The Pentacon Six System
by TRA

Using Pentacon Six & M42 Lenses on Fujifilm GFX Cameras


As indicated here, Pentacon Six and M42 lenses can be used on Fujifilm GFX cameras via two ingenious adapters from Hartblei.

I here show the results of initial tests using both M42 and Pentacon Six lenses on a GFX camera.  The size of the GFX sensors is
43.8 × 32.9mm.  Lenses for the Pentacon Six are designed to cover the format 54mm × 54mm (or perhaps 56mm × 56mm) , so coverage of the smaller-sized GFX sensor is assured.  But lenses with the M42 mount are designed to cover the format 36mm × 24mm, so it would be surprising if they were to cover the GFX sensor adequately.

M42 lenses

The M42 screw-thread mount size was introduced by Zeiss Ikon, Dresden in 1946 for their “Contax S” reflex Contax camera, which was a version of the pre-war Contax 35mm rangefinder camera with a built-in mirror to enable the users to see the subject through the lens, instead of through a separate viewfinder.1  This avoided the parallax error of all viewfinder cameras, where the viewfinder cannot cover exactly the same area that will be exposed to the film, because it is situated above the lens.  This led to the well-known characteristic of cutting off the tops of people's heads in close-up photographs.

Using a separate viewfinder also leads to particular problems in two other situations:
  • Using long focus or telephoto lenses.
  • Macro photography.
In both cases, ensuring accurate focus is impossible, and so it accurate composition of the image, as the viewfinder does not cover the same area as the lens.

1 According to Alexander Schulz in “Contax S”, Stuttgart: Lindemanns Verlag, 2008, p. 34.

The same mount was used for KW's Praktiflex in 1948 and subsequently became known as the Praktica/Pentax screw thread mount.

Reports from some who have tried lenses for 35mm SLR “analogue” cameras on “full frame” digital cameras, which have a sensor the same size as the film gate in 35mm SLR cameras, indicate that wide-angle lenses do not cope well with the digital medium, directing peripheral image rays at an acute angle that is not totally captured by the digital sensor, resulting in “vignetting” or darkening of the corners of the image.  Since the GFX sensor is significantly larger than 35mm SLR format or digital “full frame” format, we must anticipate problems.

It must be emphasised that coverage is not enough; the image resolution must also be adequate within the resulting image.  With all lenses, not only does light intensity decrease progressively outside the area designed to be used, so does the resolution.  This is not a fault, as we are talking of an area of the projected image that was never designed to be used.

We carried out tests  with a selection of lenses in M42 mount, shooting at a wide range of apertures.  Here, for reasons of space, we will only show one shot from each lens.  In cases where there was vignetting, the point where the vignetting started was generally more diffuse at the wider apertures and sharper as the smaller apertures.  In some cases coverage improved as the lens was stopped down.

As a very stringent test for vignetting and distortion, I mostly took pictures of a brick wall – not very inspiring, but very revealing of any defects!
 

Here is how I got on.

20mm f/2.8 Carl Zeiss Jena Flektogon
Disappointing, but to be expected.  Fuji collaborated with Hasselblad in the design and manufacture of the XPAN camera range, which had a panoramic format of 65mm × 24mm.  For the GFX camera, Fujifilm offer a simulated “XPAN format”, which is obviously not 65mm wide.  The 20mm Flektogon might just about cover this format in the GFX.

There is a sharper cut-off in the top left corner, presumably caused by an obstruction, possibly even in the camera itself, blocking the rays of light from the lens.

The original image is very sharp, although of course the image size has been reduced massively for reproduction here.  There is no point in showing an enlarged view of the resolution; if the coverage of the format is not adequate, we will not use it on this lens on the GFX.  On the Praktica VLC 35mm analogue camera it produces superb, even stunning, results.
[20Flekf11_GFX.jpg]
25mm f/4 Carl Zeiss Jena Flektogon
This lens was calculated in April 1958 and first manufactured in 1958 or 1959.  (For the first production run, the date is missing.)  Its last production run was completed on 31st March 1965, after which it was discontinued by Zeiss.  The first production run of the 20mm f/4 Flektogon had been completed in August 1963, and this clearly became the ultra-wide angle lens of choice.  (In 1971 a recalculation of the 20mm Flektogon resulted in its maximum aperture being increased to f/2.8.)

