AF Micro-Adjustment.... What Multiplier? 50D

[John_Vito]

Hi All,

Quick question about the Multiplier to use when micro-adjusting auto-focus lens. So far I seen two recommendations:

• 50x the focal lentgh of the lens
• 100x the focal length of the lens

What does Canon recommend? Any real world results/experiences?

Just received my new 50D! Been an XT and XTi shooter a long time. As they say, "you don't miss things if you never had it." Man I missed a lot sticking with the Rebel series. (No regrets... the XTi has been doing yeoman duty for years... shot everything from jewelry catalogs to weddings)

Best,

John

[John_Vito]

Well I was just given this link:

Tech Tips - The Digital Journalist

Recommends:

Camera-to-subject distance should be no less than 50 times the focal length of the lens.

But can the distant be further?

[Dennis_Vied]

I'm just speculating here, but it sounds like they want it to be focused on a distance which will insure that the focal range extends to infinity. One way to do that is to use the hyperfocal distance.

You might do some comparisons with the hyperfocal distances for various f/stops and focal lengths, to see how they compare with the recommended multiplication factors of 50x and 100x. That would give you a feel for whether it is ok to go beyond 50x. I'm thinking it would be ok to go beyond 50x, that it would not compromise the micro-adjusting process.

But then again, I'm just speculating, as I haven't done that yet.