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 Topic  |
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Alec Scott
tablemix
Australia
3 Posts |
 Posted - Dec 05 2023 : 5:00:08 PM
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Hey,
Does anyone happen to be selling a working Zenit 18?
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sean perry
seany65
United Kingdom
337 Posts |
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Fred_L
France
226 Posts |
Posted - Sep 18 2024 : 2:12:35 PM
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Hi!!
Are you looking for a body only or with 1.7 square square apperture lens?
Working camera means fully working ? Shutter and meter or shutter only??
Fred |
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liukai
28 Posts |
Posted - Sep 19 2024 : 07:10:18 AM
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| I also really want to collect a Zenit 18 |
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Fred_L
France
226 Posts |
Posted - Sep 19 2024 : 11:50:45 AM
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| OK I understand but do you need body or body with lens and what type of lens? |
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Milo Schekkerman
Valkir1987
Netherlands
200 Posts |
Posted - Sep 20 2024 : 05:47:47 AM
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| I wonder if it uses the same type of circuitry as the Praktica EE2, which uses an optocoupler as 'memory' to store the exposure value during exposure. (the value normally gets lost when the mirror flips up) |
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sean perry
seany65
United Kingdom
337 Posts |
Posted - Oct 03 2024 : 7:05:13 PM
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| I've never heard of an "optocoupler", I presume any camera with any sort of automatic exposure, (whether Speed, Aperture or programmed) uses one? |
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Milo Schekkerman
Valkir1987
Netherlands
200 Posts |
Posted - Oct 20 2024 : 11:39:10 AM
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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. |
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Juhani Halmeenmaki
cedricfan
Finland
1020 Posts
My Collection
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Posted - Oct 20 2024 : 11:50:40 PM
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I did wonder the same thing about compatibility many years ago, and the have different resistance values.
Best regards,
Juhani |
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sean perry
seany65
United Kingdom
337 Posts |
Posted - Nov 12 2024 : 7:30:49 PM
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| Milo, Thank you for the explanation of what an optocoupler is. |
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Topic |
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Looking for a Zenit 18
