Build in meters
Yes, the light meter in my Sony Alpha A99V is a piece of wonder, but no matter which metering mode you use, it still works the same way as other camera meters works – by measuring reflected light. This is why your camera may get the exposure wrong. Dealing with the fact that the optimum exposure is not at all simple. Relying on your camera’s meter, will inevitably put you into a situation rendering you with under or overexposed images.
The reason for this comes down to the way your camera’s meter works. It measures the light reflected from the subject, and then smartly calculates what it thinks the best exposure is accordingly. Imagine that you are shooting a wedding, some nasty looking women in white is sitting besides some poor soul dressed appropriately in black. The ambient light level, and the optimum exposure, is the same regardless of which of the persons you take the photo. Homing in on the person women in white, your camera’s meter will give you a very different suggested exposure setting than if you had chosen to photograph the poor soul. The reason for this is that the woman in white reflects more light. So taking a photo of the couple and you are in trouble, the reason is that the camera assumes all the tones within the scene that it is metering to average out to 18% grey, and it just doesn’t is such cases. If the object of your attentions has many light tones, your camera will underexpose the image. The camera’s meter gives an exposure reading that renders the light tones as grey and this result in underexposure by up to two stops.
Sekonic L-308S Flashmate
A dedicated light meter accomplishes measurement of incident, reflective and strobe light with more accuracy and finesse. It is my point of view that it also enables the photographer to be able to read light better. It will help calibrate your eye, and mind, to light in any particular environment. Soon you will be able to judge required settings for proper exposure without having to meter, with great accuracy.
I am using the L-308S Flashmate it is a compact little digital light meter from Sekonic. Easy to pocket and is able to read both ambient light and flash exposures, and works in reflected and incident modes. As to be expected with a meter from Sekonic (Leading company) is it be very accurate, the settings I get from it have been spot on for most of the time. I do think it has a plastic feel to it, but the layout of buttons is nicely and comfortable. It can be set to follow your cameras EV intervals easily. You can set the meter to read in 1 stop, 1/2 stop and 1/3 stop increments. I can recommend having a quick look through the manual of the meter.
It is very easy to find these meters at Ebay, as it seems many mistakenly find them redundant. B&H also seems to have enough of them Sekonic L-308s Light Meter, Sekonic L-208 Twin Mate Meter,Sekonic L-358 Flash Master