The Pentacon Six System
by TRA

Stitching Images to get a Wider View,
Part Two:

Using the Hartblei Pentacon Six to Fujifilm GFX shift adapter



[P6_shift_GFX_01_s.jpg]

This adapter opens up the possibility of using any of the vast range of lenses with the Pentacon Six mount on Fujifilm GFX cameras.  For the purposes of this section, we can define two categories of lenses:
  • Non-shift lenses
  • Shift lenses.
Let us first look at using Pentacon Six non-shift lenses on Fujifilm GFX cameras via the shift adapter.  We are of course aware that it is possible to use Pentacon Six non-shift or shift lenses on GFX cameras via the basic Hartblei Pentacon Six to GFX adapter, (illustrated here). However, for this page we looking at stitching images, and especially at how the Hartblei adapters can expand our posibilities (and the effective frame size!) with the GFX cameras.

Using non-shift Pentacon Six lenses on GFX cameras via the Hartblei shift adapter

This Hartblei shift adapter has click stops at 15° intervals.  One could therefore rotate it at “three-click” intervals, in order to take component shifted images at 45° intervals, as with the highly-sophisticated Hartblei adapter for using Mamiya 67RB/RZ lenses on GFX cameras, as descibed above.  The result would be a “cross-shaped” image with extra inserts at each intersection of the “cross” members.  See here.

However, for our first stitch test with this adapter, we decided to rotate the shift adapter by two click stops for each shifted image, a rotation of 30°.  For this test we used a Bronica Zenzanon 6×6 lens that had been especially adapted for use on the Pentacon Six.  We can find further information on that lens here.  The resultant stitched shape is as in the following image.


40mm Zenza Bronica in P6 mount 1/250 f/11 400 ISO on Fujifilm GFX50S via Hartblei P6-GFX shift adapter Benro tripod and ball head
[40mm_Zenza_Pano_30deg_s.jpg]

Click on the image here to see it larger (although far from the original size!).  Any banding that may be visible in the sky or elsewhere has been introduced by the jpeg compression.
  
I started by taking a non-shifted image of what would become the centre section of the subsequent stitched image.  I then shifted 12mm left and shot my first shifted image for this series.  I then rotated by two click stops to take the next image, and so on, taking a shifted image at each 30° rotation interval, thus creating twelve peripheral images. 

The resultant 13 images were stitched in Photoshop, which in fact did not use any part of the central image for the final stitch.  I have not corrected any of the vignetting that can be seen with a few shots, although the Photoshop option to remove vignetting in stitched areas was selected.

Stitching thirteen images takes some time and results in an image file of significant size.

In my initial tests of the 40mm Zenzanon, here, I discovered that at full shift there was a reduction in resolution at the left and right edges of the images that it produced, and this test confirms that.   The 50mm Mamiya ULD lens gives much better results.

The 40mm Zenzanon was designed to cover 6×6 format, which is defined by some manufacturers as 54mm×54mm (see here), while others define it as 55mm×55mm or 56mm×56mm.  The Fujifilm GFX sensor is 44mm wide.  When we use shift to add an extra 12mm on each side, we are calling on the lens to cover a width of 68mm.  However, the acceptable coverage of a lens is determined by its diagonal, not by its width.
  • The diagonal of a 54mm×54mm square is a little over 76mm. 
  • The diagonal of a 55mm×55mm square is a little under 78mm.
  • The diagonal of a 56mm×56mm suare is a fraction over 79mm. 
So regardless for which “6×6” image dimension the Bronica Zenzanon 40mm lens was designed, it should have an excellent level of resolution and light intensity within an image circle of at least 76-79mm.  So there should be no difficulty for it to cover 57mm width in portrait orientation (33mm for the sensor + 12mm shifted in one direction + 12mm shifted in the opposite direction) and 68mm width in landscape orientation (44mm for the sensor + 12mm shifted in one direction + 12mm shifted in the opposite direction).  The result observed here is therefore very disappointing.

For more on image circles, see the diagram here
.
 

Image Circles in Reality

Mamiya states that its lenses for the RZ67 series are designed to cover the format 56mm×69.5mm.  The diagonal in this case is a little over 89mm and all Mamiya 67 lenses tested so far shifted on a GFX camera fully cover the format, even when shifted 12mm in opposite directions.

The failure of the Zenzanon lens to cover the format with adequate resolution may also account for the vignetting on the outer corner when the Zenzanon lens is shifted diagonally 12mm away from the centre.

