Shooting 35mm Film in a 6×17 Roll Film Extension Back

A panoramic format is one where resulting images have an aspect ratio of at least 2:1 (such as the 6cm x 12cm format) (Frich, 2012, p. 10). The 6×17 format (6cm x 17cm) is a panoramic format for 120 (medium format) film. It’s aspect ratio of 2.83 is comparable to that of Ultra Panavision 70mm (which has an aspect ratio of 2.76). Potentially because of the limited utility of the panoramic format, Hicks & Schultz (2001, p. 48) identify both 6×12 and 6×17 formats (and surely, by extension, 6×24) as “freak formats.” That said, others have suggested that only images with an aspect ratio higher than 3:1 (such as 6×24) can qualify as panoramic. While proprietary (dedicated) 6×17 cameras have been (or continue to be) manufactured by Fujifilm, Linhof, Gilde (Dr. Kurt Gilde) and Art Panoram (Hicks & Schultz, 2001, p. 48), there are extension backs in 6×12, 6×14, and 6×17 formats (with and without masks) that can be used with 4×5 (4in x 5in) and 5×7 (5in x 7in) large format cameras. The one used here is the Da Yi 6×17 120 roll film extension back for 4×5 cameras.

The goal here is to use 35mm film in a 6×17 extension back, to produce a much more extreme panoramic aspect ratio. For 35mm film, the dimensions end up being 24 (24mm being the height of a 35mm frame) by 170 (170mm being the width of the film gate). This simplifies to 12×85 (an aspect ratio of approximately 7:1). All of the restrictions that apply to 120 film, as used in a 6×17 camera or film back (e.g. lens selection), also apply here.

Aside from the roll film extension back itself, there are two other necessary elements. One is the 35mm to 120 adapter, designed by Clint O’Connor, and downloaded from Thingiverse ( The adapter was 3D printed using Nylon PA12.

35mm to 120 adapter

35mm to 120 adapter


The other is a 120 spool, in particular a Fuji “Easy Load” 120 film spool, with the center catch.

120 film spool comparison

120 film spool comparison – the Fuji EZ Load spool is on the right, with the center catch clearly visible.


The steps for preparing the roll are straightforward:

  1. Cut the film leader off.
  2. Use a hole punch (6mm diameter was used here) to allow the film leader to affix to the catch on the Fuji (take-up) spool. (Alternatively, the leader can be taped to a regular 120 spool.)
  3. Attach the 135 to 120 roll adapters to the 135 film canister.
  4. Load like you would regular 120 film.
Film preparation steps

Film preparation steps


Loading 35mm film into a 6x17 back

35mm film loaded into a 6×17 extension back, with the assistance of adapters.


There are a few other important notes for this process. The hole for viewing the frame numbers printed on 120 backing paper must be taped to prevent accidental opening and exposure of the back of the film. Because of how the Da Yi extension back works, the take-up spool cannot be turned backwards (that is, the film cannot be rewound back into the cassette like a typical 35mm camera). Thus, it is necessary to remove the film from the extension back inside a changing bag. You can use either the top or bottom adapter to wind the film back in. The take-up spool can be removed in daylight (and also serves to prevent the film leader from being taken completely into the cassette). If the film is being sent to a lab, it is necessary to specify “do not cut”.

Focusing, on the ground glass, is done within either the green lines (within sprocket holes) or the red lines (the width of the film).

Ground glass focusing lines.

Ground glass focusing lines. Green is inside the sprocket holes; red is the edge of the film.


The number of turns necessary to allow for sufficient (but not excessive) rebate (gap between frames) ranges from 5 to 3.5 turns. The rebate will increase as film is loaded onto the take-up spool after being exposed, so fewer turns are needed as shots are taken. A roll of 36 exposures appears to fit just fine on the take-up spool – there is no apparent scratching or other damage.

The table below summarizes my results (assuming a typical roll of 36 frames):

Shot numberNumber of turns

Some of the results from the first tests are below. Each image was scanned on an Epson V850 Pro at 1200 DPI. The resolution of each scan is 7800 px by 1150 px (or roughly 9 megapixels).


35mm film in a 6x17 film back. Ilford HP5+. Fujinon 90/8.

