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Author Topic: Canon EF 50 F1.2L And EF 35 F1.4L Sharpest Settings  (Read 6161 times)

Bosman

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Re: Canon EF 50 F1.2L And EF 35 F1.4L Sharpest Settings
« Reply #15 on: September 15, 2012, 12:28:43 AM »
The 50L has focus shift - as you stop down from wide open, if back focuses, but at some point (which is dependent on subject distance) the thicker DoF overcomes the back focus.  So, if plotting the sharpness of the 50/1.2L based on autofocus (assuming it's AFMA'd normally, i.e. at f/1.2), I'd expect it to be sharp at f/1.2, then get progressively softer as you stop down until somewhere in the f/2.2-f/3.5 range, then get progressively sharper again, peaking at f/4 or f/5.6 then dropping again after f/11 when diffraction sets in.

What the heck are you doing lurking on these forums Neuro... you should be teaching a class on optics somewhere ...
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Re: Canon EF 50 F1.2L And EF 35 F1.4L Sharpest Settings
« Reply #15 on: September 15, 2012, 12:28:43 AM »

Viggo

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Re: Canon EF 50 F1.2L And EF 35 F1.4L Sharpest Settings
« Reply #16 on: September 15, 2012, 01:59:51 AM »
At 1.2 the depth of field on the 50mm L at close distances is about 4 millimeters. If you or the subject moves the slightest bit, it will not be in focus where you intended.

I usually compensate by shooting at F2 or 2.8 and find it very sharp at those f stops.

Ai Servo on the 1d x takes care of that.

Will the 5d miii do the same in Ai servo?

For a portrait with small movement I say they're very similar yes. If you work with the 85 L the difference in response is much better on the 1d x. But with the 1d will also track the eyeball of å running 3 year old at f1.2.
1dx, 24-70 L II, 50 Art, 200 f2.0 L

koolkurkle

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Re: Canon EF 50 F1.2L And EF 35 F1.4L Sharpest Settings
« Reply #17 on: September 20, 2012, 01:40:06 PM »
Neuro said,

"The 50L has focus shift - as you stop down from wide open, if back focuses, but at some point (which is dependent on subject distance) the thicker DoF overcomes the back focus.  So, if plotting the sharpness of the 50/1.2L based on autofocus (assuming it's AFMA'd normally, i.e. at f/1.2), I'd expect it to be sharp at f/1.2, then get progressively softer as you stop down until somewhere in the f/2.2-f/3.5 range, then get progressively sharper again, peaking at f/4 or f/5.6 then dropping again after f/11 when diffraction sets in."

So Neuro, here's the question, and I'm just spitballing.  Is there a workaround for the 50 1.2L's focus shift?  Have you ever AFMA'd your 50 1.2L at other apertures than f/1.2?  It seems you could generate a lens adjustment lookup table for the lens based on f-stop to squeeze the most sharpness from the lens.  I know you said it depends on subject distance, but the DIGIC knows what that is and could factor it in.  If there is utility in this approach, the next logical step would be convincing Canon to provide the capability to enter lens adjustment values based on f-stop.
« Last Edit: September 20, 2012, 01:42:44 PM by koolkurkle »

Studio1930

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Re: Canon EF 50 F1.2L And EF 35 F1.4L Sharpest Settings
« Reply #18 on: September 20, 2012, 02:59:35 PM »
Neuro said,

"The 50L has focus shift - as you stop down from wide open, if back focuses, but at some point (which is dependent on subject distance) the thicker DoF overcomes the back focus.  So, if plotting the sharpness of the 50/1.2L based on autofocus (assuming it's AFMA'd normally, i.e. at f/1.2), I'd expect it to be sharp at f/1.2, then get progressively softer as you stop down until somewhere in the f/2.2-f/3.5 range, then get progressively sharper again, peaking at f/4 or f/5.6 then dropping again after f/11 when diffraction sets in."

So Neuro, here's the question, and I'm just spitballing.  Is there a workaround for the 50 1.2L's focus shift?  Have you ever AFMA'd your 50 1.2L at other apertures than f/1.2?  It seems you could generate a lens adjustment lookup table for the lens based on f-stop to squeeze the most sharpness from the lens.  I know you said it depends on subject distance, but the DIGIC knows what that is and could factor it in.  If there is utility in this approach, the next logical step would be convincing Canon to provide the capability to enter lens adjustment values based on f-stop.

I tried the AFMA for my 50 1.2L and I found that it also varies by focus distance.  Basically there was no way to get an accurate adjustment unless you only shoot at a certain aperture and distance.  I sent my 50L back and spent my money on other glass.
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Bosman

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Re: Canon EF 50 F1.2L And EF 35 F1.4L Sharpest Settings
« Reply #19 on: September 20, 2012, 05:32:08 PM »
My focal results from 50L from 5 ft of the target shows F4.5 to be sharpest with Micro adjustment of 8. It drops dramatically from there to F1.2. Sharpness peaks from F4 to F5.6 as i had guessed before testing.
I don't have the 35 but the 24L and it was best at F4 +7 micro adjustment.
This will be best for me given this is my distance from subject more often than not.
« Last Edit: September 20, 2012, 05:35:13 PM by Bosman »
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Re: Canon EF 50 F1.2L And EF 35 F1.4L Sharpest Settings
« Reply #19 on: September 20, 2012, 05:32:08 PM »