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12-14-2018, 02:58 AM   #1
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Samyang 14mm F2.8 ED AS IF UMC auto-aperture problem

Hello!

I have a problem with a second-hand Samyang auto-aperture lens.

The camera body is unable to read the aperture setting when the "A" position is selected on the apertue ring. The display indicates "F--".

Following the lens manual I have checked the following option in the settings menu:
Using aperture ring -> Prohibited/Permitted
"Shutter will not release when aperturering is not set to the "A" position.

When the aperture ring is set to the auto position on the lens, the body is unable to take a photo.


My question:
Has anyone else encountered a similar problem? Is it common, and do you know of any solution/fix?


Here is a more detailed description of the problem, and my observations so far:


When the Auto position is selected on the aperture ring, the body is unable to read and/or control the aperture opening.

Also it seems that when controlling the aperture manually from the lens aperture ring, it does not provide the correct aperture value to the body, hense the correct f-number is not written in the photo information.


This leads me to believe that there is a communicational problem between the lens and the body.

The previous owner of the lens confirmed that he also experienced the same issue with his camera body. He claims that the problem existed since he bought the lens brand-new. Therefore i have no reason to believe that my camera body is faulty.

Any experience you have regarding this issue will be highly appreciated!

12-14-2018, 07:40 AM - 1 Like   #2
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QuoteOriginally posted by sky_light Quote
This leads me to believe that there is a communicational problem between the lens and the body.
Probably.

I don't have this lens but another inexpensive 3rd party lens (my cub scout do all 28-300 lens that I don't have to care about) that sometimes exhibited this behavior. It use to be more common but I gave the connectors on the lens and camera a good cleaning (electrical contact cleaner sprayed on a microfiber cloth and rubbed on the contacts) and the problem has all but disappeared. I always rubbed the cloth across the contacts in the same direction so that they would rotate to clean all sides. It took several sprays and many passes each time but it works pretty reliably now. Before cleaning the contacts I found that if I dismounted and remounted the lens it would often work after a few attempts.
12-14-2018, 08:14 AM   #3
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Many thanks for the feedback!

The problem I exhibited fits the description. However, the previous owner claims that the lens has been like this since he purchased it new, which is very strange and might indicate a possible defect.
12-14-2018, 08:31 AM - 1 Like   #4
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QuoteOriginally posted by sky_light Quote
However, the previous owner claims that the lens has been like this since he purchased it new, which is very strange and might indicate a possible defect.
Maybe. Who knows if everything was clean to begin with when it was assembled or if some oil/dirt got in the wrong place at the wrong time. It could also be some slight corrosion or oxidation on a contacts. Those conditions would likely be corrected with a contact cleaning. If it is a bad connection with the spring or something other issue in the lens a contact cleaning wont resolve it. Either way a cleaning with a cloth and electrical contact cleaner couldn't hurt and may resolve the problem. If it doesn't then the it points to a problem inside the lens that is a defect.

12-14-2018, 09:36 AM - 1 Like   #5
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On my KP I leave setting "24 using aperture ring" checked on "2 shutter will release when aperture ring is not set to the "A" setting".

This allows me to take pictures in "A" and on manually chosen apertures, the aperture doesn't show when set manually though....AE-metering works when using the green button when aperture ring is set manually.


This could solve the issue with the shutter not releasing, but not the rest....
12-14-2018, 01:52 PM - 1 Like   #6
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Yes, this is an 'A' type lens with auto-aperture functioning ..... It can only communicate the aperture to the camera with the aperture ring in the A position, so the behaviour you see with the manually set apertures is normal.

The problem is with the A setting, so it's either a mechanical issue with the aperture ring not engaging into A properly, or the contacts as the other responders have described.
12-22-2018, 05:17 AM - 1 Like   #7
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This happens sometimes with my 14 mm f.2.8 too and also with my Samyang 85 mm f.1.4

Normally I just take it off and on again or adjust it from "a" to f 22 and back to "a" and it will read
12-22-2018, 07:14 AM - 1 Like   #8
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I seem to recall others have similar problems with Samyang and/or Irix lenses. Quality Control is probably the issue. Possibly the contacts internally have gotten non-conductive grease on them or the tolerances through out are sloppy enough that contacts (internal and external) don't line up enough for continuity. Cleaning and moving the lens in the mode and switch in and out of "A" mode "break-in" the fit better. If not live with using green button metering or replace the lens with a different copy. And hope the new copy works better.

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