[rwhynacht]

Have you tried cleaning the contacts on the lens and camera mount? If you have other lenses I would definitely try them as well

What happens if you shoot with the aperture fully closed in viewfinder mode (in Av mode, ISO 100, tripod or resting on a flat surface)?

Is the exposure compensation set at +-0?

I keep the lens and mount very clean but went over them just in case. Exposure comp has been at 0. Multi segment metering, In AV at f/22, ISO 100 in optical view mode it calculated a 4 sec exposure (I am currently in a very dim room). The image is slightly dim. When I turn on live view mode at same settings, it sets the shutter at 30" and the histogram jumps to the right - actually a bit blown out.
Opening the aperture causes speed to plummet in AV mode and image at f/11 is very underexposed in optical mode. (1" exposure in OVM vs. 20"+ in LVM) will try diff lenses when i can.

[stevebrot]

Any thoughts?

If there is a metering problem, the camera will meter different settings in live view than when using the optical viewfinder. This is more easily seen by comparing shutter speeds between the two in Av mode with fixed ISO and identical framing/lighting. The camera should call for the same or similar speeds in both live view and through the viewfinder.

If it is an aperture control issue, the camera will not consistently stop the lens down properly regardless of what is metered or manually set on the camera. This you can tell by manually setting a narrow aperture and long shutter speed and looking through the front of the lens when the shutter is released. If the lens does not stop down as expected, there is a control problem or a damaged mechanism in the lens. Likewise, if the lens is not supposed to stop-down or is closing down more than expected, one can manually set to wide-open and check to see if that setting is respected.


Steve

[rwhynacht]

Since returning from vacation I was able to test my k-70 with multiple lenses. All lenses produce dark images in all the auto modes. Manually setting aperture ring on vintage lenses to the metered readings produced ok images every time.

Not sure why I was initially getting better results with live mode- but that has now failed as well and dark images result from both modes.

I am sending the camera for repair under mastercard extended warranty and will post an update once it comes back. In future will travel with an old manual lens so i can take at least a few vacation photos if/when it fails again.

[photogem]

First thing I would try is a reset!

[reh321]

Since returning from vacation I was able to test my k-70 with multiple lenses. All lenses produce dark images in all the auto modes. Manually setting aperture ring on vintage lenses to the metered readings produced ok images every time.

Not sure why I was initially getting better results with live mode- but that has now failed as well and dark images result from both modes.

I am sending the camera for repair under mastercard extended warranty and will post an update once it comes back. In future will travel with an old manual lens so i can take at least a few vacation photos if/when it fails again.

You reported over in the K-70 Underexposed Photo Reports - Page 8 - PentaxForums.com thread

Precision Camera just replaced the “aperture control assy” and “resistor chip” on my k-70.
The nearly black images in all auto modes are gone. Exposures are now correct and the repair was performed astoundingly quickly.

Reading over your past posts, if I understand correctly, at first you got dark images only when using Optical Viewfinder, but later you got them in LiveView also?

I wonder if the "resistor chip" was connected somehow to the slow motion failure.

[rwhynacht]

You reported over in the K-70 Underexposed Photo Reports - Page 8 - PentaxForums.com thread


Reading over your past posts, if I understand correctly, at first you got dark images only when using Optical Viewfinder, but later you got them in LiveView also?

I wonder if the "resistor chip" was connected somehow to the slow motion failure.

Correct. When i first found images severely underexposed, live view was still giving better exposure. Subsequent tests a week later were dark in both modes but the metering function appeared ok: Manually setting aperture ring on vintage lenses to the setting that the camera calculated resulted in correctly exposed images.

[photogem]

Since returning from vacation I was able to test my k-70 with multiple lenses. All lenses produce dark images in all the auto modes. Manually setting aperture ring on vintage lenses to the metered readings produced ok images every time.

Not sure why I was initially getting better results with live mode- but that has now failed as well and dark images result from both modes.

I am sending the camera for repair under mastercard extended warranty and will post an update once it comes back. In future will travel with an old manual lens so i can take at least a few vacation photos if/when it fails again.

The update never arrived here in this thread, but "rwhynacht" mentioned the outcome here, when he wrote:
2 months ago I got the aperture assembly replaced on my K-70

So after all predictions: It was just the solenoid which failed

which in a way he explained here:

Shooting a K-70 for over a year. No exposure problems. Today began getting nearly black images in all modes: AV, TAV, M, Auto. My 1st thought was aperture block failure but after some testing found live view appears to expose correctly. Optical view is around 5 stops under exposed. Also pop up flash shots are equally under exposed in both modes. I have only 1 lens with me currently (Sigma 17-50 2.8) so I have not tried an older manual lens yet, but I doubt it's lens or app block related. Any thoughts?

LiveView does often work when the solenoid is not working anymore.

The K-70 (and K30/50 K-S1/2) use f4 preset for LV metering but actually the aperture is fully closed and yet the camera can meter.
The solenoid actuates twice in LV and receives more mA for the second actuation.