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Meyer oreston 50/1.8 side switch help.
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PostPosted: Tue Oct 15, 2019 4:42 am    Post subject: Meyer oreston 50/1.8 side switch help. Reply with quote

Got this lens in M42 mount. There is a side switch that seems to be able to work in A and M mode by pressing it. But somehow I couldn't make it work. I suspect it is malfunctional. If you own the same lens, can you please let me know it works in its normal condition? Thanks.

I wanted to add what I observed:

1. I set an aperture value and then press the side switch, the aperture blades close to the value I set. At f/11 and f/16, aperture blades close to its set value then open a little bit. Feeling like some spring mechanism can't hold the blades. At f/16, if I press the side switch once, for f/11,5.6,4,2.8, 2, and 1.8, I don't need to press the switch again and the aperture sets. Once it reaches f/1.8, the switch resets to its top position and for all other values, I need to press the switch.

2. By pressing the aperture pin at the lens rear and setting the aperture, the aperture blades don't close, i.e., always open. For a regular M42 lens, if holding the pin down and setting the aperture, even if A mode, the blades close.

Many thanks.


PostPosted: Tue Oct 15, 2019 7:13 am    Post subject: Reply with quote

This is my copy of the Oreston f/1.8:


#1



On my lens, the iris, stop down pin and preview button are all decisive. No waffling here. Wink
When the aperture ring is stopped down and either the pin or button are pressed, the iris closes down fully without hesitation. Even when I press the pin first, the iris stops right down when the aperture ring is turned. And as soon as the pin or button are released, both they and the iris snap back promptly.

I don't know much about this lens, but it does sound as though yours is defective. Mine has a quirk, too. When the aperture ring is set to f/1.8 and the stop down pin or preview button are pressed, the iris closes down a bit to about f/2.
Maybe quality control wasn't the best on these Orestons?


PostPosted: Tue Oct 15, 2019 4:10 pm    Post subject: Reply with quote

55 wrote:
This is my copy of the Oreston f/1.8:


#1



On my lens, the iris, stop down pin and preview button are all decisive. No waffling here. Wink
When the aperture ring is stopped down and either the pin or button are pressed, the iris closes down fully without hesitation. Even when I press the pin first, the iris stops right down when the aperture ring is turned. And as soon as the pin or button are released, both they and the iris snap back promptly.

I don't know much about this lens, but it does sound as though yours is defective. Mine has a quirk, too. When the aperture ring is set to f/1.8 and the stop down pin or preview button are pressed, the iris closes down a bit to about f/2.
Maybe quality control wasn't the best on these Orestons?


Thank you very much for your detailed information. I guess mine IS defective to some extent.


PostPosted: Tue Oct 15, 2019 4:48 pm    Post subject: Reply with quote

vivaldibow wrote:

Thank you very much for your detailed information. I guess mine IS defective to some extent.


Sure, you're welcome. If you try to fix your lens, I'd be interested to hear how it goes.


PostPosted: Wed Oct 16, 2019 6:18 am    Post subject: Reply with quote

Lens likely just needs to be CLA'd, I've done several of these. Even if you don't see oil on the blades, there is likely oil in the aperture mechanism that is preventing the blades from opening/closing correctly.