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Image Circle of Contax 645 Lens

marc aurel

Active member
Hi Marc -

It's very important to stress the sensor here. With the 24 TSE at least, there is a significant difference on FF MFDB when you go from f/8 to f/11, and another improvement from f/11 to f/16.

The diagonal of the MFDB is 14mm longer than that of the A7R, so it's perhaps not surprising that if you're "only" shifting 10mm on the A7R you're not getting into the zone where stopping down starts to make a big difference.

Looking at your test image, I'm assuming that you're shifting up 10mm in portrait orientation - that means the image circle required to cover that shift is actually just 61mm.

The TS-E image circles are a lot larger than that - they have to be a minimum of 67.2mm to cover the IQ180 used in my earlier linked example.

It's great to see these lenses getting used on a wide range of cameras and formats - they are incredibly versatile - but care needs to be taken not to interpret results of tests on one format as being relevant to another. I wouldn't dream of shooting these lenses at f/8 on FF MFDB unless I wasn't at all worried about the corners.

Kind regards,

Gerald.

Hi Gerald,

of course you are right - you can not simply take results from one sensor size to another. I didn't mean to do that. I was just trying to give an impression of what happens when you use the outer parts of the image circle and present the results in a way that can be easily consumed.

But the pixel size of the A7R is very close to that of the IQ250 that I referred to (4,9 vs. 5,3). Both have no AA-filter and are made by Sony. So resolution on pixel level should be similar if you use the same lens and aperture. The image that the lens projects is the same, you just use a larger part of it.

With that in mind - I admit you're right. My recommendation for f8 unshifted would be wrong for a MF sensor - because you use parts of the sensor that are further away from the centre. The corner of an unshifted IQ180 sensor is 33,6mm from the centre, the corner of an unshifted IQ 250 is 27,5mm from the centre - very close to where I took my crop from. And for that crop - 30mm from the centre - yes, f16 looks even better than f11. But the centre gets a bit worse already at f11 because of diffraction, and a bit more at f16. So there is a tradeoff. From what I have seen - the Contax 35mm for 645 holds sharpness better and does not need to be stopped down to f16 to do this. As much as I love the TS-Es - they are great and offer extreme wide angles, but they are not perfect for a MF sensor in my opinion.

I would be really interested to see a well done comparison between the Contax 35mm for 645 versus the HR Digaron 32mm with an IQ 250.

Best regards - Marc
 
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chrismuc

Member
Marc: comparison Rodenstock 32 vs. Contax 645 35 w/ 44x33mm Sony sensor

image circle & color cast:
Voidschatter tested here

http://www.getdpi.com/forum/medium-...32-40-70-90-desaturation-mazing-artifact.html

the Rodie 32 with the Sony 50MP back and found that the maximum shift with acceptable (= correctable) amount of corner color shift is 12mm rise at landscape orientation. This means the Rodie 32 in combination with a 50MP CMOS back has a usable image circle of 72mm.

The Contax 645 35's image circle is a bit larger with 78mm with allows also full lateral shifts of 12mm (without color cast correction in post!) or combinations of left/right and up/down to a certain extent.

sharpness:
At f11 diffraction limits the contrast at 40 l/mm to 69 %, therefore I expect sharpness of the two lenses to be quite similar.
 

chrismuc

Member
I want to proceed reporting about my tests using 645 and 6x6 lenses mounted to the prototype Alpa Contax shift adapter / Alpa FPS / IQ180.

First the list of tested lenses:

1. Contax 645 (mounted directly to the Contax shift adapter)

Contax 645 35f3.5 Distagon
Contax 645 55f3.5 Distagon
Contax 645 80f2 Planar
Contax 645 120f4 Apo Makro-Planar
Contax 645 140f2.8 Sonnar
Contax 645 210f4 Sonnar

2. Mamiya 645 (lens mount converted to Contax 645)

Mamiya 645 200f2.8 Apo

3. Hasselblad V (with Hasselblad V - Contax 645 adapter)

CF 50f4 FLE Distagon
CF 100f3.5 Planar
CF 150f2.8 Sonnar
CF 180f4 Sonnar

Like mentioned before, I always stiched four pics to one file.
- left 12mm
- left 12mm + up 12mm
- right 12mm + up 12mm
- right 12mm
This results in images 76mm wide and 52,5mm high with about 150 MP resolution.

Following links to the stiched files:

Contax 35f3.5 and 55f3.5
see previous post in same thread.

