exposure compensation question

windoze

im taking a break from shooting and doing some more reading (yuck) and learning my camera (20D).... in order to get even better images in a variety of situations....

so ive been practicing taking images with and around snow. im starting to "fully" understand why you add EC in a snowy scene and I have the experience now of seeing the effects of these changes on the subjects in my images. ive also noted before in my previous posts ( but never answered) that when I increase EC the Shutter speed is slower. I understand that when you add 1 stop of EC you decrease the shutter speed and open more the aperture as a result. But my question is .... how does this happen if im already using the smallest aperture value? For example Im shooting at f/5.6 and I add 1 stop EC -> the shutter speed decreases what happens to the aperture setting? Im asking because ive noticed that when I add EC the subject in my image looks more "blurrier" than it would have if i didnt add the EC.... would this help explain that effect?? or is it just because ive reduced "unintentionally" the shutter speed?

the next question - It seems to me that most who use the 20D seem to prefer to use the "evaluative metering mode". My understanding is that this mode will take into account the subject brightness, front and back lighting etc. So if the camera is taking this into account, might using EC result in an unproperly exposed image even further...... thereby making this whole game of using EC just a guessing game..... and maybe this is why Ive read that Shay will still use the evaluative metering mode and rely on the histogram to properly expose a image..... so would "you" recommend instead then using the center weighted averaging metering mode when adding EC in a snowy situation?

Does this make sense???


troy

Steve Cavigliano

windoze wrote:

im taking a break from shooting and doing some more reading (yuck) and learning my camera (20D).... in order to get even better images in a variety of situations....

so ive been practicing taking images with and around snow. im starting to "fully" understand why you add EC in a snowy scene and I have the experience now of seeing the effects of these changes on the subjects in my images. ive also noted before in my previous posts ( but never answered) that when I increase EC the Shutter speed is slower. I understand that when you add 1 stop of EC you decrease the shutter speed and open more the aperture as a result. But my question is .... how does this happen if im already using the smallest aperture value? For example Im shooting at f/5.6 and I add 1 stop EC -> the shutter speed decreases what happens to the aperture setting? Im asking because ive noticed that when I add EC the subject in my image looks more "blurrier" than it would have if i didnt add the EC.... would this help explain that effect?? or is it just because ive reduced "unintentionally" the shutter speed?

the next question - It seems to me that most who use the 20D seem to prefer to use the "evaluative metering mode". My understanding is that this mode will take into account the subject brightness, front and back lighting etc. So if the camera is taking this into account, might using EC result in an unproperly exposed image even further...... thereby making this whole game of using EC just a guessing game..... and maybe this is why Ive read that Shay will still use the evaluative metering mode and rely on the histogram to properly expose a image..... so would "you" recommend instead then using the center weighted averaging metering mode when adding EC in a snowy situation?

Does this make sense???


troy

Troy,
EV Comp could be called Shutter Speed Comp. I use mainly M and Av when shooting. In M I have to manually change whichever parameter I desire (open or close aperture or slow down/speed up shutter speed). In Av mode EV comp is Shutter Speed Comp. IOW, if you dial in positive comp you will slow the speed down resulting in a longer exposure (good for darker/less well lit subjects). If you dial in negative EV comp, you will increase the speed resulting in a shorter exposure (good for white birds/white highlights). I love this because when I am shooting white birds, I get anywhere from 2/3 to 1/23 stops faster speeds because of the EV comp I dialed in. So bottomline is, in Av mode using EV comp will not effect your aperture setting.

I'm not sure how this works in Tv mode, but I would expect it to be the same. For sure it would have to work the same once you've hit your max aperture.

Your "blurier" problem is likely due to slower shutter speeds.

Question 2

Troy, I think this will be dependent on what you're shooting. If I am trying to properly expose a bird, I will use center-weighted, as I really don't care about the rest of the scene that much. If, I am shooting a landscape, I'll use evaluative as I care avbout properly exposing the entire frame. As Shay mentions, there's no substitute for chimping the histo after firing off the shot. Unless, like me, you are so friggin blind you can barely find the LCD, let alone see what it is displaying....

