Maxime writes:
I wanted to show you a modification that I did to the film guide of my Rondinax 35. From the very beginning, I was getting serious scratches on my negatives, It was always on each sides of the last 4-5 frames. At first, I thought my camera’s rollers were at fault, but the same thing happened with rolls shot with other cameras. I tried to thoroughly clean the tank, the same thing happened again. Then I decided to smoothen the underneath of the film guide which is the only part which is in contact with the negatives. This last part worked, it significantly reduced the scratches, but even polished to a mirror the scratches were still very visible. I’m a tinkerer by nature so I thought of way to prevent the underneath of the guide from touching the frames, I used a self adhesive PTFE to make skates which the guide about 1mm over the negative and only touch it on the edges of the frames. I’ve developed a few rolls since and the scratches are gone.
Scratch along the left hand side
Showing PTFE tape on the film guide
Rondinax 
I think I have this problem, but I don’t understand what Maxime did to solve it, and I cannot tell from the photo where the PTFE tape makes contact with the guide and where not. My film guide squeezes the sides of the film such that only the they, but not the frames, touch the guide … at least, in theory. I can’t see whether the film guide in the photo is the same as mine.
Hello there,
the film guide squeezes the film during the loading phase, however, the other side of the guide touch last layer of frames during the whole developing period. Here’s a technical graphic: https://i.imgur.com/rtT0CQF.png
The PTFE I used is meant to make skates for computer mice, it’s about ¼ of a millimeter thick (CorePad Skatez Universal). I used a D.E razor blade to cut the pieces and relied on my eyes for the approximative width. I made it as thin as possible so it would only touch the very edges of the frames (The area we usually trim out). So far so good. 🙂
A neat idea, an alternative is to just pop the tank into a dark bag once the film is cut and loaded and remove the film guide prior to processing.
Alternatively if your feeling extravagant shoot 34 out of a 36 film or 20 out of a 24!
Hello there fellow Rondinaxian,
I resisted the idea of getting a dark bag because it thought it would defeat the purpose of a daylight loading tank…however that’s obviously the easiest way to do it and 100% effective. Before doing my mod, I thought of a way to attach a string to the frame counter which would protrude outside the tank and would lift the guide when pulling it… it was unpractical idea hahah
Great!
Just a follow up on this old post. It’s been 2 years since I’ve done this modification, it is still holding and my negatives are still scratch free. The skates never peeled off, even when I experimented with C41 which requires a temperature around 38C.