Setting on my camera... - DPChallenge Forums

10/15/2003 09:26:44 AM · #1

There is a setting on my camera with a symbol that looks like [+/-]. The plus is light on dark background and the minus is dark on light background... What does this setting do and when is it appropriate to use? I think I have down all the other settings finally. (Now I want a new camera and a new set of settings to learn!)

RickDN

Canon EOS-10D

10/15/2003 09:29:00 AM · #2

Originally posted by toocool:

Uh.. "exposure value" or "white balance" ???
Play with it and see....

10/15/2003 09:29:55 AM · #3

I don't think it is white balance because that is in another menu! What does exposure value affect?

RickDN

Canon EOS-10D

10/15/2003 09:33:03 AM · #4

Originally posted by toocool:

I don't think it is white balance because that is in another menu! What does exposure value affect?

Well, on my ancient Mavica-81, it seems to be like a sensitivity switch, it lightens or darkens the image yet keeps the contrast the same (somehow)

Canon EF 70-300mm f/4.5-5.6 DO IS USM

10/15/2003 09:35:19 AM · #5

Now I'm gonna HAVE to play with it as I've been trying to take some night time shots of light colored objects lit up and they almost always come out over exposed in the light parts!

rgordon

Canon PowerShot A70

10/15/2003 09:54:06 AM · #6

toocool, I have a similar setting/symbol on my Canon Powershot A70. When I get home from work tonight, I'll consult the manual for the exact definition/use (on my camera at least). I think RickDN is on the right track with what it's for.

cpanaioti

Canon EOS-40D

10/15/2003 10:15:58 AM · #7

That symbol is for exposure compensation.

For your night shots you'll want to underexpose so the bright areas don't get blown out. The setting usually goes from -2 to +2 in 1/3 increments.

Colette

Canon EF 17-40mm f/4.0L USM

10/15/2003 10:34:38 AM · #8

The setting is probably for exposure compensation.

The meter in your camera is the part that works out what the exposure of the scene should be. With this information, it works out what aperture and what shutter speed to use to get enough light in.

The meter works on the assumption that every scene you ever point your camera at is, on average, a mid toned grey colour. It can't tell if the scene is mostly white (snow for example) or mostly dark (a black dog close up) and will tend to make white grey or the black grey.

Exposure compensation allows you to give your camera hints to help it make the blacks actually black or the whites actually white.

Typical examples
(white) Snow or a sandy beach in bright sun +2
(lighter than 'average') Sky +1
(darker than 'average') Dark wood -1
(black) Black dog on coal -2

These aren't absolutes, but should at least give you an idea on how to use this feature. A good example to work with would be a white sheet of paper. Take a shot with and without compensation and notice how without any adjustment, it comes out grey.

Taking control of the exposure is key to getting decent pictures for more interesting subjects - it is well worth learning.

One caveat: The discussion of metering above assumes that you are using a meter mode that works for an average tone. These are usually the center weighted, spot or partial modes. Newer cameras have matrix or evaluative modes that try and recognise a scene from stored representative samples. These meter modes don't always meter for an average tone, so exposure compensation should really not be used at all for evaluative or matrix modes - as you don't know what the camera has decided the scene is - you can effectively compensate twice in these modes.

I typically use the matrix modes for normal scenes, but if the subject is very dark or very light, or the light is more interesting, I tend to switch to a meter mode where I know what is going on and either use manual exposure or exposure compensation to work with it.

jimmythefish

Canon EOS-10D

10/15/2003 11:06:31 AM · #9

These might be misleading...just to clarify, a -2 will underexpose and lead to a darker image, while +2 will overexpose.

Originally posted by Gordon:

Typical examples
(white) Snow or a sandy beach in bright sun +2
(lighter than 'average') Sky +1
(darker than 'average') Dark wood -1
(black) Black dog on coal -2

Message edited by author 2003-10-15 11:06:45.

10/15/2003 11:24:47 AM · #10

Originally posted by jimmythefish:

These might be misleading...just to clarify, a -2 will underexpose and lead to a darker image, while +2 will overexpose.

