Why can't we crowdfund a 645 ultrawide?

SylvainB · 05-05-2021, 11:07 AM - **4 Likes**

Originally posted by Wasp

Reproducing a hundred year old design is one thing. Designing and producing an ultra wide retrofocal with autofocus is another. Even Pentax in their heyday never built anything wider than a 25mm. One of the widest medium format DSLR lenses ever. Hasselblad and Zeiss never managed anything close to this. It is quite rare, apparently.

The closest to this is the Mamiya Sekor 28mm f/4.5.

In short, I really don't think anything wider on a full frame 645 DSLR is doable - otherwise it would have been done when the market was still there.

You just forgot to mention Hasselblad HCD 24mm f/4,8, designed to work on 49x37 sensors for their DSLR line-up (but which actually works quite well on 54x40 sensors).
You can buy one, new or 2nd hand, anytime you want.

**SteveinSLC** · 05-05-2021, 11:32 AM - **2 Likes**

Originally posted by SylvainB

You just forgot to mention Hasselblad HCD 24mm f/4,8, designed to work on 49x37 sensors for their DSLR line-up (but which actually works quite well on 54x40 sensors).
You can buy one, new or 2nd hand, anytime you want.

Yowza. Assuming you have an extra $7000 for a 1mm gain on the Pentax 25. That's where the problem is with this idea in general. Designing and manufacturing this sort of lens is costly, and the market is very small. Meaning that for any entity to see an ROI, the price has to be very high (which then limits the market even more).

SylvainB · 05-06-2021, 04:05 AM - **2 Likes**

Originally posted by SteveinSLC

Yowza. Assuming you have an extra $7000 for a 1mm gain on the Pentax 25. That's where the problem is with this idea in general. Designing and manufacturing this sort of lens is costly, and the market is very small. Meaning that for any entity to see an ROI, the price has to be very high (which then limits the market even more).

It's not really that one would want to pay more for 1mm over the D(F)A 25mm from Pentax, it's that right now, there is on the market a very wide angle lens designed for a DSLR medium format camera that can cover larger than 33x44mm sensor. So it is doable, I was reacting to that. Moreover, the D(F)A 25mm can cover only 33x44, so to speak, because Pentax doesn't have a larger sensor. So you can shoot with 24x36 equivalent of 20mm on Pentax 645 digital, and 16mm on Hasselblad H. It's quite a big difference, to me.

I agree with the rest of your comment, of course (cost and market size). And that should answer the question of the OP

**TDvN57** · 05-06-2021, 06:41 AM

This article says the Laowa 15mm tilt lens has an image circle of 65mm. K-mount now available. Perhaps they can make a P645 mount. Was apparently designed for FF and MF and gives +/-8mm tilt in MF and +/-11mm I FF.

Laowa 15mm f/4.5 Zero-D Shift available in Leica L-mount and Pentax K-mount | Digital Camera World

**kaseki** · 05-06-2021, 08:27 AM - **1 Like**

Originally posted by SylvainB

... Moreover, the D(F)A 25mm can cover only 33x44, so to speak, because Pentax doesn't have a larger sensor. ...

At the time of production, the DFA was also to be used in the 645 film cameras, which by our definition are full frame. That is why its lens hood is shorter. I haven't tested it on my 'N' yet, but testing is on my bucket list.

See description at SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW Reviews - 645 Wide-Angle Primes - Pentax Lens Reviews & Lens Database

**barondla** · 05-06-2021, 09:12 AM

Originally posted by TDvN57

This article says the Laowa 15mm tilt lens has an image circle of 65mm. K-mount now available. Perhaps they can make a P645 mount. Was apparently designed for FF and MF and gives +/-8mm tilt in MF and +/-11mm I FF.

Laowa 15mm f/4.5 Zero-D Shift available in Leica L-mount and Pentax K-mount | Digital Camera World

Image circle covers 645 digital, but would it focus to infinity? L mount flange distance is 20mm, even less than Fuji mf. Pentax 645 needs about 70mm! Don't see that happening.