I hope I understood tyour questions and that I was able to help some

Steve

windoze

Steve Cavigliano wrote:

Troy,
EV Comp could be called Shutter Speed Comp. I use mainly M and Av when shooting. In M I have to manually change whichever parameter I desire (open or close aperture or slow down/speed up shutter speed). In Av mode EV comp is Shutter Speed Comp. IOW, if you dial in positive comp you will slow the speed down resulting in a longer exposure (good for darker/less well lit subjects). If you dial in negative EV comp, you will increase the speed resulting in a shorter exposure (good for white birds/white highlights). I love this because when I am shooting white birds, I get anywhere from 2/3 to 1/23 stops faster speeds because of the EV comp I dialed in. So bottomline is, in Av mode using EV comp will not effect your aperture setting.

I'm not sure how this works in Tv mode, but I would expect it to be the same. For sure it would have to work the same once you've hit your max aperture.

Your "blurier" problem is likely due to slower shutter speeds.

Question 2

Troy, I think this will be dependent on what you're shooting. If I am trying to properly expose a bird, I will use center-weighted, as I really don't care about the rest of the scene that much. If, I am shooting a landscape, I'll use evaluative as I care avbout properly exposing the entire frame. As Shay mentions, there's no substitute for chimping the histo after firing off the shot. Unless, like me, you are so friggin blind you can barely find the LCD, let alone see what it is displaying....

I hope I understood tyour questions and that I was able to help some

Steve

Regarding question#1 - i actually understand what you said . And I now agree that my blurrier pics are probably a direct result of increasing exposure compensation. I also understand that in Av mode the size of the aperture does not change with increasing or deceasing exposure compensation .

Regarding question#2 - ive come to thinking during the day that if considerations are given to overriding exposure compensation, the best way is probably what Shay suggests is to use evaluative metering mode and them use the histo to guide changes in exposure compensation. I think that this method is what those who are experienced in the field have come to trust. For me it has been important to be able to "think" out in understandable terms what I should do instead of just relying on good advice...... i also would now definetly consider using center weighted averaging when shooting birds ... to date ive only used evaluative metering.

what's the point of all this to me? I think ( hope) I can begin to tweak the settings for even better images before i even get to post.


troy

Rohirrim

windoze wrote:

im taking a break from shooting and doing some more reading (yuck) and learning my camera (20D).... in order to get even better images in a variety of situations....

so ive been practicing taking images with and around snow. im starting to "fully" understand why you add EC in a snowy scene and I have the experience now of seeing the effects of these changes on the subjects in my images. ive also noted before in my previous posts ( but never answered) that when I increase EC the Shutter speed is slower. I understand that when you add 1 stop of EC you decrease the shutter speed and open more the aperture as a result. But my question is .... how does this happen if im already using the smallest aperture value? For example Im shooting at f/5.6 and I add 1 stop EC -> the shutter speed decreases what happens to the aperture setting? Im asking because ive noticed that when I add EC the subject in my image looks more "blurrier" than it would have if i didnt add the EC.... would this help explain that effect?? or is it just because ive reduced "unintentionally" the shutter speed?

the next question - It seems to me that most who use the 20D seem to prefer to use the "evaluative metering mode". My understanding is that this mode will take into account the subject brightness, front and back lighting etc. So if the camera is taking this into account, might using EC result in an unproperly exposed image even further...... thereby making this whole game of using EC just a guessing game..... and maybe this is why Ive read that Shay will still use the evaluative metering mode and rely on the histogram to properly expose a image..... so would "you" recommend instead then using the center weighted averaging metering mode when adding EC in a snowy situation?

Does this make sense???


troy

I think Steve explained this well, but just to add a couple more thoughts.