35mm film in a 6×17 film back. Ilford HP5+. Fujinon 90/8.


35mm film in a 6x17 film back. Kodak Ektar. Fujinon 90/8.

35mm film in a 6×17 film back. Kodak Ektar. Fujinon 90/8.




Frich, A. (2012). Panoramic photography: From composition and exposure to final exhibition. Waltham, MA: Focal Press.

Hicks, R., & Schultz, F. (2001). Medium and large format photography: Moving beyond 35mm for better pictures. New York, NY: Amphoto Books.


Bronica ETRSi Battery Compartment Cover Replacement Part

The Bronica ETR series were 6×4.5 film SLR medium format cameras manufactured by Zenza Bronica in Japan from 1976 to 2004. The series consisted of the original ETR (January 1976), the ETRC (October 1977), the ETRS (January 1979), the ETR-C (January 1979), modified ETRS (July 1982), and the ETRSi (October 1989) (Gonzalez, 2016). Production of the ETRSi ended in December 2004; full technical support for the ETRSi ended seven years later, in December 2011.

The ETRSi incorporated a number of changes over the preceding ETRS, namely improvements in the focusing screens, shutter speed dial, and in sound and light-deadening material in the interior of the camera (Gonzalez, 2016). One other relevant change was the enlargement of the battery cover over that of the ETRS (#2912) to that of the SQ-A (#1912) (Gonzalez, 2016).

The battery cover in place on the bottom of the Bronica ETRSi

The battery cover in place on the bottom of the Bronica ETRSi

As is often the case, various parts of such a camera system can go missing – the eyepiece, the winding lever, the battery cover, and so forth. In the case of the battery cover, replacements are hard to find. The only other (efficient) way to obtain a replacement battery cover would be to buy a broken ETRSi camera body. Though this is useful from a long-term repair perspective, it is not entirely feasible if just the battery cover is needed. The intent here was to create a 3D model of a ETRSi battery cover in order to allow for 3D printing of replacements.

FreeCAD screenshot of battery cover 3D model

FreeCAD screenshot of battery cover 3D model

Using the original part as a guide, I constructed a 3D model using FreeCAD. I decided to keep it close to the original part in terms of design. That said, the grip/groove pattern was changed slightly, in order to make it easier to shift over. Because of the lack of a finish on the replacement battery cover, it is easier to remove from the camera body, as compared to the original battery cover (due to the rougher, as opposed to smooth, surface finish).

The part was test printed by Sculpteo (Paris, France). The total cost, with shipping, ended up being €6.00 (~$9.00 CAD; ~$7.25 USD).

The materials and related characteristics were:

Process: Multijet Fusion
Material: Nylon PA12 (Black)
Finish: Raw

Original and replacement battery cover

Original (bottom) and replacement (top) battery cover

Part Download

The part can be downloaded from Thingiverse.


Gonzalez, D. (2016). Bronica medium format cameras. Retrieved from

Converting Raumbild-Verlag Stereographs To Anaglyphs

These converted stereographs (German: raumbilder “space pictures”) are from an album entitled “Bad Reichenhall – Berchtesgaden” published by Raumbild Verlag between 1945 and 1948. Bad Reichenhall and Berchtesgaden are towns in the Bavarian Alps in Germany. The album consists of 20 stereograph cards, with each card being 6 cm by 13 cm. The album also contains an adjustable stereograph viewer (German: raumbildbetrachter “space image viewer” or raumbildbrille “space image glasses”). In contrast to the ones produced during World War II, these stereographs are focused on the scenery of Bad Reichenhall, Berchtesgaden, and the surrounding areas.