The 25mm Flektogon produces a sharp image but does not cover the GFX format, which is not surprising.

[25Flekf11_GFX.jpg]
28mm f/2.8 Schneider-Kreuznach Super-Angulon Shift lens
There is some reduction in image brightness towards the corners, easily within the correction possibilities of imaging software, so this makes a potential excellent wide-angle lens for the GFX 50S, with an angle of view on the larger format approximately equal to that of a 24mm lens on 35mm (“full-frame”) cameras.

This lens has a somewhat warmer colour rendering than the two Flektogon lenses shown above, probably closer to the original colours of the subject.

With the hard test of this brick wall, we can also see a small amount of barrel distortion.  This would not be noticeable with most subjects.
[28SuperAngf11_GFX.jpg]
35mm f/2.8 Schneider-Kreuznach Curtagon
Far too much vignetting.  Might cover the “XPAN” panoramic format.  Well, we really should not expect wide-angle lenses designed for 35mm cameras to cover this larger format.

The colour balance is virtually identical with that from the two Flektogon lenses.
[35Curtagonf11_GFX.jpg]
35mm f/2.4 Carl Zeiss Jena Flektogon
With a small amount of correction for vignetting, this does just about cover the format.  Quite good!

Standard Carl Zeiss Jena colour balance.
[35Flekf11_GFX.jpg]
35mm f/2.8 Arax Tilt/Shift lens for 35mm cameras
Does cover the format from f/8.  As it is a shift lens, which has a larger image circle than a non-shift lens, this is not surprising.  There is a small amount of barrel distortion, which it frequently found with wide-angle lenses.

 [35Araxf11_GFX.jpg]
50mm f/1.8 Carl Zeiss Jena Pancolar
Possibly covers the format at f/8 or f/11 but the larger image format of the GFX reveals barrel distortion.  The Pentacon Six 50mm Medium Format Flektogon should be much better.  See below.

[50Pancolarf11_GFX.jpg]
80mm f/1.8 Carl Zeiss Jena Pancolar
With careful correction of vignetting in the corners, this possibly covers the format, but a Medium Format 80mm lens will be better.
[80Pancolarf11_GFX.jpg]
135mm f/3.5 Carl Zeiss Jena Sonnar
The best of the lot!  Excellent coverage,  This could be a great portrait lens on the GFX camera, and it is small and light weight.

Click on the image to see it larger. 
However, I have had to reduce its size substantially and save it with a very high jpeg compression factor for upload to the internet and hosting on this website.

The original file produced by the GFX camera is 8256 pixels wide × 6192 pixels high, equivalent at 300 ppi to 69.9 cm wide × 52.43 cm high.  The reduced version accessed here by clicking on the image to the right is 2500 pixels wide.  This is my standard “larger size” for images on this website that can be accessed by clicking on the displayed image.

[135Sonnarf8_GFX_s.jpg]
200mm f/2.8 Carl Zeiss Jena Sonnar lens
Good coverage, definitely usable!

Click on image to see it larger.
[200Sonnarf11_GFX_s.jpg]
200mm f/4 Pentacon (Meyer-Optik Görlitz) lens
Good coverage, definitely usable!

Click on image to see it larger.
[200Pentaconf11_GFX_s.jpg]

I am grateful for the following comments from Hartblei:
I would highly recommend to you the Helios 44 X, where the higher the "X", the better the resolution. This lens is outstanding although it is adding a bit of a blueish cast. It covers the GFX sensor and vignetting appears at >f8.
The vignetting of the Arsat 35 shift may come from the narrow throat of the shifting module [in the lens] that was adjusted to 35mm format.

58mm f/2 Helios lens
The lens tested here was manufactured in 1988 and appears to be multicoated on the back element as well as on the front one.

