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05-30-2019, 09:03 AM   #1
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Pentax D-6x7 series

Ok, I admit it at once. Its just a weat dream, but there are nothing wrong about dreaming. Especially about Pentax gear. Larger and larger sensors are available for camera producers. Some of the biggest today are Sony IMX 211 and 411. Other companies have even larger sensors, but highly specialized and extremely expensive. Who would be the first to launch a "mass" market 6x7 sensor? (at the price of a family car) Anyway, I have digged into the specs of the 6x7 lenses, full frame lenses and made a spreadsheet about what lenses I would suggest to go with such a system. Any thoughts? Which lenses would you pick?

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05-30-2019, 09:51 AM   #2
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The 105mm/2.4 is THE legendary lens for the 6x7 line. The rendering of that lens is something special. Not sure if you intend the 105/2.8 to be a refined version of that with new coatings.... but keeping the optical construction of the 105/2.4 would provide a natural attraction for everyone who has been awed by the results of the classic original.

As to the question of digital 6x7 in the first place ... I am not going to pour cold water on this idea. I merely offer two thoughts:

* 6x7 is the perfect format to adopt in mirrorless form. You get massive image area, and keep the size and weight of the camera in check. Plus, digital resolves so much detail that avoiding a swinging mirror would be useful. Having a shallower flange focal distance would also make buying new, native lenses attractive (while still allowing folks to use old classics by way of adapter.)

* I wish existing mainstream digital medium format was even actually 6x4.5 Everybody, including Pentax, should be honest that they are actually selling 345 cameras, not 645 cameras. I don't think 345 is really enough to warrant the jump from 36mmx24mm "full frame" formats. 645 is where most of the digital MF action should be.
05-30-2019, 09:56 AM   #3
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No love for the 165mm that is the current classical portrait focal in Pentax's 6x7 format?
05-30-2019, 10:25 AM - 1 Like   #4
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The 180/2.2 would be a interesting lens for the 6x7 system, though I would be afraid to see the size/weight of this thing..

Phil.

05-30-2019, 06:49 PM - 1 Like   #5
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QuoteOriginally posted by gofour3 Quote
The 180/2.2 would be a interesting lens for the 6x7 system, though I would be afraid to see the size/weight of this thing..

Phil.
Indeed! To get a decently sharp lens, 180/2.2 on 6x7 would probably end up requiring a 95 mm or 112 mm filter and weighing a solid 2,000-3,000 grams.

The 200/4 for 6x7 takes a 77mm filter and weighs 756 g. Scaling that design up to f/2.2 adds at least 31 mm to the filter size, makes all the glass elements 6X heavier, and probably requires a more complex optical design to make it decent.

Or look at the Canon 200/2. It's 2500 g and costs $5,700 but only covers a small image circle of 35mm cameras. Adapting that design to double image circle would make the lens even bigger and heavier.

Fast apertures in 6x7 make for massive, expensive lenses.
05-31-2019, 03:43 PM   #6
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I would think the newer designs like the M*300/4 ED IF which I loved...and the frighteningly sharp 100/4 Macro should both be part of any modern system. Both those lenses came out just after the 67II and have not only newer design, but also newer coatings. The newer lenses seemed to produce vibrant colors much better than the previous versions. Gawd I miss shooting Velvia transparencies through these two lenses--and blowing them into 30x40 Ilfochromes...
06-01-2019, 03:49 AM   #7
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QuoteOriginally posted by filmamigo Quote
The 105mm/2.4 is THE legendary lens for the 6x7 line. The rendering of that lens is something special. Not sure if you intend the 105/2.8 to be a refined version of that with new coatings.... but keeping the optical construction of the 105/2.4 would provide a natural attraction for everyone who has been awed by the results of the classic original.

As to the question of digital 6x7 in the first place ... I am not going to pour cold water on this idea. I merely offer two thoughts:

* 6x7 is the perfect format to adopt in mirrorless form. You get massive image area, and keep the size and weight of the camera in check. Plus, digital resolves so much detail that avoiding a swinging mirror would be useful. Having a shallower flange focal distance would also make buying new, native lenses attractive (while still allowing folks to use old classics by way of adapter.)

* I wish existing mainstream digital medium format was even actually 6x4.5 Everybody, including Pentax, should be honest that they are actually selling 345 cameras, not 645 cameras. I don't think 345 is really enough to warrant the jump from 36mmx24mm "full frame" formats. 645 is where most of the digital MF action should be.
I totally agree, but I believe D-6x7 will need higher resolution lenses with AF (and of course MF ring). Some lenses for daylight (the limited series) and some for shallow depth of field and night photography (the large aperture series). I also believe backwards compatibility is important, and that mirrorless short flange is the way to go.

The large aperture series should offer a significant aperture advantage over equivalent 24x36 full frame lens. I intentionally made the selection of tele lenses small because i believe 6x7 are about capturing more of the frame and have higher tolerance for cropping. Tele easily gets too heavy and expensive too.

Also leaf shutter is intentionally left out of the line up because I believe its not important. There are several ways to work around the fast flash sync problem. But it should be compatible with old leaf shutter lenses.

Yes, the 345 format will dissapear just like the APS-H format did. As far as I know all except one of the D-645 lenses supports full 645 frame. That makes me believe that Pentax already planned for a future full 645 frame camera and the death of 345.
06-01-2019, 04:13 AM   #8
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Whoa up there, how could you possibly go for f5.6 on the 600mm when way back they even went for f4.
I love the idea though

06-01-2019, 06:58 AM   #9
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QuoteOriginally posted by garywakeling Quote
Whoa up there, how could you possibly go for f5.6 on the 600mm when way back they even went for f4.
I love the idea though
Great!