An experienced user of shift lenses with GFX cameras comments, “The problem of Zenzanon 40mm (also Distagon 40mm) is that the increasing of coverage would immensely enlarge the lens itself. Therefore optical designers had always a lot of compromises with widest angle lenses of each system. Carl Zeiss went with increasing the optical quality at the edges, Bronica [did not].”

The manual for the Hasselblad FlexBody presents a very interesting diagram on the shift potential of various Carl Zeiss Oberkochen (West German) lenses that were designed for Hasselblad 6×6 cameras:


[Shift_potential_CZO_lenses.jpg]
The original can be seen here: http://www.hasselbladhistorical.eu/PDF/HasManuals/Flexbody.pdf (page 1).


We do indeed see that even the Carl Zeiss Oberkochen 40mm Distagon provides virtually NO shift potential.


File Sizes

Here I give some data on typical file sizes with the thirteen consituent images of the above picture.  It would apparently have worked adequately with the twelve  peripheral images.

To the right I reproduce the pixel dimensions and the physical document size numbers from the above stitched file.  We see that the Pixel Dimensions are over 757 megapixels.  These numbers do not change depending on the format, but the file size obviously does.  Both the original
16-bit file and the file reduced to 8-bit were too big to save in the standard PSD format, which is limited to a maximum size of 2GB, so these files were saved in the .PSB format.

Here are the file size details derived from the images taken with the GFX50S camera:

The Photoshop image size table reproduced on the right is taken from the 16-bit Tiff file.
  

Pixel Dimensions
Total file size
16-bit Tiff file with all thirteen layers
757.1M
6.15G
8-bit Tiff file including all thirteen layers plus three correction layers (Levels, Color Balance, Curves)
378.6M
2.90G
8-bit JPEG, uncompressed
370.3M
370.3M

I note here at at 300 Pixel/Inch I have obtained a images that would print 88.98 centimeters high, almost exactly the same height as a Pentacon Six image scanned on the Epson Perfection V750 PRO scanner.  The width is of course greater than the width of the corresponding Pentacon Six square image.  However, we are not comparing like with like, as the figures for the Pentacon image are based on a single frame, not multiple images stitched together as here.

  

[40Z_50S_16bit_pixdat.jpg]

We can thus see that using the Pentacon Six as a source for images is still highly valuable, especially as many images, for instance of moving subjects, do not readily lend themselves to taking multiple shots and then stitching them together.

Here are the file size details derived from the equivalent thirteen images taken with the GFX100 camera:

Inevitably, the pixel dimensions are double those obtained with the GFX 50S camera.

The Photoshop image size table reproduced on the right is taken from the 16-bit Tiff file.

  

Pixel Dimensions
Total file size
16-bit Tiff file with all thirteen layers
1.41G
11.7G
8-bit Tiff file including all thirteen layers plus three correction layers (Levels, Color Balance, Curves)
723.3M
5.08G
8-bit JPEG, uncompressed
708.9M
723.3M

While the resolution and print-size / cropping potential of the GFX100 image is far superior to that of the GFX50S image, no difference would be discernable if the whole image were displayed on a computer screen, for which reason the GFX100 image is not reproduced here, especially as it is not possible to host the larger original-size image files on this website.

Here we have an image file that at 300 Pixel/Inch will print larger than a Pentacon Six image.  However, again we need to remember that the Pentacon Six image would be obtained with a single frame, whereas this image is the result of stitching together thirteen frames.  One also needs to consider the cost of a Fujifilm GFX100, compared with the cost of a Pentacon Six TL in perfect working order.

Large file sizes do of course impact on the time taken by the computer to process images, especially for opening, stitching and saving, as well as on computer storage requirements (hard disk space needed).  This becomes a consideration with the next image here.


[40Z_GFX100_16bit_pixdat.jpg]

Getting more information in the corners

Taking a picture at every 30° of rotation produces images with two intermediate “corners”
at each intersection of the “cross” members.  What would happen if we took a picture at every rotational click-stop on the Hartblei Pentacon Six to Fujifilm GFX shift adapter?  Let us find out!


40mm Zenzanon in P6 mount, Hartblei P6 to GFX shift adapter, GFX 50S, Benro tripod & head, 1/250 f/11 200 ISO Picture taken at every 15° of rotation
This set of pictures was taken the day after the previous example, above, and the lighting conditions were slighty different, with thin cloud intermittently in front of the sun resulting in a reduction in image contrast.  This could be corrected during processing, but on this website I normally present images with minimal or no corrections.

