High ISO Performance
Before discussing the camera's ergonomics, menu system, and Live View features, I want to first talk about the
camera's performance at high ISO settings. I have to say that the EOS 5D Mark II is the first camera I have ever used
where you don't have to worry about your ISO settings. Images taken at ISO 100 through ISO 1600 look virtually identical - on screen
and in print - very clean. Images shot at ISO 3200 show a slight increase in noise, but still barely noticeable especially in prints
- and images shot at ISO 6400 look better than shots I used to get at ISO 400 with my budget-priced Rebel XTi.
The EOS 5D Mark II also offers a 12,800 and 25,600 ISO modes, and while I've seen worse I wouldn't recommend using them.
You might be able to get away with using ISO 12,800 in an emergency - knowing that you'll want to use heavy noise reduction
in post production and make sure you don't make large prints at this ISO.
The EOS 5D Mark II also offers a new auto ISO mode where you can let the camera automatically choose the ISO setting for you
while you adjust the aperture and shutter. Until this camera came along I would never, ever have let a camera decide that
for me because of noise levels at higher ISO (even ISO 400), but with the 5D Mark II it's a usable feature.
I have always equated the advantage of lower noise at higher ISO to being able to capture better pictures in lower lighting.
While this is definitely one benefit, I never gave thought to the advantages it would provide for daylight photography.
It does, and in a dramatic way. Set the camera to ISO 1600 and all of a sudden you have the ability to use a small aperture
(f/13 or f/16) during the day, while still capturing enough light to be able to use a higher shutter speed (1/125th, 1/250th etc.).
This helps when capturing wildlife since you're often in the woods or shooting late in the day when lighting isn't at its brightest.
When shooting with my older Rebel XTi I was pretty much forced to stay at ISO 400 or lower in order to keep noise under control. A lower
ISO meant either a larger aperture (very shallow depth-of-focus) or a slower shutter speed (blurred action). Suffice to say that
being able to shoot using ISO 1600, 3200, and even 6400 with very little added noise is a BIG deal.
The illustration below shows the same scene shot at two different ISO settings. The left side captured using a high ISO with smaller aperture,
the right side captured using a lower ISO setting which forced a larger aperture. Notice how much further (greater depth) into the woods you
can see when shooting with a smaller aperture). Now, imagine a scene where you were capturing flock of birds flying past you. With greater depth,
more of the flock would be in-focus.