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05-16-2009, 06:24 AM   #76
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QuoteOriginally posted by Bophoto Quote
FA31/1,8 are a wide lens for 24X36, now it´s a "47,5mm" lens on APS.
And the rumours before was a DA* 30/1,4, but that´s to close to FA31 ltd.
OK, 50/1,4, 1,7, 2 and 1,2 are Pentax tradition, so we can expect a 30mm with f1,2,
1,0 are to expensive to sale enough and 1,4 are to close to FA31.
At the time then K50/1,2 was on sale, Pentax was big and also had 50mm with 2,0, 1,7, 1,4 and a Macro f4(but not so many zooms).

But to be a little different from FA31 ltd and also a tradition from M40/2,8 and FA43/1,9, Pentax can make a DA28/1,2(that is "43mm"), if not Pentax have plans for a 28mm limited.
I'd like to see two DA30:
* one DA*30 WR /1.2 or /1.4
* one cheap DA WR /1.8 to replace FA35/2

Both SDM of course.

05-16-2009, 07:04 AM   #77
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30/f1.0 would really equivalize APS-C and 35mm in terms of DOF and noise performance (at least at that focal lenght... f2.8 zooms @FF would still come in faster)... but if there is a system which needed a good f1.0 lens, APS-C Pentax is it...

much more efficient and profitable than launching a FF camera line...
05-16-2009, 07:12 AM   #78
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QuoteOriginally posted by jay Quote
a 30mm f/1.0 lens (or any f/1.0 lens, for that matter) is impossible. The K-mount doesn't support anything faster than f/1.2

but a reduced frame APS-C f/1.0 lens should be possible. just take a look at the exit pupil of the 31mm f/1.8 limited Pentax could have made that lens f/1.4 without breaking a sweat.
05-16-2009, 07:26 AM   #79
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QuoteOriginally posted by Digitalis Quote
but a reduced frame APS-C f/1.0 lens should be possible. just take a look at the exit pupil of the 31mm f/1.8 limited Pentax could have made that lens f/1.4 without breaking a sweat.

Have you seen the exit pupil of the A 50/1.2? It fill the whole lens mount!

05-16-2009, 09:15 AM   #80
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QuoteOriginally posted by RawheaD Quote
I think it is physically impossible to make a 30/1.0 lens for a PK mount camera, irregardless of how big you make the primary element. I think it's impossible to make a 50/1.0 lens for a PK mount camera. The register is too long (and the mount opening is too narrow).

I believe the Canon mounts (EF for sure, I don't know about FD) are the only ones for SLR with a register short enough and mount opening wide enough to barely make a 50/1.0 possible. Obviously, shorter the focal length the harder it gets (because of the register), so a 30/1.0 is not possible even on EF, let alone PK.

Somebody correct me if I'm wrong (just learned about this principle recently ;-)

I'm pretty sure there was a 1.0 Noct-Nikkor back in the Seventies, actually, I forget the FL.

I'd be pretty surprised to see a 1.0 lens coming out at this point in history: high-ISO performance is getting better and is a turn of the dial away: lenses that wide open are invariably pretty soft, and the viewing advantage doesn't count for nearly as much with good AF available. (frankly, with a lot of the screens out these days, the brightening means you don't see visible differences in the finder faster than a certain point, anyway. )
05-16-2009, 09:22 AM   #81
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QuoteOriginally posted by jay Quote
a 30mm f/1.0 lens (or any f/1.0 lens, for that matter) is impossible. The K-mount doesn't support anything faster than f/1.2.

Recall the K-A mount uses 5 metal contacts that are either shorted or open to tell the camera what the maximum open aperture is, and the minimum aperture.

The two "fastest" patterns are 10001 for a f/1.2 - f/16 lens, and 11111 for an f/1.2 - f/22 lens.

So, Pentax would have to, at the minimum, add an extra pin to the mount somewhere. This seems rather unlikely.

EDIT: Actually, I realized 11001 and 11000 both cause the camera to report f--, so they're unused. If they did introduce a 30mm f/1.0 lens, they would be able to use one of the unused combinations -- but the lens wouldn't be backward-compatible with existing camera bodies.
Pretty sure w/ modern lenses the "a" contact f stop indicator is overridden by serial digital communication w/ the chip on the lens.. The pattern contacts are unnecessary for current lenses.
05-16-2009, 09:37 AM   #82
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QuoteOriginally posted by Pål Jensen Quote
Have you seen the exit pupil of the A 50/1.2? It fill the whole lens mount!
Yeah, but that's full-frame. An APS-C-specific lens would have a proportionally smaller exit pupil.

