Strange auto focus behaviour in 7D

maboleth · Jul 10, 2012

Today I went on the beach with 100mm IS L f2.8 lens and 7D and it missed every shot - they were all backfocused even on f8. It drove me crazy.

Then I put +5 on MA and it was better and usually spot-on. However, after few hours I returned home and noticed that +5 MA was bad, I disabled it and it's now focusing ok.

My question is - what happened? It was very hot and humid... can that interfere with the way AF works?

On a personal note - I'm not so fond of 7D's auto focusing and cannot wait to sell it and buy 5d mark3... I always had some kind of weird focusing "issues" with it... I make money with photography and I got used to it, but I find it not that accurate. But today was a complete disaster.

Thanks.

--
http://ivframes.com -- my official site
http://facebook.com/ivframes -- become a fan
http://travelingnome.ivframes.com -- bits of this and that

TTMartin · Jul 10, 2012

What focus mode?

Which autofocus point selection mode, Single-point AF (Manual selection), Zone AF (Manual selection of a zone), Auto select 19-point AF, Spot AF (Manual selection), or AF point expansion (Manual selection)?

What was your subject?

Was it moving?

Dale Buhanan · Jul 10, 2012

When you set MA to +, you move the focus plane further back. So if it was back-focusing before, +5 MA would make it back focus even more. -MA pulls the focus plane back closer to you. +MA moves the focus plane further back, away from you.

As to why your lens behaved differently from on the beach to back home... I have no idea. My guess woud be the contrast of the focus target you were trying to focus on... but that really is only a guess. I have not experienced anything like that with my own 7D --- (yet at least)

maboleth said:
Today I went on the beach with 100mm IS L f2.8 lens and 7D and it missed every shot - they were all backfocused even on f8. It drove me crazy.

Then I put +5 on MA and it was better and usually spot-on. However, after few hours I returned home and noticed that +5 MA was bad, I disabled it and it's now focusing ok.

My question is - what happened? It was very hot and humid... can that interfere with the way AF works?

On a personal note - I'm not so fond of 7D's auto focusing and cannot wait to sell it and buy 5d mark3... I always had some kind of weird focusing "issues" with it... I make money with photography and I got used to it, but I find it not that accurate. But today was a complete disaster.

Thanks.

--
http://ivframes.com -- my official site
http://facebook.com/ivframes -- become a fan
http://travelingnome.ivframes.com -- bits of this and that

--
kind regards
Dale

maboleth · Jul 10, 2012

Sorry, I meant it was front focusing... I was using single point, one shot mode.

I tried using other point modes too, but that didn't help. The 7D was focusing instantly but every shot was bad.

The light was good, the people (subjects) weren't moving and the scene had good contrast. But something was wrong... I was really @#^#! how my 7D treated this ultra-fast focusing L lens, that is well-known for accuracy.

So I just wanted to know did anyone experience something similar? As I said I'm not so fond of the hyped 7D's AF module, but today was a complete mess that I never experienced before. I can only blame the weather... for now.

--
http://ivframes.com -- my official site
http://facebook.com/ivframes -- become a fan
http://travelingnome.ivframes.com -- bits of this and that

Shamus1 · Jul 10, 2012

I've had a 7D since it came out and have never been 100% happy with the AF. I also have a 1DMkIV, 1DMkIII, 5DMkIII... Finally tired of it and sent it to Canon. Surprise, it had an AF issue which they fixed and now it is dead on. Wasn't consistently bad, but enough not to be reliable. Sorry I waited to send it.

maboleth · Jul 10, 2012

Yes shamus, unfortunately where I live, there's no "reliable" Canon service. We have the official service, but they aren't just good enough.

I already sent my 7D to the service few weeks after I bought it and they said nothing was wrong, even though they wrote "calibrated AF sensors" on the warranty plate. However, I haven't noticed any improvement at all. It just wasn't reliable, at least not the way I wanted.

But I got used to it, I do get sharp photos now, most of the time, without complains, but today was a complete consistent mess.
Can't wait to sell it and buy 5DMK3, honestly.

Shamus1 said:
I've had a 7D since it came out and have never been 100% happy with the AF. I also have a 1DMkIV, 1DMkIII, 5DMkIII... Finally tired of it and sent it to Canon. Surprise, it had an AF issue which they fixed and now it is dead on. Wasn't consistently bad, but enough not to be reliable. Sorry I waited to send it.

