Understanding Exposure

[KellyL]

[As I see it, in this situation all the meter could do would be to confirm your suspicion about the background being too dark. What would you do to correct the situation? Would you move the subjects to another area that was more balanced with the background? Would you put up some sort of flag/gobo/screen to lessen the light on the subjects? Would you somehow try to add light to the background?

What do you think would be different if you used an incident meter instead of using a reflected meter and a gray card?

John...those are the questions I am working to answer.

First, I liked this spot, near the old antique gas station and the old pump, so given this situation and not having any lighting equipment with me other than my flash, I don't know what I would have done. It seems counter intuitive to want to reduce the amount of light on the subject, but that might have been the best suggestion. Kirk is constantly telling me that I need to learn to control the light...one way or another.

[Jason Hermann]

I think that was a good idea to post that blown Highlight photo Kelly!! It's a perfect example of what AUTO will do in those particular conditions that we cannot control. If we can control the light like in your second photo, Auto would do a very good job and any adjustments needed would be fairly easy in PP.

Thats what I'm thinking anyway at this point

Jay

[cyclohexane]

I'm thinking a couple of things here. Primarily even though there's a picture with the text, and I know it's using the AF points, I still don't know how it's deriving the settings as it takes in the "scene".

The page seems to only cover the meter used in the EOS-1, EOS-3, and EOS-1D/DS series, given the mention of 45-point AF and 21 zones. For one thing, the Rebel XT/350D uses a 35-zone evaluative meter, and does not have 45-point AF. However, the concept is the same. The key here that I was looking for is that there is no mention of COLOR. Therefore, I believe we can assume with reasonable conviction that the evaluative meter still works towards something like middle grey. Nikon's version of evaluative metering (dubbed "3D Color Matrix Metering"; we're on version II right now) weighs color information into the exposure calculation, which just adds another variable to make things more confusing. =)

As for how it determines your exposure, it probably weighs the zones under and around the selected AF point to a greater degree than the rest of them, and compares the entire scene to many, many others programed into the firmware as exposure data. I covered this pretty early in the thread in a post on matrix metering where I called the work "voodoo", because you can't really get inside the meter's head 100% unless you designed it or have one of the engineers who worked on it explain it to you (maybe even more than once, heheh).

So evaluative metering is probably best for snapshots? And by using the partial and center-weighted metering, because the camera is aiming it's settings for middle gray I should have an easier time concluding how the exposure is effecting the image?

Yes to the second question. The first question really depends; I personally don't like it because I don't quite know what it's doing; the concept is pretty basic (view a bunch of zones, note subject placement, compare with similar data, and output exposure data) but like I just said I don't quite know what it's doing.

If I can repeat the shot (after chimping) or the shot really doesn't matter, I'd be willing to use evaluative/matrix, but a lot of my work is spontaneous, which means I need my metering down almost right away, and I know I can get down pat quicker in more situations with center-weighted or spot ("partial" is a fairly large spot meter) than I can with evaluative/matrix.

I've been going through some early work of mine where I really didn't know what the heck I was doing and just let matrix metering figure it out, and there was a 75-80% keeper rate in terms of exposure, but those 20-25% other scenes where the meter got confused really stunk. If I had started with center-weighted (assuming I paid attention to what I was doing) or spot, I think I could have had a 85-90% keeper rate for those same situations.

Edited: That description was for slr cameras, not digital. I'm assuming it's semi-safe to say it's almost parallel to how the digital cameras work.

Yes, the concept of metering hasn't changed much, depending on what you include under the term. If you were shooting slide film, you can basically keep doing the same thing you were doing, but if you were shooting color negatives you can't overexpose several stops like you used to.

[KellyL]

I was just reviewing Bryan Peterson's book, Understanding Exposure, and he gets very frustrated with folks who constantly ask him in his classes what the correct exposure should be. He wants people to think about the CREATIVE exposure...thinking DOF and film speed...and states, once the creative exposure has been determined, "the real question isn't "What should my exposure be?" but "From where do I take my meter reading." However, before I answer that quesiton, let's take a look at the foundation upon which every exposure is built: light!" He then goes on for several pages discussing front light, back light, side light, changing light, morning light, evening light. But I don't know if he ever answers that question. And THAT is the question that started this thread. And now, after typing that, I am thinking that is what everybody has been trying to share. Kirk and Brooks want us to understand the light range that our cameras will pick up, so we can see the image on our digital sensor prior to shooting it, and make adjustments. That is a first step to the question...

