The quality of long exposures is determined mostly by the amount of noise a camera produces. The lower the noise levels, the better the exposure. This is especially true if you are shooting lots of nightscapes or night skies, where most of the photo is black.
And Brendan Davey shoots a lot of night photos, in fact he shoots enough of them that it was worth a while for him to create a database which compares the amounts of noise each camera (or camera sensor) produces.
To build the database Brendan too three images with each camera at ISO 3200 (not uncommon for shooting the skies). The first images with 1 second exposure, the second with a longer 30 seconds exposure and the last one is a 5 minutes exposure. While this test may seem random, it actually lets you know what is the amount of noise you will have at each of the settings before applying any noise reduction.
Since the tests are all done in relatively “sterile” conditions it gives a good estimation of which camera will produce better low-light, long-exposure images. Here are the setting that Brendan uses:
- Camera body with body cap only.
- View finder shut or covered, and preferably in a dark room.
- Ambient Temperature is ~21degC (room temp).
- ISO 3200.
- Long exposure NR off, or lowest if not an option.
- Standard NR off, or lowest if not an option.
- RAW recording with the max bits per channel (normally 14).
- Normally in M or B mode.
I thought it would be interesting to pit three cameras together: The Canon 5DSR, Sony A7RmkII and Nikon D810.
It is not surprising that the Sony comes up on top.
While it’s obvious that some cameras are better than others, there are a few key points to consider when considering those tests for a purchasing decision (below suggestions from Brendan):
- The age of the camera.
- If the camera supports fully disabling NR (some do not, and in some models it can affect the RAW file).
- Additional processing applied to the image regardless of the NR settings.
- The size and pixel density of the sensor.
- The accuracy of the ISO, in some cases this can be almost a full stop out either side of 3200. (1600-6400 ISO).
- Manufacturing variation (tolerances).
Is noise something you consider when getting a camera