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10-21-2008, 07:09 PM   #16
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Why would you ever want to focus past infinity?

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10-22-2008, 06:44 AM   #17
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QuoteOriginally posted by nulla Quote
Why would you ever want to focus past infinity?

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to boldly go where no man has gone before

You're right, probably for focussing on beings from an alternate dimension. Silly me.

But seriously, yeah, sounds like this is just part of the manufacturing process and a way to make the lenses cheaper to make...
so, does the 16-50 go past infinity?
10-22-2008, 08:52 AM   #18
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Pentax added focus range limiters to large supertelephotos too--to minimize "searching" due to the long "throw" of the focus system.

Regarding focusing past the infinity mark--according to the Pentax Operating Manuals for several FA* telephoto lenses (80-200, 300/2.8, 600/4, 250-600/5.6)
"The distance scale on the lens stops slightly past the infinity mark. This allows the lens to focus on a point past the infinity scale in the case where a temperature change causes the focusing point to shift."
10-22-2008, 02:02 PM   #19
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QuoteOriginally posted by Miserere Quote
My question would be...why focus at infinity at all? You're throwing away half of your DoF by doing so. Hyperfocal is the way forward.
I think focusing at infinity can be very useful to obtain the maximal sharpness of objects located at infinity... like stars and the moon. When I take this type of pictures, a very precise focus is needed and I feel the hyperfocal rule would not give optimal results.


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