While you are shooting in Av mode the camera will only change Shutter Speed when you change Exposure Compensation. This allows you to keep the f-Stop you want and still be able to modify exposure.

When shooting in Tv the camera will only change Aperature.

When shooting in P mode the camera will change one or both - sorry I don't know when/why the camera will choose which one to change.

pathfinder

Rohirrim is correct as was Ian in their description of + and - Exposure Compensation.

I tend to use Evaluative metering most of the time and I almost always shoot in Av or manual.

I would like to suggest that we learn what are appropriate exposures out of doors when shooting objects lit by the sun - that then allows us to judge whether we believe what the meter is telling us or not. And then we can shoot in manual mode or Av or Tv as needed because we know what we need for exposure.

The Sunny 16 rule goes back 50 years or so to the times when there were no meters. Basically it says that for a medium toned object lit frontally by the sun from 2 hours after sunrise to 2 hours before sunset, that the exposure is 1/ISO for a shutter speed at f16. That single statement gives rise to all the data in the following table.


The idea of using spot metering for birds sounds good, Troy, but can be rather challenging to keep the spot on the bird in flight - I can't begin to do that.

It is easier if you understand that a bird in flight is functionally in the shade ( usually unless late afternoon sunshine is able to shine on it) and shaded objects typically require 2 stops more exposure than sunlit objects - so start with a sunlit exposure for the given ISO and dial in 1.5 to 2 stops more light. I think Andy uses + 1 2/3 EV for birds in the sky.

That is the real beauty of histograms - you get real time feedback on your exposures. And when you shoot white birds you know you must have bright spike near the far right of your histogram or you are underexposed.

Meters meter for grey cats on neutral grey blankets, not for white cats in the snow or black cats sitting on a coal pile. Understanding +/- EV compensation lets you catch all three situations.

erich6

pathfinder wrote:

...a bird in flight is functionally in the shade...

Could you please elaborate on what this means? If you shoot evaluative against the sky doesn't the camera try to expose the sky down to 18% level or so? Isn't that what drives you to push the exposure up in compensation?

Erich

pathfinder

What I meant and explained poorly was that many birds in flight are shot from below, and thus are in their own shadow, and only lit by light reflected from beneath them - the meter reads the sky which is MUCH brighter than the birds undersides, thus needing the + 1 2/3 EV.
Obviously, some birds are sunlit when flying in the late afternoon or early morning sunlight - this does not apply to them then. They may or may not need +ev then depending on the lighting situation. Another reason to shoot RAW to give you a little more margin when shooting rapidly moving objects that are hard to meter carefully. Have I explained this any better?:):

That is why I suggested learning the SUnny 16 rule - It gives you a standard to judge your meter by in your head. The sun's output does not change - although cloud cover does of course.

erich6

pathfinder wrote:

What I meant and explained poorly was that many birds in flight are shot from below, and thus are in their own shadow, and only lit by light reflected from beneath them - the meter reads the sky which is MUCH brighter than the birds undersides, thus needing the + 1 2/3 EV.
Obviously, some birds are sunlit when flying in the late afternoon or early morning sunlight - this does not apply to them then. They may or may not need +ev then depending on the lighting situation. Another reason to shoot RAW to give you a little more margin when shooting rapidly moving objects that are hard to meter carefully. Have I explained this any better?:):

That is why I suggested learning the SUnny 16 rule - It gives you a standard to judge your meter by in your head. The sun's output does not change - although cloud cover does of course.

Thank you! This makes sense to me now.

ginger_55

Well, I know all that stuff, not that it always applies as there are many ways to skin a cat, etc.

My problem is that I HAVE to look at the button I push on my Canon 20D, and I have to see where the EV is, I can't do it blind. Same on the al servo and other one.

It seems the Nikon shooters just move fingers/thumbs, and it can all happen immediately.

What do you, as a Canon shooter, do to make this process easier and faster?

For instance, I have a Snowy Egret posing, -EV a lot, then a Little Blue Heron, up the EV, then a hawk is flying by, all in 5 minutes........I am going to lose, probably, all except one.

