Exposure - Trying to understand something so complex?

I've been shooting in manual mode from the second week I got my camera (about a year ago) and to this day I still get confused over exposure. I've read books and tried different pictures but I can never seem to figure it out.

My question is this:

On my 50D, I use the AF On to set my focus and use my shutter button to actually take the picture (no focusing on the shutter button). However, I'm always confused about the who exposure/light meter.

Many books explain to use a center weighted meter, point it at a middle gray (blue sky, red brick, green grass, gray card etc), half press the shutter button to lock the exposure then recompose the shot to whatever your shoting. However, I'm a little confused as to whether or not my camera is actually "locking the exposure".

On AV/TV I can use exposure lock, and get a warm and fuzzy feeling when I see the * sign show up. However on manual, the exposure lock doesnt work (which I assume is because you can manually set whatever exposure you like, again, this is confusing to me). Do most of the photographers here focus on the subject, meter on a middle gray then compose the shot or am I just really confused about the whole process.

Also, after I set my middle gray tone and lock it in by half pressing the shutter, when I then go to recompose the shot, my light meter is bouncing every which way. Even though it's bouncing all over, is my exposure already locked as I haven't taken my finger off the shutter button yet. Along with this, if I want at the moment after I lock in my exposure from basing it off the sky/middle gray and I want to lets say go one stop below the middle, do I use my other finger to turn the dial on my shutter speed control or what.

As you can see, I'm a bit confused. I'm trying to really understand how this all works and so far, I keep coming up with more questions rather then answers. I thought someone who understands all this could explain it to me. Thanks!

In manual mode your exposure lock is you phisically not changing the settings. your meter bounces around as you recompose as your meter picks up different levels of brightness throught the image. and you do not need to half press in manual mode. You are mixing the way a AV shooter would shoot with the way a manual shooter shoots.

Aaaah, that makes sense then. None of the books I've read distinguish between AV/Manual so it's hard to tell. So does metering also not matter or does it when shooting manual.

I'm wondering because when I use spot metering for example, is it taking the light reading from the spot or is it still taking the reading from the entire picture. For example, if I'm using manual mode to take a sunset, most books say to meter off the right/left of the sun, does it matter in manual?

Metering is just a way for the camera to suggest the correct exposure for any given scene. In manual mode the meter bar on your camera is just telling you what it thinks the exposure should be relative to your manual settings. If you are in manual mode then it means you know what the exposure you want is so you just ignore the meter.

Most of the time I just leave the camera in Av mode, evaluative metering, and bracket exposures. Or just check the histogram and using exposure compensation to adjust.

BioSpark wrote in post #9354152
Aaaah, that makes sense then. None of the books I've read distinguish between AV/Manual so it's hard to tell. So does metering also not matter or does it when shooting manual.

I'm wondering because when I use spot metering for example, is it taking the light reading from the spot or is it still taking the reading from the entire picture. For example, if I'm using manual mode to take a sunset, most books say to meter off the right/left of the sun, does it matter in manual?

In spot metering and manual shooting mode the camera will meter using the spot in whatever direction the camera is pointed. The critical thing is to point it at whatever it is you want to use to establish your exposure (say it's the sky), then adjust your f-stop (aperture) and shutter speed until you will get the exposure you want (say 1 1/2 stop more than the exposure that would put the meter right in the center, so as to not over-expose the sky and also get a better exposure for the darker parts of the scene). Once you move the camera it will continue to spot meter from whatever the camera is now pointed at so the meter guide may be moving up and down the scale as you move the camera, but your exposure settings (f-stop and shutter speed) will not change. As long as you set them properly for whatever it is you want to be the basis for your exposure, you'll be OK.

You might want to take a look at this explanation of camera exposure and metering; there's lots of other good stuff at that site also:
http://www.cambridgein​colour.com/tutorials/c​amera-metering.htm

BioSpark wrote in post #9353827
On AV/TV I can use exposure lock, and get a warm and fuzzy feeling when I see the * sign show up. However on manual, the exposure lock doesnt work (which I assume is because you can manually set whatever exposure you like, again, this is confusing to me).

In M mode, it's not that you can set whatever exposure you want, it's that you must set the exposure.

Regardless of what mode the camera is in, the in-camera light meter is determining what it believes to be the "correct exposure" for the scene. Now in Av/Tv/P modes, the camera uses that "correct exposure" to adjust either the shutter speed, aperture, or both - depending upon whether you're in Av, Tv or P mode. In M mode, the in-camera meter is used just to move the needle to say what it thinks the exposure settings you've dialed in in M mode match what it thinks the correct setting is, or whether it thinks you're settings are too high or low.

All sorts of things can fool the in-camera's meter, so it may jump all over the place when in fact the lighting conditions aren't really changing.

Maybe this will help:

Av (Aperture Priority) Shooting Mode - You pick the f-stop and the camera picks the shutter speed based on what the meter tells it. The exposure the meter tells the camera may change depending on the metering mode, because each metering mode is designed to consider different parts of the scene and sometimes to calculate the exposure in different ways. You can use the exposure lock button to lock the exposure once you've pointed the camera where you want it to be to decide the exposure and pressed the shutter button or whatever other way your camera allows you to start metering.

Tv (Shutter Priority) - Same as above except you pick the shutter speed and the camera picks the f-stop.

Manual - You pick the f-stop and the shutter speed. You decide what these should be from the information the meter gives you, which may be different depending on which metering mode you select. The meter will give you the same information it gives the camera in Av or Tv mode, but you, instead of the camera, decide what to do with that information. You don't lock the exposure using the exposure lock button, because it's locked as soon as you adjust the f-stop and shutter speed and don't make any other changes to those. You can "unlock" the exposure at any time before actually taking the picture by changing the f-stop and/or shutter speed.

