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10-25-2014, 12:51 PM   #1
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Vivitar 70-150 mm lens on K100D

I have seen advice in these Forums on using vintage lenses on modern Pentax DSLR cameras. Usually I can get these older lenses to expose correctly on my K100D. However, I have a problem with a Vivitar 70-150 mm,f/3.8 close-focus lens. No matter what I tried, I get a very under-exposed image. Here's what I did:
1. Set the lens to M
2. Set the aperture to f/8
3. Set the camera dial to Av
4. Set the camera body to MF
5. Choose an ISO of 800
6. Focus, press the AE-L button and hold, and press the shutter release.

The image is sharp but underexposed. I get the same result when I set the dial to P or Auto Pict.

What am I doing wrong? Could the camera be faulty? I'd like to get to the bottom of this problem because this lens is really sharp and solidly made.

10-25-2014, 12:56 PM   #2
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QuoteOriginally posted by P. Soo Quote
3. Set the camera dial to Av
Set it to M mode

QuoteOriginally posted by P. Soo Quote
6. Focus, press the AE-L button and hold, and press the shutter release.
Use the exposure preview button (on the on/off switch) instead of the AE-L button.

Here are the full instructions:

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10-25-2014, 01:00 PM   #3
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QuoteOriginally posted by Adam Quote
Press the green button instead of the AE-L button.
The K100D doesn't have a green button, so use the AE-L button instead. The main thing is putting the camera in M-mode. I get very good metering on the K100D with fully manual lenses.
10-27-2014, 09:35 AM   #4
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Original Poster
Thanks Adam and Paulh. I seem to have solved the problem using your advice. The image still seems a little underexposed which may be a characteristic of the lens, but I can handle this. Thanks again.


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