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86 Quick Guide for the Impatient User

TIP: Unlike its predecessor, the A77 II allows Auto ISO in Manual Exposure
mode. (Normally that is seen as incompatible, since (for example) if you
wanted to underexpose by 1 stop, the AUTO ISO might kick in and raise the ISO
sensitivity to guarantee an average exposure – defeating your artistic vision!)
But Nikon owners have been screaming for this feature for years. So if you set
your camera to Manual Exposure and discover that the image is not getting
brighter or darker when you adjust the controls, this is why. Just remember to
set it to a fixed ISO when in Manual (and remember to change it back when you
switch to any other exposure mode).

3.5.4 SPECIFYING AUTO ISO BOUNDARIES

If you don’t care for the fixed limits of Auto ISO described above, the A77
II allows you to customize both the low and high boundary of what the
camera will choose while in Auto ISO. When in the ISO menu and you’ve
selected Auto, just move to the right. Hitting UP and DOWN now will
change your minimum AUTO ISO value; then move to the right once more
and you’re adjusting your Maximum Auto ISO. Notice that with this
feature you can set the upper end of ISO as high as 25,600 (which I
strongly discourage). I keep mine set to between 100 and 3200 for casual
shooting. I’ll set the ISO to something higher (and switch to RAW mode or
MFNR mode) when there’s just no other choice.

3.5.5 LESS-THAN-100 ISO VALUES

Notice that the first two ISO choices (“80” and “100”) have bars above and
below them, as seen in the right image in Figure 3-10. Why the bars?

The short answer is that this CMOS sensor actually has a native speed of
ISO 100. Technically, it can’t be less sensitive than this. When you set the
camera to ISO 50, 64, or 80, the system simply pays less attention to the
signal (resulting in slightly less dynamic range!) to simulate the lower
value. If you want proof, have another look at the ISO test shots from a
few pages ago and notice that the noise level for ISO 50 and 100 are
identical. Thus, unless you need the slow speed for technical work (like
shooting waterfalls with motion, where the slowest shutter speed gets you
the most beautiful flowing water effect), there’s actually little technical

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