While 127 film isn't realy that hard to get, it is only available in a very narrow choice of types. Sometimes it's nice to shoot something a bit different. Also for testing, you might prefer to burn half a roll of 35mm than your hard fought for efke 100, so I thought I'd see what happened if I loaded up one of my TLR's with HP5...
I cut a notch in the backing paper where the film needed to start so I could find it in the dark, and simply rolled the 35mm film and paper onto a 127 spool, taping them together at the appropriate point. Of course all of this had to be done in a changing back (or a good darkroom). Then the film could be loaded into a 127 camera as normal.
It all worked perfectly (more or less). The negatives are exposed right to the edges (sometimes), and so I could choose to keep them in the final image (which I did for the purposes of this test - just to show that it is 35mm).
The two minor problems are a result of the film not being held as tightly as it should be. 35mm isn't as wide as 127, so the film can wander around in the gate. Aside from the unpredictability of framing, the top and bottom of the image isn't always square.
The biggest potential problem is that the film might not be held sufficiently flat that the image stays in focus. The jury on that is still out: In the image of the skooter at the top of the page, the image is generally very sharp, but there are area's which are more blurred than I'd expect. The apperture was f/8 here, and the depth of field is pretty tight, so it's not clear how much of the focus is simply regular depth of field and how much is the film.
When I used flash later in the evening the increased film speed allowed me to double the guide number on my flash (compared to iso100), and stop down to f/22 at distances of a couple of meters. This gave great depth of field, and meant I didn't have to worry too much about focus.
The slightly burnt out areas are the scan honest! (the print was fine).