On my Canon Rebel Xti, how do I mess with the light metering?

Question

I have an assignment in photo to take pictures with different levels of light. When I push the a/v +/- button, nothing happens. I am using the camera in full manual. Anybody know how to get it to work?

I'm not too sure I have a 'creative' setting...

The exercise is just about metering. We cannot change anything else. It has to be the same object. I understand how metering works, I just need to know how to do it on my specific camera. I would think you push the button, it works, but that is not the case.

The button that has the three choices isn't what I want either. The assignment says we must have one photo for every stop on the scale, and those three settings are automatic. Maybe the camera does not allow you to change it?

Answer 1

****EDIT 1****

You said: "The assignment says we must have one photo for every stop on the scale"

Then you're messing with exposure compensation. The other poster was on a similar track, and I thought his response could be correct too, but I think there's a disconnect in terminology here. What he's talking about IS the camera metering technique, it affects how much of the photo area the camera meters to determine the exposure.

My next guess would be that you do have to use the +/- button, so try this. Put the camera in a creative mode like Av or Tv. Take a picture. Note the camera's exposure. Now you have to PRESS AND HOLD the +/- button and then TURN THE MAIN DIAL NEAR THE SHUTTER RELEASE. You should see the exposure needle adjust accordingly to one side or the other of the exposure needle. This is exposure compensation, and I'm thinking if you need a photo at "each step", it means you must take a photo at each increment (1/3 stop). So, take a pic at exact exposure (needle in the center), press and hold +/-, turn it one click to the right/left, take a pic, press and hold +/-, turn another click in the same direction. Repeat. I do not own an XTI, but this is usually the standard operating procedure for Exposure Compensation (EC). Look it up in the manual if my method doesn't work. I'm not sure what modes EC works in, I do't know if it works in the auto modes (Sports, Portrait, etc), but I do know it works in Av/Tv/P, so try adjusting EC in the auto modes as well.

*****ORIGINAL RESPONSE*****


When you're in full manual, the +/- more than likely doesn't do anything. That button forces the camera to adjust the settings it chose/metered by that amount, that is, say for example the camera decides that f/4, 1/60 is the best in Tv mode and you dial in -1/3, it will shorten the exposure. HOWEVER, in your case....

The camera doesn't decide anything. In manual mode, YOU decide the exposure, so adjusting the av +/- won't do anything. What you need to do in manual mode is watch the exposure meter in the viewfinder. The "ideal" exposure according to the camera is when the exposure needle is right in the middle e.g. where the || is in my illustration

<--(-2)--(-1)--||--(+1)--(+2)-->

I think when you say take it with different levels of light, your instructor wants you to adjust different variables, such as shutter speed and aperture, to see how it affects your exposure. If you adjust the exposure such that the needle slides towards the negative (-) side, your pictures should come out darker, because negative designates a shorter exposure, thus less light is let in. Shortening exposure means decreasing the aperture (higher the number, smaller the opening), or increasing the shutter speed (e.g. 1/200 is less light than 1/100)

Check out the link below, it's an awesome simulator that can show you quickly how adjusting the aperture and shutter speed affects exposure.

Answer 2

If you're in Manual Mode you control the camera. Actually, you could do this in Aperture Preferred Mode since as you control the f-stop the camera will adjust the shutter speed. If you're outside on a sunny day you might be able to do it hand-held but a tripod is suggested.

Set your ISO to 200 (unless your instructor says different. It really doesn't matter because the relationship holds.) The following is a hypothetical example of what will happen.

f2, 1/2000 sec.
f2.8, 1/1000 sec.
f4, 1/500 sec.
f5.6, 1/250 sec.
f8, 1/125 sec.
f11, 1.60 sec.
f16, 1/30 sec.

ISO 100

f2, 1/1000 sec.
f2.8, 1/500 sec.
f4, 1/250 sec.
f5.6, 1/125 sec.
f8, 1/60 sec.
f11, 1/30 sec.
f16, 1/15 sec.

All seven of your exposures in both examples are IDENTICAL. As you "stop down" i.e., let in less light, the shutter speed decreases to allow enough light to expose your film/sensor for correct exposure.

Here's why: f2.8 admits 1/2 as much light as f2; f4 admits 1/2 as much light as f2.8, etc. For correct exposure the shutter speed has to get slower.

The only discernible differences you'll see is an improvement in image quality from f5.6 to f11 and an increase in Depth of Field from f4 on through f16.

Answer 3

The "common" lights is three:a million (generally referred to as two:a million) in which the "important mild" which units the shadow produces an publicity a million 'f'give up brighter than the "fill mild" which fills within the shadow. You can be higher off should you get an incident mild flash meter to degree the lighting independently from the area to the sunshine supply making definite there's that one give up differential among the 2 lighting. If you're utilising a virtual digital camera, set the 'f' give up to the surroundings given at the meter to the important mild; if utilising a movie digital camera, deliver the publicity +a million/two give up over what the sunshine meter says. (e.g. if the meter mentioned 'f' eight, then set the digital camera among 'f'five.6 and 'f'eight) p.s. 'f'eight is a well publicity for 'f' give up of a portrait as it'll hold the intensity-of-discipline shallow adequate to blur the backgound and but deep adequate to allow well area element in a head/shoulders portrait.

Answer 4

I have an XTi and it's simple, turn it on and at the back of the body..ISO, AF, WB and "Metering", push the button (on the left side) for Evaluative, Partial or Center--Weighted average. Once you have made your choice push the button in the center "SET" and then push the shutter half way down and or just push the shutter half way down then your set for that metering mode.

Answer 5

you can't use it in full manuel and adjust the light. I don't have the exact camera, I have the XT, but for me I have to change it to the "creative" settings and then I go to the menu and am able to change the levels. Hope this helps at least a little :)