I know similar questions have been answered but I have a specific unusual addition that I can’t work out. Developed tri-x 400 in d76 1:1 last night using the timings from the packaging that have worked spot on for me before. The negatives came out completely transparent including the leader that should have been black. The edge markings are all present and look normal. The transparent leader made me thing fixer was used before developer although I’m sure I didn’t!if fixer was used first though I thought the edge markings would also be transparent? I’m sure the film was from the camera not unused, and I’m sure it spooled all the way in the camera as winding it back in at the end felt like a normal length of time. If the developing process was correct in that the markings are present why is the leader transparent?! I tested some developer and fixer after with the cut off winder portions - developer made it black, fixer made it clear. Only explanation I can think is if Kodak don’t expose their markings onto the film but they are somehow printed such that they are no longer indicative of a correct developing process... far fetched? Help!!!
The most likely culprit is your camera. Here are the steps I would take to troubleshoot this issue. I realize a few of them have already been covered by yourself but for completeness I've included them. if you answer "No" you've found the problem.
- Open the camera without any film loaded and fire the shutter (you may need to depress a switch to trick it into thinking the back is closed if your shutter will not fire with the back open.) Does the shutter move?
- Set the shutter to a long time (1/2 second or longer) Does the shutter stay open as long as you've selected? cycle between the shortest exposure available and longer exposures. Does the shutter adjust with each exposure or is it always short no matter what you select?
- If your camera is an auto-winder, does the take-up spool turn with each exposure? If it is a manual winder, does the spool rotate evenly through the entire lever throw or only "stutter" a few times?
- Set the camera to bulb and open the shutter with a normal (~50mm) lens attached. If there is a manual aperture, open and close it. If there is electronic aperture control, perform test shots at various apertures. Does the aperture open all the way or does it stay closed?
- Take your camera and a new spool of film from another batch into your darkroom. Spool off the leader plus a few inches and the cut a new leader tab. Load this film into the camera without ever allowing light to strike it. Make a few long exposures in a sunny environment. Develop the film. Do you see several over exposed frames or just one?
- Shoot film from the same batch in a different camera/ lens/ environment just to rule out random, rarer failures. Did anything change?
I've seen this issue 4 times and for three of them it was because the shutter had failed and was either not opening or was only firing at its native rate (1/250s on this particular camera) and also not opening the iris to shoot. If you are expecting a long exposure and get a short one, you could be so underexposed nothing is visible on the film.
The 1 instance in which it was not the shutter at fault was my doing. I had substituted a friend's unexposed roll with one I'd already developed and reloaded. It was just a scouting trip and I copied all of his shots so nothing would be lost... He was still pretty unhappy since I waited until he spent an hour trying to figure out the source of his problems. Then again this is the same guy who exposed an image of his rear end onto every sheet in my paper safe...
As Alan pointed out it is also possible that you mixed up the rolls but if, like most photographers I know, you mark each roll as it comes out of the camera, then that is unlikely.