Contax 80f2
https://dl.dropboxusercontent.com/u...er/Contax-645_80f2@f11_l12_u12-r12+rulers.jpg
total image circle: about 86mm
sharp image circle: about 74mm

Contax 120f4 Apo Macro
https://dl.dropboxusercontent.com/u...-645_120f4ApoMacro@f11_l12_u12-r12+rulers.jpg
total image circle: about 100mm
sharp image circle: about 79mm

Contax 140f2.8*
https://dl.dropboxusercontent.com/u...Contax-645_140f2.8@f11_l12_u12-r12+rulers.jpg
total image circle: about 81mm
sharp image circle: about 78mm

Contax 210f4
https://dl.dropboxusercontent.com/u...r/Contax-645_210f4@f11_l12_u12-r12+rulers.jpg
total image circle: about 99mm
sharp image circle: about 79mm

Hasselblad V lenses via a Hasselblad V to Contax 645 adapter:

Hasselblad V 50f4 FLE
https://dl.dropboxusercontent.com/u...sselblad_V_50f4FLE@f11_l12_u12-r12+rulers.jpg
total image circle: about 96mm
sharp image circle: about 78mm

Hasselblad V 100f3.5
https://dl.dropboxusercontent.com/u...sselblad_V_100f3.5@f11_l12_u12-r12+rulers.jpg
total image circle: about 100mm
sharp image circle: about 75mm

Hasselblad V 150f2.8
https://dl.dropboxusercontent.com/u...sselblad_V_150f2.8@f11_l12_u12-r12+rulers.jpg
total image circle: about 101mm
sharp image circle: about 78mm

Hasselblad V 180f4
https://dl.dropboxusercontent.com/u...Hasselblad_V_180f4@f11_l12_u12-r12+rulers.jpg
total image circle: about 100mm
sharp image circle: about 92mm

Mamiya 645 lens (converted to Contax 645 mount):

Mamiya 645 200f2.8 Apo
https://dl.dropboxusercontent.com/u...iya_645_200f2.8Apo@f11_l12_u12-r12+rulers.jpg
total image circle: about 91mm
sharp image circle: about 88mm
(Att: I focussed not exactly on front of the center car but eventually slightly behind.)

Unfortunately the motive with the cars in the BMW exhibition hall is not the most useful because not always parts of the motive are in the relevant area of depth of field outside the center.
So while it’s easy to see the total image circle, it is a bit difficult for the longer focal lengths to see well the sharp image circle.
I have to do the test again with a plain house wall with detailed structure.

Also the curvy Zaha Hadid architecture of the building covers any information about geometrical lens distortions:)

In case of using a 44x33mm digital back (IQ150, IQ250, P40+, Credo 40, Credo 50, Hasselblad CFV-50 aso.), the image circles of all tested lenses despite the Contax 645 35f3.5 and the Contax 645 80f2 would be sufficient to cover full shifts in both directions at the same time!

From the excel calculations you can see the maximum shifts horizontally and vertically within the sharp image circles.

And I added a calculation for a 2.5 to 1 ratio panoramic picture by stiching two left and right shifted shots. The image circles of the tested lenses allow 13.000 to 16.000 pixel wide 2.5/1 pano pics with 72 to 106 MP resolution.

I intend to use the Alpa Contax shift adapter mainly with the Contax 35, the Hasselblad 50 FLE, 100 and 180. Together with the 17 & 24 TSE lenses using the Alpa Canon mount for the FPS, this provides a nice range of wide angle to medium focal length lenses with certain shift capabilities, good sharpness, lack of color cast, reasonable priced (after heavily investing in the cam + two mounts and the back ... ;-) without using a dedicated tech cam and Schneider/Rodenstock lenses.

Enjoy,

Christoph

link to the image circles coz the thumbnail pic is too small
https://dl.dropboxusercontent.com/u/18437364/Alpa-FPS+Contax-Shift-Adapter/Image-Circles.png
 
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rupho

New member
Christoph,
You got to stop this , soon there are no more Contaxt lenses on the market :)
Kidding aside thanks for you great contributions , you are a living well of knowledge.
I did not expect the 32 HR to shift less on the IQ250 as compared to the IQ260
Again thanks
 

chrismuc

Member
Thx Grischa,

actually my purpose is to encourage

Zeiss (+ Kyocera?)

- to release an updated version of their 645 camera (modern AF)
- to update their 645 lens line (add 25, update 45 and 210)

Sony

- to release a 54x40mm version of their 44x33mm CMOS sensor

Phase One

- to reconsider their back prices

:)
 

kimyeesan

Member
I used to have that Contax MF zoom - pretty good lens, and not bad value for the glass/ elements involved. Heavy though. No idea if it up to digital or not, sold it many years ago.

All I can say is stay away from current generation Rodenstock Tech lenses. Especially the 90mm HR-SW. You will not be happy with any Contax or Hasselblad lens once you've seen what that can do.
Too late, I have HR 23, 32, 50 and 70 and about to get the new HRSW 90...