Bob continues to suggest auto. He is an accomplished teacher and knows the Zone system quite well. His knowledge far surpasses that of many folks here on the Camel. But full AUTO discards the notion of Creative Exposure. But...are not shutter priority and aperture priority also auto settings? If they are considered auto settings, then that would take care of the creative side of exposure.

[jfrancho]

Av and Tv are "automatic" in the sense that the camera locks one particular aspect of the exposure, aperture or shutter speed, and chooses the other setting based on what the meter reads, keeping it at the preset exposure compensation (EC). In other words, the meter indicator is static until you change the EC.

In M mode, the meter indicator is not static, and when you change one setting, either aperture or shutter speed, the meter indicator will change. Then you would manually adjust the second setting to center the meter indicator.

In other words, Av and Tv are as "automatic" as the information being fed to the camera's metering system.

Now, add to this a reading off a white wedding gown, and you will either use + EC in Tv or Av mode, or choose exposure settings in M mode that give a reading that is to the right of center on the meter indicator.

[PavelOlavich]

Originally Posted by KellyL

I was just reviewing Bryan Peterson's book, Understanding Exposure, and he gets very frustrated with folks who constantly ask him in his classes what the correct exposure should be. He wants people to think about the CREATIVE exposure...thinking DOF and film speed...and states, once the creative exposure has been determined, "the real question isn't "What should my exposure be?" but "From where do I take my meter reading." However, before I answer that quesiton, let's take a look at the foundation upon which every exposure is built: light!" He then goes on for several pages discussing front light, back light, side light, changing light, morning light, evening light. But I don't know if he ever answers that question. And THAT is the question that started this thread. And now, after typing that, I am thinking that is what everybody has been trying to share. Kirk and Brooks want us to understand the light range that our cameras will pick up, so we can see the image on our digital sensor prior to shooting it, and make adjustments. That is a first step to the question...

Bob continues to suggest auto. He is an accomplished teacher and knows the Zone system quite well. His knowledge far surpasses that of many folks here on the Camel. But full AUTO discards the notion of Creative Exposure. But...are not shutter priority and aperture priority also auto settings? If they are considered auto settings, then that would take care of the creative side of exposure.

Those that can, do...those that can't.....how does that old saying go?

Full auto means just that....the camera automatically does the thinking INSTEAD of the photographer. Leave full auto to the snap shooters.

For serious shooting one should take advantage of the settings M, Av, Tv as required. You do your skill training no good in full auto. Using M, Av, Tv forces the photographer to think about the light, and the composition. True Av, and Tv are not fully automatic; lets call them semi-automatic.

Sure one can make a great picture in full auto, but to fully squeeze out the best quality, the quality that a good composition deserves, one often needs to tap into the creative zone a camera can provide.

As to exposure, I think one needs to attain the ability to use his human eyes, to scan a composition, to look at it as a camera would, determining how the light will be received by the film or sensor, the width of the dynamic range of the scene, those sorts of things, and when one attains this skill, composing and determining creative exposure comes a little easier. For digital, mastering how to use the histogram really helps to, and one must never judge exposure by the image displayed on the back of his camera...it lies.

As to metering modes, I mostly use evaluative, as I find it very accurate most of the time, and really, with the advent of the histogram, metering is much easier, and with digital it is often less important which metering mode one uses, with some exceptions of course. Evaluative places more weight on the active Focus Point used....it's a weighted average across several zones...it really works great.

[brian.austin]

Originally Posted by PavelOlavich

Those that can, do...those that can't.....how does that old saying go?

I wonder if you see the irony in this statement considering your novel-like posts...

[expensive_hobby]

Thanks for noticing my slow piecing together the puzzle, Kelly. I'm not totally sure just how "there" I am yet, but I know I've gained quite a bit of ground these past few days.

But I'm also not naive to the fact one simple thing can create changes. For example I wanted to see the effect/difference that would happen to the meter reading by simply placing a polarizer on one of my lenses. The reading changed by two stops. But that's not something I think I'm ready to dive into just yet.

