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10-23-2015, 05:38 PM   #1
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Will Pentax ever make a 16-35mm equivalent in medium format?

Is Pentax ever going to make a 16-35 lens equivalent in Medium Format for the Pentax 645Z? I have a Canon 5D and the only reason I don't want to buy the Zmis because I like ultra wide angle.

10-23-2015, 06:15 PM   #2
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The equivalent would be the DA 645 28-45/4.5. With an 89 diagonal field of view at 28mm, it's one degree wider than the DA 15 Limited.
10-23-2015, 06:18 PM   #3
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QuoteOriginally posted by scottyb70 Quote
Is Pentax ever going to make a 16-35 lens equivalent in Medium Format for the Pentax 645Z? I have a Canon 5D and the only reason I don't want to buy the Zmis because I like ultra wide angle.
The best answer I can come up with is this, call their R&D department and their marketing dept. They may not provide the information you are seeking, since this is a very competitive business. I would like to know what you discovered.

Hope this helps,

Tony
10-23-2015, 08:49 PM   #4
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Here is a table comparing field of view across the various sensor slzes...


10-24-2015, 02:33 AM   #5
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QuoteOriginally posted by aremmes Quote
The equivalent would be the DA 645 28-45/4.5. With an 89 diagonal field of view at 28mm, it's one degree wider than the DA 15 Limited.
I think the idea was equivalent to 16-35 on full frame. 28-45 is far away from that, it is 22-35 on full frame.

To answer the question: No, there will be no 20-45mm for Pentax 645. Because you can't reach the high optical quality the 28-45 offers even wide open, when doing such a big zoom range in the wide angle region. There might be a 20-28/4.5 or similar one day, off course. But again as big as the 28-45, at least, and at least as expensive.

By having to discontiue the 25mm, the 645 sysem lost quite a lot of its wide angle abilities. Not only because it was 19mm full frame equivalent instead of 22mm (rounded), but also in case even this was not enough, at least the Japanese version was for full 4.5x6, so by taking a film body with you, too, there was the option to get even 15mm FF equivalent. Off course with the other characteristics film has.

In my opinion on the day they knew the 25mm will have to be discontinued, they should have put a 20-28mm on the roadmap.
10-24-2015, 05:38 AM   #6
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Thanks Donesteban, that is what I wanted to know. I really like the wide end. I am mad they discountinued the 25mm. I read the 25mm is soft at the corners and I not as sharp as the 28-45 and people have been having problems with the lens. Is this true? This is what is keeping me leaning towards the 5DsR, my 16-35mm is used about 85% of the time on my camera. I really like how the photos look from the Pentax 645.
10-24-2015, 05:59 AM   #7
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QuoteOriginally posted by scottyb70 Quote
Thanks Donesteban, that is what I wanted to know. I really like the wide end. I am mad they discountinued the 25mm. I read the 25mm is soft at the corners and I not as sharp as the 28-45 and people have been having problems with the lens. Is this true? This is what is keeping me leaning towards the 5DsR, my 16-35mm is used about 85% of the time on my camera. I really like how the photos look from the Pentax 645.
Medium format cameras need to accept some limitations compared to 35mm due to the increased sensor size. The 28-45mm will remain the defacto wide-zoom for Pentax MF, any wider than that and they'll have to make a new prime lens to replace the old 25mm, which could actually cover full 645, so it wasn't well-matched to the D/Z's sensors.

Lenses wider than 28mm on any MF camera are a big rarity, and are usually optimized for smaller sensors, whereas Canon is a big innovator in the wide-angle lens space, with amazing lenses like the 17 & 24mm TS-E and the 11-24mm. They have the technology to mold lenses into shapes pretty much no other company has.

If there's anything good that came out of the discontinuation of the 25mm is that Pentax now has a good reason to design a replacement.
10-25-2015, 08:43 AM   #8
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I surely hope Pentax will come up with a replacement for the 25mm, and a wider one while they are at it. I use the K3 and Sigma 10-20mm for my U-WA needs, and would love not to have to carry it with me all the time. That said, a 25mm for the 645 would be too close to the 28-45 to make sense for me to buy one at the likely asking price. Best would be if they replaced the 25mm with a 20-28mm f/4.5 or even f/5.6, which should make it easier to design, or with a prime in the 20-22mm range (16-19mm FOV on 35mm), again f/5.6 would be OK by me to keep size and weight at bay; fundamental, though, is to have a filter ring, nothing of the 25mm silly rear filter. This will be a lens destined to landscape / architecture photographers, so the lack of a easy option to filter it on the front of the lens (Grad ND anyone??) would make it a no-go for me (and, I am sure, for many more photographers potentially interested in such a lens).