I can understand what it can do and yes, it's spectacular.

But I really like those Zoom lens opportunity and also as a package, SLR lens tends to be more transportable and also more 'solid' built... not sure if I used the correct word or not...
 

kimyeesan

Member
I am fortunate enough to have tried out the Pre production version of the Contax Shift Adaptor today. I am very happy to report that it is an amazing piece of kit. Albeit that it still need some work in terms of ergonomics. Contax lens is amazing!

Contax 645 45-90mm@45mm 3 Image Stitched
This lens is the lowest resolving lens of the bunch, as I found out today.
 

T.Dascalos

Not Available
Thx Grischa,

actually my purpose is to encourage

Zeiss (+ Kyocera?)

- to release an updated version of their 645 camera (modern AF)
- to update their 645 lens line (add 25, update 45 and 210)

Sony

- to release a 54x40mm version of their 44x33mm CMOS sensor

Phase One

- to reconsider their back prices

:)
Excelent information Chris... very helpful for those that expect to use their Contax lenses on Cambo Actus too, if Cambo will release a Contax mount adapter version of their battery powered automatic aperture control lens adapter.

I believe that Contax manufacturing rights are 10 years old by the 31st of December this year... I think that the international law gives the right to Zeiss (owner of Contax rights) to overcome Kyocera contracts after 31/12/2015 and thus, it is very possible to see a resurrection of the C645 system if another maker or Zeiss itself decides to enter the MF market with an alternative camera platform.

In my opinion, C645 camera needs very little improvements in order to be adapted on todays standards, an up today AF system is the major spec that it lacks.
 

narikin

New member
I have been reliably informed that Zeiss have no interest at all in MF lens production nowadays - the numbers are just far too small to make it worthwhile. The money is all in FF compatibles.

(The fiasco of the Zeiss-Sinar M lens range, add weight to that opinion. I doubt 300 of these MF Zeiss lenses were sold worldwide. Shame)
 

T.Dascalos

Not Available
I have been reliably informed that Zeiss have no interest at all in MF lens production nowadays - the numbers are just far too small to make it worthwhile. The money is all in FF compatibles.

(The fiasco of the Zeiss-Sinar M lens range, add weight to that opinion. I doubt 300 of these MF Zeiss lenses were sold worldwide. Shame)
That maybe true, but surely Zeiss are interested for Contax name not to "die". If another company is interested to replace Kyocera, then there is no risk for Zeiss as to license them for resurrecting the name.

In fact, there maybe interest from Leica to do so... If one thinks about it, Leica needs a system as to "bridge" Leica S with Sinar products. The resurrection of Contax from a maker like Leica could both provide a platform for Sinarbacks to be used on an "in-family" MF platform and also has a lens system that is fully dedicated with the Leica S series of cameras.
 

T.Dascalos

Not Available
In fact a lens line like Contax, as Chris states above, maybe perfect for Sinar to enter the "small view camera" market after Cambo (Actus) and Arca (Universalis) did. Surely one can't expect Sinar not to compete with Arca or Cambo in the same field.

Lets not forget that Leica now has the T-series in production of which the mount is also a mirrorless that can take a FF sensor, with C645 lenses and a focal plane shutter the T-series can be a perfect supplement for a "small" Sinar pro view camera platform of which the image area could be future upgraded by using an MFDB (multishot?) on it.

Surely, the work that Leica does now with its 007 CMOS sensor and its LV capabilities, is expected to pass on Sinarbacks in the near future them being "family members".
 

drevil

Well-known member
Staff member
I believe that Contax manufacturing rights are 10 years old by the 31st of December this year... I think that the international law gives the right to Zeiss (owner of Contax rights) to overcome Kyocera contracts after 31/12/2015 and thus, it is very possible to see a resurrection of the C645 system if another maker or Zeiss itself decides to enter the MF market with an alternative camera platform.
the name rights went back to zeiss, several years ago, to my knowledge.

i also see little hope that zeiss would lease the name again to make another MF system with updated C645 lenses, as much as i would hope so!

as it has already been stated, a C645 II body would need a modern AF system, more power efficient electronics and tada, what else do you need.
i love my contax for its simplicity!
 

T.Dascalos

Not Available
the name rights went back to zeiss, several years ago, to my knowledge.

i also see little hope that zeiss would lease the name again to make another MF system with updated C645 lenses, as much as i would hope so!

as it has already been stated, a C645 II body would need a modern AF system, more power efficient electronics and tada, what else do you need.
i love my contax for its simplicity!
Although one can't be sure on what was the agreement between Zeiss and Kyocera or who was responsible for the discontinuation of the product line, I remember Zeiss claiming on their web side until 5 years ago that they own the name "Contax", I don't think that there was ever name rights that where passed to another company (or Kyocera) from Zeiss. To my knowledge there was a contract so that Kyocera would produce products approved by Zeiss and market them which lasted for several decades and that production was stopped by Kyocera because it was not profitable to them.