Originally Posted by cyclohexane

The page seems to only cover the meter used in the EOS-1, EOS-3, and EOS-1D/DS series, given the mention of 45-point AF and 21 zones. For one thing, the Rebel XT/350D uses a 35-zone evaluative meter, and does not have 45-point AF. However, the concept is the same. The key here that I was looking for is that there is no mention of COLOR. Therefore, I believe we can assume with reasonable conviction that the evaluative meter still works towards something like middle grey. Nikon's version of evaluative metering (dubbed "3D Color Matrix Metering"; we're on version II right now) weighs color information into the exposure calculation, which just adds another variable to make things more confusing. =)

As for how it determines your exposure, it probably weighs the zones under and around the selected AF point to a greater degree than the rest of them, and compares the entire scene to many, many others programed into the firmware as exposure data. I covered this pretty early in the thread in a post on matrix metering where I called the work "voodoo", because you can't really get inside the meter's head 100% unless you designed it or have one of the engineers who worked on it explain it to you (maybe even more than once, heheh).

Thank you for further clarifying this.

Originally Posted by cyclohexane

Yes to the second question. The first question really depends; I personally don't like it because I don't quite know what it's doing; the concept is pretty basic (view a bunch of zones, note subject placement, compare with similar data, and output exposure data) but like I just said I don't quite know what it's doing.

If I can repeat the shot (after chimping) or the shot really doesn't matter, I'd be willing to use evaluative/matrix, but a lot of my work is spontaneous, which means I need my metering down almost right away, and I know I can get down pat quicker in more situations with center-weighted or spot ("partial" is a fairly large spot meter) than I can with evaluative/matrix.

Yes, I started to go back to the first post in this thread, but unfortunately my children on summer break take precedence to my understanding this. I slip in when I can, and that's the best I can do for now. But I do have every intention of going back and reading every single post.

What has intrigued me, and I'll give a specific example, is this:
Both of my daughters are ice skaters. Nothing is ever the same when they are on the ice. The ice itself is literally white, as is the lower half of the wall below the plexiglass. Leotards, in every color of the rainbow and more, generally have some type of glitz to them, along with the silverness of the actual blades.

Now regular open public sessions and their actual lessons will give me a wide range of colors, pretty continuous lighting and contrast. Yet full fledged performances never offer continuous lighting as they move across the ice. Is it predictable? Sort of, but not really. I do not have time to be metering this and that looking for the *perfect* exposure. So I'm curious if that's going to be the best time for me to use evaluative. My opinion would be yes.

[expensive_hobby]

Originally Posted by KellyL

I was just reviewing Bryan Peterson's book, Understanding Exposure, and he gets very frustrated with folks who constantly ask him in his classes what the correct exposure should be. He wants people to think about the CREATIVE exposure...thinking DOF and film speed...and states, once the creative exposure has been determined, "the real question isn't "What should my exposure be?" but "From where do I take my meter reading." However, before I answer that quesiton, let's take a look at the foundation upon which every exposure is built: light!" He then goes on for several pages discussing front light, back light, side light, changing light, morning light, evening light. But I don't know if he ever answers that question. And THAT is the question that started this thread. And now, after typing that, I am thinking that is what everybody has been trying to share. Kirk and Brooks want us to understand the light range that our cameras will pick up, so we can see the image on our digital sensor prior to shooting it, and make adjustments. That is a first step to the question...

Sorry Kelly, it appears we got seriously off track of your intentions for this thread: creative exposure.

The part I've bolded, I'm also thinking that is the first step.

[cyclohexane]

Yet full fledged performances never offer continuous lighting as they move across the ice. Is it predictable? Sort of, but not really. I do not have time to be metering this and that looking for the *perfect* exposure. So I'm curious if that's going to be the best time for me to use evaluative. My opinion would be yes.

Actually, I'd disagree. My opinion is no.

Those are the exact situations where matrix/evaluative consistently fails- noncontinuous lighting indoors. I'd be using spot off the face of the subject and be twirling my thumb as the light changed, or maybe using aperture priority if I could keep my spot meter in place while the skater moves. Of course, I'd shot RAW if I could to account for small exposure errors.

[PavelOlavich]

Originally Posted by brian.austin

I wonder if you see the irony in this statement considering your novel-like posts...

I fail to see the irony. Perhaps there is none. As usual. You see, I don't teach. I do. About 6,000 shutter accuations on average per week.

Now I remember...."Those that can, do. Those that can't, they teach"....Woody Allan had his own spin ".....Those that can't, they teach. Those that can't teach, teach gym", or something like that.

