In this page you'll find a technical test. Please refer here for an introduction, details
and testing method.
- standard: from 100 to 25600 ISO with 1/3 EV steps
- extended: 50 ISO, 51200 ISO and 102400 ISO
Gain. The measured gains
follow quite accurately the power law. Exceptions are 50 ISO, as
expected, that is exactly the same as 100 ISO (only JPG files are
affected, RAW are absolutely identical). Another exception is 102400 ISO
that is a little bit less sensitive than declared.
- Unity gain at 575 ISO
- Read noise. A
decrease is found up to 6400 ISO. Using 12800 ISO or more produces no
on the read noise (and even worser, read noise appear to increase a
little bit for 25600 ISO and above). So I advise not to use anything
more than 6400 ISO,
the only effect of using more is to reduce the dynamic range. Obviously
this advice is valid only for RAW files, in JPG it is worth using higher
best results in low light circumstances mainly use 6400 ISO.
- Dynamic range.
a full well capacity of 13235 ADU, the approximate dynamic range is
computed and reported both in the table and graph below. The best
dynamic ranges are both at 100 ISO and 200 ISO; but also 400 ISO has a
very similar dynamic
range. Using 50 ISO does not improve in any way the dynamic range (in
the RAW files). Above 400 ISO the dynamic range start to decrease
noticeably. For best results on bright subjects, use 400 ISO or less.
- 1/3 stop sensitivities. Main result: absolutely don't use them!
In example 1000 ISO has the same read noise of 800 ISO, but lower
dynamic range, so it is better to use 800 ISO. And 1250 ISO has the same
read noise of 1600 ISO and also the same dynamic range (because
saturation is at a lower level, 11177 ADU), so there is no advantage to use 1250 respect 1600 ISO. As a general rule, simply avoid 1/3 stop ISOs!
To distinguish between true and software interpolated sensitivities, the
best method is to look at the histogram of a nearly uniform image
(like a flat field). The result is shown in the figure below, and the
Gain and read noise
- 51200 ISO and 102400 ISO are not true sensitivities, as expected.
- 1000 and 1250 ISO (intermediate 1/3 stops sensitivities): as
explained above, they do not produce anything better that full stop
ISOs. So I advise to avoid them. Also looking at the histogram of the 1250 ISO image, something strange appear.
- 100, 200, 400, 800, 1600, 3200, 6400, 12800, 25600 ISO are true.