What do the Canon shooters do with their thumbs and fingers?

ginger

bwg

ginger_55 wrote:

Well, I know all that stuff, not that it always applies as there are many ways to skin a cat, etc.

My problem is that I HAVE to look at the button I push on my Canon 20D, and I have to see where the EV is, I can't do it blind. Same on the al servo and other one.

It seems the Nikon shooters just move fingers/thumbs, and it can all happen immediately.

What do you, as a Canon shooter, do to make this process easier and faster?

For instance, I have a Snowy Egret posing, -EV a lot, then a Little Blue Heron, up the EV, then a hawk is flying by, all in 5 minutes........I am going to lose, probably, all except one.

What do the Canon shooters do with their thumbs and fingers?

ginger

for the 20d make sure you have the on switch to fully on (dunno what else to call it, it's the second "on" position.

the dial by the shutter will control aperture or shutter speed depending on the priority mode you are in. The big dial on the back will control the EV.

I use my finger for the little dial and my thumb for the big one. unless i'm upside down.

Rohirrim

ginger_55 wrote:

Well, I know all that stuff, not that it always applies as there are many ways to skin a cat, etc.

My problem is that I HAVE to look at the button I push on my Canon 20D, and I have to see where the EV is, I can't do it blind. Same on the al servo and other one.

It seems the Nikon shooters just move fingers/thumbs, and it can all happen immediately.

What do you, as a Canon shooter, do to make this process easier and faster?

For instance, I have a Snowy Egret posing, -EV a lot, then a Little Blue Heron, up the EV, then a hawk is flying by, all in 5 minutes........I am going to lose, probably, all except one.

What do the Canon shooters do with their thumbs and fingers?

ginger

As webguy said use the big wheel on the back of the 20D. This is how I do it.

• Assuming your in Av mode
• Press shutter release 1/2 way down.
• Check the exposure meter in the view finder
• Dial in the desired exposure compensation using the big wheel
• You should easily be able to do this without taking your eye away from the viewfinder.
• Take picture
• Recompose, reset exposure if needed and shoot again.

Arthur Morris just sent out an e-newsletter that covers this for birds.
From Birds as Art Bulletin 190 (www.birdsasart.com)

Exposure Simplified

Here are the basics.

Get in the habit of working in Av Mode and adjusting the exposure suggested by your camera’s evaluative or matrix meter reading by dialing in exposure compensation.

When the sun is out at full strength, that is, on a clear day at least an hour after sunrise or at least an hour before sunset, your camera’s evaluative or matrix meter is smart. It is rare in these conditions that you will need to compensate more than 1/3 stop in either direction.

When you are working in the shade, or when it is cloudy or overcast, or when the sun is out at less than full strength, then your camera’s evaluative or matrix meter is dumb. You will need to help it out in order to get the exposure that you want. The closer your scene is to white, the more you will need to help the meter.

1: If the sun is out at full strength and what you see in your viewfinder averages to a middle-tone or lighter and there are no white or bright highlights, you can use the metered exposure.

2: If the sun is out at full strength and what you see in your viewfinder averages to darker than a middle-tone and there are no white or bright highlights, you can use the metered exposure less 1/3 stop.

3: If there bright or white highlights in #1 or # 2, use 1/3 stop less light than recommended above.

4: If you are working in the shade, if it is cloudy or overcast, or if the sun is out at less than full strength and what you see in the viewfinder averages to a middle-tone, the best exposure will always be either the metered exposure or the metered exposure + 1/3 stop.

5- If you are working in the shade, if it is cloudy or overcast, or if the sun is out at less than full strength and what you see in the viewfinder averages to lighter than a middle-tone, you will need to add light to the metered exposure to come up with a pleasing exposure. The lighter the scene, the more light you need to add.

For scenes a bit lighter than a middle tone, add 2/3 stop of light.

For images well brighter than a middle tone, add 1 full stop of light.

