Forum Feed beta

I've never heard of an "optocoupler", I presume any camera with any sort of automatic exposure, (whether Speed, Aperture or programmed) uses one?

During exposure the mirror flips up and the measured value for the exposure time gets lost.
This value needs to be stored electronically (or digitally). Praktica used conventional electronics and storing this exposure value was difficult.
What they did is let the exposure meter light an Led, which would shine on the light sensor for the shutter times. During exposure the Led continued burning. This is the 'optocoupler' Praktica used until better IC's were at hand to replace them. I only knew about this until I stared working on some EE2 cameras and found similarities to the Zenit 19, except for the automatic exposure.
And that's why the Zenit 18 is probably so rare and expensive. I even wonder if the electronic aperture coupling fo the MC Zenitar 1.7 50mm works on Praktica as well.

I did wonder the same thing about compatibility many years ago, and the have different resistance values.
Best regards,
Juhani

Milo, Thank you for the explanation of what an optocoupler is.

For anyone interested, there is another Zenit 18 for sale on ebay, it is being sold by Gray's of Westminster (in England) which is a very reputable company and which has their own website. They've been going for many years. Anyway it comes with a Russian language Manual and another piece of paperwork. It has an f3.5 135mm Jupiter lens. They show it with a 50mm f1.7 lens as well but that isn't included, for some reason.

Well don't I feel a bit stupid! The Zenit 18 I said was listed by Grays of Westminster was actually listed by someone else, BUT the location was Grays in London. I should've noticed this. It's been sold now, so I'm wondering if Alec bought it?

hello!
What are you really looking for?
Zenit 18 body only or with original lens?
Fred

I found this interesting repair instruction, with the original schematic. It does not show an optocoupler circuit like the Praktica EE2/EE2. But it uses and IC for the memory instead.
When this camera was produced (1980-1987) the Praktica B series was already in production.
https://fotoussr.ru/articles/zenit-18-repair/

A dutch photo store has one on stock for a good price:
https://www.marktplaats.nl/v/audio-tv-en-foto/fotocamera-s-analoog/m2303656621-zenit-18-zeldzaam

What amount of money are we talking about, if I am ready to sell this camera in full factory equipment and in excellent condition.(ME-1 lens, passport, box, belt).