Thanks,
barondla

mikeSF · 05-06-2021, 09:35 AM - **1 Like**

Originally posted by Wasp

I can see why they went to the trouble of building this lens. Incidentally, the swirly effect seems less pronounced when the lens is used on a 35mm camera...

wow, swirly bokeh!

---------- Post added 05-06-21 at 09:39 AM ----------

Originally posted by Ed Hurst

Like Mike, I too wouldn't be looking for anything that duplicates or is similar to the 25 or the 28-45. It would need to be appreciably wider to get my interest. The only area where I'd diverge from Mike's view is the speed... Because one of my main applications is astro, I'd want it to be at least f4 and ideally faster :-). If we could get a lens like that to happen, and to a high standard, I'd be in!

I do like my astro too, and I didn't want to get greedy, but yeah, a fast wide lens would be amazing...but I suspect over $5,000 USD.

Last edited by mikeSF; 05-06-2021 at 09:45 AM.

SylvainB · 05-07-2021, 03:54 AM

Originally posted by kaseki

At the time of production, the DFA was also to be used in the 645 film cameras, which by our definition are full frame. That is why its lens hood is shorter. I haven't tested it on my 'N' yet, but testing is on my bucket list.

See description at SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW Reviews - 645 Wide-Angle Primes - Pentax Lens Reviews & Lens Database

I completely agree with you, kaseki, I just meant that for the moment, there is no Pentax camera with a larger sensor than 33x44 to put behind, so no way to take advantage of the larger coverage of the DFA. So, with a DFA or a DA, you are stuck with an equivalent of 20mm on a Pentax 645 digital camera today.

**tmoses** · 05-07-2021, 07:59 AM

Are we not at the point with "stitching" that you could make as wide as you want, if you have a decent panohead on your tripod?

**kaseki** · 05-07-2021, 08:16 AM

For a bit more perspective w.r.t. the Pentax 25mm vs. the Laowa, consider this gedanken experiment. The 25-mm DFA parameters (glass dimensions, thicknesses, and spacings are changed to 3/5 their present values. (Glass types are kept the same.) The result would be a lens with the same field of view but 15mm in EFL. The image circle would be reduced to 3/5 of the original, perhaps marginal for the Z focal plane when starting with whatever amount the 25mm DFA overlaps the film image boundary.

However, the back focal length would also drop to 3/5 of 70-whatever-mm. The 25mm already has glass in flange plane. So this element would have to be about 28 mm deeper into the mirror box. This would make the result like the Laowa, which as far as I can determine from a quick review is only suitable for MF if the camera design is mirror-less.

**barondla** · 05-07-2021, 09:43 AM

Originally posted by kaseki

For a bit more perspective w.r.t. the Pentax 25mm vs. the Laowa, consider this gedanken experiment. The 25-mm DFA parameters (glass dimensions, thicknesses, and spacings are changed to 3/5 their present values. (Glass types are kept the same.) The result would be a lens with the same field of view but 15mm in EFL. The image circle would be reduced to 3/5 of the original, perhaps marginal for the Z focal plane when starting with whatever amount the 25mm DFA overlaps the film image boundary.

However, the back focal length would also drop to 3/5 of 70-whatever-mm. The 25mm already has glass in flange plane. So this element would have to be about 28 mm deeper into the mirror box. This would make the result like the Laowa, which as far as I can determine from a quick review is only suitable for MF if the camera design is mirror-less.

Agree with you. Don't see any way the Laowa 17 could work on a Pentax 645 at infinity. Doubt they designed the lens from scratch for MF. It happens to have enough image circle and the mirrorless flange distance was within spec. A happy bit of luck.

Thanks for the explanation,
barondla

**mattb123** · 05-07-2021, 10:06 AM

I didn't know about that Mamiya SEKOR 28mm. Those would adapt ok to Pentax 645 wouldn't they?
Does anyone know if there an older manual version of this lens? The AF would be wasted when it's adapted. If an older version was more affordable I might be interested.
I have the Arsat 30mm adapted from Pentacon and it is ok but not great. A higher quality lens and slightly wider would be nice.

zjacreman · 05-07-2021, 01:58 PM - **1 Like**

Originally posted by mattb123

Those would adapt ok to Pentax 645 wouldn't they?

