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Author Topic: Shot wedding with 5DIII, dissapointed in AF  (Read 39132 times)

shizam1

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #75 on: April 02, 2012, 05:08:53 PM »
I just did some shots in my basement, lighting was dark, ISO 1600 f/2.8 and 3 second shutter speed.

It would take 2-3 seconds to acquire focus, and changing between expansion mode and not didn't do anything.

So at least for my camera, in really dark scenes, changing that setting won't give better AF performance.

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #75 on: April 02, 2012, 05:08:53 PM »

Bosman

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #76 on: April 02, 2012, 05:14:02 PM »
I just did some shots in my basement, lighting was dark, ISO 1600 f/2.8 and 3 second shutter speed.

It would take 2-3 seconds to acquire focus, and changing between expansion mode and not didn't do anything.

So at least for my camera, in really dark scenes, changing that setting won't give better AF performance.
now try it with a 70-200 instead of an 85mm F1.2 or whatever you used.
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shizam1

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #77 on: April 02, 2012, 05:15:55 PM »
I just did some shots in my basement, lighting was dark, ISO 1600 f/2.8 and 3 second shutter speed.

It would take 2-3 seconds to acquire focus, and changing between expansion mode and not didn't do anything.

So at least for my camera, in really dark scenes, changing that setting won't give better AF performance.
now try it with a 70-200 instead of an 85mm F1.2 or whatever you used.

I actually used my 70-200 f/2.8L II

Bosman

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #78 on: April 02, 2012, 05:20:52 PM »
I just did some shots in my basement, lighting was dark, ISO 1600 f/2.8 and 3 second shutter speed.

It would take 2-3 seconds to acquire focus, and changing between expansion mode and not didn't do anything.

So at least for my camera, in really dark scenes, changing that setting won't give better AF performance.
now try it with a 70-200 instead of an 85mm F1.2 or whatever you used.

I actually used my 70-200 f/2.8L II
DOH! That sucks man, what are you going to do? Do you have a 1d to test against it?
Wait...3 sec shutter speed? I wonder if that has a bearing on anything...just hinking im going to try some tests myself now.
« Last Edit: April 02, 2012, 05:22:31 PM by Bosman »
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altenae

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #79 on: April 02, 2012, 05:21:37 PM »
How dark is 2.8 @1600 ISO with 3 seconds exposure ??
Just a question, but what do we expect from the AF with this kind of darkness ??

Bob Howland

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #80 on: April 02, 2012, 05:31:52 PM »
How dark is 2.8 @1600 ISO with 3 seconds exposure ??
Just a question, but what do we expect from the AF with this kind of darkness ??

I was wondering that myself. Using an Excel application just downloaded from the Internet, it is EV -2.6, which is less than the lower limit specified by Canon. I really wish that somebody would check this, though. There are bunches of charts on the Internet, but most assume a constant ISO of 100.

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #81 on: April 02, 2012, 05:39:08 PM »
Is this the one you are talking about:

http://learn.usa.canon.com/resources/articles/2011/1dx_af_pts_article.shtml

edit: this is for the 1DX, but it is helpful as well:

http://www.learn.usa.canon.com/resources/articles/2012/1dx_guidebook.shtml?categoryId=12
No it wasn't, I haven't seen that one, I'll have to have a read later in the week.

The article I was thinking of was actually for the 1D X, not the 5D MkIII and isn't specific, but it states that you shouldn't use single point spot for low light (which is irrelevant to this thread and obvious to most of us anyway) and that point expansion is to improve tracking. Reading between the lines, it suggests that point expansion shouldn't be used for slow moving/stationary targets. So while it isn't clear, it's suggestive that single point is the best option for low light. Of course, whether that makes it it any quicker isn't guaranteed.
That is helpful information. If you find the link back that would be sweet.
This link has good info at the Canon learning center.
http://www.learn.usa.canon.com/dlc/search/search.spr?keyword=Rudy%20Winston&filterBy=Article
The AF system starts on page 4, with the bit I was referring to on page 5.
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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #81 on: April 02, 2012, 05:39:08 PM »

itsnotmeyouknow

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #82 on: April 02, 2012, 05:39:34 PM »
How dark is 2.8 @1600 ISO with 3 seconds exposure ??
Just a question, but what do we expect from the AF with this kind of darkness ??

I would say too much!

Bosman

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #83 on: April 02, 2012, 05:43:45 PM »
I just can't make my camera have problems like you describe, but yea, who handhold focusses 3 sec long and expects the camera to take less than a couple seconds to focus, not me.
The only thing i check for focus speed or if i want to reset it is to wing the focus ring way outta focus in which case a lot of cameras will struggle with what do do in those darker situations whereas in good lighting it moves the elements quickly into place. Between the 70-200 and the 50f1.2 getting to a place of focus takes much longer on the 50f1.2 but then the barrel focussing is so precise it must move on a much smaller threaded motor. I think of like the 85 and 50 f1.2 as going from a normal thread screw on most lenses to a super fine threaded screw that takes a lot longer to thread a nut on. Once i have things in focus within a general area the focus snaps to the next thing.
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Bosman

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #84 on: April 02, 2012, 05:46:43 PM »
Is this the one you are talking about:

http://learn.usa.canon.com/resources/articles/2011/1dx_af_pts_article.shtml

edit: this is for the 1DX, but it is helpful as well:

http://www.learn.usa.canon.com/resources/articles/2012/1dx_guidebook.shtml?categoryId=12
No it wasn't, I haven't seen that one, I'll have to have a read later in the week.

