Anyone used FoCal for 5D MKIII lens calibration?

ajax_andy

ajax_andy

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Andy
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I'm having a few issues with one of my lenses which when I've done my own test varies wildly from about +3 out to going all the way up to +20 and it still being out... think I need something more specific than a tripod and a lens test sheet. I've heard mixed things about FoCal with newer bodies so wondered before I make the plunge and buy it if anyone had used it with the MKIII?
 
Done all my lenses on both the 5DIII and 1DX, never had an issue. Just wish Canon would sort out their SDK and let Focal work in fully automatic mode rather than manual on these 2 cameras. I hear that the 7DII is the same ie you have to use the MSC mode.
 
Yep used it for all my lenses on the 5D3 and my old 7D. Haven't got round to sorting the 6D yet though.

Works well, although I do each lens twice to ensure consistency. Only downside with the 5D3 is that it's not fully automatic and you have to change the adjustment settings as directed during the process.
 
Yup did my new 5d mk3 this morning. Focal can be temperamental at times though. Got one disconnect with 3 lenses where as my 7D used to drop connection a fair bit.
The process is a little odd I find, especially the target setup but its not tricky. Version 2 is about to land very soon so I imagine it will be a bit slicker and its a free upgrade.
 
Another vote for FoCal.......yup it's a shame it's not fully automatic with the 1 Dx, 5D3 or 7D2, blame Canon!!
 
I bought FoCal but it's not exactly consistent in its results... case in point (but I've found it with all my lenses) the 24-70mm f/2.8:

8 tests done now and the results were:
-2
-1
0
0
-2
-2
0
-3

So which is it? Doing one final test and if it's -2 or 0 I'll just use the law of averages and go for that
 
Yeah from trial and error I've just been taking averages of a load of repeats at the same and different focal lengths, Just remember to keep the distance to the subject you're focusing on the same but at least a good 5 meters or so, or ideally the distance you most often take photos at because of course the mfa changes slightly on focusing distance (not much but if you set it up at an extremely close distance or extremely long distance the mfa will be wrong for the opposite)
 
N01Chris said:
Yeah from trial and error I've just been taking averages of a load of repeats at the same and different focal lengths, Just remember to keep the distance to the subject you're focusing on the same but at least a good 5 meters or so, or ideally the distance you most often take photos at because of course the mfa changes slightly on focusing distance (not much but if you set it up at an extremely close distance or extremely long distance the mfa will be wrong for the opposite)
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yeah I'm a little restricted for space in my office where I need to do it so I'm only about 2.5 metres away but It'll have to do... most of the lenses are pretty much only 1 click out so hopefully that means the variance at different distance shouldn't be too pronounced
 
ajax_andy said:
I bought FoCal but it's not exactly consistent in its results... case in point (but I've found it with all my lenses) the 24-70mm f/2.8:

8 tests done now and the results were:
-2
-1
0
0
-2
-2
0
-3

So which is it? Doing one final test and if it's -2 or 0 I'll just use the law of averages and go for that
Click to expand...

There are a few things that need to be understood when talking about consistency. Your camera body aims to focus within 1/3 of the depth of field when using an f/2.8 lens so that will give a spread in values. The actual unit of MA is 1/8 of the single side depth of focus (not depth of field) and this will vary relative to the depth of field with the aperture used (f/2.8 in your case). So, a spread of magnitude 3 is well within the spec of the camera body even before one considers any backlash present between the focus motor and the helicoid gearing that moves the elements/groups. In other words, a difference of 3 is remarkably consistent.

Bob
 
Canon Bob said:
There are a few things that need to be understood when talking about consistency. Your camera body aims to focus within 1/3 of the depth of field when using an f/2.8 lens so that will give a spread in values. The actual unit of MA is 1/8 of the single side depth of focus (not depth of field) and this will vary relative to the depth of field with the aperture used (f/2.8 in your case). So, a spread of magnitude 3 is well within the spec of the camera body even before one considers any backlash present between the focus motor and the helicoid gearing that moves the elements/groups. In other words, a difference of 3 is remarkably consistent.

Bob
Click to expand...

Ahh ok thanks that's a good explanation :) So basically it will always have some variance but taking the average in to consideration I should be pretty much ok?
 
ajax_andy said:
Ahh ok thanks that's a good explanation :) So basically it will always have some variance but taking the average in to consideration I should be pretty much ok?
Click to expand...
It's not easy to put numbers to it without getting overly technical as the effect of each unit of MA varies with focal length and max aperture even before considering the effect of target distance (magnification) but trust me, a spread of 3 units is not going to trouble you at all.

Bob
 
ajax_andy said:
yeah I'm a little restricted for space in my office where I need to do it so I'm only about 2.5 metres away but It'll have to do... most of the lenses are pretty much only 1 click out so hopefully that means the variance at different distance shouldn't be too pronounced
Click to expand...

Well according to my research the minimum distance should be 50 times the focal length of that lens, I took this to be 50 times the longest focal length of your zoom so for a 24-70 you should multiply 70 by 50 (3500mm) which is 3.5m so you might get away with it if the lens's you're calibrating are less than 70 but like you said it shouldnt be that pronounced
 
N01Chris said:
Well according to my research the minimum distance should be 50 times the focal length of that lens, I took this to be 50 times the longest focal length of your zoom so for a 24-70 you should multiply 70 by 50 (3500mm) which is 3.5m so you might get away with it if the lens's you're calibrating are less than 70 but like you said it shouldnt be that pronounced
Click to expand...
The concept behind the 50 x FL is to reduce the possibility that any uncorrected (or over corrected) spherical aberrations impact on the AF sensors. If using the centre point then there's less likelihood of these aberrations having too much detrimental effect as they're less likely to be present on the optical axis.

Bob
 
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