Raumbild Verlag was founded by Otto Wilhelm Schönstein (1891-1958) in the early 1930s (Hotze, 2015, para. 1). The company was moved to Munich in 1939 (Hotze, 2015, para. 2). Heinrich Hoffmann (1885-1957), Adolf Hitler’s official photographer, had by that point become a partner in the company (Schröter, 2014, p. 191). Continuing from his demand in 1937 that Schönstein “should withdraw to a subordinate, more technical position,” Hoffman moved from being a partner to that of managing director in 1939 (Schröter, 2014, p. 191). Schröter (2014, p. 191) contends that Schönstein “could not do anything against it because of Hoffmann’s prominent position.” In addition to Hoffmann, Hitler himself seemed to take an interest in stereoscopy, along with Albert Speer, the Minister of Armaments and War Production, which Schröter (2012, p. 136) suggests “has something to do with the ideology of space in National Socialism.” Despite this, Martins and Reverseau (2016, p. 171) argue that the propaganda value of the books was undermined by, amongst a few factors, “a break between image and caption that prevented the viewer/reader from experiencing the potentially synergistic reinforcement between image and text that was a cornerstone of Nazi photographic propaganda.” According to Uziel (2008, p. 244), photographers in the Wehrmacht Propaganda Troops (“Propagandakompanien der Wehrmacht”) were equipped with 3D cameras, from at least January 1940. The photos were sent on to Raumbild Verlag, which is considered by Uziel to have “practically monopolized the field of 3D photography in Nazi Germany” (2008, p. 245).

Each set of cards was expensive. Martins and Reverseau (2016, p. 173) note the 35 Reichsmark purchase price of a 1941 stereoscopic photo album, comparing it to the monthly rental cost of four-room apartments in the city of Nuremberg in 1940. Calculating the modern equivalent of 35 Reichsmarks can be difficult, given that the currency no longer exists, along with the amount itself being about 80 years old. Edvinsson (2016) suggests an approximate value ranging from about $200 to $800 Canadian dollars (in 2015), using the CPI and gold and silver values. Marcuse (2013) provides a conversion rate of 2.5 Reichsmarks to one US Dollar in 1940. Using the Bureau of Labor Statistics (2017) CPI inflation calculator, the amount of $14 USD in 1940 is roughly $245 in 2017. Martins and Reverseau (2016, p. 173) conclude that such stereoscopic photobooks could rightfully be considered luxury items.

Each stereograph was scanned on an Epson V850 Pro at 2400 DPI. The resulting scan was touched up (e.g. removal of scratches, dust, dirt, and other imperfections originating from the creation process or from age and storage) and then sharpened in Photoshop with Smart Sharpen at 65% and a radius of 1 px. The stereograph images themselves are not very sharp (as seen under 10x and 22x loupes), so a smaller radius was not likely to be helpful in producing better sharpness.

While the viewing glasses for these stereographs are not too difficult to acquire, it is still an obstacle to viewing the images as they were intended (i.e. in 3D). The goal here was to see whether these stereographs can be converted to anaglyphs (red-cyan). I have not been able to find any previous attempts at this goal. Overall, I believe the goal was achieved, and the experience with the anaglyphs is similar to that with the intended stereograph viewer.


Overview of the steps of the anaglyph creation process.

Overview of the steps of the anaglyph creation process.


A selection of the stereographs, with their original captions immediately below:


"Sonnige Terrassen-Hotels und Villen in Berchtesgaden"

“Sonnige Terrassen-Hotels und Villen in Berchtesgaden”





"Am Marktplatz in Berchtesgaden"

“Am Marktplatz in Berchtesgaden”


"Der Blick zum Watzmann"

“Der Blick zum Watzmann”


"Wildromantische Landschaft am Obersee"

“Wildromantische Landschaft am Obersee”


"Alter Brunnen am Marktplatz in Berchtesgaden"

“Alter Brunnen am Marktplatz in Berchtesgaden”



Bureau of Labor Statistics. (2017). CPI inflation calculator. Retrieved from

Edvinsson, R. (2016). Historical currency converter. Retrieved from

Marcuse, H. (2013). Historical Dollar-to-Marks currency conversion. Retrieved from

Martins, S. S., & Reverseau, A. (2016). Paper cities: Urban portraits in photographic books. Leuven, Belgium: Leuven University Press.

Schröter, J. (2012). The transplane image and the future of cinema In A. Petho (Ed.), Film in the post-media age (pp. 125-142). Newcastle upon Tyne, UK: Cambridge Scholars Publishing.

Schröter, J. (2014). 3D: History, theory and aesthetics of the transplane image. London, UK: A & C Black.

Uziel, D. (2008). The propaganda warriors: The Wehrmacht and the consolidation of the German home front. Bern, Switzerland: Peter Lang Publishing.