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11-24-2007, 12:29 PM   #1
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Why these uneven numbers: 21, 31, 43 and 77??

Sorry for asking these dumb question. After switching from Sony/Minolta equipment these summer to Pentax, I showed a photo-friend of mine my new lens collection. And he asked the question you read above. Why not 20mm and 30mm and so on??


11-24-2007, 01:28 PM   #2
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other manufacturers round their numbers off to the nearest standard 21 -> 20, 77 -> 75, pentax uses the actual numbers
11-24-2007, 02:05 PM   #3
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Why not? .
11-24-2007, 02:11 PM   #4
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QuoteOriginally posted by Jerry Thirsty Quote
Why not? .
Why not what, please?


11-24-2007, 02:39 PM   #5
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QuoteOriginally posted by TKH Quote
Why not what, please?

Why not use the actual focal length number. "77" is not really different than "28" or "35" or "85" or "135" which are other popular lengths.
11-24-2007, 10:10 PM   #6
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I think its a good question. I myself prefer to imagine that the designers pushed the envelopes of cost/perfomance/size etc and the perfect balance happened to be the resulting focal length/apertures/price Somehow, 31/1.8 feels more like a sweet spot to me than 28/2.8 or 35/2 etc, heh.

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