--
http://ivframes.com -- my official site
http://facebook.com/ivframes -- become a fan
http://travelingnome.ivframes.com -- bits of this and that

mmullen · Jul 10, 2012

maboleth said:
Today I went on the beach with 100mm IS L f2.8 lens and 7D and it missed every shot - they were all backfocused even on f8. It drove me crazy.

Then I put +5 on MA and it was better and usually spot-on. However, after few hours I returned home and noticed that +5 MA was bad, I disabled it and it's now focusing ok.

If it was hot out that will change the AF calibration. Canon has improved the temperature stability of the AF mechanisms in newer cameras like the 7D but the high pixel density will show the smallest errors clearly. That is a testament to the resolving power of a 7D.

Also, the AF system has a EV specification of EV -1 to EV 18. The AF works best in the middle of this range. You were likely near the bright end of the range.

--
Mike Mullen

EDWARD ARTISTE · Jul 10, 2012

Ah, the legendary 7d AF rears its head once again.

I for one dont know what to do with mine...dont much trust it for portraits and/or street photography.

I may trade up to a 5d mkii. Without decent AF, its pretty useless. thank goodness for my t2i.

Shamus1 said:
I've had a 7D since it came out and have never been 100% happy with the AF. I also have a 1DMkIV, 1DMkIII, 5DMkIII... Finally tired of it and sent it to Canon. Surprise, it had an AF issue which they fixed and now it is dead on. Wasn't consistently bad, but enough not to be reliable. Sorry I waited to send it.

--
'Only the dead have seen the end of war'

Karl Gnter Wnsch · Jul 11, 2012

EDWARD ARTISTE said:
Ah, the legendary 7d AF rears its head once again.

If there is an issue that is bothering you do have it serviced. If you don't have it serviced (which only a complete and utter moron wouldn't do if there is an issue) stop moaning, it's helping nobody!
--
regards
Karl Günter Wünsch

mmullen · Jul 11, 2012

EDWARD ARTISTE said:
Ah, the legendary 7d AF rears its head once again.

The 7D has the best AF of any APS-C camera ever! Which is to say it has more speed, versatility and more accuracy compared to any other APS-C AF.

--
Mike Mullen

liquid stereo · Jul 11, 2012

I must say I love it. The only issue I've had is when shooting with the 400/2.8 L, and the subject was close to some power-lines. It would go back-and-forth, very rapidly, focusing on the osprey or the power-line. I think I may have needed to slow the speed of the AF or just change my angle (field-of-view).

Other than that, I simply love the 7D. The AF absolutely rocks.

Cheers!

EDWARD ARTISTE said:
I for one dont know what to do with mine...dont much trust it for portraits and/or street photography.

I may trade up to a 5d mkii. Without decent AF, its pretty useless. thank goodness for my t2i.

Shamus1 said:

I've had a 7D since it came out and have never been 100% happy with the AF. I also have a 1DMkIV, 1DMkIII, 5DMkIII... Finally tired of it and sent it to Canon. Surprise, it had an AF issue which they fixed and now it is dead on. Wasn't consistently bad, but enough not to be reliable. Sorry I waited to send it.

Click to expand...

--
'Only the dead have seen the end of war'

Jerry-astro · Jul 11, 2012

Karl Gnter Wnsch said:
EDWARD ARTISTE said:

Ah, the legendary 7d AF rears its head once again.

Click to expand...

If there is an issue that is bothering you do have it serviced. If you don't have it serviced (which only a complete and utter moron wouldn't do if there is an issue) stop moaning, it's helping nobody!
--

Karl, this guy much prefers sitting in this forum and whining rather than actually doing something about his problem. I'm sure most everyone here would be delighted if he simply replaced his camera and moved to a different forum (probably to whine some more about that one).

Boky · Jul 13, 2012

mmullen said:
Also, the AF system has a EV specification of EV -1 to EV 18. The AF works best in the middle of this range. You were likely near the bright end of the range.

--
Mike Mullen

yeah.... sunny day, a lot of light, fast lens => oversaturated AF servo.

Boky

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Strange auto focus behaviour in 7D

maboleth

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TTMartin

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Dale Buhanan

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maboleth

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