miss the shot anyway. Center focus and recompose works well enough.

For reference, I'm talking about 1600, f/2.0 and 1/45~1/60th in terms of light. Just to give you an idea of why I'm struggling. This is like one light bulb on low light.

i tried both (5d is belong to my cousin), AF on 40D is faster, and not hunting at low light, while 5D is somewhat keep hunting (but once the AF is locked, its very accurate, i felt more accurate than my 40D ( please anyone confirm this as i only played the 5D for 15 mins, and i tried centre AF only) thanks