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05-16-2011, 07:56 AM   #1
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MFD at 1:2

Hi and good day to all
I am considering the DF-A 100/2,8 WR and since it is impossible to get a real-life experience with it for me, I would like to ask owners here at PF. What is the working distance with this lens at 1:2 magnification ratio please?

05-16-2011, 04:34 PM   #2
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I looked at the spec's on the pentax web site.

in the specifications the lens shows as 1:1 magnification at 303mm

this is from focal plane, so considering the lens is 80mm long and regester distance is about 46mm, this means working distance of about 174mm
that means that the internal focusing costs about 10-15mm in focal length to get to 1:1

as a result I would expect 1:2 to be at about 400 mm from the front of th elens
05-16-2011, 10:45 PM   #3
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Original Poster
QuoteOriginally posted by Lowell Goudge Quote
I looked at the spec's on the pentax web site.

in the specifications the lens shows as 1:1 magnification at 303mm

this is from focal plane, so considering the lens is 80mm long and regester distance is about 46mm, this means working distance of about 174mm
that means that the internal focusing costs about 10-15mm in focal length to get to 1:1

as a result I would expect 1:2 to be at about 400 mm from the front of th elens
thanks Lowell!
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