Vivitar 70-150 mm lens on K100D

**psoo** · 10-25-2014, 12:51 PM

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.

Adam · 10-25-2014, 12:56 PM

Originally posted by P. Soo

3. Set the camera dial to Av

Set it to M mode

Originally posted by P. Soo

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:

https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html

**paulh** · 10-25-2014, 01:00 PM

Originally posted by Adam

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.

**psoo** · 10-27-2014, 09:35 AM

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.

10-25-2014, 12:51 PM	#1
psoo Site Supporter Join Date: Jan 2012 Location: Long Island, NY Posts: 485	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
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Originally posted by P. Soo 3. Set the camera dial to Av Set it to M mode Originally posted by P. Soo 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: https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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10-25-2014, 01:00 PM	#3
paulh Site Supporter Join Date: Sep 2010 Location: DFW Texas/Ventura County, CA Photos: Gallery \| Albums Posts: 33,273	Originally posted by Adam 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
psoo Site Supporter Join Date: Jan 2012 Location: Long Island, NY Posts: 485 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.