I remember once a Phase One executive that happened to be on a conversation for the matter where I was present, that Phase One offered a good amount of money to Kyocera so that they would retire from the contract with Zeiss and resurrect Contax by making a new contract with Zeiss (Zeiss was in agreement for that), but it seems that Kyocera wasn't satisfied with the compensation and P1 moved to invest on Mamiya because of that.

To my believe, there is some time under law (which I believe is of 10 years) that there is automatic disengagement from the contract between Zeiss and Kyocera. I also know that servicing of Contax products in Europe was done by Tritec (using genuine parts) in Germany and that it was authorised by Zeiss.

Never the less, Contax ergonomics and lens quality has continuously satisfied me for the last 10 years and It never passed from my mind to drop the system for another. If a new body would be introduced, I would of course expect it to have a better AF system (the lenses become extremely fast and accurate focusing when used on my Nikons via the JAS adapter I recently got), rechargeable battery with more life, permanent mirror lock to use with multishot backs for while the process lasts and perhaps (even) faster shutter so that sync speed could be risen further. I would surely wouldn't want the ergonomics or the design to change... I wouldn't even complain if Av mode would be dropped completely.
 

drevil

Well-known member
Staff member
i was in mail contact with zeiss once, they told me the name rights are back at zeiss now and it was especially pointed out that zeiss never made any cameras themselves, never, it was always other companies using the name.

i also heard that phase was heavily interested in aquiring contax(kyocera) technology instead of mamiya

but as already said, zeiss seems not interested anymore in investing into MF lenses. they make a big buck of money these days with 35mm lenses and smaller.

sad but true
 

T.Dascalos

Not Available
but as already said, zeiss seems not interested anymore in investing into MF lenses. they make a big buck of money these days with 35mm lenses and smaller.

sad but true
It certainly seems that MF lenses market has shrunk considerably during the past decade... MF camera market is much smaller in the digital era than they used to be with film, but this may be about to change soon... The recent introduction of Cambo Actus & Arca universals is expected to be followed by other makers soon (Sinar, Silvestri ...etc). There is also a tendency for larger sensors for cinema/video use... Lets not forget that cinema was always a market that historically interests Zeiss.

If all the above will be combined with a possible C645 resurrection, I find it very possible that Zeiss interest on that market will be attracted back, especially as they already have very good designs to be based on from the past and a lot of new technology to develop them further, without investing from start to create a line.

IMO it all has to do with how promising the (possible) investor would be. I believe that if the investor would be a company with "heavy" name (like Leica) and if Sony (a traditional Zeiss companion) will decide to join the group of makers with larger sensor cameras for video/cinema, then it would certainly be on Zeiss interest to re-enter the larger image circle lenses market.
 

Alan Johnston

New member
I am new to GetDPI and this thread. I have four Contax 645 lenses and a converted NAM-1 adapter to Canon mount. I also just purchased a HCam Mirex Canon to E-mount adapter (version 2) to use these Contax lenses (T&S) with my Sony A7RII and A7II. I belatedly discovered that putting the Mirex into the equation means no f-stop adjustment is possible (since this is electronically by 'wire' with 645 lenses).

Stefan Streib put me onto this thread and so I am asking for feedback on this issue - he mentioned that Christoph Kugler has some experience with this situation. Cheers.
 

chrismuc

Member
Hi Alan, welcome using Contax 645 lenses on a non-Contax 645 camera ;-)

Using Contax 645 lenses

- either w/ Mirex Contax 645 - Canon EF shift adapter + Canon EF camera
- or w/ Contax NAM-1 adapter (Conorus converted) + Hartblei/Mirex Canon EF - Sony E shift adapter + Sony E camera

you will have to mount the Contax 645 lens first either to a Contax 645 camera or via the Contax NAM-1 adapter to a Canon EF camera, set they wanted aperture (e.g. f11) at the lens barrel, push the DOF button on the camera (so the aperture will close to the desired value) and unmount the lens. The lens will stay at this aperture.

Actually the same procedure like using a Canon EF lens (e.g. the TSE lenses or the 11-24) with the Hartblei/Mirex Canon EF - Sony E shift adapter on a Sony E camera

This is of course a bit uncomfortable but for architecture, interior design and landscape where you mainly would use an aperture around f8 ... f13 it is not such a big drawback to pre-set it. And using life view, the focusing at such rather closed aperture still work very well.

Enjoy, Christoph
 
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