K10D shows two exposures for same shot

pentkon52 · 07-05-2009, 05:33 AM

Just wondering if any one has come across this.

I have notice it with the Pentax 50-200 and the Sigma 300 F2 APO with the sigma 1.4 tele.

Camera sometimes shows two different meterings for the same shot. Friday i was set up shooting some birds in my yard. I noticed the images were way underexposed, did some looking and found this.
The information in the finder, when shutter button depressed 1/2 way showed one thing and the top LCD showed something different, by quite abit.
Example, view finder showed 1/80 at F6.3 and the lcd shows 1/500 at f6.3 (in Av mode here.Camera in AV mode and manual focused.

Any ideas, dirty contacts, battery maybe.?? or metering problem. I think i took out a 2 year extra warranty through Henrys.

Dave

Oh, when looking at the photo info in camera, the info that showed on the lcd screen was what was captured.

kittykat46 · 07-05-2009, 08:09 AM

Its happened to me before, but here's what I found after I walked through the problem.

Unless your camera is mounted on a tripod, its very possible the camera was metering on a very different scene when you looked through the viewfinder and when you looked at the top LCD. This is especially so if you are using a telephoto lens. At 200mm focal length, just 10 degrees rotation, and you are looking at a totally different scene.

Another factor to consider is that when your eyes are not pressed against the viewfinder, it will allow light to enter from the outside and disrupt the exposure metering. Especially outdoors with bright sunshine. (There's actually a caution against this in the Pentax user manual).
Logically, it will likely underexpose the scene, because the sensor is receiving more light than it should be.
If there is some reason you need to take the shot with your face away from the camera, set AE-lock first, then take the shot later.

I've never encountered this situation again once I understood what was happening, and knew what to do.

Nanthiel · 07-05-2009, 08:14 AM

What kittykat46 said. You could also simply try covering the viewfinder with your hand, when your face isn't there.

pentkon52 · 07-05-2009, 10:17 AM

Yes the camera was tripod mounted.

I understand about the finder letting in some light etc, but my question is why, after 45 odd years of taking photographs is it happening now,.:-)

Its a random thing, once in a while. I should have added that switching to manual metering, i get the exposure the finder wanted to give my, but was over ridden by the LCD metering.

Very odd.

Dave

pentkon52 · 07-06-2009, 04:43 AM

I replicated the shooting conditions on Sunday, and no eronious readings.

Looking more now like an off/on metering snag or lens and camera not talking properly.

Dave

stevebrot · 07-07-2009, 11:25 PM

Originally Posted by pentkon52

Yes the camera was tripod mounted.

I understand about the finder letting in some light etc, but my question is why, after 45 odd years of taking photographs is it happening now,.:-)

Two of my cameras came with a eyepiece cap and another actually has an eyepiece shutter to avoid this issue. It was never a problem until the advent of automatic exposure. Even now, it is not too much of a problem unless:

There is strong light directly into the viewfinder -or-
The subject is in dim light with the viewfinder in stronger light -or-
When using a manual aperture lens in Av mode

That last case can be pretty interesting. I first noticed the problem when working on tripod with my Jupiter-9 85/2 (pre-set aperture). I would frame the shot, focus and stop down the lens (in Av mode). When I backed away from the camera before doing the exposure I was shocked to see a two stop difference in the shutter speed! With the lens stopped down, most of the light in the viewfinder was coming in the "back door". Shade the ocular with my hand and the shutter speed went down. Move my hand...back up. Very entertaining.

Probably the main reason I never noticed it when shooting film was that none of my cameras had a topside LCD display. When my eye was away from the viewfinder I was "shooting blind". When I got the pictures back, I probably just said..."well, there is another bad exposure"...

Steve