To test for image noise during long exposures during the day we used an IR filter to get exposures of 30 seconds.
To examine how the Canon 5D handles long exposures during daytime we mounted a Hoya R72 IR filter on to the Canon 24-105mm F4 L IS lens and went to a nearby bridge offering views of Melbourne across the Eastern Freeway. We used a 30 second exposure and varied the aperture in manual exposure mode.
Given that with the R72 filter the red channel is much more sensitive than the green or blue, I have just taken the green channel in preparing these images. The RAW files are available on the camera test page
for those who wish to examine the images themselves. The JPEGs below
are 100% sections from the center of the images. They were prepared in
Photoshop from TIFFs. The TIFFs had been converted from the RAW in
Canon’s own Digital Photo Professional software.
Please note that the sunlight level was varying a little throughout this series of images (unavoidable this time of year here :), so the variation in density is due to this.
Noise Reduction On
Some wind here blurred the image for this one, but you can still see the noise is quite low.
Noise Reduction Off
Noise is still very well controlled with the 5D during long exposures, even at 1600ISO. As I am finding with most cameras I test, noise reduction is really not particularly helpful. The one thing it does do is remove the hot pixels, the ones that saturate during long exposures. However, with most cameras it is a pretty simple matter to clone the small number of them out.