Exposure Compensation and AEB

Jim and Preston, if this needs to go in another forum please feel free to move it.  Thanks.

Today when I went out I was going to learn how to use exposure compensation.  I found out that you can't use exposure compensation on the Canon 7D unless you are in Auto, Aperture Mode or Shutter Mode.  The way I learned, at the very strong urging of a former NPN member who spent a day with me for free several years ago, was to shoot Manual.  Obviously I still have a lot to learn shooting Manual, but that's what I'm comfortable with at this point.

The 7D does have Automatic Exposure Bracketing, which is it will create three photos at your selected shutter speed and the shutter speed some distance above and below that, wherever you have the brackets set.  I did use that today, and that was pretty cool.

Those of you who have been following along with the issue I have had at times with underexposure, do you think I should switch from Manual so that I can use Exposure Compensation?  Or do you think I should just working on better exposure selection in Manual?  If you use Aperture or Shutter Mode, which one do you use?  Thanks very much.
 

Obviously I still have a lot to learn shooting Manual, but that's what I'm comfortable with at this point.

If you feel good about using manual mode I would continue and use the AEB you mention to see if that helps with exposures. As I only have ALL manual gear I obviously only shoot in manual mode. With that said I most always select an aperture and adjust shutter speed manually up and down. I do use a handheld spot meter to verify my need for those changes.

Do you use the camera spot meter or the matrix metering? Both work you just need to verify and understand what you're trying to accomplish in each case. It sounds like it would be a good idea within reason to try the bracketing for awhile and see how that aids in the exposure process long term. 

I've used Nikon cameras since I started in the early 1970's and have never used Canon, so I can't say anything useful about how your camera handles exposure.

In general, I keep my cameras on auto exposure and use aperture priority (I set the aperture and the camera meter sets the shutter speed based on my ISO value and the light it sees). Back in the '70's most cameras had "match needle" meters - they read the light entering the lens and the photographer adjusted aperture and/or shutter speed until two needles lined up (i.e., matched). When Nikon and other makers added auto exposure I gladly accepted it and used it immediately instead of manually making adjustments to match the needles. I can't imagine going back to the early '70's, especially with active subjects and variable lighting conditions.

Since the majority of my subjects are birds I usually work at maximum aperture (or one stop down) and whatever shutter speed the camera provides. That way I get the highest shutter speed possible for the selected ISO and the ambient light level. The meter is set to Matrix (I think Canon calls this Evaluative). I have a function button set to switch to Spot metering and I use this a lot with backlit subjects.

I also use exposure compensation in Matrix mode, dialing in plus or minus 1/3rd, 2/3rds, or even a full stop based on the subject and setting. This is something that most photographers learn to do with lots of experience. Typical subjects requiring negative compensation are Ring-necked Duck, Hooded Merganser, Northern Pintail, and most egrets.

What would help answer your question about how you should work it would help to know how you determine exposure now:

• do you use an external meter to determine the ambient light?
• do you perform some sort of "match needle" to adjust the camera to agree with what the internal meter is suggesting?
• do you just guess based on time of day and color of subject?
• do you use the spot meter and carefully select a medium toned part of the scene?
• do you use the clumsy table of exposure adjustments that some authors put in their books?
• or do you have some other method of working?

Barbara:

You posed a couple of questions:  AEB and Exposure compensation:

AEB:  I would not recommend using that to "solve" your exposure issues.  That is not the right answer.  Imagine this scenario:  You are shooting and what you really need is to add more light to the subject by 1 stop.  If you use AEB, assuming you are going to shoot 3 images, you are going to get 3 frames:  To do this you need to go into the camera menus and set the bracketing amount.  Let's assume  you've set it to one stop increment in the bracket.  Now you take 3 frames.  1 frame is 1 stop under the metered value, 1 frame is at the metered value and 1 frame is 1 stop over the metered value.  Great:  2 of those 3 are trash because they are the wrong exposure.  If your guess was right that you needed 1 stop of extra light, you might have one useable frame (the one at +1) and it took you a long time to get it going through the menus to get AEB on and shoot the frames.

