[jct us101]

You have any idea how expensive this lens is going to be?

[Prognathous]

As a matter of fact, a symmetrical lens with f/1.0 is impossible for the PK-mount. Period.

1. Who said it needs to by a symmetrical 50mm lens? I'm sure we're all fine if it's an asymmetrical 50/1.0
2. For the sake of discussion, what about a symmetrical 85/1.0? Ignoring the cost, does your math tell you that this would be "impossible for the PK-mount"?

Prog.

[Jonson PL]

DA*400/4 ED (IF) SDM would be excellent, (and very likely). I hope for ring-type. But else it is gonna be a perfect size/weight ratio, and a new design. Exactly as I had hoped for.

For a long time, there has been a gap in the super-tele offering

the rest seems veeery strange.. 50mm 1.0 makes no sense at all. and 20mm f2.8 also makes no sense. they already have 21mm limited and 20mm is not wide in aps-c and if they were planning on making ff lenses then the first thing they should make is a 24-70 and 70-200 f2.8 pair, that would pretty much cover ff initially in just 2 lenses.
faking a pic of the lens roadmap is not particularly hard

DFA*20/2.8 SDM makes plenty sense. Close to the 18/2 limited that Carl Weese from T.O.P. was wishing for. This would be a completely sealed lens, and come close to substitute the 31 lmt. focal lenght that we used on film format. (31 mm is just a little long for a fast wide-angle prime on crop).


Though I do agree that it seems a little weird, how the DFA 50 mm, suddenly changed to a STAR nomination. Particularly, when the first picture resembled the 645 lens a lot.

But seems Hoya is heating up Pentax. First cleaning up, and now really putting full steam under the development.

You really should go back one post and read the post by RawheaD I had linked there.

sorry, I hadn't read that far, when I posted

Good post

You're welcome

[falconeye]

1. Who said it needs to by a symmetrical 50mm lens? I'm sure we're all fine if it's an asymmetrical 50/1.0
2. For the sake of discussion, what about a symmetrical 85/1.0? Ignoring the cost, does your math tell you that this would be "impossible for the PK-mount"?

Ad 1. Nobody said it to be symmetrical.

Note however that most 50mm SLR lenses are symmetrical or at least, have a pupil magnification of 1. I am still curious to learn if an SLR lens with pupil magnification < 1 does exit.

Ad 2. Did I mention 50mm anywhere? What I said applies to all focal lenghts.

[Jonson PL]

Note however that most 50mm SLR lenses are symmetrical or at least, have a pupil magnification of 1. I am still curious to learn if an SLR lens with pupil magnification < 1 does exit.

Bjørn Rørslet writes more about exit pupil diameter/entrance pupil diameter and Effective aperture, though I didn't understand most of it :
Need for Speed: Very Large Aperture Lenses

a DFA*20/2.8 is nice - an updated FA20/2.8 I assume ?

You could be right. I hope they work more on the design though. FA 20/2.8 is good, but not exceptional

Where's my DFA 600 f4?

Can be ordered out of Japan.


Personally, I wouldn’t mind a 500/5.6 either.

didnt say it wasnt useful, but if you were going to start building an ff lens lineup it would be a very strange place to start.

It would be a good place to start. Fast ultra-wide, is what we can’t have with crop. But is possible with FF

I would say the same, and it's a good time to improve on Pentax's older FA lens line up and make the lenses as good as they can get. though Pentax making a 50mm f/1.0 lens would be very interesting indeed, either pentax are breaking a few laws of physics or they have found a way to get over the limitation of the K lens mount. I can think of one way they can do it...and it involves FREE.

a 135mm f/2.8 limited...why not f/2? I would like that! I have been itching for a longer limited.

I would love a 135/2.
Else a compact 135/2.8 limited could be awesome. I had thought of maybe a 120 mm, or 135mm f/4.5., coming in at 240 grams, and 5-6 cm length. But a f/2.8 135 mm, would probably be more useful for most.

[Mark D]

As we're about to be hit with a second 25% -50% Pentax lens price rise in four months here in the UK, just give me a kmount on the Tokina lenses ( and a plastic bag for WR) and I'll be happy.

[MrEspie]

The 400mm F4 seems the most plausible to me. Mostly because of a few hints one of the Pentax Canada reps dropped me at the Henry's show last weekend, lol. If that's what he was hinting at, we can expect to see it in the next year.

[falconeye]

Bjørn Rørslet writes more about exit pupil diameter/entrance pupil diameter and Effective aperture

Thanks for the link. I think, I am now officially confused as well

Anyway, these lenses seem to have P<1:


P=0.4: Rodenstock XR-Heligon 75 mm f/1.1
P=0.4: Rodenstock TV-Heligon 50 mm f/0.75
P=0.8: Noct-Nikkor 58 mm f/1.2
P=0.9: Nikkor-O 55 mm f/1.2 CRT lens

Then, he states that N_eff (effective aperture) = N (1 + m/P) where m is the magnification. I think that this refers to DoF which is not as shallow with P<1 as one would expect. Note, that this effect is null at infinite focus (m=0).

So, lenses with P<1 do exist.

However, the 50 mm Heligon is 80 mm long with a focal plane just 4 mm after the rear lens. Unfeasible to use at infinite focus with an SLR. So, it doesn't prove the point.

The Noct-Nikkor 58 mm f/1.2 is described here: Nikon | Imaging Products | NIKKOR - The Thousand and One Nights, Tale 16 : Ai Noct Nikkor 58mm f/1.2. It has a hand-polished aspherical front glass element and costs about $3000+ as a used lens. It is an SLR lens.

If Bjørn Rørslet is correct that P=0.8 for this lens, then yes, a f/1.0 could be made for the PK mount. However, I found no further reference that this lens has P<1. So, I reserve a personal opinion here and leave the question open for myself. Esp. as the entire topic is further complicated by the fact that even a small exit pupil may actually be closer to the focal plane than any lens element and thus, still be subject to vignetting...

[jeffkrol]

The Repro Nikkor lens has a maximum aperture ratio of f/1 or f/1.4 (Effective aperture ratio: f/2 or f/2.8 at 1:1 reproduction) and the optical system features symmetrically arranged elements, which corrects all aberrations.
Repro Nikkor 85mm F1.0 Supersonic Macro Lens

55 f1.2
CRT Nikkor 55mm F1.2
TV-Nikkor 35mm F0.9 Big Fast Super Light
Had to show this 35mm f.9 on camera:


Just wanted to add a "ballpark" price of a equivalent lens:
Pre Photokina 2008: Along with the M8.2, Leica has unveiled the world’s fastest asphercial lens, the NOCTILUX-M 50 mm f/0.95 ASPH. offering the market a faster lens than the SUMMILUX-M 50 mm f /1.4 ASPH. The wide maximum aperture gives extremely shallow depth of field and very low light capability. Priced at £6290 it will be made available in February 2009.
http://www.dpreview.com/news/0809/08091505leica_50mm_f0_95.asp
http://us.leica-camera.com/photography/m_system/lenses/5915.html
Currently $9995US at B&H

Review of .95. Seems there may be no technical reason to assume an f/1 couldn't be made w/ current technology... Practical reasons abound though....
http://www.imx.nl/photo/leica/lenses/page29/nx095_1.html

[nixcamic]

If pentax made a 50mm f/1 with the DOF of a f/1.2 or 1.4 that would be quite amazing, think of it, it gives you a stop more to shoot at, its like using higher iso.