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11-18-2012, 08:38 PM   #1
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K Mount lens on K-30

I have a Pentax-A and another K Mount Vivitar Lens.

My K-30 recognizes Pentax-A lens and I can use either the A setting to let the camera control the aperture or I can set it manually by using the green button to force camera to calculate the correct exposure settings (all manual). But I cannot use the manual feature (stop down using the green button) with the Vivitar lens. I read somewhere that it is because of the anodized back of the lens. Neither of these lenses have any electrical connection to the camera. Why does it behave like this? Is there a way I can use manual stop down with Vivitar's Pentax K mount?
Any one?

11-18-2012, 09:18 PM   #2
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Do you have custom function 23: 'Using aperture ring' enabled (set to 2)? This is necessary to use non-K lenses (either screw-mount that don't reach the contacts on the mount, or 3rd-party lenses with insulated mounts like the Vivitar).

The 'A' lenses do have an electrical connection of sorts - there is a pattern of either plain metal or insulated dots on the lens mount that touches the contacts on the camera when the lens is locked in place. This tells the camera that the lens is attached, and what the range of apertures for the lens are. From this, the camera can determine how far to move the aperture arm to get the desired aperture.
11-18-2012, 09:39 PM   #3
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QuoteOriginally posted by THoog Quote
The 'A' lenses do have an electrical connection of sorts - there is a pattern of either plain metal or insulated dots on the lens mount that touches the contacts on the camera when the lens is locked in place. This tells the camera that the lens is attached, and what the range of apertures for the lens are. From this, the camera can determine how far to move the aperture arm to get the desired aperture.
To explain further, if the camera sees all of the contacts shorted it will assume you are using an M series K mount lens. If it sees none of them shorted, it assumes you have no lens mounted.
11-20-2012, 05:18 AM   #4
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Thanks for the comments. Yes I do have "using aperture ring' enabled" set to 2. I was hoping that there must be a magical way I can use Vivitar with K-30! The lens in question is f/1.7 I bought from ebay.

11-20-2012, 06:16 AM   #5
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Put a piece of aluminium foil over the contact points between the lens and camera mount, that should short the contacts, giving the result elliott is talking about.
11-20-2012, 07:30 AM   #6
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Even without the aluminum foil (or buffing the mount on the lens to bare metal), the Vivitar should work in M (manual) mode like a M42 screw-mount lens. It will behave differently from the A lens, however. In manual mode, depending on whether the lens is a M42 or K/M, and whether you have Auto-ISO turned on, the K-30 may not lift the mirror when you press the green button, but it is still metering. It takes some getting used to.
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