5D3 Microfocus - Wide / Telephoto

Hi,
I was wondering if anyone can explain the functioning of the microfocus on this body,
regarding focal lengths between the max wide and max telephoto...

I have a Sigma 70-200 2.8 that I microfocus adjusted,
positive 5 on the wide, positive 8 on the telephoto...

Let's say I want to shoot around 135 (halfway between wide and telephoto)

does the camera choose the wide offset, or the telephoto offset?
or, does it do some fancy magic and use a setting between 5 and 8?

thanks!

From what I've read the offset is applied linearily based on registered end values.

Which would be the only reasonable thing to do.

billinvegas wrote in post #15267111
Hi,
does the camera choose the wide offset, or the telephoto offset?
or, does it do some fancy magic and use a setting between 5 and 8?

thanks!

I doubt it is 'fancy magic', probably just some boring old math.

The camera probably assumes a linear curve fit for MA vs. focal length. So it can write two equations from your settings:

8 = m(200) + b
5 = m(70) + b

Then the camera solves to find that m = 3/130 and b = 3.38.

So at 135mm the camera would calculate an MA of about 6.

Take a photo at 135 and view playback on the lcd then press info button and the ma will show there.

I just tried it on my lens! Ma varies at different lenghts.