Slide projector puzzle

I’ve been going through old family slides with our trusty old Braun Novomat

After looking at a few slides I realised that the slides couldn’t be focused across the full width of the image. You could have the left, right or middle of the slide in focus, never the whole slide.

Having realised that there had to be an optical problem I started delving deeper and found that there’s a “carriage” that the main lens screws into that is controlled by the autofocus mechanism and the carriage had “jumped the rails” so to speak, probably after the project had been dropped at some time in the past.

Anyhow, after the escape of several pingfuckits and much swearing, I got it all back together. Now I can focus the whole slide (hooray!) but the autofocus mechanism doesn’t appear to be doing anything.

Or at least, it didn’t *seem* to doing anything until I chanced on some black and white slides. When projecting these the AF slowly goes in and out of focus non-stop, winding the focus from one extreme to the other.

Anyone know why this should be? I’ve double checked and it’s just the B&W slides that cause this problem.

It would be nice if the AF worked for colour slides but I can live without it.

Tim

I did my own too, with FP3 and basic chamicals.

As I recall:

- develop normally and rinse

- bath of potassium dichromate to bleach the image, then rinse

- expose film to bright light (photoflood)

- develop again, using developer with a small amount of fixer added

- rinse and use fixer

These slides were bought somewhere. There’s text on the slides.

Tim

I remember my dad getting an Agfa B&W reversal film which was exceptionally slow - 16 ASA, I think. I took some photos on it and processed it, but the slides are a bit dark and muddy, so I must have under-developed it as a negative or over-developed it after the reversal when it was a positive.

I've forgotten the details of the development process. I can't even remember whether was chemical reversal or used a measured exposure to a lightbulb in the spiral. It was probably about 40 years ago.

Much more useful is the 400 ASA Ilford B&W film that is processed using C41 like a colour negative. That gave phenomenally fine grain compared with conventional negative. And it tolerated a very wide range of over/under exposure, with "hidden" detail in either highlights or shadows depending on exposure time of prints, in addition to normal detail for a normal exposure. But it was a pain to process, with extra steps and the need for higher temperatures.