Nope, Mamiya 645 has a shorter flange focal distance than Pentax 645 (per the table here). You can adapt a longer flange mount to a shorter one (that's why mirrorless cameras are so promiscuously adaptable) but not a shorter one to a longer one.

**mattb123** · 05-07-2021, 03:24 PM

Originally posted by zjacreman

Nope, Mamiya 645 has a shorter flange focal distance than Pentax 645 (per the table here). You can adapt a longer flange mount to a shorter one (that's why mirrorless cameras are so promiscuously adaptable) but not a shorter one to a longer one.

Oh well. Thanks for the info!

angerdan · 05-16-2021, 04:38 AM

Originally posted by barondla

Just a well built rectilinear ultrawide that covers full frame 645.
With crowdfunding, the company wouldn't have to build it unless enough people paid up. Wonder what the development cost of such a lens would lens would be?

The time of an experienced optical engineer who is able to develop a new optical formula for a 645 lens. And the time for engineers who construct the mechanics and tubus of the lens.
So if three people have to work on it for six months and no costs for software license, patent registration etc would be needed, you can calculate with 360 working hours multiplying with an wage of ~$30 you'd get $11.000.
Of course it could be at least double of that.

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05-05-2021, 11:07 AM - 4 Likes	#46
SylvainB Senior Member Join Date: Dec 2015 Location: Paris area Posts: 215	Originally posted by Wasp Reproducing a hundred year old design is one thing. Designing and producing an ultra wide retrofocal with autofocus is another. Even Pentax in their heyday never built anything wider than a 25mm. One of the widest medium format DSLR lenses ever. Hasselblad and Zeiss never managed anything close to this. It is quite rare, apparently. The closest to this is the Mamiya Sekor 28mm f/4.5. In short, I really don't think anything wider on a full frame 645 DSLR is doable - otherwise it would have been done when the market was still there. You just forgot to mention Hasselblad HCD 24mm f/4,8, designed to work on 49x37 sensors for their DSLR line-up (but which actually works quite well on 54x40 sensors). You can buy one, new or 2nd hand, anytime you want.

05-05-2021, 11:32 AM - 2 Likes	#47
SteveinSLC Site Supporter Join Date: Mar 2017 Photos: Gallery \| Albums Posts: 568	Originally posted by SylvainB You just forgot to mention Hasselblad HCD 24mm f/4,8, designed to work on 49x37 sensors for their DSLR line-up (but which actually works quite well on 54x40 sensors). You can buy one, new or 2nd hand, anytime you want. Yowza. Assuming you have an extra $7000 for a 1mm gain on the Pentax 25. That's where the problem is with this idea in general. Designing and manufacturing this sort of lens is costly, and the market is very small. Meaning that for any entity to see an ROI, the price has to be very high (which then limits the market even more).

05-06-2021, 04:05 AM - 2 Likes	#48
SylvainB Senior Member Join Date: Dec 2015 Location: Paris area Posts: 215	Originally posted by SteveinSLC Yowza. Assuming you have an extra $7000 for a 1mm gain on the Pentax 25. That's where the problem is with this idea in general. Designing and manufacturing this sort of lens is costly, and the market is very small. Meaning that for any entity to see an ROI, the price has to be very high (which then limits the market even more). It's not really that one would want to pay more for 1mm over the D(F)A 25mm from Pentax, it's that right now, there is on the market a very wide angle lens designed for a DSLR medium format camera that can cover larger than 33x44mm sensor. So it is doable, I was reacting to that. Moreover, the D(F)A 25mm can cover only 33x44, so to speak, because Pentax doesn't have a larger sensor. So you can shoot with 24x36 equivalent of 20mm on Pentax 645 digital, and 16mm on Hasselblad H. It's quite a big difference, to me. I agree with the rest of your comment, of course (cost and market size). And that should answer the question of the OP

