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12-08-2014, 10:33 AM   #1
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Exposure problems with the K-50

I have a K-50. I have a Quantaray 70-300mm lens attached to it. The rig is on a tripod. I'm shooting some static test shots using tungsten light. I have the camera set on auto focus. I have the "Custom Image" set at 0.0 for all options. I have the white balance set for "tungsten." I have the program dial set at TaV. I have the shutter set for a 2 second delay. I have the ISO set for 200-800. I have the lens set at the "A" position on the aperture ring. I have the AE meter set for "Center Weighted."


I'm ready to shoot. I push the shutter release button half way down, the lens focuses on the subject. I then release the shutter release button and push the "Green Button." It indicates that I need a shutter speed of 1/180th of a second. The ISO indicator on the view screen begins to blink "200" and finally stops at "AUTO." I make the exposure and I get image #1 below.


I change the shutter speed manually to 1/80th and I get what I consider a good exposure, as shown in image #2 below.


My questions are:


1. Does the "Green Button" indeed decide what shutter speed is needed under the prevailing conditions?


2. If the answer to question #1 is "YES," then how do I reset the exposure values in the camera so that I don't have to continually adjust them contrary to
what the "Green Button" is telling me?


3. If I'm all washed up as to the true function of the "Green Button" is, then can someone clue me in?


Thanks for any help you guys/gals might be able to furnish this dullard!


Dewman
SW Idaho, USA


Last edited by Dewman; 03-25-2015 at 04:36 PM.
12-08-2014, 10:55 AM   #2
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The centre is mainly just plain white. This will lead to under exposure. The camera will treat the light info as an average gray. Just as with snow pictures you will get under exposure. Try Matrix metering or spot metering on a gray part of the duck.
12-08-2014, 11:04 AM   #3
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QuoteOriginally posted by Dewman Quote
I have a K-50. I have a Quantaray 70-300mm lens attached to it. The rig is on a tripod. I'm shooting some static test shots using tungsten light. I have the camera set on auto focus. I have the "Custom Image" set at 0.0 for all options. I have the white balance set for "tungsten." I have the program dial set at TaV. I have the shutter set for a 2 second delay. I have the ISO set for 200-800. I have the lens set at the "A" position on the aperture ring. I have the AE meter set for "Center Weighted."


I'm ready to shoot. I push the shutter release button half way down, the lens focuses on the subject. I then release the shutter release button and push the "Green Button." It indicates that I need a shutter speed of 1/180th of a second. The ISO indicator on the view screen begins to blink "200" and finally stops at "AUTO." I make the exposure and I get image #1 below.


I change the shutter speed manually to 1/80th and I get what I consider a good exposure, as shown in image #2 below.


My questions are:


1. Does the "Green Button" indeed decide what shutter speed is needed under the prevailing conditions?


2. If the answer to question #1 is "YES," then how do I reset the exposure values in the camera so that I don't have to continually adjust them contrary to
what the "Green Button" is telling me?


3. If I'm all washed up as to the true function of the "Green Button" is, then can someone clue me in?


Thanks for any help you guys/gals might be able to furnish this dullard!


Dewman
SW Idaho, USA
The green button re-meters the scene and adjusts the setting to what it thinks is the correct exposure. It can change different settings when in different modes. For instance, when in Av mode, you can have it adjust the shutter or the ISO to get the correct exposure.

I use it when I'm in HyperProgram mode. I might see something moving and scroll the shutter dial to freeze its motion. Or want shallow depth of field and scroll the aperture dial to get what I want. After that, I want to get out of Av or Tv mode, and return to MTF HyperProgram which attempts to use the sharpest aperture of the lens. So I just hit the green button and I'm back in HyperProgram.
12-08-2014, 11:37 AM   #4
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QuoteOriginally posted by Dewman Quote
3. If I'm all washed up as to the true function of the "Green Button" is, then can someone clue me in?
Green button is going to re-meter the scene and set values to what it thinks things should be as enoeske says. But I'm confused why you would be using it in this situation? If you are in TAv then the camera already metered the scene, no need for the green button. It is useful in manual or hyper program or for stop down metering with non-'A' capable lenses but not needed in this situation.

Note that the green button will use the settings in menu as to what priority to use when metering. I think the default is 'program line' which might not work so well with that lens. You might check to see what the 'green button' settings are. I've never used a k-50 so it might be a little different.

12-08-2014, 12:13 PM   #5
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The paper still looks very grey, Dewman - which by convention is what all cameras try to meter for.

Try an even slower shutter speed.
12-08-2014, 01:04 PM   #6
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Original Poster
I think I have discovered my problem. I was totally confused as to what TAv mode actually does. The way MY camera functions is, with the settings I have now.... shutter speed set at 1/90th, aperture at f:19.... (just arbitrary numbers) the camera will adjust the ISO accordingly within the parameters I have told it to use in order to obtain a correct exposure. For some goofy idea, I was pushing the Green Button, thinking I needed to do that in order to "meter the scene." I went outside and shot several test shots WITHOUT using the Green Button and they were fine and dandy.


Strictly pilot error.... and a feeble mind!


Thanks guys. I'd still be mumbling obscene things about the ancestors of the people who invented pixels if it wasn't for your help.


Dewman
SW Idaho, USA
12-08-2014, 01:24 PM   #7
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As another test, go take a picture up close of a black automobile. Then do the same with a white automobile. Compare your results.
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