For images that average to white, add 1 1/3 stops of light.

In white-out conditions add 2 full stops of light.

6- If you are working in the shade, if it is cloudy or overcast, or if the sun is out at less than full strength and what you see in the viewfinder averages to darker than a middle-tone and their are no bright or white highlights, you can use the metered exposure.

Because of the wordy qualifications that needed to be included above, the principles may seem more complex than they really are. To simplify things even further, consider the following:

Situation #1- Sun out, middle tone or brighter = 0.

Situation #2- Sun out, darker than a middle tone = -1/3.

Situation #3- Sun out, bright highlights against middle tone = 1/3; against dark = -2/3.

Situation #4- Sun in, middle tone = 0 or +1/3.

Situation #5- Sun in. Lighter than a middle tone = +2/3.

Well brighter than a middle tone = +1.

White: +1 1/3.

White-out conditions: +2.

Situation #6-Sun in, darker than a middle-tone = 0.

geraldfinnegan

Simple rule of thumb

windoze wrote:

im taking a break from shooting and doing some more reading (yuck) and learning my camera (20D).... in order to get even better images in a variety of situations....

so ive been practicing taking images with and around snow. im starting to "fully" understand why you add EC in a snowy scene and I have the experience now of seeing the effects of these changes on the subjects in my images. ive also noted before in my previous posts ( but never answered) that when I increase EC the Shutter speed is slower. I understand that when you add 1 stop of EC you decrease the shutter speed and open more the aperture as a result. But my question is .... how does this happen if im already using the smallest aperture value? For example Im shooting at f/5.6 and I add 1 stop EC -> the shutter speed decreases what happens to the aperture setting? Im asking because ive noticed that when I add EC the subject in my image looks more "blurrier" than it would have if i didnt add the EC.... would this help explain that effect?? or is it just because ive reduced "unintentionally" the shutter speed?

the next question - It seems to me that most who use the 20D seem to prefer to use the "evaluative metering mode". My understanding is that this mode will take into account the subject brightness, front and back lighting etc. So if the camera is taking this into account, might using EC result in an unproperly exposed image even further...... thereby making this whole game of using EC just a guessing game..... and maybe this is why Ive read that Shay will still use the evaluative metering mode and rely on the histogram to properly expose a image..... so would "you" recommend instead then using the center weighted averaging metering mode when adding EC in a snowy situation?

Does this make sense???


troy

I shoot film a lot and 2 cameras are old, no light meters, and one you have to estimate distance as well. Since you can't do all these modern measuring tehniques, most advice I read from those also using no meter is this: in anything but the darkest clouds or blinding sun, use 1/125 at f8 or f11 and go down a half or full stop if it's back-lit or if you want to bring out detail in a scene under the sky, or if it's very cloudy. Blinding sun or reflected off of white, go up to a half or full stop. Experiment and you'll figure teh sweet spots for you own camera. The rest is printing, or digital finishing. At least for film, modern films are so forgiving that you can be over and just take the added light away during post-processing. On the other hand, shooting with too little light isn't fixable because there's nothing there. So, go over a little and fix it later if you have to. Use Manual for this rule of them, so the camera won't be constantly correcting you.
Also, for the fastest focusing, set it at the highest aperture number you can without having to make the shutter too slow for whatever you want to shoot - moving or still e.g. - and if it's light enough and you can get it to around f22 and you're not using a highly telescopic lens, set the focusing to manual and forget it. Everything beyond about 20' to 30' (depending on the lens) will be in focus anyway due to good depth of field. You'll be able to shoot faster than auto-focus and metered. Just click away. Experiment with this too with your own lens. Shoot along the length of a long fence. You'll be able to see at different apertures where everything beyond a particular distance is in focus.
Jerry

jerry

Mike Lane

I prefer partial metering. Put your snow in the circle in the viewfinder, and set the exposure manually until you see +1.67 to +2.00. Recompose and focus your shot without changing the exposure and take the shot.