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05-09-2009, 08:27 AM   #1
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Sigma 105 f2.8 EX DG Macro

I just got this lens from KEH last night and was wondering since it didn't come with a manual, Why does the focus slide? Is that for manual use only? I thought this was a true 1:1 macro. When do you use the limiter switch? is that for close ups?

Thanks For any Help

05-09-2009, 10:24 AM   #2
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a - it is true 1:1 macro
b - limiter works as follows: if it's in full position, lens will search for focus from 0.313m to infinity. The limiter blocks the lens barrel movement from or to 0.4m (roughly). So if you are fucused closer than 0.4m and engage limiter you'll be able to focus only between 0.313 and 0.4m. If you're focused past 0.4m and engage limiter you'll be able to fucus between 0.4 and infinity. It's very practical. If you're doing macro you (or camera if you're doing AF) won't have to hunt all the way but just between 0.313 and 0.4. And if you're using the lens as tele you don't need the close focus ability, which slows down the AF quite a bit, so you can limit it over 0.4m and gain faster focus speed.
c - focus rings slides to engage/disengage AF. You still need to flip the switch on your camera body though!!! But if you're using AF on camera with focusing ring in M position it's going to rotate! So it's more practical to put it to AF position where it's going to be loose and therefore more comfortable to hold.

I hope this answers all your Qs

05-09-2009, 07:53 PM   #3
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Thanks Peter That's what I needed to know.

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