So how many shutter accuations have you made last week Brian? Now that's Irony!

[brian.austin]

Originally Posted by PavelOlavich

So how many shutter accuations have you made last week Brian? Now that's Irony!

It's "actuations".

I claim no "pro" status or elite knowledge of all things photography. You do.

I make no diatribes slamming other's theories and practical knowledge. You do.

I do not make veiled personal attacks while turning around and doing the same thing that I claim to be above. You do.

But, to satisfy your curiosity, I had about 500 shots last week of family, friends, and my wife's grandfather's airstrip home after attending his funeral. And, unlike you, I can prove that with some previously posted images:

http://www.photocamel.com/forum/land...gone-west.html

http://www.photocamel.com/forum/port...e-ps-work.html

To save you the trouble of expending brain cells, this is where you pull out the "I don't need to post images to justify my superior photographic knowledge" post. Or you could simply link one of the many posts we've seen before.

Same ole' Pavel...

[jfrancho]

Take it off line.

[kgphoto]

cyclohexane basically said why I want you all to "KNOW" what is going on in front of you as it relates to exposure. Under 80% of conditions, auto will work. I am not satisfied with a 20% failure rate. Under certain conditions auto will provide a 100% failure rate. Way too much for me.

Extreme contrast between subject and background and or harsh lighting is where auto fails. If you get in to the habit of always looking at a scene and understanding what is there and setting or adjusting accordingly, you will find it becomes second nature and fast. You may adopt certain approaches that help you to cope with the lighting conditions you are frequently in. These will be informed short-cuts that take into account your specific wants and desires and shooting conditions.

I don't know how a camera computer could "read" a scene and decide what you think is important. That, IMHO, is up to the photographer.

[jfrancho]

I don't know how a camera computer could "read" a scene and decide what you think is important. That, IMHO, is up to the photographer.

Good point.

80% of conditions auto will work.

That is probably true, but I would say that you'd have to reverse that ratio to express my own satisfaction with what AE generates. For me, I choose to manually expose based on my personal preference of the portrayal rather than any deficiency in the camera system.

[kgphoto]

Originally Posted by jfrancho

Good point. That is probably true, but I would say that you'd have to reverse that ratio to express my own satisfaction with what AE generates. For me, I choose to manually expose based on my personal preference of the portrayal rather than any deficiency in the camera system.

J,

Not sure what you mean by reversing the ratio. It seems your next sentence says it is working, you just don't like the portrayal? Just trying to follow your point.

[jfrancho]

I was agreeing with you. 80% of the time, the exposure would be acceptable, but I would only like the exposure 20% of the time, using AE. At least, I think we are agreeing...

[KellyL]

Originally Posted by KellyL

Can we say GRAY CARD??

Finally, out of the camera, an exposure that looks half way decent.

Gray card, gray card, gray card, gray card. Kelly has been lazy gray card.

I used my $500 spot/incedent meter to meter the gray card. Set the camera according to the settings and went to town. This was without flash. All natural light.

Pensive: This is the post I was trying to answer. It was on page 10. I had been thinking about what John challenged me to do, and had not gotten back to him. Didn't want him to think I was ignoring him.

[JohnC]

Originally Posted by KellyL

But full AUTO discards the notion of Creative Exposure. But...are not shutter priority and aperture priority also auto settings? If they are considered auto settings, then that would take care of the creative side of exposure.

I see a BIG difference between using AV or TV mode vs full auto (green zone, PROGRAM, or AUTO setting). in the full auto zones the camera is picking both aperture and shutter speed. And it may even be deciding to pop up the built in flash, if your camera has one. All you do is point and shoot.

I liken AV and TV modes more towards manual control. You are making a conscious decision about how you want the scene to look. Are you more interested in depth of field? Go into AV mode and select the aperture you need. Do you need to stop motion? Go into TV mode and select the shutter speed you need. You can use the exposure compensation dial then to adjust your exposure. But in either case you are engaged and making decisions with the help of the built-in meter.

[JohnC]

Not a direct challenge just to you. Open for anyone. What do you do in these situations where the dynamic range of the scene exceeds the capture ability of the film or sensor? Do you expose for the highlights and let the shadows go black? Do you expose for the shadows and let the bright areas blow out? Do you average and have black shadows and blown highlights? Do you do something else?