Converting a 116 camera to use 120 film

I’ve fancied a 6×12 camera for a while, but they are expensive. Right now I don’t have the spare cash to buy either a dedicated 6×12 camera or a 6×12 back for my Horseman 45HD, so I shelved the project for “the future”.

… Until I saw a 1925 Zeiss Ikon Icarette 500/15 for about the price of a beer. The body is in pretty poor condition but the bellows are good and the lens and shutter work like the day they were made. It’s a 12cm 1:4.5 Tessar in a Compur shutter with speeds from 1s to 1/250, which is remarkably good for the day.

Zeiss Ikon Icarette 500/15
Zeiss Ikon Icarette 500/15

The Icarette takes now-obsolete 116 film which was discontinued in 1984 but a quick search reveals these can be converted to accept 120 film and can take 6×11 negatives. I’m not particularly good at making things so I attempted to convert the camera to accept 120 film in the simplest way possible while spending no money. I got lots of detailed information from the document Convert a Six-16 Folding Camera for Use with 120 Film and this is what I decided to do.

Spool adapters

First things first – the 120 film has to fit properly. I’m lucky enough to own one 116 spool which I will use as the take-up spool, since it fits properly with the winding knob. However this does mean I’ll need to unload the camera in the darkroom, as the 120 film won’t be tightly pressed against the end cap of the spool to keep the light out.

To pad out the 120 supply spool, popular options include making a pair of shims out of metal, or making them from plastic using a 3D printer. These are both good, robust options but I don’t have a 3D printer and I’m terrible at metalwork. I cut up two wallplugs and used them to pad out the 120 spool. It rotates freely and seems to be quite strong.

Cutting wallplugs
Cutting wallplugs
120 roll in 116 camera with wallplugs
120 roll in 116 camera with wallplugs

Film mask

The film gate on a 116 camera is approximately 62mm tall, while the total width of 120 film is 61mm. This means when the 120 film is held across the film gate, is it unsupported at the edges and prone to curling. To fix this, I made a mask that makes the film gate a bit narrower and will support the 120 film. Black craft card would be ideal but I used some strips of card taken from food packaging, blackened with a permanent marker. It is strong enough without being too thick. I reckon it is about 0.3mm thick so hopefully won’t affect the focal plane too much. I glued it in place using a small amount of PVA glue and a paintbrush. If I decide to reverse the modification, this will be easy to peel off.

Cardboard film mask for top & bottom
Cardboard film mask for top & bottom
Film gate with cardboard mask
Film gate with cardboard mask

The new height of my film gate is 56mm, the same as most standard 120-format negatives. I retained the width of the original 116 film gate at 108mm, although I did also glue some strips of card at the left and right edges to make the new film gate all the same height and ensure the best film flatness.

Film advance

120 film has three sets of frame markings on the backing paper (6×4.5, 6×6 and 6×9). The position of the red window on 116 cameras reveals the 6×4.5 markings of 120, which isn’t useful. Elsewhere online I found a guide which explains how to use these markings to expose 120 film in a 116 camera.

Exposure 120 frame number
1 3
2
3 8
4 10½
5 13
6 15½

It is helpful to look at the backing paper of a used film in advance to work out what half a frame looks like through the red window. I have scanned part of a strip of Ilford 120 backing paper and marked in green where the frames for 116 cameras should be. Approximately, it is just after the second circle has passed the red window.

As we look at this strip, the top row of numbers is for 6×4.5, the middle row is 6×6 and the bottom row is 6×9. Remember in a 116 camera, this strip of film would be upside-down with the film passing the red window from left to right, with the numbers increasing.

120 backing paper
120 backing paper

First test

I shot a roll of Ilford FP4+ in the nature reserve near my home to test this camera, and my conversion work. Let’s start with the good points:

  • The shutter works well at all speeds
  • The lens glass is clean and clear
  • The bellows and film door are light-tight
  • The alternative method of counting frame numbers works

Now the bad.

  • One of the film masks I glued in place came loose and obscured every frame
  • The extra spacing of the film mask (about 0.3mm) was sufficient to make the images very soft
  • The sports finder is missing so I was using the tiny waist-level brilliant finder. It’s very hard to get the camera level so all but one of my test photos have a wonky horizon.

To-do list

It’s clear my method of making a film mask by sticking cardboard on top of the metal spoils the focus. I’m going to look into doing as the original article suggested, and suspend some plastic strips inside the film gate, level with the metal. I’ll also glue it properly so it doesn’t come loose during film advance!

I may consider adding a cold shoe (aka accessory shoe) to the camera so I can use an auxiliary viewfinder or even a bubble level to keep the camera straight.

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