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Pentax DSLR's with KA lenses


Stickleman 9 83 3 England
9 Mar 2016 11:41AM
Hi, I used to use Pentax SLR's in the early 90's and had a couple of 'A' lenses in the cupboard doing nothing, anyway someone at work has recently bought a used K7 as a starter camera and I offered them to him to use on his K7 after checking online they could be used in auto functions as he is a beginner. I assumed that when the lens was mounted set to 'A' the aperture could be changed using the control wheel, but it can't and no auto functions are available. When the lens is mounted on the camera he gets the flashing 'F--' symbol and no control of aperture, if 'A' is disengaged and lens ring permitted in the menu the 'F--' ceases to flash but can only be used in manual (which is correct) Are we missing something here or not setting something correctly in the menu ? I feel a bit of a fraud even though I didn't charge him for the lenses.Thanks in advance.

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PRC 5 253 United Kingdom
9 Mar 2016 1:30PM
I don't know for sure, but this link may be of help.

Philip
petebfrance 8 2.9k France
9 Mar 2016 1:44PM
A quick check here suggests that the F-- symbol is requesting the focal length for the shake reduction system as the camera is not picking it up automatically. My K50 does the same, and once the focal length is entered it works fine with the lens set on A.
Stickleman 9 83 3 England
9 Mar 2016 2:54PM
Thanks for the links. After reading those and a bit further research it seems I was correct in thinking the control wheel should change the aperture when the lens is set to 'A' . Looks though either the camera or lenses aren't working as they should, will be Saturday before I can check. Thanks.
petebfrance 8 2.9k France
9 Mar 2016 3:59PM
Just a thought and probably unlikely. The control wheels on mine (and presumably the K7) are configurable - I set mine up 'wrongly' (well, differently, I suppose) once so that the front wheel ended up controlling the aperture in Av and was then struggling to change it with the rear wheel (which I'd set to ISO, I think)Blush It took me a while to figure out what I'd done. So if the control wheel changes apertures for the other lenses as it should but not your A lenses, it sounds as though something is wrong, otherwise it could just be how the camera is configured.
Stickleman 9 83 3 England
9 Mar 2016 8:17PM
I'll check that but even if the control wheels were configured wrongly (differently) I would've expected the display to show an f number not F--.Thanks.
petebfrance 8 2.9k France
9 Mar 2016 9:39PM
That's true - I've just checked mine and the f number shows up as normal. It does seem that what you are getting is how an M lens would behave (I don't have any Pentax ones but do use some old M42 lenses and they are easy enough to get on with for static subjects using stop-down metering) - most odd.
wsteffey 13 13 United States
10 Mar 2016 3:35PM
Try the pentaxforums.com.. They are Pentax experts and are a good source of everything Pentax
11 Mar 2016 6:43AM
Check that the lens is truly engaged on 'A', this requires the small button on aperture ring to be pressed prior to shifting it all the way over so that the the 'A' indicator lines up perfectly with the aperture marker. Might not be this, but worth checking.
Stickleman 9 83 3 England
12 Mar 2016 6:33PM
Well no further forward really, the camera works perfectly with A/F lenses but not with the two KA's and as we haven't another KA lens to test with we'll just have to assume it's both lenses that are faulty. Thanks for the replies and advice.
petebfrance 8 2.9k France
12 Mar 2016 8:19PM
Not much I can add, then. I was going to mention the possibility of the lens not clicking properly into the A position but Rick got there first. The aperture ring on the only A lens I have, a 50mm f2, is very stiff and requires a bit of force to get it there whereas the F lenses are much smoother. It should click in - sounds mechanical to me, and almost like forcing it into position with what I consider to be an unreasonable amount of force.....
GeorgeP Plus
13 59 25 United States
21 Mar 2016 2:23PM
I find that the F-- signal on my K5 when using KA lenses is a sign that the contacts on the lens and the body are not "making contact". Sounds silly but check that the contacts on the camera and lens are clean. Then check the fit. I have discovered that there is some little play at the mount and slightly twisting the lens a fraction can restore connection between the lens and the body.

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