The Most Difficult Topic - Exposure

Inspired by the sudden power off in my building during a rare gathering of my team.

Many times when we used our camera, set everything to auto and expect perfect result, sometimes we feel that the camera has not done its job to capture the right exposure. The modern camera is very smart to know how to interpret light, but in some occasions the exposure cannot be accurate without certain adjustments.

Let me show you a few examples and you will know what am I talking about. All three photos are not supposed to be technically perfect, it is a demonstration, but for fear of the copyright penalty, I dare not take existing samples from internet or books.

All three are shot with spot metering taking the exposure off the exposure card.

Metered the black card.

Metered the white card

metered the grey card.

You can see all three exposures were different. Why? Much was written about this, but we all tend to focus on too much technical explanation. Let me try to simplfy the explanation: .

The meter is taking the world as a average of black, white and everything in between.

Because the camera treats everything as average grey, it is very easy to be fooled. In the above examples, the black card was reproduced as grey, the white card as grey and the grey card, of course as grey. Since the reference light reflected is considered grey, the exposure with the black card has too less light reflected, therefore the camera increases more exposure to make it seen as grey. Similarly for the white card the camera thinks that the light is too bright, therefore reduced exposure. The grey card is neutral, therefore it should be correct.

The three pictures were a bit underexposed because even after light is restored in my apartment, it is still not bright enough. (joking). Anyway, I hope you see what I am trying to say because this is the most difficult subject to explain, came back next week after you experienced for yourself.

What is the result of such exposure? Since the exposure is not correct,  your pictures are ruined. Don't go and sue the camera company because exposure is the most difficult subject and we have not talked about different exposure for different colour yet.

The examples show that if you have a dark subject, similar to the one with the black patch in the middle of your picture, the surrounding subjects will be recorded too bright, so please use the +/- button to reduce exposure by - 0.5 to -1.

Similarly, if the subject is bright, eg. a guy wearing white, you should remember the second example which was under exposed and increase exposure by +0.5 to +1.

Can you see the flower is now captured very similar to the original?

If the subject is a bit average in brightness, then you can trust your camera's autoexposure.

The one taken on grey card is reproduced here again for easy reference.

For colour, it is a bit more complicated. As a general rule, for bright colour e.g. orange, yellow the exposure may need to be increased by +0.3 to +0.7

For dark brown, dark green , the exposure should be reduced by -0.3 to -0.7.

Now, the most difficult to understand subject has been covered. So, do you still trust your camera? For purist, trusting your camera's exposure should not be your practice anymore because if you are seeking perfection at the moment when you press shutter, then without taking into consideration the error made by the camera, you will always have about 30% of your picture off the correct exposure. Some can be adjusted in post processing through software, some cannot, (anyway you will not do any adjustment because you are a purist).  You want to be a purist, you want the direct OOC (out of camera) image to be perfect, however, trusting your camera's exposure is not something a purist should pursue.