[40Z_GFX50S_15deg_Pano_s.jpg]

  
I started by taking a non-shifted image of what would become the centre section of the subsequent stitched image.  I then shifted 12mm left and shot my first shifted image for this series.  I then rotated by one click stop to take the next image, and so on, taking shifted images at 15° rotation intervals, thus creating twentyfour peripheral images. 

The resultant 25 images were stitched in Photoshop, which in fact again did not use any part of the central image for the final stitch.  I have not corrected any of the vignetting that can be seen with a few shots, although the Photoshop option to remove vignetting in stitched areas was selected.

I took the images used to create this composite with a Fujifilm GFX50S.  Given the number of constituent images and the resultant file size, we didn’t dare try it with the Fujifilm GFX100!  The computer was struggling enough to process all 25 images used in this stitch.

When the consituent images were stitched in Photoshop, it again in fact did not use any part of the central image for the final stitch.  I have not corrected any of the vignetting that can be seen with a few shots, although the Photoshop option to remove vignetting in stitched areas was again selected.

One can imagine taking an infinite number of images, which could cause a gentle curve to be reproduced at each corner, although whether or not most computers designed for individual or domestic use would be able to cope with “an infinite number of images” is a different question.

From a distance, the image format looks rather like the earlier generation of cathode-ray tube televisions which were in 4:3 format and did not have square corners (nor particularly straight sides!).  The sensor in the GFX cameras does of course have the same 4:3 format, although with straight edges, and square corners in non-stitched images.

Click on the image here to see it larger (although far from the original size!).  Any banding that may be visible in the sky or elsewhere has been introduced by the jpeg compression.


File Sizes

Here I give some data on typical file sizes with the twentyfive consituent images of the above picture.  It would apparently have worked adequately with the twentyfour  peripheral images.

To the right I reproduce the pixel dimensions and the physical document size numbers from the above stitched file.  We see that the Pixel Dimensions are over 780 megapixels.  Both the original
16-bit file and the file reduced to 8-bit were too big to save in the standard PSD format, which is limited to a maximum size of 2GB, so these files were saved in the .PSB format.

Here are the file size details derived from the images taken with the GFX50S camera:

The Photoshop image size table reproduced on the right is taken from the 16-bit Tiff file.
  

Pixel Dimensions
Total file size
16-bit Tiff file with all thirteen layers
780.3M
11.5G
8-bit Tiff file including all thirteen layers plus three correction layers (Levels, Color Balance, Curves)
390.1M
5.38G
8-bit JPEG, uncompressed
386.8M
390.1M

Again we have a file that will print larger at 300 Pixels/Inch than a single Pentacon Six frame, which is not surprising.

  
[40Z_GFX50S_15deg_Pano_16bit_pixdat.jpg]

Using Pentacon Six shift lenses on GFX cameras via the Hartblei shift adapter

To achieve stitched images with square corners from shifted images, we have two options:
  • only shift on one axis, for instance to widen the image area captured or to increase its height
  • use a shift lens on the Hartblei shift adapter.
Shifting only on one axis

With the 12mm shift in any direction that the Hartblei Pentacon Six - Fujifilm GFX adapter provides, we can increase the effective sensor width from 44mm to 68mm or the height from 33mm to 57mm.  Bearing in mind that the camera can be in horizontal or vertical orientation, the resultant (stitched) image is flexible and can be enormous.  An example of this can be seen here (although even greater shifts were used in this example by combining the lens shift and the adapter shift in the same direction).  (Scroll down to the images of the yellow railway station.)

Using Pentacon Six Shift lenses on the Hartblei shift adapter

Again, the potential is impressive, but this time we can shift in two directions and still get square corners.  As well as the 12mm shift provided by the Hartblei adapter, most of the shift lenses in the Pentacon Six mount also offer a 12mm shift.  By shifting the lens on one axis (for instance, to the left and to the right) and the adapter on the other axis (in this case, up and down) one can easily achieve the 3 × 3 format illustrated here.

There is a wide range of 45mm shift lenses available, built using the optical elements of the Arsenal Kiev Mir-26
Б lens.
There are two 55mm shift lenses, the Arsat shift and the scarce Schneider-Kreuznach Super-Angulon PCS.
There is at least one 65mm shift lens, based on the Arsenal Kiev Mir-38
Б.

To see more on these lenses and reports on most of them, go here and follow the links from that page.


To go back to the introduction to Hartblei lens adapters, click here.

For a detailed introduction to the Hartblei Mamiya RZ67 – Fujifilm GFX system, see here.

To go back to the initial tests of Pentacon Six & M42 lenses on the GFX, via Hartblei adapters, click here.

For the introduction to stitching, see here.

To go back to the Lens Data page, click here.

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© TRA May 2022