The article I was thinking of was actually for the 1D X, not the 5D MkIII and isn't specific, but it states that you shouldn't use single point spot for low light (which is irrelevant to this thread and obvious to most of us anyway) and that point expansion is to improve tracking. Reading between the lines, it suggests that point expansion shouldn't be used for slow moving/stationary targets. So while it isn't clear, it's suggestive that single point is the best option for low light. Of course, whether that makes it it any quicker isn't guaranteed.
That is helpful information. If you find the link back that would be sweet.
This link has good info at the Canon learning center.
http://www.learn.usa.canon.com/dlc/search/search.spr?keyword=Rudy%20Winston&filterBy=Article
The AF system starts on page 4, with the bit I was referring to on page 5.
I don't know which article you are referring to as page 4...The link i provided had several articles on it.
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DavidRiesenberg

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #85 on: April 02, 2012, 05:52:12 PM »
Yeah, it's very dark but I just tested it myself and I found it very situational. When it did manage to focus, it did it in about 1-1.5s. But it was extremely hard to find something with enough contrast to even achieve lock. The room was lit by and LCD screen btw which cast a pretty even dim light. As a contrast, AF was as quick as ever when I aimed it at charger LED. Lens was 50mm f/1.2

Bob Howland

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #86 on: April 02, 2012, 05:58:45 PM »
FWIW, I found the LV calculator I used here:

http://www.pentaxforums.com/forums/photography-articles/88197-excel-2003-lv-light-value-calculator.html

I compared its output, at three different sets of values, with the table on Wikipedia Exposure Value page and they agree.

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #87 on: April 02, 2012, 06:01:11 PM »
Mine so far focuses instantly in low light, but I've only been using the default center spot.  My 5D MK II was also instant, but a hair slower, and the 5D MK II was one of the fastest low light AF bodies around.
 
I did turn off all the lights in my studio and verifying that it would not AF, then as I added light so that it needed ISO 102000 to focus at 1/60 and f/4, it took 3 or 4 seconds to AF.  As the light became enough to use ISO 25600, focus was fast.  I was using my 135mm L to test this.
 
I haven't tried the AF assist light on my 580 EX II, because it did not need it in what I considered to be extreme low light.  I'm wondering if the issue might have been related to the flash unit.  I'll try mine again tonight and try to duplicate your problem, it would be good to know if something is triggering this, or if your AF has a problem, or if mine also has a issue that I did not see. 
 
I do lots of extreme low light photography in near darkness and focus is perfect and fast with my MK II, so focusing in very low liight is a must for me.
 
 

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #87 on: April 02, 2012, 06:01:11 PM »

shizam1

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #88 on: April 02, 2012, 06:04:13 PM »
How dark is 2.8 @1600 ISO with 3 seconds exposure ??
Just a question, but what do we expect from the AF with this kind of darkness ??

It was pretty dark :)  It was my basement.  I wasn't shooting in an environment that dark the other night.  Lighting was spotty though ( literally, with lot's of mini-floods creating mood ), so I'm sure some spots were darker than others.

Anyway, my the point of the original post, was in dark situations, the 5DII focused as fast as the 5DII, and I was kind of hoping for some improvement.  As well, switching from single AF point to the expansion or vice versa didn't seem to make much difference under those dark conditions.

Kernuak

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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #89 on: April 02, 2012, 06:04:37 PM »
Is this the one you are talking about:

http://learn.usa.canon.com/resources/articles/2011/1dx_af_pts_article.shtml

edit: this is for the 1DX, but it is helpful as well:

http://www.learn.usa.canon.com/resources/articles/2012/1dx_guidebook.shtml?categoryId=12
No it wasn't, I haven't seen that one, I'll have to have a read later in the week.

The article I was thinking of was actually for the 1D X, not the 5D MkIII and isn't specific, but it states that you shouldn't use single point spot for low light (which is irrelevant to this thread and obvious to most of us anyway) and that point expansion is to improve tracking. Reading between the lines, it suggests that point expansion shouldn't be used for slow moving/stationary targets. So while it isn't clear, it's suggestive that single point is the best option for low light. Of course, whether that makes it it any quicker isn't guaranteed.
That is helpful information. If you find the link back that would be sweet.
This link has good info at the Canon learning center.
http://www.learn.usa.canon.com/dlc/search/search.spr?keyword=Rudy%20Winston&filterBy=Article
The AF system starts on page 4, with the bit I was referring to on page 5.
I don't know which article you are referring to as page 4...The link i provided had several articles on it.
Sorry, I was referring to the article I forgot to link to.

http://cpn.canon-europe.com/content/education/technical/eos_1d_x_explained.do
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Re: Shot wedding with 5DIII, dissapointed in AF
« Reply #89 on: April 02, 2012, 06:04:37 PM »