Ok, so after reading this forum and doing a little one on one with my camera I think I might of figured it out. So correct me if anything Im about to say is incorrect.

In manual, you use the metering modes to determine your exposure. Your exposure is made up of grays (as the camera sees it) and by trying to find a "middle" gray color (whibal, red brick wall, green grass, blue sky) you are determining your exposure. If you use evaluative metering and there is a lot of middle gray in your picture then you can accurately take the picture. However, if there isn't a ton of middle gray your camera is going to give you an inaccurate light meter. So, you need to set your metering to center weight and determine a middle gray/compose.

So lets say your shooting flowers, the light is bouncing off the flowers which is giving an inaccurate meter reading, so you have to use your spot meter/center weight to find a middle gray, set your aperature/shutter based on that then compose the shot with the camera.

The reason why exposure lock doesnt work in manual is because your setting your aperature/shutter control based on the light meter and what it reads then composing. If the light meter bounces when you recompose it doesn't matter because you already set your settings based off the middle gray you found.

Am I on the right track?

Statements like "All sorts of things can fool the in-camera's meter, so it may jump all over the place when in fact the lighting conditions aren't really changing." don't really make sense and are, in my opinion, an excuse to blame the tool. I've used everything from no meter, to external hand-held, to selenium cell to in-camera meters starting with a Pentax Spotmatic back in 1965. Today's meters are very, very accurate. It's the operator that usually is "jumping all over the place." Over the years I've learned how to use spot metering in M mode quite well. It's a matter of practice and thought. I've never trusted evaluative fully (although I use it quite a bit in certain situations because it's pretty good and is much faster than me adjusting manually.) When you get a badly exposed photo, look at the histogram AND the scene photographed. Mentally analyze what fooled the meter (or you) and learn from it. One of the absolutely great things about digital is that you can miss the exposure (by a small amount, say 1 stop) and pretty much salvage it in PP.

Biospark:

This might help you as you work through getting decent exposures in Manual mode. When I wasn't sure, I'd quickly flip the camera back to green box mode, see what it said in terms of apeture and shutter speed, then approximated it in manual and got pretty good results.

Let me also say that I took some good advice from POTN. The advice was: 'Put the camera in manual and learn how to expose properly.' My 1st camera saw green box mode fewer than a half dozen times. It's not difficult to shoot in M as you're clearly learning now! In about 6 months, you'll be able to look at something you want to shoot, do a couple of quick adjustments and be pretty much spot on with exposure without even looking through the camera. Setting up proper exposure soon becomes second nature.

About metering. Another good example I learned from was trying to shoot those little black-capped chickadees we see in the birding section here at POTN. If you use EVALUATE metering mode, the camera is taking into account a fairly decent area of the frame to evaluate and deliver a proper exposre. What happens when you focus in on that little birds head is that the white part of the bird's head was always blown out to a point where definition is lost.

Moving to SPOT evaluating allows the camera to evaluate the exposure based on a much smaller portion of the frame and to better expose for where the camera and focus point lands. Result: I would spot meter for the white areas on the bird's head, adjust the shutter accordingly and get a much better balanced image of the bird without blownout whites.

Hope the examples helped. I'm still learning like you.

dave

KCMO Al wrote in post #9365432
Statements like "All sorts of things can fool the in-camera's meter, so it may jump all over the place when in fact the lighting conditions aren't really changing." don't really make sense and are, in my opinion, an excuse to blame the tool.

What I briefly mentioned about fooling the in-camera meter is expounded upon better in https://photography-on-the.net/forum/showthre​ad.php?t=54281.

There's no substitute for knowing your gear and how it all works. And with that you can learn how the in-camera meter behaves and adjust accordingly. All I was trying to point out is that for someone relatively new, they may think that the exposure/lighting is changing more often than it really is because of how much more the in-camera needle will show changes vs how often it really does change.

BioSpark wrote in post #9359994
Ok, so after reading this forum and doing a little one on one with my camera I think I might of figured it out. So correct me if anything Im about to say is incorrect.

In manual, you use the metering modes to determine your exposure. Your exposure is made up of grays (as the camera sees it) and by trying to find a "middle" gray color (whibal, red brick wall, green grass, blue sky) you are determining your exposure. If you use evaluative metering and there is a lot of middle gray in your picture then you can accurately take the picture. However, if there isn't a ton of middle gray your camera is going to give you an inaccurate light meter. So, you need to set your metering to center weight and determine a middle gray/compose.

So lets say your shooting flowers, the light is bouncing off the flowers which is giving an inaccurate meter reading, so you have to use your spot meter/center weight to find a middle gray, set your aperature/shutter based on that then compose the shot with the camera.

The reason why exposure lock doesnt work in manual is because your setting your aperature/shutter control based on the light meter and what it reads then composing. If the light meter bounces when you recompose it doesn't matter because you already set your settings based off the middle gray you found.

Am I on the right track?

The meter is designed to show 18% grey as the correct exposure (irrespective of metering mode).

Metering modes only affect the area the camera analyses to decide the "correct exposure". Evaluative & centre weighted=100% (centre weighted with a bias to the centre obviously), partial=9% and spot=3.5% IIRC.

The trick with exposing correctly is to know what the important tones are, what the meter is telling you and how it can be fooled.

Anything with dramatic light or dark will skew what the meter tells you.

You can always bypass the meter altogether- learn how to judge the light by eye (sunny 16 rule can help as a guide - http://en.wikipedia.or​g/wiki/Sunny_16_rule ). Just adjust the aperture, shutter speed and ISO to suit.

For example Sunny day = F16, shutter speed 1/100 and ISO 100. For a Portrait at f2.8, the correct shutter speed would be 1/3200 (5 stops).