K-30 Overblown exposures

Started Dec 30, 2012 | Discussions thread
DS21
Senior MemberPosts: 1,637Gear list
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Re: Check out these photos
In reply to Simon Devlin, Dec 30, 2012

Simon Devlin wrote:

This first photo with an overblown sky/background was taken with the other lens (Pentax-A 50mm f/1.7).

I shall write the EXIF data as it is getting zapped in the upload/download process.

1/25sec, Aperture priority, 0 EV, F11, ISO 100, Multi-segment (There is EXIF data stating 'Max Aperture F1' )

​Now this is interesting:

This was the lens where the majority of overblown sky shots occured, the Pentax-A 28mm f/2.8.

The following 2 shots occur within 21 seconds of one another, I simply turned around and shot the other side of the mountain.

The camera ​settings were not ​modified during the short duration.

The first was shot into the sun in the shadow of the mountain.

EXIF DATA: 1/50sec, Aperture priority, 0EV, F4, ISO 100, (Max Aperture F1)



The next one was shot 21 seconds later. This was shot looking away from the sun in the shadow of the mountain.

EXIF DATA: 1/200sec, Aperture priority, 0EV, F4, ISO 100, (Max Aperture F1)



If the camera is working on spot or centre weighted metering despite multi-segmented being selected, then surely the over-exposure should not have been justified by the camera.

"Brad99 wrote:

Old manual A lenses only use centre weighted metering as far as I remember, so I would expect that shot to come out as it did."

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Simon
Legacy lens lover

Another explanation might be the lens is very susceptible to veiling lens flare when pointed against the sun, the flare would dramatically reduce contrast through the lens, and that can confuse the metering sensor as if it is looking at the very low contrast scene, resulting in overexposure as it is trying to push the average brightness higher to avoid noise (totally wrong in this case, but the camera does not know the flare diffused the light through the lens). The value of 1/50s is totally wrong for that scene, maybe there is some oil film or some other dirt inside the lens on lens elements, causing the strong flare.

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