Auto loading cameras: how does the body know that there is a film inserted?

Started 4 months ago | Discussions thread
Overrank Senior Member • Posts: 4,176
Re: Auto loading cameras: how does the body know that there is a film inserted?

dominik015 wrote:

Hi guys, i just bought a "not working" Minolta Maxxum 7000 today. And as i expect with such deals at my local cam shop, the auto loading system doesn't work. As with most auto loading bodies that i buy, i just put in the film and i expect it to advance. But that doesn't happen. In this case, my Minolta just shows the flashing 0 when i put in the film (which means that its still waiting for film). Or a Nikon body that i bought- the same story, it just acts like there is no film in it.

That makes me wonder: How do these cameras detect it when you put film in it? And what could be the cause for such malfuntions?

I think it varies from camera to camera but I think quite a few (most ?) use some sort of infra-red sensor to detect the sprocket holes as it pulls the film though, plus possibly a sensor on the wind on spool too.    This is one reason why you’re warned away from using auto load cameras with infrared film like HIE and EIR (aerochrome) .  The infrared films that are available now aren’t sensitive at the wavelengths the sensors operate at, but for these older infrared films with a extended range the sensors can fog the film.

And if someone has a fix for that Maxxum, please let me know : )

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