FA 28-70/f4. Problem to detect lens identity on K-5.

mrmentera · 08-30-2011, 02:44 PM

Just got the FA 28-70/f4 in the mailbox. Bargain on ebay, I thought....

On my K-5 it seems to be a K or M lens if I look att the exif.

However, it autofokus sometimes but it always says MF on the lcd. One strange thing is also that the lcd shows an aperturevalue, while the top-screen just show F--, as in the viewfinder. I can change the value on the lcd with the thumbscrew, but in Av-mode it dont give right exposure.
I have cleaned the contacts, the lens and the apertureblades look really good. K-5 is ok with my other lenses.
Whats the problem? Bad contact inside the the lens? Broken chip?
Easy to fix?

Adam · 08-30-2011, 03:22 PM

Sounds like it might be defective. Is the aperture ring in the A position?

mrmentera · 08-30-2011, 03:43 PM

Yes it is in A. I moved the aprturering back and forth. And defective in som way, yes.
Intresting though why there is different info on the both screens. Is one the cameras signal to the lens and the other the feedback from the lens, ackording the aperture?

I saw some nice pictures here:
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/66446-fa-28-70-f4-question.html

Lots of parts, but this must be something "electrical"?
What do you think?

08-30-2011, 02:44 PM	#1
mrmentera Forum Member Join Date: Nov 2009 Location: Falun Posts: 90	FA 28-70/f4. Problem to detect lens identity on K-5. Just got the FA 28-70/f4 in the mailbox. Bargain on ebay, I thought.... On my K-5 it seems to be a K or M lens if I look att the exif. However, it autofokus sometimes but it always says MF on the lcd. One strange thing is also that the lcd shows an aperturevalue, while the top-screen just show F--, as in the viewfinder. I can change the value on the lcd with the thumbscrew, but in Av-mode it dont give right exposure. I have cleaned the contacts, the lens and the apertureblades look really good. K-5 is ok with my other lenses. Whats the problem? Bad contact inside the the lens? Broken chip? Easy to fix?

08-30-2011, 03:22 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Sounds like it might be defective. Is the aperture ring in the A position? 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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08-30-2011, 03:43 PM	#3
mrmentera Forum Member Join Date: Nov 2009 Location: Falun Posts: 90 Original Poster	Yes it is in A. I moved the aprturering back and forth. And defective in som way, yes. Intresting though why there is different info on the both screens. Is one the cameras signal to the lens and the other the feedback from the lens, ackording the aperture? I saw some nice pictures here: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/66446-fa-28-70-f4-question.html Lots of parts, but this must be something "electrical"? What do you think?