Understanding Exposure

[kgphoto]

Kelly,

I don't mean to bust your chops too much!

I can't explain it any better than Brooks did. He did an excellent job. I wish I could see the pictures you posted as I type this. It would make it so much easier to refer to them.

As far as your band camp shots, reproduced here, you have lost the high light detail on the shirts and some of the skin. That shows the upper end of your exposure range. Had you stopped down and added a little flash into the shadows, you would have have richer tones in the colors. That is how I would have handled it. Or shot in softer light(open shade).

By the way if you shot at ISO 100 at 1/60 and f:16 you have OVER exposed, not underexposed the image capture. This slides your whole range up one stop, which is why you have detail in the shadow and burnt high lights. Most of the time, people expect to see darkness when they look at shadows, so it is more natural to have them dark and rich colors.

I think the rest of your questions were answered by others. If not, please ask again.

[KellyL]

Thanks Kirk. I was hoping that my comments didn't sear you. I was frustrated because I thought...shortcuts? If I were looking for shortcuts I wouldn't try to have a greater depth of understanding. I very, very much appreciate all of your help you have given me. You have followed my posts faithfully and have always been willing to pull me to a new level of professionalism, which is one of the great reasons to belong to the Camel.

And I realized later that I had gotten that backwards...as far as the exposure is concerned. I still get those numbers and directions confused at times...even though I know. I was surprised it stood as typed as long as it did without someone else correcting me. And you didn't even have to say "Brace yourself".

I understand about the softer light. My plan was to go to band camp in the evening and take some pictures, but I discovered band camp was ending at 5:00 instead of 8:00 like it had the previous two days. I was too wrapped up in Camel talk on Monday and Tuesday to get myself out there when the light would have been better. That being said, when I follow the band this fall, I will be following them in bright conditions and shooting from the sidelines like I did here. I think I'll take my Metz out with me next time and practice with it. That powerful little puppy may be able to add the light I need to bring up the shadows just a tad.

Michael, I understand what you are saying. It makes sense.

Harry...you are on the other page, so I can't see your comments...and Pensive...so I will type from memory. PLEASE DON'T LET MY INSECURITIES AND QUEST FOR BROADER UNDERSTANDING MESS UP WHAT YOU ALREADY KNOW! Our cameras have been designed by egineers who know that they have to produce the best camera with light meters they possibly can...a benefit of a free market economy. Since Canon and Nikon and Olympus (for Mr. Pickles and Mitch...MVB) are competing against each other, they are going to make sure you have a fine instrument in your hands.

I do have a tendency to overthink...but if I regiment myself to overthink in the safety of this forum, or when I practice my shooting, then when it counts I will have built up a huge knowledge base from which to operate. I want an iceberg so I can use the tip.

[Max@Home]

Originally Posted by KellyL

I set my camera to Aperture priority...

..and what aperture did you pick ?

...and went to shoot. I think I used center weighted metering. For each shot I then took meter reading off of the cheek recomposed with button half pushed down and shot. This was with my 70 - 200 f/28 L lens. I think I am learning how to use it more successfully.

...mhhh... they still don't look completely right... focus-wise... when taking meter reading, did you also take and lock AF ??

...maybe try to take center-weighted meter reading and lock that with * button on back, then recompose and use the appropriate AF point - on the eye...

...€0.02...

Max@Home

[expensive_hobby]

Originally Posted by Max@Home

..and what aperture did you pick ?

Allow my novice self to show just how *brilliant* I am. You can pick your aperture when you set up a-dep? I'm thinking my camera doesn't allow that.