Best,

Vieri

10-26-2015, 09:36 PM   #9
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QuoteOriginally posted by scottyb70 Quote
Thanks Donesteban, that is what I wanted to know. I really like the wide end. I am mad they discountinued the 25mm. I read the 25mm is soft at the corners and I not as sharp as the 28-45 and people have been having problems with the lens. Is this true? This is what is keeping me leaning towards the 5DsR, my 16-35mm is used about 85% of the time on my camera. I really like how the photos look from the Pentax 645.
as much as i like my 645z, the canon 11-24 is an absolute screamer of a lens. Try it out.
10-27-2015, 05:15 PM   #10
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I agree, Pentax need a new wide lens to accompany this brilliant 645Z sensor/body. I owned the DA25mm because it was the widest, knowing quite well of its short comings.. the extra few mm on the wide end was important to me and my work. I have since sold the 25mm and now have a dedicated 35mm wide angle set up .. at least until a new wide comes out for the 645Z.
10-27-2015, 10:08 PM   #11
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I too would definitely like to see something wider than 25mm on 645D/Z, perhaps a 21mm prime.

And despite what the FOV chart says, I find in practice the DA15mm on APS-C is slightly wider than the DFA25mm on 645D. I haven't done a scientific comparison of this yet, but have a strong feeling it is true.
10-28-2015, 12:09 AM   #12
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QuoteOriginally posted by mikeSF Quote
I too would definitely like to see something wider than 25mm on 645D/Z, perhaps a 21mm prime.
I would like to see this too, but we both know that such a lens if designed for the existing 645 system would be impractically large and heavy. In order for this to be an achevable goal something has to change = and in my mind the biggest obstacle to this is the existing 645 flange.

In order to accomplish this I think going for a mirrorless design would make this a much more practical and achievable goal. Wide angle lenses designed for mirrorless cameras with a short back focus lenses are considerably smaller than retrofocus SLR lens designs. In a way similar to Hasselblad and the SWC( remember that camera?) With such a design goal in mind, a mirrorless MFDC with the same 645Z 44X33mm sensor and a fixed super wide 15~24mm f/4 zoom lens, that would be about 11.7 -18.2mm in 35mm terms. The added benefit is that it may be possible to design the camera with integrated movements, rise, shift and possibly tilt.


Hasselblad Arcbody*, next to the Gilde G617 MST* and the Ebony 617S is one of the few mirrorless medium format cameras that offer the freedom of tilt/shift movements.

*both of these are discontinued.

Last edited by Digitalis; 10-28-2015 at 04:07 AM.
10-28-2015, 01:02 AM   #13
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QuoteOriginally posted by Digitalis Quote
...

a mirrorless MFDC with the same 645Z 44X33mm sensor and a fixed super wide 15~24mm f/4 zoom lens, that would be about 11.7 -18.2mm in 35mm terms. The added benefit is that it may be possible to design the camera with integrated movements, rise, shift and possibly tilt.

...
If Pentax will ever produce such a camera, I'll buy one in a heartbeat. I'd prefer something like 15-30mm, just to get some more flexibility on the long end. F/4 would not be really feasible IMHO, f/5.6 is a better bet if you want to keep size, weight and price under control, getting better image quality while minimising design problems. Movements would be a bonus, a filter thread would on the other hand be a requirement for such a camera (no silly and unuseful pseudo-hoods a-la-25-mm, please!)
10-28-2015, 03:52 AM   #14
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QuoteOriginally posted by The Madshutter Quote
I'd prefer something like 15-30mm, just to get some more flexibility on the long end. F/4 would not be really feasible IMHO, f/5.6 is a better bet if you want to keep size, weight and price under control, getting better image quality while minimising design problems.
On a mirrorless MF camera a 15-24mm lens with a constant aperture of f/4 wouldn't be as big as you think. Though to be fair, to create a lens with an image circle large enough to allow for extended movements, speed may be sacrificed in the name of increased coverage. A lens with the coverage of a 67 lens would just about do the trick.

Though as you mentioned, filters could be potentially problematic as the front element of such a lens would most likely have pronounced curvature. However there are specialized filter holders made by the filter maker: Lee, that are designed for lenses with this characteristic: like the Sigma 8-16mm f/4.5-5.6 and the Nikkor 14-24mm f/2.8G

(Incidentally, the lens on that Hasselblad Arc body is none other than the Rodenstock APO-Grandagon 45mm f/4.5. Rodenstock currently still make wide angle digital medium format lenses, the widest of which is the HR Diagron-S 23mm f/5.6 with a 72mm filters and a 70mm image circle, weighing in at 780g - about the same weight as the DA*200mm f/2.8)

Last edited by Digitalis; 10-28-2015 at 04:03 AM.
10-28-2015, 08:01 AM   #15
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i like the thought of a wide zoom as you described with tilt-shift, but for my purposes, I would be perfectly happy with a 21mm f/5.6 manual focus prime. I realize this may not have the mass appeal to be viable, but that's all i need, lol
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