QuoteOriginally posted by jeffkrol Quote
Pretty sure w/ modern lenses the "a" contact f stop indicator is overridden by serial digital communication w/ the chip on the lens.. The pattern contacts are unnecessary for current lenses.
True, there's a serial communication protocol on the 7th pin of the lens -- but I believe it only transmits the lens size, subject distance and focal length of the lens, and not the maximum/minimum aperture. Then again, I've never really sat down and deciphered it -- I'm only going off what I've read before.
05-16-2009, 10:50 AM   #83
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It also transmits MTF data on FA series and newer lenses, aperture is still controlled by the 6 other pins, try covering them with some tape Also, in this modern price cutting age, why would they include those 6 other pins if they sent the aperture data over the 1 serial pin? (one does wonder why they don't send it that way)

05-16-2009, 11:14 AM   #84
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QuoteOriginally posted by nixcamic Quote
It also transmits MTF data on FA series and newer lenses, aperture is still controlled by the 6 other pins, try covering them with some tape Also, in this modern price cutting age, why would they include those 6 other pins if they sent the aperture data over the 1 serial pin? (one does wonder why they don't send it that way)
For compatibility purpose but I agree that in this case they would have dropped them on DA lenses since hey are not supposed to be used with film bodies.
05-16-2009, 11:37 AM   #85
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There could of course be a new aperture protocol implemented in the K-7, but that doesn't explain why it goes to F:1.0 if such lenses indeed are impossible...
05-16-2009, 11:39 AM   #86
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If it helps to see for optical speculations, btw, I snapped this and put it online when someone was wanting to know how to tell different Canon mounts apart, but the lens on the right happens to be my 50 1.2.



Looks like it *might* actually just be pretty tight to try and put a rear element bigger than that in a Pentax mount, but as has been mentioned, it wouldn't have to cover full frame.
05-16-2009, 11:51 AM   #87
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We have to remember that 30mm at f/1 is a slightly smaller exit aperture (I think, just mentally calculated I may be very very wrong) than 50mm at f/1.2, and that its only covering aps-c which will also help a great deal. Not that I believe they'll actually make this lens, but I do think its quite possible and if they somehow manage to make it, and make it somewhat affordable, mad props to them.
05-16-2009, 12:11 PM   #88
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QuoteOriginally posted by Art Vandelay II Quote
It's really hard to beat Canon on lens pricing. Plus their range is so vast; aside from pancake primes they have everything covered. If IS isn't important to you it's hard to outdo them. I've often wondered how Sony can ask $1800 for their 70-200mm f/2.8 when Canon's non-IS 70-200 f/2.8 is every bit as nice and only $1100. Pentax asking $1500 for the f/4 60-250mm while the non-IS Canon 70-200mm f/4 is only $600 is equally as troubling. I understand Pentax asking maybe $1000 for it, but $1500 is over the top.
Well, that's what a large installed base can do. Good for Canon. Pentax just doesn't have that luxury at all, as with Sony.
05-16-2009, 01:34 PM   #89
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QuoteOriginally posted by Digitalis Quote
but a reduced frame APS-C f/1.0 lens should be possible. just take a look at the exit pupil of the 31mm f/1.8 limited Pentax could have made that lens f/1.4 without breaking a sweat.
I agree, the APS-C size does not need as large a clear aperture through the K-mount for a 30mm F1.0 as a 50mm F1.0 on a FF size sensor. BTW Pentax had a prototype 300mm F2.0 and 20mm F1.4 for 35mm (FF) K-mount film cameras.


05-16-2009, 01:42 PM   #90
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Much as I would love an F1 lens, can you imagine the price? If the Leica Noctilux 50mm F0.95 at £6700 is anything to go by, i think not.

However with Leica having the most expensive lenses around, a Pentax will be cheaper. For instance the Leica Summilux 50mm F1.4 is £2100, yet the Pentax FA 50mm F1.4 is a mere £150, and the new DA* 55mm F1.4 is £380-£480 depending on who you buy from. So, if we take the ratio of say 4-5x (on the 55mm) then for a possible 30mm F1, we are looking at £1400 for a 30mm F1.
hmmmmmmmmm

That is a lot, and would it be worth it? Well if it was the best 30mm, then yes, but it is too much for mere mortals.
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