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09-08-2015, 06:07 PM   #16
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many people suggest the 28-45mm but that wouldn't be wide enough for me

09-08-2015, 10:02 PM   #17
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I understand most people today are only shooting 33x44mm in the Pentax 645 system.

I am one o the few still using both. I have quite often both the 645D and the 645N with me. I use the digital picture for printing, and the slide film in a projector.

Have thought about the 28-45, as it is a superb lens, even wide open it is great. The reason I dcided not to buy it: The 35 A I own is ecellent, too, it i great wide open, too. 35mm is of course not 28mm, but still OK for many things. And if I would need 28mm und the 645D, I just take the 645N body and the 35mm lens and do a scan (using the 645D and the 120 macro) of the slide later. Off course this is less resolution than using the 645D directly, but 20 MP at very good shaprness and fine details is realistic when using 4.5x6 film. I am not shooting permanently wider than 35mm on my 645D, so I don't pay the quite high price of the 28-45mm just to get those few mm extra over the 35mm with the full 645D resolution and dynamic range, instead of the slide scan.

With the 25mm DFA it would be different. It would not replace my 35mm, it would be on top of it. 25mm on the 645D and 35mm on the 645N is nearly a match. And I would have the option to go really wide for a few special cases, using the 645N and the 25mm. The price of that lens was the same. Might well be you have to stop that one down to get shapr corners. For me, this is a small disadvantage, comapred to the possibility to have the wider lens right from the start, plus the option to go even wider using the 645N. 25mm on the 645N is about 15mm on a Nikon FX or Canon 5D.

Off course, Pentax could also bring a 20-28mm lens for 33x44mm to cover these wide angle needs. Typically, they are not covered in medium format. In my optinion, 20-28 plus 45-85 is more attractive for landscape photography than 28-45 and 45-85 and no gap in between. The 28-45 is mor interesting when combining it directly with longer lenses, for example 28-45, 90, 150-300.

If they are brining something like 20-28mm, I think again about buying one of the new lenses. For the time beeing, there is still the idea of maybe one day buing a 25 DFA in Japan 2nd hand. Until then, I use my 17mm Tokina on the D700.
09-09-2015, 03:11 AM   #18
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Hello Pentax 645 guys!
Question: Does anybody use the original Pentax 645 25f4 D-FA lens on a Pentax 645 camera with film? If yes, how is the corner quality? Within the 44x33mm image circle of the digital Pentax 645 the lens shows a certain amount of CA towards the corners but if this is corrected in post the sharpness is still very good. Does towards the corners of the 56x41.5mm film image film circle the corners mainly show more CA or also significantly decreased sharpness (at +/- f11)? Can someone scan a sharp f11 image with corner details and upload to a dropbox or send to me (christoph@kuegler.info)?
I am using a Contax 645 system with a IQ180 54x40mm digital back and if the lens is still pretty good towards the corners of the IQ180 image circle I would consider to buy one 2nd hand and modify the mount to Contax 645 to use it at fixed f11 and MF. That would be really cool because the widest lens for the Contax 654 is 35mm.
:-)
Thx Christoph
09-13-2015, 09:46 AM   #19
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The real reason the 25mm was discontinued was because one of the elements in the lens was made by a third party manufacturer that couldn't do so anymore. The 28-45mm was on the horizon already so it made perfect sense to drop the lens.

09-13-2015, 10:29 AM   #20
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QuoteOriginally posted by trusharp Quote
The real reason the 25mm was discontinued was because one of the elements in the lens was made by a third party manufacturer that couldn't do so anymore.
That begs the question why they didn't find another supplier.
09-13-2015, 04:32 PM   #21
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QuoteOriginally posted by lytrytyr Quote
That begs the question why they didn't find another supplier.
I guess because they found another suitable lens in the form of a 28-45. Even the CS people refer to the 28-45 as the 25 replacement.
09-13-2015, 04:50 PM   #22
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QuoteOriginally posted by algrove Quote
I guess because they found another suitable lens in the form of a 28-45. Even the CS people refer to the 28-45 as the 25 replacement.
That's one further reason for dropping the 25mm, along with the front element and potential SDM issues.
Pentax also went with a zoom rather than a prime for wide angle on the Q system,
and the same may soon be happening in FF K mount.
09-13-2015, 11:06 PM   #23
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QuoteOriginally posted by lytrytyr Quote
That begs the question why they didn't find another supplier.
They should get into bed with Canon. 11-24mm. 17 & 24mm TS-E. Say what you will about their cameras, but hot damn if they don't have the craziest and most accomplished lens designers in the industry.

They are one of few companies that produce their own fluorite glass, and have some of the most advanced lens moulding systems that let them make the front elements needed for their extreme lens designs.

09-16-2015, 10:05 PM - 2 Likes   #24
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A 28-45 cannot replace a 25mm, even if you skip the fact the 25mm can be used on full 645, while the 28-45 can't. 25mm i noticable wider than 28mm, ans 28mm on 33x44mm ist not really that wide.
WIth a prime lens, most common super wide lenses in landscape phtography in the 135 film format (or DSLR "full format") hve between 16 and 20mm. In case of zooms, they typically start at 17 or 18mm. These are the most common ones, not the most extreme ones. 28mm on 33x44 is about 21mm on 135 format. That's a bit too long. The 25mm was at about 19mm , so within that range.
I can understand they can't build the 25mm anymore if one supplier can't supply anymore. And it might be hard to replace the supplier, too. But then you need at least a clear roadmap: We present the 28-45 now, and we are working on a wider lens für 33x44mm, too. Be it a prime between 20 and 24mm, be it a 20-28mm zoom. Should be feasible, if that lens isn't supprting full 645 either.

The 645D and 645Z are optimized for ladscape use (although they can be used for other thigs, too). And for this kind of photography Pentax should have a wider option then just 28mm. Or consider to grow thee sensor.

If they engage Canon designers, they will probalby build a 22/4. With T&S. Covering full 645 when not shifted. And 33x44mm with using shift, too. Their 17mm T&S is almost covering the image circle of a Pentax 67!
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