5D3 & 600ex-rt + AF assist beam = slower focus

[jaayres20]

Not of specific relevance to the thread, but, I recently got some 600EX-RT's and because of this thread I tried the AF assist beam with my 1Ds MkIII and my slowest focusing lens, the 100mm IS L Macro with the limiter switch to full range. This is normally an invitation to hunt for what seems like several seconds as it racks from infinity to MFD and back.

 So I went into a completely dark room with a popcorn ceiling and couldn't believe how fast the AF was! MUCH faster than in normal light even when I started the focus at MFD or infinity, I also tried selecting edge points on the AF, all shots were perfectly focused too, seriously, it focused like the 70-200 f2.8IS in normal light, practically instantly.

So that means it is the 5d3 with any kind of AF assist beam that is causing the issue. That is so frustrating because the camera is great in so many ways and this almost ruins it. 

[echelonphoto]

That fix is not acceptable...if you set to release priority...you get oof images half the time....so that really defeats
the reason for buying a camera with supposedly better af....what a farce!

[Marsu42]

That fix is not acceptable...if you set to release priority...you get oof images half the time....so that really defeats
the reason for buying a camera with supposedly better af....what a farce!

Actually that was exactly my thought when I read it, but since I don't own a 5d3 (yet) and just am trying to figure out if to get a 6d instead it's hard to say if people are either protective of their expensive investment or - the other side - overcompensating and bashing it because of disappointment. Unfortunately this issue is not something I can test myself in a photo store, so I have to rely on owner's opinions.

The other problem is to define "low light" because nowadays photogs aren't running around with light meters anymore, so that's another cause for the contradicting opinions on how serious this is (with or without af assist).

Last not least, Canon ignoring this either means it's a non-issue silently fixed in the next fw or a really serious problem :-p

[echelonphoto]

Actually....the 6d seems to have this same problem...just saw a thread on it. I guess Canon fixed one thing and
broke another (the response to focus assist infrared). I just did and extreme test....took both cameras into the
bathroom and turned off all the lights...total darkness. Use flash and the 24-105....the mark 2 focused just about
as fast as you could shoot and even on a totally flat wall...no contrast. The mark3 hesitated all over the place and
half the shots were oof.

[Marsu42]

Actually....the 6d seems to have this same problem...just saw a thread on it. I guess Canon fixed one thing and
broke another (the response to focus assist infrared).

Can you give the link to the 6d thread?

I wonder if the 6d could really have the same problem given the fact that it uses nearly the same af as the 5d (minus some af assist points, plus better center low light af). I'm ok if it doesn't af in my bathroom, but it should be able to do dark meetings/receptions :->

Btw: Did you use a 600rt for your test? What af mode (single point/all/...)?

[echelonphoto]

The thread is right in this same forum

[echelonphoto]

Sorry....it was the 600D

[echelonphoto]

The flash I used in the test was the 600 rt. Yes, my toilet paper was perfectly sharp with 5d2

[neuroanatomist]

Happens on the 1DX too...
They didn't care tbh - it's not a problem apparently.

Not on my 1D X.  One flash of the AF assist lamp, then the AF confirm beep happens immediately (and the focus is accurate).  Does that in low light with a low contrast subject, does it in a pitch black room with the camera pointed at a blank white wall.  Works with the center AF point selected, works with an edge AF point selected (only difference is the center point just projects a thin, vertical red strip whereas with an off-center point the full grid is projected).  Same behavior, same fast AF lock with the assist lamp on both a 600EX-RT and a 430EX II.

[Louis]

This problem is so huge, Im surprised that so many people have not come forward with this problem, 100s of photographers are being paid to shoot jobs in low light and I am certain they use a 5D3 also, maybe Canon does know about this problem and may address it soon, I really hope they do, as It worries me to even accept a job now because of this

[jaayres20]

Happens on the 1DX too...
They didn't care tbh - it's not a problem apparently.

Not on my 1D X.  One flash of the AF assist lamp, then the AF confirm beep happens immediately (and the focus is accurate).  Does that in low light with a low contrast subject, does it in a pitch black room with the camera pointed at a blank white wall.  Works with the center AF point selected, works with an edge AF point selected (only difference is the center point just projects a thin, vertical red strip whereas with an off-center point the full grid is projected).  Same behavior, same fast AF lock with the assist lamp on both a 600EX-RT and a 430EX II.

Do you happen to have a 5D3 as well that you could test?

[neuroanatomist]

Do you happen to have a 5D3 as well that you could test?

Sorry, no.

[Area256]

I have a 60D and 580EX II, and I have the same problem (focus takes 2-3 seconds and often misses with AF assist).  I don't understand why this happens, but judging by the comments here it's a common issue for Canon.  The "fix" is fairly simple: disable the AF assist light and aim for high contrast areas on your subject.  Even with the 60D's more basic AF, I've never had a serious problem in dark halls, as long as I pick good spots. Was hoping they would fix this for the 5D3 and 600ex-rt, but sounds like we are still stuck using non-assisted AF.  Since I don't have a firmware update to fix this, I assume it won't happen with the 5D3.

[Marsu42]

I have a 60D and 580EX II, and I have the same problem (focus takes 2-3 seconds and often misses with AF assist).

Ok, now it's getting really strange - at least with my 60d and the 70-300L & 100L the camera near focuses instantly without hunting with the af assist beams of the 430ex2 and 600rt. It takes just a little longer than in good light because it beams, focuses, beams again and does the final focus. If your 60d hunts then there's definitely something wrong with your setup.

[nubu]

After reading this post I checked my 5DIII and the 600ex flash together with the 24-105 lens and had no problems to quickly focus in completely dark rooms even at structureless walls by the help of the assist pattern... I have no idea what is wrong with your systems... I was trying both single central point as well as all points available.