Chapter 4: Histogram and getting good exposure and white balance in problem situations

Learn to recognize scenes of when your camera and flash get fooled

Flash Reflection in mirror behind subject is causing image to be underexposed

Problem background lighting situations happen when the background is other than neutral tone or there are some highly reflective surfaces. The one that I learned first was when there was a very bright window behind my subject (also a mirror or any kind of glass behind the subject). When I took a flash picture (in the old days using film and TTL flash) I would get an underexposed image. As the camera thought there was enough light on the scene and turned the flash off early. This was a big problem back then as I would not know what exposure I got until the prints came back from the photo store. Another example would be a bride wearing an all white dress or you could have someone up against an all white background such as a wall or sky. These are situations where the camera and flash can be fooled.

Subject in dark clothes and dark hallway behind causing overexposure

The opposite problem is when the subject and/or background behind him are dark in nature. You could be in a dark church photographing the groom with the background far away which has the same effect. Now the camera and flash will struggle to light up the whole area to create a neutral gray tone. Your subject being closer to the camera than the background gets overexposed.

When changing the subject in the viewfinder

Lastly, you need to pay attention to where your subject falls within the viewfinder/LCD screen of your camera. If you put the subject to one side and have the rest of the screen filled with white or black, then you run the risk of having an exposure problem. One easy fix is to put the subject in the center and/or zoom in on him or her to eliminate the problem background. But one can’t do tight headshots of everyone. What then does one do? Canon has two built-in functions to solve just such problem situations that will be discussed later on in this course.

Learn to recognize mixed lighting situations and what to do about white balance

Canon’s Av program mode also becomes a problem in mixed lighting situations.

Pro photographers call it “dragging the shutter” or you may have read about it being known as slow synchro flash photography. The problem is that you get a color cast bleed of ambient (the problem light) into the correct white balance of the flash. Inside with tungsten overhead lights the orange tone now overpowers that of flash and your subject looks like they got an improper suntan! Not a fun fix in photoshop, let me tell you. Outside you run into a similar situation when doing fill flash when under a tree at high noon. The sun bounces light off the green grass up into the faces of your subjects as the flash is too weak to overpower the green cast. This is another fun fix in photoshop. The true fix is to avoid these situations altogether.

My answer: Inside use a filter on your flash to match the room light and set your camera’s white balance to that. Outside don’t use fill flash at high noon on a sunny day. Use flash main instead and under power the ambient light with it. I’ll show you how to do this later in another lesson.

Also, inside I suggest you stay close to window light when combining flash and light that is already in the room. Better known as daylight, the light coming through the window is roughly the same color temperature as the flash. As long as outside is not too sunny with a lot of green grass (causing a green cast to get bounced in your window) you won’t have to worry about changing your white balance. Just turn off any room lamps and use the existing light coming through the window. E-TTL flash is king here as you only need to kick up the ISO and you can create so many cool effects when doing portraits!  Auto white balance is fine to use here.

Use filter on flash and set white balance to tungsten when using flash with inside tungsten lights

When the room is lit with tungsten light, you will have a white balance mismatch. My Canon 600 EX-RT flash came with an orange filter (SCF-E1) and special attachment (SCH-E1) for just this purpose. You put it on the flash head and set your white balance to flash. And the camera will magically blend the two. The other problem is with fluorescent lighting. You will need to purchase a green filter to tape over the flash head for this. Then set you white balance to fluorescent.

Note: When you don't have a filter with you to put over the flash you can underexpose the ambient light by two stops as a quick but not perfect fix.