05-06-2021, 06:41 AM	#49
TDvN57 Loyal Site Supporter Join Date: Jul 2011 Location: Berlin Photos: Gallery Posts: 1,150	This article says the Laowa 15mm tilt lens has an image circle of 65mm. K-mount now available. Perhaps they can make a P645 mount. Was apparently designed for FF and MF and gives +/-8mm tilt in MF and +/-11mm I FF. Laowa 15mm f/4.5 Zero-D Shift available in Leica L-mount and Pentax K-mount \| Digital Camera World

05-06-2021, 08:27 AM - 1 Like	#50
kaseki Loyal Site Supporter Join Date: Dec 2017 Photos: Gallery \| Albums Posts: 1,138	Originally posted by SylvainB ... Moreover, the D(F)A 25mm can cover only 33x44, so to speak, because Pentax doesn't have a larger sensor. ... At the time of production, the DFA was also to be used in the 645 film cameras, which by our definition are full frame. That is why its lens hood is shorter. I haven't tested it on my 'N' yet, but testing is on my bucket list. See description at SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW Reviews - 645 Wide-Angle Primes - Pentax Lens Reviews & Lens Database

05-06-2021, 09:12 AM	#51
barondla Site Supporter Join Date: Sep 2006 Location: midwest, United States Photos: Gallery \| Albums Posts: 5,716 Original Poster	Originally posted by TDvN57 This article says the Laowa 15mm tilt lens has an image circle of 65mm. K-mount now available. Perhaps they can make a P645 mount. Was apparently designed for FF and MF and gives +/-8mm tilt in MF and +/-11mm I FF. Laowa 15mm f/4.5 Zero-D Shift available in Leica L-mount and Pentax K-mount \| Digital Camera World Image circle covers 645 digital, but would it focus to infinity? L mount flange distance is 20mm, even less than Fuji mf. Pentax 645 needs about 70mm! Don't see that happening. Thanks, barondla

05-06-2021, 09:35 AM - 1 Like	#52
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,622	Originally posted by Wasp I can see why they went to the trouble of building this lens. Incidentally, the swirly effect seems less pronounced when the lens is used on a 35mm camera... wow, swirly bokeh! ---------- Post added 05-06-21 at 09:39 AM ---------- Originally posted by Ed Hurst Like Mike, I too wouldn't be looking for anything that duplicates or is similar to the 25 or the 28-45. It would need to be appreciably wider to get my interest. The only area where I'd diverge from Mike's view is the speed... Because one of my main applications is astro, I'd want it to be at least f4 and ideally faster :-). If we could get a lens like that to happen, and to a high standard, I'd be in! I do like my astro too, and I didn't want to get greedy, but yeah, a fast wide lens would be amazing...but I suspect over $5,000 USD. Last edited by mikeSF; 05-06-2021 at 09:45 AM.

05-07-2021, 03:54 AM	#53
SylvainB Senior Member Join Date: Dec 2015 Location: Paris area Posts: 215	Originally posted by kaseki At the time of production, the DFA was also to be used in the 645 film cameras, which by our definition are full frame. That is why its lens hood is shorter. I haven't tested it on my 'N' yet, but testing is on my bucket list. See description at SMC Pentax-D FA 645 25mm F4 AL [IF] SDM AW Reviews - 645 Wide-Angle Primes - Pentax Lens Reviews & Lens Database I completely agree with you, kaseki, I just meant that for the moment, there is no Pentax camera with a larger sensor than 33x44 to put behind, so no way to take advantage of the larger coverage of the DFA. So, with a DFA or a DA, you are stuck with an equivalent of 20mm on a Pentax 645 digital camera today.

05-07-2021, 07:59 AM	#54
tmoses Site Supporter Join Date: Jul 2009 Location: Montgomery, TX Photos: Gallery \| Albums Posts: 66	Are we not at the point with "stitching" that you could make as wide as you want, if you have a decent panohead on your tripod?