This result looks excellent.  I shot it hand-held at f/11 and I see that I didn’t have the camera perfectly level.  However, the coverage is perfect, there is no distortion and resolution is excellent right into the corners.  This lens can be used any time on the GFX camera with confidence.

A slight shadow on the left-hand edge about two-thirds of the way up is the shadow of a street light, as I shot this test quite late on an April evening, shortly before sunset and the sun was low in the sky and behind the nearby street light.

Click on the image to see it larger, although, as always, this larger image is greatly reduced from the size produced by the GFX camera, and it is saved with an extremely high jpeg compression for internet purposes.



[58mm_Helios_f11_GFX01_s.jpg]
58mm f/2 Helios lens
Here is a second shot taken with the same 58mm Helios lens.  The clear sky reveals the virtually-complete lack of vignetting or reduction in light intensity.  This image, too, was shot late on an April evening, resulting in deep shadows in the bottom part of the image.

Again I have shot this hand-held and at f/11.  Other tests at all apertures show that the resolution and contrast are extremely good from at least f/8.

Click on the image to see it larger.  The high jpeg compression of the larger image has produced the beginnings of some banding in the sky.  This is of course not present in the original image.


[58mm_Helios_f11_GFX02_s.jpg]

Pentacon Six mount lenses

Format coverage on the GFX sensor will of course be no problem for the medium format lenses designed for the Pentacon Six / Kiev 6C / Kiev 60 / Exakta 66 of 1984-2000.  I first tested two lenses in this mount:

80mm f/2.8 Carl Zeiss Oberkochen Planar in Pentacon Six mount
This is the only example that I know of in which this lens is in the Pentacon Six mount.  Coverage is very good at all apertures.  With this adapted version of the lens, care must be taken when focussing.

Click on the image to see it larger.
 [80Planarf11_GFX_s.jpg]
120mm f/2.8 Arsenal Vega 28Б (Russian B) lens This is very good and could become my default lens on this camera.  Not only is coverage excellent at all apertures (as expected), it is extremely sharp.

Click on the image to see it larger.

 [120Vegaf11_GFX_s.jpg]

Medium Format lenses designed for use on the Pentacon Six and equivalent cameras have an image circle that is far wider than that of the GFX cameras, so how do they perform shifted, using the Hartblei shift adapter?  This allows shifts of up to 12mm in any direction.  I have tested the following lenses at f/11 with five shift positions:

  • Zero shift
  • Fully shifted up
  • Fully shifted down
  • Fully shifted left
  • Fully shifted right.
This was done with the camera in horizontal (“landscape”) format.

30mm f/3.5 Arsat MC Fish-Eye lens (a multi-coated version of the Arsenal “Zodiak” lens)
Excellent resolution and coverage at zero shift.  Vignetting at full shift and some chromatic aberrations visible near the edges.  Full shift up (shown here to the right): top left-hand corner cut off.

With the inevitable rectilinear distortion of a fish-eye lens, a far better option may be to use the 28mm Schneider-Kreuznach 35mm “full frame” (24×36mm) PC-Super-Angulon lens (at zero shift), via the Hartblei M42 to GFX adapter.  However, when the features of a fish-eye lens are required, this one is excellent, both on the Pentacon Six and on the Fujifilm GFX.  It must also be remembered that the 28mm Schneider-Kreuznach shift lens is not very common, and it usually commands quite a high price.

Click on the image to see it larger.

The banding in the sky that may be observed with some of these images, especially in the larger version of the image, is an artifact introduced by the jpeg compression.

[30mm_fully_UP_GFX_s.jpg]
40mm f/4 Schneider-Kreuznach Curtagon lens in Exakta 66 mount
Format coverage excellent, however slight resolution fall-off at left and right edges, even with zero shift.  Significant resolution loss at edges and 1 stop light loss at edges at full shift.  Here we show the worst: fully shifted right.

Click on the image to see it larger.

I would advise against using this lens fully shifted.


[40mm_Curtagon_fully_R_GFX_s.jpg]
40mm f/4 Bronica Zenzanon – S lens in Pentacon Six mount
Coverage and resolution excellent at zero shift.
At full shift, slight resolution fall-off very close to left and right edges.  Definitely usable on the GFX, even shifted 6-8mm.


