The light metering in modern cameras is great and in most cases the camera’s automatic (or semi automatic) modes do a good job at setting exposure – but the camera sets exposure based on the assumption that whatever you are photographing is of average brightness (about 18%, if you care about the technical details), this works great for average scenes but fails miserable for scenes that are mostly bright or dark.
The stereotypical examples for photographs that are white are snow and brides but since I don’t have either of those here I’m going to photograph milk – a bowl of white milk on a white plate on a white tablecloth.
I’ve put my camera on a tripod, attached my 50mm lens, switched the camera to Av mode (A on some brands), set the aperture to f/3.2 for a shallow depth of field and let the camera work it’s magic:
This image actually looked pretty good on the camera’s screen and I could only see how dark it is on my computer screen – that’s why you can’t trust your camera’s screen to judge exposure and you have to look at the histogram, the histogram is a graph that shows you the brightness of the image, there’s almost t always a way to view the histogram in the camera when you preview the photo, here is the histogram for this picture:
See that bump in the middle? that means that most of the image brightness is almost in the middle, that would be fine for most images but with all that white we want this picture to be much brighter.
So what do we do? we actually have two solutions to this problem:
The Good – Exposure Compensation
Your camera has something called “exposure compensation” – it’s a way to tell the camera “do what you meant to do just do it X stops brighter/darker”.
If you want something to look white but not be over exposed it should be about 2 stops brighter than average, for the following photo I’ve set exposure compensation to +1 and two thirds:
This image actually looks too bright in the camera preview – just to remind us we can’t use the camera preview to judge exposure, and the histogram for this image:
See the big bump on the right? that means most of the pixels in the image are very bright and the fact the bump doesn’t touch the right edge means we haven’t over exposed the image – perfect.
The Better – Manual Mode
Using exposure compensation is good but there’s an even better way – use manual mode, yes the big scary manual mode, it’s actually easy in this case.
To set your exposure in manual mode just zoom in (or get close) so your camera only sees white, set you camera to one of the semi-automatic modes and set your expose compensation, now take a test shoot and check the histogram, if you are happy with the results just switch to manual mode and set the same values the camera used.
So why use manual mode if you use the same settings as in the auto mode? because now the settings won’t change if the white animal you are photographing jumps in front of a dark rock or if the bride dressed all in white is joined by a groom in a black suite.
Let’s take our milk image in manual mode:
And now add something big and black just to fool the camera’s light meter:
See how the white milk keeps the exact same color between images?
You can see the black hat is actually seriously underexposed but I don’t care because the white milk is my subject – and in manual mode the camera doesn’t try to second guess me and compensate – keeping details in both the whites and the blacks is a topic for another day.
Hope you enjoyed this tutorial, now it’s time to use our setup to eat breakfast.