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Old Nov 4, 2005, 9:39 PM   #1
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Well, here goes the public display of my ignorance. Just got my 28-135 IS lens and can find nothing in the booklet about the distance scale. Can anyone explain it's use for me? I've searched around and found no info so far.

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Old Nov 4, 2005, 11:14 PM   #2
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For decoration??? :blah:

Seriously... Most Canon zooms if not all are varifocal in design which means the focus changes as you zoom in or out (Yes - the 'L's too which is why I prefer Nikon/Sigma/Tokina zooms because most are parafocal instead, i.e. theses lenses hold focus when the focal lenght is changed)!
-> Do this as an experiment on your 28-135:
1. At the widest zoom setting (28mm) focus on something up close and record the distance scale by the white marker
2. Now zoom to 135 without touching the focus ring on the same object and notice how the lens goes out of focus
3. Do another AF lock @ 135mm instead and check the distance scale again - not the same as before (@ 28mm) right?

The object hasn't move (and you didn't move) so which distance scale to use??? :?

The red zoom ticker marks are normally use for infrared film, but for dSLRs which are almost blind to this frequency spectrum they become even less relevent... :sad:
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