Extended ISOs: Why you SHOULD use ISO 50! Video Lecture | Capture like a Pro: Digital Photography Tutorial - Professional Skills

forever we've been telling people not to
use the extended ISOs on their camera
your camera has like it's based iso is
usually 100 sometimes it's 160 or 200
but usually it's 100 and then it will
have extended ISOs below that like iso
50 and if you shoot wrong and you should
be if you care about image quality and
stuff then those extended iso is all
they do is they take an a picture at
your base iso and then basically
overexposure to stop but then correct
for that impost hope that makes sense
think of it this way if you take a
picture in RAW at iso 100 on this camera
and then you take a picture at iso 50
with the same shutter speed aperture
it's going to be the exact same picture
even though you change the ISO all
that's happening is that completely
software adjustment the raw file itself
will have exactly the same information
in it so because it was the same for the
longest time we recommended people not
use it after all why would you all
you're doing is essentially giving up a
stop of dynamic range in highlights well
I finally figured out a good reason to
do that it won't make any difference if
you're the type of very carefully looks
at your histogram measures everything
perfectly but I realize most people
don't do that including me I was
shooting at the base ISO but not over
exposing it when I could now by using
the extended low ISO I found I can
reduce the noise and base iso images by
a full stop
producing much cleaner pictures let's
take a couple pictures to demonstrate
okay you're not going to see any
difference at a glance but if you zoom
way in you'll see that noise is visible
in the sky at both ISO 50 and ISO 100
however the ISO 50 image has less noise
right about half and that makes sense
because the shutter was open twice as
long because the ISO was half the speed
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YouTube's compression will hide some of
the noise so I cranked up the contrast
to make the difference more noticeable
if you're the type who feels their
images are noise free at the base I so
this technique won't matter to you but
if you make big prints and you want the
most perfect image possible doubling the
optimal image quality for free with no
post-processing is pretty exciting now
you might not notice that on Instagram
or Facebook or whatever but if you're
the type of cares about your image
quality and you're making a big print
it's going to make a difference
increasing the exposure three stops to
test the dynamic range and recovered
shadows we again see that the iso 50
image is noticeably cleaner the extended
iso would lose dynamic range and heavily
overexposed highlights so check your
histogram and be careful about clipping
while you're clipping off a stop of
overexposure and the highlights you're
gaining a stop of dynamic range in the
shadows so you'll be able to recover the
highlights as much but you'll be able to
recover the shadows more and for most
people that's more important here's an
example with more extreme dynamic range
I expose for the highlights leaving most
of the image in deep shadow the extra
noise in the iso 100 image is obvious
even though I used a 50 megapixel five
dsr all cameras will show the same
relative improvement to optimal image
quality
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for detailed information about dynamic
range visit SDP depth io / dynamic range
for detailed information about ISO visit
SDP dot IO /i so that's a quick tip I
hope it helps to improve your images
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