Exposure Compensation:  You said you are using Manual exposure.  That's just fine.  That means you are in control of both the selected shutter speed and the selected aperture.  On your Canon 7D (unless you changed the default behavior), the front control dial changes the shutter speed, the rear control dial changes the aperture.  All Exposure compensation means is that you are using a different metered value than suggested.  Even in Manual mode, you have a metering scale in the viewfinder so you can choose a combination of shutter/aperture to "match" the light.  If you want your exposure to be something different than having the meter showing the middle of the scale (as metered), change one of the two dials and you are doing exactly the same thing as exposure compensation.  Let's use some numbers as an example:

You look through the viewfinder and set the shutter speed to 1/1000 and the aperture to f/5.6 for the particular lighting conditions.  Then you see a bird in flight that is going to need 1 more stop of light because it is a darker subject on a lighter background.  Turn your back dial to f/4 and you've accomplished the goal.  In effect you have added +1 via "exposure compensation".  You're just doing it with a manual dial.  You could have also turned the front dial to 1/500 and left the original aperture at f/5.6 and you would have accomplished the same goal.  

So, you do have the capability to do exactly the same thing as exposure compensation as you have full control in manual over both aperture and shutter speed (and of course ISO).  You've already taken control by using Manual exposure (and for birds in flight I STRONGLY recommend using that mode).  Just learn to change the exposure as you are looking through the viewfinder with either the front dial to affect shutter speed, or the rear dial to affect aperture. 

Using the front or real control dial is MUCH faster than shooting a series of images in AEB mode.  

Hope that makes sense.
 

Paul, Richard and Keith, thank you.  All of your comments make sense to me.  I'm so glad this has happened, because I feel like I will do much better with my camera after this.  But if I'm asking too much here, I totally understand.  I am so lucky to have whatever information you can provide.

Keith, what I've been doing this time around (as in starting the beginning of last summer when I started nature photograph again) is using the Q button and looking at the screen to change my settings.  I had forgotten about the front and rear dials.  I just tried that and it's MUCH MUCH MUCH quicker.  I remember that I used to do that now.  I need to start that again.  It's crazy that I haven't been doing that.

The only default behavior I've changed is using the center of the three small buttons to focus.

Paul, Richard and Keith, I've been using evaluative metering since I realized I shouldn't be using spot metering all the time.  Is there a way to change metering with a dial or a button?  I'm thinking from what you guys said that I would be using evaluative metering most often but spot metering for some circumstances?  If that's the case, for which of these should I use spot metering:  white bird, blue sky; white bird, dark sky; dark bird, blue sky; dark bird, dark sky; small bird in bush or tree, which usually involves shade; anything against green vegetation.

Richard, my answers to your questions.

• do you use an external meter to determine the ambient light?  No, but I would if you think it would help.
• do you perform some sort of "match needle" to adjust the camera to agree with what the internal meter is suggesting?  Not sure what a "match needle" is or why the camera wouldn't agree with the internal meter?
• do you just guess based on time of day and color of subject?  See last question below.
• do you use the spot meter and carefully select a medium toned part of the scene?  I've been using evaluative metering lately (see above).
• do you use the clumsy table of exposure adjustments that some authors put in their books?  No, I haven't seen those.
• or do you have some other method of working?  When I enter the area, I take a couple of shots of vegetation, adjust the settings, repeat until it looks good.  Then I make changes mostly to shutter speed as the morning gets less foggy and brighter.  If it gets really bright before I leave, I lower the ISO.  If I'm trying to get two or more birds in focus at one time, I usually go to f11.  As you've commented, I normally use f7.1 for birds because I seem to get the best sharpness there.  If I occasionally get the chance to try a flower, I normally use whatever I need to use to get sharpness but blur the background.  I check the histogram on the camera and use that to adjust the shutter speed.

Again, thank you all for whatever further information you can provide.

When I enter the area, I take a couple of shots of vegetation, adjust the settings, repeat until it looks good.  Then I make changes mostly to shutter speed as the morning gets less foggy and brighter.  If it gets really bright before I leave, I lower the ISO.   ... I check the histogram on the camera and use that to adjust the shutter speed.