05-07-2021, 08:16 AM	#55
kaseki Loyal Site Supporter Join Date: Dec 2017 Photos: Gallery \| Albums Posts: 1,138	For a bit more perspective w.r.t. the Pentax 25mm vs. the Laowa, consider this gedanken experiment. The 25-mm DFA parameters (glass dimensions, thicknesses, and spacings are changed to 3/5 their present values. (Glass types are kept the same.) The result would be a lens with the same field of view but 15mm in EFL. The image circle would be reduced to 3/5 of the original, perhaps marginal for the Z focal plane when starting with whatever amount the 25mm DFA overlaps the film image boundary. However, the back focal length would also drop to 3/5 of 70-whatever-mm. The 25mm already has glass in flange plane. So this element would have to be about 28 mm deeper into the mirror box. This would make the result like the Laowa, which as far as I can determine from a quick review is only suitable for MF if the camera design is mirror-less.

05-07-2021, 09:43 AM	#56
barondla Site Supporter Join Date: Sep 2006 Location: midwest, United States Photos: Gallery \| Albums Posts: 5,716 Original Poster	Originally posted by kaseki For a bit more perspective w.r.t. the Pentax 25mm vs. the Laowa, consider this gedanken experiment. The 25-mm DFA parameters (glass dimensions, thicknesses, and spacings are changed to 3/5 their present values. (Glass types are kept the same.) The result would be a lens with the same field of view but 15mm in EFL. The image circle would be reduced to 3/5 of the original, perhaps marginal for the Z focal plane when starting with whatever amount the 25mm DFA overlaps the film image boundary. However, the back focal length would also drop to 3/5 of 70-whatever-mm. The 25mm already has glass in flange plane. So this element would have to be about 28 mm deeper into the mirror box. This would make the result like the Laowa, which as far as I can determine from a quick review is only suitable for MF if the camera design is mirror-less. Agree with you. Don't see any way the Laowa 17 could work on a Pentax 645 at infinity. Doubt they designed the lens from scratch for MF. It happens to have enough image circle and the mirrorless flange distance was within spec. A happy bit of luck. Thanks for the explanation, barondla

05-07-2021, 10:06 AM	#57
mattb123 Site Supporter Join Date: Apr 2010 Location: Colorado High Country Photos: Gallery Posts: 10,873	I didn't know about that Mamiya SEKOR 28mm. Those would adapt ok to Pentax 645 wouldn't they? Does anyone know if there an older manual version of this lens? The AF would be wasted when it's adapted. If an older version was more affordable I might be interested. I have the Arsat 30mm adapted from Pentacon and it is ok but not great. A higher quality lens and slightly wider would be nice.

05-07-2021, 01:58 PM - 1 Like	#58
zjacreman Senior Member Join Date: Sep 2017 Location: Bogota Photos: Albums Posts: 120	Originally posted by mattb123 Those would adapt ok to Pentax 645 wouldn't they? Nope, Mamiya 645 has a shorter flange focal distance than Pentax 645 (per the table here). You can adapt a longer flange mount to a shorter one (that's why mirrorless cameras are so promiscuously adaptable) but not a shorter one to a longer one.

05-07-2021, 03:24 PM	#59
mattb123 Site Supporter Join Date: Apr 2010 Location: Colorado High Country Photos: Gallery Posts: 10,873	Originally posted by zjacreman Nope, Mamiya 645 has a shorter flange focal distance than Pentax 645 (per the table here). You can adapt a longer flange mount to a shorter one (that's why mirrorless cameras are so promiscuously adaptable) but not a shorter one to a longer one. Oh well. Thanks for the info!

05-16-2021, 04:38 AM	#60
angerdan Pentaxian Join Date: Feb 2015 Photos: Gallery \| Albums Posts: 2,643	Originally posted by barondla Just a well built rectilinear ultrawide that covers full frame 645. With crowdfunding, the company wouldn't have to build it unless enough people paid up. Wonder what the development cost of such a lens would lens would be? The time of an experienced optical engineer who is able to develop a new optical formula for a 645 lens. And the time for engineers who construct the mechanics and tubus of the lens. So if three people have to work on it for six months and no costs for software license, patent registration etc would be needed, you can calculate with 360 working hours multiplying with an wage of ~$30 you'd get $11.000. Of course it could be at least double of that.