Why is Correct Exposure not always Correct?

Hi there!

In this beautiful middle-season, I have big problems in deciding where to set my laptop to work: it’s too hot to stay in the sun, but too cold to stay in the shade or inside, in my studio (I mean… it’s cold for me)

If you knew me, you would not be suprised: I wear long sleeves also during Summer. In Italy. :mrgreen:

Anyway, yesterday we were talking about Correct Exposure, which is subjective, Best Exposure, which is what we try to achieve when shooting, and the fact that not always the light meter in our camera sees what we see.

I’ve been avoiding being too technical, because this is not a course, but a Project and I’m taking this as a “talk between friends”, so today I will make no exception and try to explain things trying not to be boring (just to clarify: I don’t think that being technical means being boring, I mean that I can be boring when going too technical!).

As we said here, Exposure depends on three things:

– ISO values (the sensor’s sensitivity to light);
– Aperture (to determine the amount of light entering the camera) ;
– Shutter speed (to determine for how long the light is allowed to pass through the aperture).

Professional photographers use an external light meter, which measures the light falling on the subject/scene, but since you don’t need one of these tools to shoot your son making bubbles with the nose, I will refer here to the camera built in light meter, which measures the light reflected by the subject/scene.

How does the camera meter work?

First, you’d better know that the camera

[su_quote cite=”‘Understanding your digital camera’ – T. Savage” url=”″]does not see colours; instead, it perceives everything in terms of brightness (black, white, and shades of grey)[/su_quote]”The meter “shakes” all and measures the blended tones as a “middle grey”, which is the universal measurement standard in cameras.

What does it mean?

Simple: if you shoot both something white or something black, and expose correctly (i.e.


you will obtain something mid-grey (also known as 18% grey).

I’m telling you this, but I suggest you to try yourself: take two cardboards, one white and one black, stick them on a wall, shoot one after the other, setting your camera for a correct exposure each time.

You should obtain two (quite) identical pictures, both 18% grey.

As I said, I’m not going too deep into this, even if it’s a very interesting subject!

I just tell you how to overcome this:

1. If you’re shooting something white, overexpose a little (just make a try and then adjust as necessary);
2. If you’re shooting something black, underexpose a little (again, make a try and adjust as necessary).

And now, since I’m freezing in my studio, notwithstanding the sweatshirt, I think it’s time to send you a big hug and go outside, in the garden, and roast myself under the sun!

Love, Beuf.

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2 thoughts on “Why is Correct Exposure not always Correct?

    1. 😀 thank you Hiram!
      I also enjoyed the image in the link. Thank you for sharing! I like this and I like comments like this 🙂

      thank you for your visit. Wish you a nice evening.

se vuoi, scrivimi cosa pensi :)

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