[kenkk]

Check the body aperture control. The example photos you shared indicate that the lens is not stopping down the aperture set and recorded in the EXIF. The only ones with correct exposure were those taken with the lens wide open (EV was the same for all in the series). This is easily assessed visually by looking into the front of the lens during an exposure cycle. If you can't see the aperture blades stop down, they are not stopping down.


Steve

ok 31 on camera.
M Mode
Front Dial Shutter speed set at 2 sec
back dial Aperture set F22.
Whilst looking into the lens from the front test fire 5 shots.
Repeat over various Fs down to F1.8. and vice versa.

All i see throughout the test shots through the front end of the lens;
- Yes when pressed it goes dark, at the end of each shot back to lighter colour, indicating movement of aperture blades. **Clarifying i don't actually see detailed blades.
- all very consistent through the F ranges, all speeds being held during the shots, if anything marginally longer at F22 than on F1.8.

Thanks Steve, for your patience, does the above help?

Ken

[Larrymc]

ok 31 on camera.
M Mode
Front Dial Shutter speed set at 2 sec
back dial Aperture set F22.
Whilst looking into the lens from the front test fire 5 shots.
Repeat over various Fs down to F1.8. and vice versa.

All i see throughout the test shots through the front end of the lens;
- Yes when pressed it goes dark, at the end of each shot back to lighter colour, indicating movement of aperture blades. **Clarifying i don't actually see detailed blades.
- all very consistent through the F ranges, all speeds being held during the shots, if anything marginally longer at F22 than on F1.8.

Thanks Steve, for your patience, does the above help?

Ken

First thing.....Get out of AV priority and go to manual mode. Then setup your camera to display depth of field preview (Pg 46 in the manual). Once that is done then get a feel for how the depth of field preview works by rotating the on/off lever to the depth of field preview point (you should hear the lens stop down if you have the aperture set to anything but wide open). Next set the lens to minimum aperture (High f number) then turn the camera to look into the lens and rotate the on/off switch to the depth of field preview point. You should see the aperture close when you rotate the on/off switch to the depth of field position. Go to AV mode repeat the test if the lens stops down in both tests then its probably not a mechanical aperture problem. This should allow you to eliminate lens aperture problems.

[kenkk]

Steve, Mike and LarryMC thanks.

Using the DOF Preview, settings are, Lens in auto aperture, camera set at AF, Mode on M, DOF preview on Optical (std default and confirmed via customisation menu).
Looking through the front of the lens and actuating aperture blade icon (camera On/off switch).

-Only thing consistent is at F1.8 no sound nor movement as expected i think.
-Battery was running low and had very inconsistent results, changed to a fully charge battery.
-at varying f's 10,16, 20, 22 i can see the blades stop down with corresponding iris sizes in relation to the f numbers.
-same results on Av.
-same results on the 77mm (much better lens to test with, larger and can see the blades in detail action)

Unfortunately test shots on both still showing blown highlights.

Thanks to all so far.
Ken

[Larrymc]

Steve, Mike and LarryMC thanks.

Using the DOF Preview, settings are, Lens in auto aperture, camera set at AF, Mode on M, DOF preview on Optical (std default and confirmed via customisation menu).
Looking through the front of the lens and actuating aperture blade icon (camera On/off switch).

-Only thing consistent is at F1.8 no sound nor movement as expected i think.
-Battery was running low and had very inconsistent results, changed to a fully charge battery.
-at varying f's 10,16, 20, 22 i can see the blades stop down with corresponding iris sizes in relation to the f numbers.
-same results on Av.
-same results on the 77mm (much better lens to test with, larger and can see the blades in detail action)

Unfortunately test shots on both still showing blown highlights.

Thanks to all so far.
Ken

Well it seems from your message that the aperture control system is working properly. Have you done a factory default reset of the camera? If not do it to make sure there are no setting that are throwing off your shots then work slowly through resetting the camera to what you want the settings to be. Also use manual ISO settings. Good luck.

[Na Horuk]

I still think the problem is somehow connected to the aperture lever. The little lever on the lens gets moved by the camera to the chosen setting. Since you used various lenses, this is probably not a lens fault, but a camera fault. Aperture problems do not necessarily mean the camera completely fails to move the aperture, it could just be that it moves the aperture too slowly or at the wrong time, the wrong distance.
So all in all, I would recommend you check the camera mount, make sure it is clean and free of damage. If reset functions and all the other things you already checked did not fix this problem, then you might have to return camera in store for repairs. I hope it is still in warranty. If you bring it in, make sure you bring along a long explanation of the problem and all the things you already tried. Sorry, I can't think of anything else, but you might want to search the forums for similar problems, maybe someone got a solution, maybe even with some other Pentax DSLR, long ago.

[kenkk]

Thanks all for your input.

Camera is in for repairs for a "Diaphragm control block".
Hopefully should be back in a few weeks.

ken