Click on the image to see it larger.
[40mm_Zenzanon_fully_R_GFX_s.jpg]
45mm f/3.5 Mir 69Б (Russian B) lens
Fantastic resolution.
TINY amount of chromatic aberration at edges.
Very minor light fall of at edges on max shift (less than 1 stop).

Fully usable even fully shifted on Fujifilm GFX cameras.


Click on the image to see it larger.

[45mm_Mir69_fully_R_GFX_s.jpg]
50mm f/4 Carl Zeiss Jena Flektogon lens
SUPERB lens
Immaculate resolution and cover including with maximum shift


Click on the image to see it larger.
[50mm_Flek_fully_R_GFX_s.jpg]
150mm f/2.8 Hartblei (an improved version of the Arsenal/Arsat Kaleinar)
Zero shift: resolution is excellent, but depth of field is very shallow, even at f/11.
Fully shifted up: as with zero shift.
Fully shifted down: very slight loss of sharpness at very top.
Fully shifted L and R: Excellent resolution.
Coverage is excellent at all settings.  There are insignificant chromatic aberrations.
Even stopped down to f/16, depth of field continues to be very shallow, as we can also see with the tree on the left in this image shot at f/11.
Perhaps best as a portrait lens.
The 180mm Sonnar is definitely sharper.


Click on the image to see it larger.
[150mm_Hartblei_fully_UP_GFX_s.jpg]
180mm f/2.8 Carl Zeiss Jena Sonnar
Fantastic cover and resolution, including at maximum shift
TINY amount of chromatic aberration at edges

It is definitely possible to use this lens for high-resolution panoramic stitched images.  One possible format would be to mount the camera vertically (on the Hartblei shift lens mount) and to shoot three images, one with zero shift, one with the camera shifted 12mm to the left and one with the camera shifted 12mm to the right.  (On stitching images, see here.)

Click on the image to see it larger.

[180mm_Sonnar_fully_UP_GFX_s.jpg]
500mm f/5.6 Arsat APO lens
Zero shift: Excellent resolution and coverage.  Tiny amount of chromatic aberrations.
12mm shift in any direction causes corner cut-off.  12mm shift to L or R causes side cut-off and loss of resolution near the edge.

This is probably OK with shifts up to 6 or 8mm.

This image is not totally sharp.  Was my focussing not spot-on, or was the tripod not up to the job?

In practice, using a 500mm lens shifted is an unlikely scenario, but it was worth testing.

Click on the image to see it larger.

[500_APO_fully_R_GFX_s.jpg]

I then tested two SHIFT lenses with the Hartblei P6-GFX shift adapter.

45mm f/3.5 Hartblei PCS shift lens (optical elements from the Arsenal Mir 26Б)
Zero shift: excellent resolution and coverage
Not surprisingly, with full shift on the lens AND on the shift adapter (!!) in the same direction, the fall-off in resolution and exposure is unacceptable.  However, this is not a realistic combination.  Better would be to use the Pentacon Six mount shift-only lenses on the Hartblei Pentacon Six to Fuji GFX Tilt adapter and the Pentacon Six mount tilt lenses on the Hartblei Pentacon Six to Fuji GFX Shift adapter, thus providing both shift and tilt capabilities for all of these lenses.
With these combinations, the shift can be in one direction and the tilt in another, so any combinations of tilt and shift direction are possible.  This creates the equivalent of the Hartblei 45mm Tilt-Shift Super Rotator lens, which is no longer available new.

Alternatively, by using the shift on the lens for one direction and the shift on the mount in another direction, one could obtain combinations such as 12mm Right, etc AND 12mm UP, etc for instance, when shooting nine images in a 3 × 3 tile, as explained here.

Click on the image to see it larger.

