AV mode VS Manual mode, metering, etc

[aroberts]

I hope this is the right spot for this thread. I have couple of questions. I mainly photograph people, this evening I was photographing my friend and ran into some problems which brings me here. So, here goes:
(I own a Canon 50D btw)
-I usually shoot in AV mode, should I be shooting in Manual? The reason I haven't before is because I seem to have to change the settings every step I take.
-I don't fully understand the metering aspect. If someone could explain it? I seem to have trouble with certain areas of the pictures being blown out while other areas are darker and I don't know how to fix this.
Sorry if these questions are confusing! Looking forward to hearing from you all. Thanks!

[kencaleno]

You need to understand basic exposure-if you go through the posts here you will find what you need.Ken

[teaking]

An understanding of exposure and metering would help. By the sounds of it if your highlights are blowing out and theres no details in your shadows you may me in difficult lighting. Try shooting outdoors if you dont alread or you may need lighting equipment.

But deffinately have a look around at exposure it will help a lot understanding why things are happening. Theres lots of good stuff around here.

[amymnc]

Make sure the meter isn't too many bars to the left or right, if so you're over or under exposed. Not sure which way, it's different with Canons and Nikon. Remember to check your ISO and all your settings...I forget that stinking ISO a lot and it'll mess me up every time.
Are you shooting in dappled light, with shadows of trees or something on your subject? Avoid it like the plague- l learned the hard way. Unless of course that's the look you're going for, wish varying shadows on people.

What is the technical name for that meter bar thingy? So I don't keep sounding like a bumbling idiot (can't reveal my true self LOL)

[aroberts]

Thanks for the suggestions. I will start searching around here, and I just ordered the book Understanding Exposure.
I usually do shoot outdoors only, I have just been having issues with the blowouts and really off colors. Trying to learn all I can!

[kencaleno]

Originally Posted by aroberts

Thanks for the suggestions. I will start searching around here, and I just ordered the book Understanding Exposure.
I usually do shoot outdoors only, I have just been having issues with the blowouts and really off colors. Trying to learn all I can!

Be careful,for that book could put you wrong-I don't know why so many recommend it. If you want to do things manually, you will be wiser to understand Basic daylight exposure-usually called the "Sunny 16 rule" This works for all outdoor photography:

Manual Exposure Metering


Your camera uses reflected light readings for exposure-light reflected from different subjects, will result in a range of tones, which your camera’s meter will try to average to give an overall exposure. It may not matter sometimes, but because any little deflection of lighting will give a different reading, and if you are photographing a wedding, for instance, it could look as if photos were taken on different days!

Incident light-light falling on the subjects is always constant.

Start using your in-built Incident exposure meter- Your eyes!

This is how us oldies who started in the late 1950’s/60’s learn to read exposure: You will often hear the term “The sunny 16 rule”, or Basic Daylight Exposure” here it is explained:

Basically four apertures are used: F16; F11; F8; and F5.6

Shutter-speed is based on Equivalent ISO#

Watching the shadows, the base settings are: ( for ISO 200)

Hard-edged shadows …………………….1/200 sec @ F16

Soft-edged shadows………………………1/200 sec @ F11

Barely visible Shadows…………………..1.200 sec @ F8

No Shadows……………………………….1/200 sec @ F5.6

Remember, these are the base settings: so variants would be:

1/200 @ F16
1/400 @ F11
1/800 @ F8
1/1600 @ F5.6
These all give the same exposure (But with different depths of field) for 200 ISO.
The other 3 settings use the same spatial relationship, the settings you choose are based on subject movement and/or depth of field desired. For instance If you want to keep the Aperture at F8:


Hard shadows……………………………1/800 @ F8

Soft shadows…………………………….1/400@ F8

Barely visible shadows…………………1/200 @ F8

No shadows………………………………1/100 @ F8 (As shadows fade, more light is required)
Heavily overcast…………………………..1/125 @ F8

Deep Shade………………………………1/60 @ F8

Pre-thunderstorm…………………………1/30 @ F8

Brightly lit store interior……………………1/15 @ F8
Well-lit stage/sports arena…………………1/8 @ F8

Well-lit house interior……………………….¼ @ F8

(Of course you would vary the F stop and shutter speed combinations to whatever would be most appropriate. )