Maybe - I was quite deliberate in not using the words overexpose or underexpose, though. The key is to get the correct exposure for what you care about. To me under or overexpose have more negative connotations. Exposure compensation is about adjusting the metered exposure to be correct for the given scene.

Simplest way though to work it out is to experiment. Find sometihng really black and take a shot to make it look black, not grey. Same with the sheet of white paper described above.

Message edited by author 2003-10-15 11:26:01.

pitsaman

Canon EOS-30D

10/15/2003 11:34:25 AM · #11

Originally posted by toocool:

EV compensation works on how much contrast you have between the subject and the background.But you have to play with it to find right exposureby watching your LCD screen or EVF.
On my Fuji3800 for Moon on dark skies I set -2,tree over snow + 0.6 ,eyes on white human face + 0.6 ,apple on black cloth - 0.9 etc.
Negative value increases shutter speed and positive makes slower.

10/15/2003 11:56:51 AM · #12

I'm assuming that the EV setting would help out in a picture like this:

What seting would you use? -2 is my best guess looking at this thread.

Message edited by author 2003-10-15 11:57:16.

10/15/2003 12:01:23 PM · #13

For that, I'd switch to a spot or center meter mode, and meter on the bright building. From that, I'd use a +1.5 exposure compensation on that value, and 'lock' the exposure if you can do that, then reframe for the whole scene.

In that way, I'd work out how to expose for the building, and suggest to the camera that I want it to expose the building as bright white, but not blown out (the +1.5). Everything else then gets left to fall into place around that exposure.

The spot or center metering makes the camera pay more attention to the area in the center of the shot - which would be the building when you meter it, and the half press to lock exposure and focus would then let you reframe for the whole shot.

The alternative way to do it, would be to meter on the black sky, and use a -2EV compensation, to indicate to the camera that you want the sky to be black, and then reframe and shoot.

The compensation that is appropriate depends on what you meter on - you then compensate to get the correct exposure for that thing you used the meter on. The meter modes just vary how much importance is given to particular parts of the scene.

Message edited by author 2003-10-15 12:02:46.

10/15/2003 12:03:46 PM · #14

Awesome! Thanks for all the input. Now I'm only mad that it's like noon here and I won't be able to re-shoot for 8 hours or more....

pitsaman

Canon EOS-30D

10/15/2003 12:07:13 PM · #15

His camera doesn't have spot metering ,I guess,EV works differently on advanced cameras compare to cheap ones,When I bought Oly5050 i had to reevaluate usage of EV drastically!

10/15/2003 12:08:29 PM · #16

Originally posted by pitsaman:

His camera doesn't have spot metering ,I guess,EV works differently on advanced cameras compare to cheap ones,When I bought Oly5050 i had to reevaluate usage of EV drastically!

It has center mode - which is why that was what I mentioned... Center weighting just ends up being a slightly larger spot :)

It works exactly the same way on expensive and cheap cameras (ignoring the more advanced evaluative modes)

You need to understand two things and then it is simple:
1/ the area of coverage of the particular meter pattern
and
2/how much away from a mid tone you want the area covered by the meter

Then with those two pieces of information, you can use EV easily to place tones where you want it in the final exposure, using the built in meter and EV values. Its that simple - there isn't anything complicated about it or more advanced in more expensive cameras.

Assuming a 5 stop range, which is resonable to work with:

+2 even lighter / white
+1 lighter
mid tone
-1 darker
-2 even darker /black

So point the meter at the thing you consider the most important tone to expose correctly - then compensate for how far away it is from a 'mid tone'.

The harder thing to learn without just trying it out, is what is a mid tone. Grass tends to be a mid green. The palm of your hand tends to be about +1 from a mid tone.

So in the case above (the building at night) you can meter on the building, and say 'make this somewhere between light and white or +1.5' or meter on the sky and say make this black and use -2

Message edited by author 2003-10-15 12:18:00.