[45mm_Hartblei_shift_both_fully_R_GFX_s.jpg]
55mm f/4.5 Arsat shift lens
Zero shift: Resolution good over most of frame.  Some loss of resolution near the edges.  Some chromatic aberrations.
Lens only fully shifted up and fully shifted down.  Resolution OK.
Lens only fully shifted left.  Very good resolution (although any defects may have been masked by out-of-focus tree branches nearer to the camera).
Lens only fully shifted right.  Edge resolution not very good.
I then tested the same lens fully shifted (12mm) and the shift adapter fully shifted (also 12mm), a total of 24mm shift.
Coverage continued to be excellent, but resolution was not adequate.
The 50mm Flektogon is much sharper, even fully shifted, and there is no chromatic aberration.
I have seen far better results with someone else’s 55mm Arsat shift lens.  There here appears to be a case of sample variation.

Click on the image to see it larger.

[55mm_Arsat_both_fully_R_GFX_s.jpg]

Given these results, buying a set of Fujifilm lenses for the GFX camera, at £1,500 to £2,500 per lens, may not be justified for a user who already has a range of lenses designed for the Pentacon Six and one or more of the Hartblei adapters.  And there are of course many other Pentacon Six lenses that were not included in these tests, including lenses with focal lengths of 65mm, 300mm, 75-150mm zoom, 140-280mm zoom, etc.  Also, by using the Hartblei shift or tilt adapters and Pentacon Six lenses, one can obtain a wide range of shift or tilt effects for the Fujifilm GFX.

Two details are missing if only Pentacon Six lenses are use on the Fujifilm GFX:
  • No EXIF data (focal length and aperture) is transmitted to the camera file when using non Fujifilm lenses
  • For really wide-angle shots on the Fujifilm GFX, Fuji’s 23mm lens is excellent and is highly recommended.  There are also wider lenses for GFX cameras from Laowa, including a 17mm lens and a 15mm SHIFT lens (for which a parallax-free mount is available!).  The Laowa lenses also do not transmit EXIF information to the camera.
For the photographer with suitable M42 or Pentacon Six lenses and a Hartblei adapter, a Fujifilm GFX camera can provide an excellent introduction to medium format digital photography.

For comparison purposes, I show here the results with the Laowa 17mm lens and the Fujifilm GFX 23mm lens.

Laowa 17mm f/4 lens for Fuji GFX cameras
We see with this lens, which is marketed for the Fujifilm GFX format, that there is progressive light intensity fall-off away from the centre of the image.  The coverage is definitely not any better than with some of the lenses designed for 35mm format, shown above.  This can be corrected relatively easily in imaging software, but it is surprising in the case of this lens.  This performance does confirm that the results obtained with some of the 35mm lenses shown above really are quite acceptable, even if some correction of light fall-off is required with some of them.

This image was shot at f/11.  At wider apertures, the reduction in brightness away from the centre of the image is even more marked and resolution does reduce substantially in the corners at maximum aperture, improving significantly at f/5.6 and becoming acceptable for most subjects at f/8, with further improvement at f/11.

Note that the white strip in the top left-hand corner of the image is part of the roof fascia: all images of the wall were taken with the camera at the same distance from the wall, as far as was possible, and the 17mm covers such a wide angle that a part of the roofing appeared within the image area!

Click on the image to see it larger.


[17mm_Laowa_f11_s.jpg]
Fujifilm GF 23mm f/4 lens for Fuji GFX cameras
As we might expect with a lens designed by Fujifilm for their GFX camera series, both coverage and resolution at f/11 are faultless.  Even at maximum aperture, light fall-off is minimal and resolution is still excellent.  Highly recommended (but check the price before making a decision to purchase it!).

We note that the colour rendering is much warmer than with most of the other lenses reported on here, similar to the results with the Schneider-Kreuznach 28mm shift lens.  However, the colour rendering of all lenses reported on here is well within required norms and can easily be tweaked in imaging software.

Click on the image to see it larger.


[23mm_Fuji_f11_s.jpg]

To go back to the introduction to Hartblei Pentacon Six to GFX adapters, see here.

For detailed information on using Hartblei adapters on GFX cameras, see here.

To see the introduction to stitching images see here.

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© TRA March 2022, Revised April 2022