I don't  understand all of this, so here are more questions (I read a bit about the 7D at dpreview to get an idea of what the meter display looks like):

1. When you take those first couple of shots of vegetation, how do you decide what exposure (aperture and shutter speed) to start with? You are set to manual (you control the aperture and the shutter speed). How do you factor in the evaluative meter reading?
2. Do you adjust the exposure controls until the exposure scale is at the zero (center) position? Or do you just guess at a starting point?
3. How do you decide how much to change shutter speed as the morning gets less foggy and brighter? Do you refer to the exposure scale and zero it out? Or do you look at the histogram and adjust the shutter speed to keep it from clipping on the bright end?
4. If you make your adjustments based on the histogram then how are you using the meter readings?
5. If you aren't using the metering scale then what difference does it make if you are set to evaluative or to spot?

 

Barbara, both Keith & Richard have in-depth usage with digital gear and can provide a world of expertise from that arena.

I have nothing to add with regard to digital in-camera metering beyond saying I use both spot & ambient readings from a Sekonic 758DR handheld unit. I also have an in-camera meter that does both but find swinging a camera around a scene to verify readings very difficult. The handheld is much easier for me.

If there is contrast, bright & dark in the scene, I spot meter for clipping points. In my case, very low at only about 1.5 stops up & down. If the light is consistent, usually shooting in shade or using a sun diffuser, then ambient works best for me. I also have a small gray pop screen I carry to aid with checking neutral or mid point ideas. 

You might also check Youtube for metering ideas, sometimes seeing things in action are easier then reading up on a subject. I learned a lot about the Sekonic 758DR and it's inner workings there.
 

1. When you take those first couple of shots of vegetation, how do you decide what exposure (aperture and shutter speed) to start with? You are set to manual (you control the aperture and the shutter speed). How do you factor in the evaluative meter reading?
2. Do you adjust the exposure controls until the exposure scale is at the zero (center) position? Or do you just guess at a starting point?
3. How do you decide how much to change shutter speed as the morning gets less foggy and brighter? Do you refer to the exposure scale and zero it out? Or do you look at the histogram and adjust the shutter speed to keep it from clipping on the bright end?
4. If you make your adjustments based on the histogram then how are you using the meter readings?
5. If you aren't using the metering scale then what difference does it make if you are set to evaluative or to spot?

1. I'm beginning to see that I really don't know what the meter reading is or does, so I need to read that before my answers have much value.  I will do that.
2. The exposure control is always at the zero position, I think.
3. I use the histogram
4. See number one.
5. See number one.

I've tried not to apologize, which I have a tendency to do, but just to be factual about this.  But I am obviously missing something major.  So I will read about exposure and metering, hopefully today, get some knowledge, and tell you what I've read.

Continued thanks.

 

 

I've tried not to apologize, which I have a tendency to do, but just to be factual about this.  But I am obviously missing something major.  So I will read about exposure and metering, hopefully today, get some knowledge, and tell you what I've read.

Barbara, no need for any apologizing thoughts on working through ANY photographic processes. Ask many and they will say exposure issues are simple. Well, unless the image is over or under exposed. What was the cause?

Aperture, shutter speed, or ISO. A change of any will cause issues if not the right selection. So, it does require understanding and how one effects the other. In the end it is just a need to obtain the right amount of light on the sensor to receive the positive outcome. That is the combined outcome of the light path opening (size), speed (length of time), and sensitivity rating.

Along with your thoughts of reading on the 7D points on the subject, I would further suggest poking around Youtube for ideas. You just need to be cautious as to some of the facts or ideas being presented there.

Barbara, take a look at the excellent tutorials at Cambridge In Color.

Here are some nice tutorials from Cambridge on Photographic Concepts. The two that are most relevant to this thread are: "Understanding Camera Exposure: Aperture, ISO & Shutter Speed" and "Understanding Camera Metering"

I hope you find them useful.
--P

Preston, those are amazing tutorials.  I've just taken a quick look at the one on understanding camera metering, and I know I will find them useful.  I wanted to thank you for posting them.