More details on the problem:
- I'm shooting these brackets in RAW, in a tripod
- the problem only happens with my IRIX 11, not my IRIX 15mm
- in M mode, I'm doing a five-stop bracket either 1.0 or 1.5 EV apart
The problem comes when I select exposures above +1 EV, usually beyond 1 second. Switching between 1 and 1.5 second resulted in several stops of overexposure. In one scene, while set on 1 second, the rear preview screen switched itself rapidly between +1 and +4 exposure! This always happens with this lens, and I've also seen it with my K-3 lll.
Having wasted time and money checking out the K-1 ll, and buying and returning another IRIZ 11mm lens which did the same thing, I guess the only step left is to try another camera. So I've ordered a new K-1 ll from B&H (now with a free battery grip) to test that with the IRIX 11mm. If it works fine, I'll know that the old K-1 is faulty. Then comes another round with Precision repair. This is NOT the best part of my Pentax ownership experience.
Thanks for your ideas and suggestions.
---------- Post added 06-07-23 at 05:26 PM ----------
Originally posted by photoptimist Here's a list of common problems that could create erratic exposures:
1) light entering the viewfinder(causes under-exposure): If your eye isn't against the camera, light from behind the camera can enter the viewfinder and fool the meter into under-exposing the image.
2) dirty lens mount contacts (both directions possible): intermittent connection between the lens and camera may provide erroneous data on the minimum and maximum aperture of the lens leading the camera to misinterpret the meter readings and to incorrectly set the aperture.
3) sticky aperture blades, weak lens spring, friction in the lens (over-exposure): in the Pentax system, the camera body "lets" the aperture close to the set value which implies that friction in the lens can prevent the proper closing of the aperture.
4) spot meter mode (both directions possible): it's not hard to end up in this metering mode and then happen to have the spot on dark or bright feature of the scene.
5) loose lightmeter sensor inside the camera (erratic over-exposure): If the sensor is knocked loose it will typically see much less light off the focusing screen and handling of the camera between portrait orientation, landscape, point up, down, or inverted for a battery change can jiggle the sensor to change the exposure.
1) I'm indoors when this happens, away from strong lighting.
2) I've sprayed the lens contacts with electronics cleaner, with no change.
3) No way for me to check on this, but a new 11mm IRIX lens also showed the problem
4) I'm in M mode, ignoring the metering and judging exposure from the rear preview.
5) I'm shooting from a tripod, so no jiggles. Other lenses and brighter scenes show no problems.