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New Contributor
Posts: 3
Registered: ‎11-24-2015
Accepted Solution

Distance Index & Scale on 100mm f/2.8L

When manually focusing the EF 100mm f/2.8L IS USM macro lens (or any lens, for that matter), is best practice to align the distance index | with the periods on the distance scale (e.g. 0.30 m) or with the magnification ratios' central colons (e.g. 1:1)?


The difference may seem subtle, but it matters when imaging (and then calibrating scale bars and measuring) tiny subjects.


- L

Respected Contributor
Posts: 1,076
Registered: ‎10-17-2012

Re: Distance Index & Scale on 100mm f/2.8L

Hello lwalker, 

The infinity position on that lens where the vertical line of the 'L' mark is aligned with the distance indicator on the scale.  For best focus it should always be checked either through Live View magnified or through the viewfinder.   

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Esteemed Contributor
Posts: 3,854
Registered: ‎06-11-2013

Re: Distance Index & Scale on 100mm f/2.8L

Don't put too much stock in the position of each distance on that scale.  Factors (in particular the physical temperature) can affect the precision of those distances.


Tim Campbell
5D III, 5D IV, 60Da
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