[jonhock]

This should be a simple question for someone "in the know". Back in the day (K1000 era) I knew that light coming in through the viewfinder would change the exposure settings. My Question is; Does light coming in through the viewfinder on my K20 or my K3 have an effect on exposure settings? Thank you all ahead of time! I been shooting photos for about 40 years and it makes me feel good about coming across things I don't know about it. (which is every time I even think about the cameras!)

[stevebrot]

Does light coming in through the viewfinder on my K20 or my K3 have an effect on exposure settings?

If you are referring to light entering through the eyepiece, the answer is the same as in the old days; yes, it can affect metering for automated exposure and in severe situations even create a light leak into the mirror box during exposure. I use my thumb to cover the viewfinder opening when shooting on tripod. One may also use the slide-on eyepiece cover that came with the camera.

BTW, this is easily demonstrated by alternately shading/covering the eyepiece while looking at the top LCD with the camera pointed at shadows, but with the rear in bright sunlight.


Steve

[Adam]

It works just like it did on the K1000, except now the aperture can be set automatically

[photoptimist]

Yes it does. The sensor for the exposure meter is located on top of the pentaprism and measures the light off the focusing screen. If you have a very dark ND filter, high magnification macro setup, or the sun is at your back and entering the viewfinder, it can significantly affect the reading and cause under-exposures.

If you meter with your eye on the viewfinder, that will work. AEL can lock the exposure reading. You can also block the viewfinder either with your hand, a little taped paper flag, or the tiny black viewfinder cover that came with your camera and is now lost somewhere in the camera box or camera bag.

[Bophoto]

But surely it can also leak some even in live wiev mode?
But so little that it can be ignored?

[macman24054]

which is every time I even think about the cameras

Me too

[stevebrot]

But surely it can also leak some even in live wiev mode?
But so little that it can be ignored?

The mirror, when in the up position, is effective in blocking light from the eyepiece. However, extremely bright light (say full sun or a blast of electronic flash) will sneak past the edges.


Steve

(...actually tested this once upon a time...)

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Last edited by stevebrot; 05-04-2018 at 11:41 AM.

[jonhock]

Thank you everyone! It's not usually a problem because I have an o-me53 eyecup on my K3 and it is easy to shade with my hand, but for those unique moments I do have a couple of the viewfinder caps.

[pschlute]

Thank you everyone! It's not usually a problem because I have an o-me53 eyecup on my K3 and it is easy to shade with my hand, but for those unique moments I do have a couple of the viewfinder caps.

Or chewing gum. Pentax recommends this one........

[mikesbike]

Of course, I assume the camera is on a tripod or other means of support, so your eye is not at the FV. Another alternate method than those very effective ones given above, unless the lighting is constantly changing requiring constant re-adjustment, instead of keeping the eyepiece constantly covered, or using the AE-L button (which is only good for a limited period), just put the camera in Manual mode and use the green button to set exposure, with the eyepiece blocked by your eye, hand, etc. while doing so. Exposure will be set according to the program line, usually that of the "P" mode. If you would rather shoot in Av or Tv mode, Hyper Manual's green button can be adjusted to follow those program lines as an alternative choice. The Hyper Manual operation is a feature exclusive to Pentax AF SLR and DSLR cameras since the PZ series of film bodies.

---------- Post added 05-29-18 at 04:19 PM ----------

Another thing, if using the Hyper Manual feature as above, and you'd rather not take time to adjust the green button to other than the default "P" mode program line, but you'd still rather have a different Av or Tv setting than that provided under the green button's exposure- after getting your setting via the green button, then hit the AE-L button, select your preferred aperture or shutter speed, and as you do so the other will follow along, preserving your exposure.