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Author Topic: Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2  (Read 1908 times)

Haponat

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Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2
« on: April 03, 2013, 03:50:08 AM »
Hey guys,

I when to Canon HQ in HK today and tried the ef 50 1.2 and 85 1.2 with canon 5d mark iii. I noticed that the black AF point on the viewfinder turned greyish. I thought the 5d mark iii that i was using was old that why the af points are not solid black anymore.

Told the staff about it and they didnt have any idea why. Hanged around and checked other lenses, then two staff came to me and told me the reason why it appears grey because the aperture is so big making the black points exposed to a large amount of light resulting to a greyish appearance. It was hard to see the af points. They asked me to try the 24-105 and the color turned black again.

I am not sure if this is the case with people owning those lenses with that body. Anything we can do to help avoid this phenomenon or how to ask canon to improve the af points with those lenses?

Thank you for reading my weird findings today.

Sorry i didnt take any photo of the af points, maybe you guys try it for yourself if u have time.

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Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2
« on: April 03, 2013, 03:50:08 AM »

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Re: Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2
« Reply #1 on: April 03, 2013, 09:05:45 AM »
I think it's normal.  I never noticed it before your post but mine does something similar.  With the 5DIII and a f/2.8 lens mounted, the point turns grayish with I point it toward a strong light source.  The effect is stronger when I tried a f/1.2 lens.  If I don't point it towards a strong light source, it is darker.  Either way, I have no problems seeing the AF point, unless trying to AF under very dark conditions.  Probably has to do with the large aperture and amount of oblique light getting around the LCD layer to make it less black, so I don't think it is something that can be improved easily.  It never bothered me before and won't bother me in the future.

Swphoto

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Re: Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2
« Reply #2 on: April 03, 2013, 10:19:48 AM »
I just checked, and you're right - the points are lighter (you can compare it by stopping the lens down using the DoF preview button - just tested f/1.2 to f/4 while pointed at my computer monitor).

However, as the previous poster said, it's never been an issue while shooting and I wouldn't have noticed it if you hadn't mentioned it.

Based on the title I expected this thread to be about something else - needing different AFMA values for the outer points vs the center point - that's an issue I notice  ;D

sandymandy

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Re: Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2
« Reply #3 on: April 03, 2013, 10:33:08 AM »
I thought the 5d mark iii that i was using was old

The earliest sold models are like 1 year old now :D Cant believe 5diii is considered old already by some :P What if u select an AF point? Is the red easier to see?

neuroanatomist

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Re: Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2
« Reply #4 on: April 03, 2013, 11:53:47 AM »
What you're seeing occurs because of the stock focus screen - they are laser microetched to be 'brighter' with slow lenses, but a consequence of that is they only show the DoF of an f/2.8 lens (approximately) even with faster lenses.  The light gets in from the wider aperture, and that 'washes out' the transmissive LCD, but you don't see the additional light through the VF. 
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RS2021

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Re: Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2
« Reply #5 on: April 03, 2013, 07:39:48 PM »
In the same vein, the shallow DOF and bokeh "seen" wide open at f/1.2 through the viewfinder doesn't correspond in 85L with the image "captured" on the sensor which will have even shallower DOF than what you saw. Even stopped down to ~f/2.0 and even if you press the DOF button to preview, the DOF/bokeh "seen" doesn't change until you stop down to about ~f/2.0+. That is one full f/stop and then some.

But the final image on the sensor will reflect the actual f/1.2 or f/1.4 you set, generating more shallow DOF and bokeh than what you saw through the finder.

Somethings to keep in mind with such fast primes.
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Re: Canon EOS 5D Mark III AF Points with 50 1.2 and 85 1.2
« Reply #5 on: April 03, 2013, 07:39:48 PM »