[expensive_hobby]

Originally Posted by Brooks

Set up your camera in manual exposure and manual focus. Focus on infinity to avoid any bellows factor and use a surface that is large enough to fill the frame AND be sharp at infinity focus. A stucco wall works well. Do a series of exposures starting at 5 stops under to 5 stops over the meter reading in increments of one stop. Using f-stops for these brackets is more exact than using shutter speeds. But you might have to adjust both f-stops and shutter speeds if you only have 9 f-stops ie: f1.4 2 2.8 4 5.6 8 11 16 22

Look at all 11 exposures and label them N-5, N-4, N-3, N-2, N-1, N ( which is the meter reading) N+1, N+2, N+3, N+4 N+5 You probably won't see any texture in N-5 and N-4 nor in N+4 and N+5. The darkest exposure that shows just a hint of texture is your shadow detail and the lightest exposure which shows some texture is your highlight detail. That's the dynamic range of your sensor. It will probably be N-3 and N+2 which is a 5 stop range. But it could shift either up or down from that range depending on your chip and whether you are using any custom curves in the raw file capture.

Printed above selection and heading out for the day in hopes I can find somewhere to test this while running 1,001 errands.

[KellyL]

Max, most were shot at 5.6. Jumped to 2.8 when I wanted greater DOF.

I need to become more nimble with the lock button. I experimented with it but haven't mastered it.

If folks are willing, I would like this thread to take a little bit of a turn. So far this discussion has focused on the theoretical/philosophical aspects of exposure. What I would really, really, really, really like to see....did I emphasize REALLY....are real world examples. Examples of where you have found yourself in specific situations where you needed to get correct exposure, what you did to get that exposure, and post a picture of that exposure.

The intent would NOT to judge composition of a picture, but exposure. Although exact conditions for the exposure you are illustrating will not be replicated by another photogrpaher, what you share may help build the "library of exposure techniques" in the mind of the photographer and help them develop a point of reference from which to build as he/she...we...find ourselves in similar situations.

I will give you an example. Mark McCall is famous for his lighting of outdoor bridal portraits. In his posts, he explains how he metered his background and what he set his Metz at to achieve the photograph that he created. You can see this here: http://www.photocamel.com/forum/wedd...ash-setup.html
Who is game?

[Brooks]

Before we jump into real world exposure examples I think it might be useful to see exactly what the meter sees when we meter a tone and either accept the exposure given as a medium grey (N) or move that exposure up to a N+1 or N+2 etc. or down to an N-1, N-2, N-3, etc.

I've done a series of exposure samples this morning in the studio. Using a MF Digital Back, I photographed a white towel lit with a single hard continuous light so that the texture of the towel is easily seen.

I metered the towel with a spot meter and made exposures at N-4, N-3, N-2, N-1, N N+1, N+2, N+3 and N+4. The N exposure is the direct exposure indicated by the meter which produces a medium grey. Remember, THE TOWEL IS WHITE> The other exposures are either more or less exposure in increments of one stop.

The point of this exercise is to visualize the differences between these exposures and to find the correct exposure adjustment to render a textured highlight and shadow area. In the world of film a textured shadow would be usually be found at N-2 exposure and a textured highlight at N+2, possibly N+3. As it turns out this is also true with digital capture and this particular digital back at ISO 100. Your digital camera might be slightly different.

As you can see from these exposures highlight detail becomes blown out between N+2 and N+3 or about 2.5 stops over the meter reading. Shadow detail holds through N-2 and almost into N-3 which would be 2.5 stops below the meter reading.

The range of usable detail (Dynamic Range) for this chip is N-2, N-1, N, N+1, N+2 or 5 stops, perhaps just a bit more into the highlights at N+2.5

Here are the tonal patches for each of these values.....

[jfrancho]

Max, most were shot at 5.6. Jumped to 2.8 when I wanted greater DOF.

You have this relationship backwards. f/2.8 provides less or shallower depth of field than f/5.6. See Online Depth of Field Calculator.

[Brooks]

Here are the remaining patches

[Brooks]

Perhaps these would be easier to compare if they were together in a greyscale...

[KellyL]

John...when will I type correctly what is in my head? I know the relationship, but my mildly dyslexic mind doesn't always let it come out right. Thanks for the correction.

[JohnC]

Dyslexia aside, can I suggest that your next "understanding..." topic be Depth of Field?

Not because I'm picking on you, but it is another often mis-understood area of photography. Your comment just opened the door for it.

[jfrancho]

DOF dovetails nicely with exposure concepts since once you establish a desired DOF, aperture is locked in, and your variables are limited to shutter speed and ISO.