K-70 User Problem with SMC Pentax F 4.5 - 5.6 100-300 mm lens

Roger Dier · 07-05-2017, 05:37 PM

I'm embarrassed to ask, but obviously, not too embarrassed.

I'm new to the K-70. I bought a used SMC Pentax-F zoom lens. I used it with the auto timer to take a few test shots of the gibbous moon. Suddenly, the camera and lens began having an argument and what shows up on the live view is the F - - blinking, no matter what ISO setting I have it at. I can't take manual or auto timed shots. If I put in the 18-135 lens that came with the camera, it works great. When I switch out to the 100-300 mm zoom, nothing happens but a lot of blinking.

I'm hoping the solution is obvious. If it is, please share.

I'll watch the thread to answer questions as fast as I can.

Thank you kindly.

**ChipB** · 07-05-2017, 05:49 PM - **1 Like**

Sounds like the contacts on the lens need cleaning - personally (and others will disagree

) I use a pencil eraser to gently go over the contacts - just be careful not to have any eraser bits go inside the lens. Good luck.

**twilhelm** · 07-05-2017, 05:56 PM - **1 Like**

ChipB is correct. The contacts are dirty. I've had the best luck with a cotton swab and rubbing alcohol. Just don't soak it, you don't want alcohol inside the lens.

Adam · 07-05-2017, 06:18 PM - **1 Like**

Originally posted by Roger Dier

I'm embarrassed to ask, but obviously, not too embarrassed.

I'm new to the K-70. I bought a used SMC Pentax-F zoom lens. I used it with the auto timer to take a few test shots of the gibbous moon. Suddenly, the camera and lens began having an argument and what shows up on the live view is the F - - blinking, no matter what ISO setting I have it at. I can't take manual or auto timed shots. If I put in the 18-135 lens that came with the camera, it works great. When I switch out to the 100-300 mm zoom, nothing happens but a lot of blinking.

I'm hoping the solution is obvious. If it is, please share.

I'll watch the thread to answer questions as fast as I can.

Thank you kindly.

Also, make sure the aperture ring is set to "A". If it's set to "A", the contacts have been cleaned, and you still can't get it to work, chances are that the aperture mechanism in the lens has issues.

Adam
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stevebrot · 07-05-2017, 08:43 PM - **1 Like**

Originally posted by Roger Dier

live view is the F - - blinking

Blinking?

To elaborate on the comments above, "F--" indicates that the body does not detect a lens that supports automatic aperture control by the body. The "F--" display is normal and expected when the lens mounted does not have contacts on the base or the aperture ring (when present) is not on the "A" position. Specifically, it means that one of the contacts, the so-called "A" contact is not detected. If neither is the case, "F--" often means that the contacts on lens and/or body are not making good contact and need to be cleaned. If that does not work and other lenses work fine, there is a fault (most likely a broken wire or something similar) in the lens.

Still, it is the blinking that is most disturbing. A blinking display usually means something as simple as the light on the subject is outside the range of the exposure system. So, now some questions:

Does it blink with the lens cap off and the camera pointed at some random daylight scene? (ISO set to 200 with aperture ring at widest setting)
If you have access to another camera, are there problems with that body as well?

Addendum: Are you sure the aperture ring is in the "A" position? There is a small button that must be pressed to allow the ring to move into place.

Steve

Roger Dier · 07-06-2017, 04:59 AM - **1 Like**

Hello Everyone,

Thank you to everyone who helped me figure this out. I cleaned the contacts with alcohol and a cotton swab, and following that, I also made sure the aperture ring was set to the "A" position. Your suggestions did the trick, and for that I am very grateful. Thank you for your help, sincerely. :-)

07-05-2017, 05:37 PM	#1
Roger Dier Junior Member Join Date: Jun 2017 Posts: 51	K-70 User Problem with SMC Pentax F 4.5 - 5.6 100-300 mm lens I'm embarrassed to ask, but obviously, not too embarrassed. I'm new to the K-70. I bought a used SMC Pentax-F zoom lens. I used it with the auto timer to take a few test shots of the gibbous moon. Suddenly, the camera and lens began having an argument and what shows up on the live view is the F - - blinking, no matter what ISO setting I have it at. I can't take manual or auto timed shots. If I put in the 18-135 lens that came with the camera, it works great. When I switch out to the 100-300 mm zoom, nothing happens but a lot of blinking. I'm hoping the solution is obvious. If it is, please share. I'll watch the thread to answer questions as fast as I can. Thank you kindly.

07-05-2017, 08:43 PM - 1 Like	#5
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Roger Dier live view is the F - - blinking Blinking? To elaborate on the comments above, "F--" indicates that the body does not detect a lens that supports automatic aperture control by the body. The "F--" display is normal and expected when the lens mounted does not have contacts on the base or the aperture ring (when present) is not on the "A" position. Specifically, it means that one of the contacts, the so-called "A" contact is not detected. If neither is the case, "F--" often means that the contacts on lens and/or body are not making good contact and need to be cleaned. If that does not work and other lenses work fine, there is a fault (most likely a broken wire or something similar) in the lens. Still, it is the blinking that is most disturbing. A blinking display usually means something as simple as the light on the subject is outside the range of the exposure system. So, now some questions: Does it blink with the lens cap off and the camera pointed at some random daylight scene? (ISO set to 200 with aperture ring at widest setting) If you have access to another camera, are there problems with that body as well? Addendum: Are you sure the aperture ring is in the "A" position? There is a small button that must be pressed to allow the ring to move into place. Steve Last edited by stevebrot; 07-05-2017 at 10:31 PM.

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07-05-2017, 05:49 PM - 1 Like	#2
ChipB Site Supporter Join Date: Nov 2007 Location: Eau Claire, WI Photos: Gallery \| Albums Posts: 2,701	Sounds like the contacts on the lens need cleaning - personally (and others will disagree ) I use a pencil eraser to gently go over the contacts - just be careful not to have any eraser bits go inside the lens. Good luck.

07-05-2017, 05:56 PM - 1 Like	#3
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	ChipB is correct. The contacts are dirty. I've had the best luck with a cotton swab and rubbing alcohol. Just don't soak it, you don't want alcohol inside the lens.

07-05-2017, 06:18 PM - 1 Like	#4
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,594	Originally posted by Roger Dier I'm embarrassed to ask, but obviously, not too embarrassed. I'm new to the K-70. I bought a used SMC Pentax-F zoom lens. I used it with the auto timer to take a few test shots of the gibbous moon. Suddenly, the camera and lens began having an argument and what shows up on the live view is the F - - blinking, no matter what ISO setting I have it at. I can't take manual or auto timed shots. If I put in the 18-135 lens that came with the camera, it works great. When I switch out to the 100-300 mm zoom, nothing happens but a lot of blinking. I'm hoping the solution is obvious. If it is, please share. I'll watch the thread to answer questions as fast as I can. Thank you kindly. Also, make sure the aperture ring is set to "A". If it's set to "A", the contacts have been cleaned, and you still can't get it to work, chances are that the aperture mechanism in the lens has issues. 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:

07-06-2017, 04:59 AM - 1 Like	#6
Roger Dier Junior Member Join Date: Jun 2017 Posts: 51 Original Poster	Hello Everyone, Thank you to everyone who helped me figure this out. I cleaned the contacts with alcohol and a cotton swab, and following that, I also made sure the aperture ring was set to the "A" position. Your suggestions did the trick, and for that I am very grateful. Thank you for your help, sincerely. :-)

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