This month we finally reached the third side of the Triangle Of Light, ISO.  Although not as exciting as the other two sides, as far as effects go, it’s very useful in allowing you to be able to capture images in lower light situations while still getting the aperture or shutter speed effect you desire.

In the room where I took this I do get a fair amount daylight in, but the outside walls of my flat are pretty thick, so even a few feet into the room there’s a lot less light available than there is at the window.  I shot this with Lockheart perched on the window ledge, and you can get an idea of just how thick those walls are, as there’s at least as much on the outside of the window as there is behind him!

At ISO 100, with Aperture f5.6, my Shutter Speed setting was 1/50:

At ISO 100, with Shutter Speed of 1/100, my Aperture setting was f4:

At ISO 6400, with Aperture f5.6, my Shutter Speed setting was 1/3200:

At ISO 6400, with Shutter Speed of 1/100, my Aperture setting was f22:

One difference you might be able to see above is that the image is starting to get grainier at the higher ISO levels.  In the days of film, this was actually quite a desirable trait in some genres, as it can evoke a certain amount of atmosphere, especially effective in black and white, candid portraits being a great example.  It depends on your camera just how soon the grain will become obvious – my Canon 7D that I use now is much less grainy than my Canon 20D ever was, in fact the 20D couldn’t even go to ISO 6400, so it will depend a lot on both the age of the camera, and the level of photographer it is aimed at.

Just to show you the difference in atmosphere, here’s one of my pub shots from a couple of years ago in colour:

And again in black and white:

With the black and white, the graininess seems to invoke a certain grittiness, while in colour the scene just seems kind of grubby.

Now lets see what you discovered: