One Rainy Morning in Perth
On my recent work trip to Perth in September I was up early as Perth was 2hr behind Sydney so I decided to go out early morning to take some landscape shots.
In one of the shot my camera was pointing west and therefore viewfinder was facing the sun. The camera showed me an exposure of 1/4th second even tough I had a Hoya HDX400 9-stop filter in front of the lens when I was expecting it to be a longer exposure. When the photo was taken it was very much under exposed to the point that you couldn’t see anything.
I started to wonder what is going on here? Then by accident when I was very close to the back of the viewfinder while pressing the shutter half way I saw the camera read an exposure that was more like 15seconds.
A light bulb went off in my head and I decided to move away from the viewfinder while holding the shutter and saw the exposure reading go to 1/4th second.
It confirmed to me that the light was coming in from the viewfinder was affecting the metering system of the camera so I removed the eye-piece and covered the viewfinder with the factory provided cover which I had strung up in the camera strap. See below image where you can see the camera is taking wrong exposures as the light is entering from the viewfinder but occasionally getting it right as I moved close to the viewfinder or standing behind the camera.
Here is a video of this experience that I recorded later at another stop that I was photographing, the audio quality isn’t the best (very windy morning) but you will see what I mean.
Update – 17 Dec 2013
This only becomes a problem when you are shooting in Aperture Priority, Shutter Priority or Fully Automatic mode. If you are shooting in Manual mode then you are not relying on the cameras metering system to judge the correct exposure.