[asb]

I have a new Pentax K-5.

I have noticed a significant underexposure problem in Program ("P") mode - atleast 1.5 stops. The green-mode exposure is correct (but green mode does not allow RAW).

While I understand that the issue can be corrected with photoshop (especially in RAW images), I would like to understand if this is normal or a defect.

Also, I was wondering if there are others in the forum who have faced a similar problem.

Regards, ASB

Equipment: Pentax K-5, Tamrom 17-50mm f2.8, Pentax 35mm f2.4

[SpecialK]

Here are some of mine...

https://www.pentaxforums.com/forums/pentax-k-5-forum/161077-odd-exposures.html

[Doanh]

People on this forum are a helpful bunch but you should post pictures to demonstrate the issue. From what I understand, underexposure can cause by bright background (eg. snow scene) or spot metering on a bright spot.

[Ash]

Indeed we do have to see the scenes you have captured, with intact EXIF to allow us to analyse the situation better. But generally auto exposure can vary according to the lighting balance on the scene, the metering mode and the AE-L mode (link with AF point or not).

[asb]

Thanks for your messages! I have actually taken exactly the same subject using "green" and "p" mode. Let me post the two images for you to review..

[asb]

Here are the images:

asb's Album: Exposure - PentaxForums.com

IMGP0926 : P mode
IMGP0927 : Green mode

Latter taken immediately after the former.

[Ash]

Something's not right with the metering - #1 is way off (1/800 at f/10) compared to #2 (1/250 f/4).
Reset your camera settings if you don't know about the things I mentioned before, and try shooting again, this time ensuring you don't move any of the e-dials when shooting in P mode.

[dvest]

The under exposed image was taken with spot meter and metered off the white towel which caused the under exposure. The other was taken with pattern metering which must be default for green mode. If you change the metering switch to pattern you should get the same exposure in either the P or green mode.

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Last edited by dvest; 04-17-2012 at 05:30 PM.

[Ash]

That's the most likely explanation, though even still the towel is considerably underexposed.

[MSL]

Well spotted @dvest. It is worth looking at the manual (p.103) which shows which settings are used (or overridden) when shooting in green mode.

[dvest]

That's the most likely explanation, though even still the towel is considerably underexposed.

The towel is white but the meter is going for 18% gray which is what it's supposed to do. Looks like it is a little under exposed. To get the towel to come out white you would need to over expose.

Just noticed white balance is also set different on each image.

[creampuff]

Rookie mistake not knowing how the metering modes differ. Nothing wrong with the camera, problem lies behind the camera.

[MSL]

Rookie mistake not knowing how the metering modes differ. Nothing wrong with the camera, problem lies behind the camera.

Not sure if you meant this as a harsh comment, but it comes across like one, at least to me. If the OP had deliberately switched from spot to pattern metering that would be one thing, but here was a case of changing from one mode to another, only to find that the metering and possibly the white balance had been quietly set to something else. Certainly a case of needing to read the manual, but even then one could easily miss the one key page and still be lost.

[dvest]

I've had my share of mistakes and am pretty sure there will be more to come!

[Ash]

Green mode defaults to matrix metering. It's more likely that the OP had his metering dial set on spot metering the whole time and din't recognise its importance in metering.