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04-23-2014, 08:08 PM   #16
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QuoteOriginally posted by alliumnsk Quote
Samyang already makes 7.5/3.5 and 8/2.8 fisheyes and announced 8/2.8 remake (24 mpx ready) and 12/2 (which is quite small too)
Sony has rather unimpressive 16/2.8 and 20/2.8, but they do use advantage of short backfocus

---------- Post added 04-22-14 at 07:05 PM ----------


Mirror in K-mount doesn't allow to make f/0.95 lenses. One can still make "invasive" lens for K-01, but the market is very small (albeit K-01 has IBIS!!)
well, since f/0.95 on aps-c is equivalent to f/1.5 of FF, and Pentax doesn't have any FF bodies, it would be little reason to make fast lenses.
Are you saying there is no reason to make fast lenses, or am I misunderstanding you? Are you sure it is correct that the mirror prevents 0.95 lenses from being made? That is interesting.

04-24-2014, 01:09 AM   #17
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Yes. Yes.
A lens for SLR camera must leave empty space (about 38mm for most) between rear element and image plane, or else lens obstructs mirror. Rear lens diameter is restricted by (internal) mount diameter minus few mm. From these two measures you can estimate which widest f-stop can be made for this mount. Canon EF is the only SLR mount where f/1.0 lens has been made, Pentax K is narrower and has slightly longer flange distance, meaning evenless room for fast lenses.
04-24-2014, 05:30 AM   #18
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QuoteOriginally posted by jeffshaddix Quote
Yarg, so many interesting lenses for E-mount. This looks to be impressive, but where are the wide angles that take advantage of the short register distance?
https://www.pentaxforums.com/forums/76-non-pentax-cameras-canon-nikon-etc/239...ml#post2787432
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