The reason I proposed f/5.6 is that a the existing 600 f/4 and even 800 f/4 are truly humongous heavyweight and must have cost insanely much. I doubt they made more then 20 of each. An updated higher resolution lower abberation optical formula would be even heavier and more expensive. I did not propose f/8 because of AF sensing becomes more difficult and diffraction may play a role in the future. The lens must have a long lifespan and be ready for higher resolution sensors at least a decade. 600/4 600/5,6 matches the light gathering ability of a 300mm f/2.8 on full frame, but at a much higher resolution. And lastly I believe strong tele is not a huge demand for a 6x7 system.

I thought out the lenses carefully, not in a hurry.

Oh well, and its time to reveal my personal favourites. If theese lenses become real I would want one large aperture wide angle for night/aurora landscape photo and one portrait lens. F/4 would be sufficient for me. So, I would go for the 75/2 WR for landscapes and the 180/4 Limited for portraits. In 36x24 terms it would equal 35mm f/0,9 and 84mm f/1,9. I might also consider to exchange the 75/2 for a 50/2,8 WR (23/1,3 equivelent).

Last edited by Simen1; 06-01-2019 at 02:56 PM.
06-01-2019, 07:12 AM   #10
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QuoteOriginally posted by photoptimist Quote
Indeed! To get a decently sharp lens, 180/2.2 on 6x7 would probably end up requiring a 95 mm or 112 mm filter and weighing a solid 2,000-3,000 grams.

The 200/4 for 6x7 takes a 77mm filter and weighs 756 g. Scaling that design up to f/2.2 adds at least 31 mm to the filter size, makes all the glass elements 6X heavier, and probably requires a more complex optical design to make it decent.

Or look at the Canon 200/2. It's 2500 g and costs $5,700 but only covers a small image circle of 35mm cameras. Adapting that design to double image circle would make the lens even bigger and heavier.

Fast apertures in 6x7 make for massive, expensive lenses.
Yes, but why go for 6x7 if you can get the same light gathering ability with a 36x24mm frame and a high end lens? Thats why i proposed several lenses at 180mm (FF equivalent 85mm portrait lens). The 180/4 limited for lightweight, affordability and high resolution. The 180/4 macro because we need a macro lens in the line up and 180 is a propriate allround focal length for that and f/4 to keep the weight and size down. The 180/2,2 would be an extreme high end lens for those that already have a 100 foot yacht and want a lens with truly out of the ordinary light gathering ability. Its 85mm f/1,0 equivalent.

@tuco: I believe the 180mm lenses would do the job for the 165mm ones. Pentax cant have 100 lenses for that system. I had to cut down on something. I believe the list of 14 lenses are more then long enough, I just couldnt figure out where to cut more. The launch plan are also quite optimistic. I gave them something to streatch for. 180mm (85mm eqv) are on the wide end of portrait lenses. A 165mm (77mm eqv) are on the very vide end. Some prefer 135mm eqv for portraits and thats what the D-6x7 300/3,5 are for. (140mm f/1,6 eqv)

Maybe I should add a portrait zoom for the lineup? A lens for head, half and full body, with shallow enough depth of field. Some prefer a 70-200 f/2,8 for portraits and allround use on 36x24mm frame. A 150-400mm f/5,6 would do the same job on a D-6x7. Maybe even push it til f/5,0.

Last edited by Simen1; 06-01-2019 at 07:56 AM.
06-01-2019, 09:53 AM   #11
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QuoteOriginally posted by Simen1 Quote
...
@tuco: I believe the 180mm lenses would do the job for the 165mm ones.
...
Sure, 180mm would be a good substitute for both a 165mm and 200mm I suppose. Do you have any experience shooting 6x7 and larger format on film? I'd add a 43mm to that list.
06-01-2019, 01:29 PM   #12
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Nope, I'm just a tech geek. Well, actually I shot one film on a Bronica 6x7 with a 80mm f/2,8 many years ago, but I wouldnt cont that as experience in terms of lenses. My focal length experience are mostly from Pentax APS-C and full frame digital cameras. Thats why I calculate the equivalences to get a feeling of use cases.
06-01-2019, 02:47 PM   #13
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QuoteOriginally posted by Simen1 Quote
Great!

The reason I proposed f/5.6 is that a the existing 600 f/4 and even 800 f/4 are truly humongous heavyweight and must have cost insanely much. I doubt they made more then 20 of each. An updated higher resolution lower abberation optical formula would be even heavier and more expensive. I did not propose f/8 because of AF sensing becomes more difficult and diffraction may play a role in the future. The lens must have a long lifespan and be ready for higher resolution sensors at least a decade. 600/4 matches the light gathering ability of a 300mm f/2.8 on full frame, but at a much higher resolution. And lastly I believe strong tele is not a huge demand for a 6x7 system.

I thought out the lenses carefully, not in a hurry.

.
I like the idea, but having the 600 f4, it is a hunk of glass with a dinner plate element out the front, but it balances wonderfully on the large camera. The other missing lens is the 400mm , equivalent to 200mm on 35mm and such a popular focal length it would be a shame to miss it, the 67 version is well loved from the M* version
06-05-2019, 07:22 AM   #14
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QuoteOriginally posted by tuco Quote
No love for the 165mm that is the current classical portrait focal in Pentax's 6x7 format?
Also a brilliant lens. Sharp, well behaved, very modern rendering. With this lens and a 90mm 2.8 you could shoot pretty well anything.
06-05-2019, 08:55 AM   #15
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QuoteOriginally posted by filmamigo Quote
Also a brilliant lens. Sharp, well behaved, very modern rendering. With this lens and a 90mm 2.8 you could shoot pretty well anything.
Yes I have both of those lenses yet I still shoot the 55/4 the most.
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