To get more exact exposure readings, you may want to bracket exposures. As you can’t use exposure compensation button when in manual made, this is what I do on my Nikon, your Dslr will have a similar action:

I set aperture to F16, and shutter-speed to 1/200, ( for Hard shadows) Take a shot, then:

2 clicks of the thumbwheel to the left-take a shot- this gives me a + 2/3 exposure
1 click to the right now, gives me + 1/3 exposure

1 more click to the right brings me back to the basic (meter as read) setting, then:

1 more click to the right gives me -1/3 exposure, and finally ,
1 more click to the right gives me - 2/3 exposure-so I have 5 exposures from 2/3rds over, to 2/3rds under exposure.

Looking at these, I choose the one that gives the most detail in the shadows and also in the highlights, without blowing the highlights-and after a while you will find you are able to guess just about right with your exposures-It is all very simple, and I hope I have explained in words that make it easy to understand.

Regards, Ken

[inkista]

Originally Posted by aroberts

I usually shoot in AV mode, should I be shooting in Manual? The reason I haven't before is because I seem to have to change the settings every step I take.

Yes, Manual mode forces you to re-evaluate your metering and your settings every exposure. However, it also gives you precise control over your exposure settings. Full Manual is better for situations where the metering will be inaccurate, and you want precise control over both the aperture and shutter speed for adjusting exposure. With Av mode, you are really only going to be sliding the shutter speed around.

I don't fully understand the metering aspect. If someone could explain it? I seem to have trouble with certain areas of the pictures being blown out while other areas are darker and I don't know how to fix this.

When you're in M mode, rather than in Av, the exposure scale in the viewfinder becomes your light meter, rather than your exposure compensation scale. What Av does is to adjust the shutter speed so that your exposure will be where it thinks a proper exposure will lie. If you're in M mode, adjusting settings so that the "needle" sits at 0 is doing the exact same thing that the camera does when you're in Av mode, with no exposure compensation.

Metering is simply measuring the amount of light that's coming into the camera, and then finding a middle value, and making sure that the exposure settings will set that value to a specific luminance. Most typically, the average "darkness" of the frame is set to middle gray. The problem with this is that it's done unthinkingly and consistently for every scene, regardless of whether or not the middle tone of the scene should be set to the middle exposure tone. It's right a lot of the time. But in two specific cases, it's usually wrong.

The first is if the majority of the frame is white. Like a snow scene. The middle tone of that scene is much lighter than a middle gray, and so this kind of metering scheme will underexpose by setting white to middle gray.

Conversely, with a scene where the majority of the frame is black (like a night shot), a value of mostly black will be set to middle gray, and the scene will overexpose. It's counter-intuitive, but the lighter the scene, the more you want to overexpose, the darker the scene, the more you want to underexpose.

This is why your camera gives you multiple metering modes, so that you can limit the area considered to what's going to work best. Sometimes you want to use evaluative to consider the whole frame, or centered to ignore the edges, and sometimes you want to use spot to worry only about the subject of the photograph, metering wise.

There is also another problem in terms of highlights and shadows which is dynamic range. The human eye can comfortably encompass about 10 stops from darkest possible value to brightest possible value. A digital sensor and computer monitor can typically only display about 5 stops. This is why you can often get a "high dynamic range" in a single shot that can be past what the sensor can display. Blown highlights, or lost shadow detail are common in certain situations, like a backlit subject. You can expose for one or the other, but probably not both, unless you're willing to merge multiple exposures, either directly with masking or through exposure algorithms like HDR.

[aroberts]

This is why your camera gives you multiple metering modes, so that you can limit the area considered to what's going to work best. Sometimes you want to use evaluative to consider the whole frame, or centered to ignore the edges, and sometimes you want to use spot to worry only about the subject of the photograph, metering wise.

Do you have an example of which metering modes are best for certain situations?

Looking at these, I choose the one that gives the most detail in the shadows and also in the highlights, without blowing the highlights-and after a while you will find you are able to guess just about right with your exposures-It is all very simple, and I hope I have explained in words that make it easy to understand.

Thanks for all of the information. I printed out your response so I can reference it. Hopefully I will also consider it to be very simple before long!

[inkista]

Originally Posted by aroberts

Do you have an example of which metering modes are best for certain situations?

Nope, not really. But the camera manual does. Page 100.