1D MKIII AF - How Dark Till No AF?

I'll give it a go again tonight in some challenging lighting. I hope it's just an isolated issue due to back lighting like you said.

GerBee wrote in post #7616200
This should be no contest for the 1DMKIII.

The second picture though, may be put off by the back lighting. This is something I find irritating with most Canon cameras actually, they do have a tendency to be disturbed by bright backgrounds.

I don't think this is limited to Canon cameras. Most would have difficulty in a situation like this I think.

I've taken out my 50mm ƒ1.4 and do not find much difficulty with it, it's never been stellar in AF but in my darkened living room I feel I'd have nailed the AF under the conditions posted.

ISO1600/Spot Metering/Right AF Point/out of camera Jpeg L

http://www.pbase.com/g​er_bee/1d_mkiii_after_​fix
One Shot:

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It's interesting, there are posters here who are reporting the opposite of some here... low light and backlit situations are MUCH IMPROVED now with the new fix.
http://www.fredmiranda​.com/forum/topic/74984​1/5#6888787

Then again, there are some reporting better high ISO performance which makes no sense.

Use an AF assist light. It'll improve your AF by 100 times in conditions like that.

And yeah, you gotta help out your AF system by putting a high contrast line on your AF sensor when you hit that AF-ON button. It's not magic, you gotta throw it something usable to work with.

picturecrazy wrote in post #7616431
Use an AF assist light. It'll improve your AF by 100 times in conditions like that.

And yeah, you gotta help out your AF system by putting a high contrast line on your AF sensor when you hit that AF-ON button. It's not magic, you gotta throw it something usable to work with.

Finally, a voice of reason. We can always count on Lloyd!

A good flash unit with AF assist will enable you to focus on a blank wall in total darkness. If you don't want flash, you can use a custom function to prevent it from firing.

Although mine had other focus issues, the 1D3 that I had last year was able to AF once at 1/8 second, f/1.2, ISO 6400 though it struggled IIRC. That would be an EV of -2.47 if I'm reading the chart right. I would say that it would be quite reliable at -1 - I didn't have mine long enough to test it that thoroughly.

My 5D2 appears to be about 1/2 stop behind.

drisley wrote in post #7614970
The 1D MK3 is by far the best low light AF camera I've ever used.

...and the beat goes on

DrPehta: If you shoot "single shot" you can add the ST-E2 to you camera and use the IR beam as an AF assist. It will not work in AI-Servo....but I have used it in completely dark rooms (I mean black) and it finds & focuses just fine......

(In case you are wondering why I would shoot in a completely dark room, I was doing some really odd ball flash shots and I did want any stray light in the room, just flash. As a result, I turned all the other lights off and found my way around with a flash light)

The ST-E2 may be an answer......good luck

GBRandy wrote in post #7617215
...and the beat goes on

DrPehta: If you shoot "single shot" you can add the ST-E2 to you camera and use the IR beam as an AF assist. It will not work in AI-Servo....but I have used it in completely dark rooms (I mean black) and it finds & focuses just fine......

(In case you are wondering why I would shoot in a completely dark room, I was doing some really odd ball flash shots and I did want any stray light in the room, just flash. As a result, I turned all the other lights off and found my way around with a flash light)

The ST-E2 may be an answer......good luck

That's why you use a ex580 or 430 instead of the st-e2, with flash disabled. You get the same beam, but you can also put it on slave mode, where it will blink the beam on and off fast enough that servo can work

basroil wrote in post #7617368
That's why you use a ex580 or 430 instead of the st-e2, with flash disabled. You get the same beam, but you can also put it on slave mode, where it will blink the beam on and off fast enough that servo can work

I need to read up on that (my flash knowledge is marginal)... you can disable the flash & use the IR AF assist without the flash firing? Excellent...albeit a bit heavy.... See two options now!

The red beam is a good answer but it's not always reliable for catching the edge point, dependent upon the lens in use.

In my theatre work currently the red beam has little effect on stage where it's mixing it up with the theatre lights.

If you want something small and cheap, and don't have an STE2, rather than using a heavy Canon flash, look into this.
http://www.sunpak.jp …products/pf30x/​index.html

However, as Gerbee says, it won't help in situations such as theatre (and should not be necessary either).