Understanding Exposure

[cyclohexane]

It seems to me that by underexposing by one stop the range of detail from highlight to shadow would be greater.

Highlights, yes, but your shadows get noisy, and a full stop of underexposure means that the shadow noise will creep into your midtones. As always, you gain some and you lose some. Take your pick. Personally, I'll take the clean midtones.

Expose to the right usually involves keeping the highlights in, but if you're printing on newsprint your highlights and shadows go anyways, so we typically just expose for our subjects and/or desired effect and let everything else fall where it does; usually it looks fine on print and on the web.

[KellyL]

Yep, wasn't as scary as I thought it was.

[KellyL]

Mr. Michael,

I have been thinking about my experiment, as suggested by Brookes, I do believe, and now I really have a better understanding that my camera has a definite five stop range. Alhtough there is still some detail in the black, most detail is lost. Detail is found readily in the five stops N-2, N-1, N, N+1, and N+2.

Now if I am to apply what I have learned from this, if I meter a highlight, I have just assigned it N, which means if I keep that reading, my shadows have dropped to N-4, and I will be losing lots of details in the shadows. So, by underexposing my highlights by one stop, I bring my shadows up one stop. Darkest shadow is now at N-3, which still retains some detail, but now my midtones are being exposed at N-1.

So why is that useful?

Why not just use the meter to expose for the 18% gray and shoot?

I guess it is because every scene is greater than a five stop dynamic range and I have to make decisions as to where I want to lose the detail. But wouldn't exposing for the midtones just require that detail is lost on both ends of the spectrum?

Brookes...please tell me why this test was important!

Kirk...please chime in...you can even say "Brace yourself..." I'tll seem like old times.

[kgphoto]

OK Brace yourself! LOL

I don't know why you make this so hard. Read the scene and either adjust the light to fit the range, or chose those elements to sacrifice to the photon gods. By calibrating the meter, camera and lens, you will have accurate info on which to base your choice.

Then it is all about how much work do you want to go through to get the "best" picture. See the obsessing thread.

[Worm324]

Great read Kelly Sry I missed you last night! That dynamic range test was very interesting indeed!

I just read what you wrote about 5 times, and I'm still a bit confused. If you expose for the highlights and assign them N, how do you know your shadows are N-4? And if you underexpose for the highlights by 1-stop, wouldn't that make the shadows 1 stop darker N-5 not brighter?

I apologize if I'm reading this wrong

In any event your assessment of underexposing a bit so you have more detail to recover, I 100% agree with. You may have a bit of noise in the shadows, but the midtone noise is going to be hard to see IMO. Unless the highlights are super bright that is and your scene looks very dark. But on average bright highlights I would much rather underexpose to have the detail in "the hair" for example and just recover the mid's by a stop or so.

Thats my thought anyway

Best,
Jay

[kgphoto]

Kelly,

Worm's question made me think of a point.

When you measure and read a scene, you visually identify a point to set at N, which would be an incident meter reading of the overall scene. IF the point that you visualize comes in at N and you like it there, that is what you start setting your camera at.

Then you look at the rest of the light values and see where they fall. If they are in range, shoot it. If not, know what will be lost and/or shift exposure to save what you can, or modify the light to get it all. You know what I would probably do.

Alternatively, you could read the range and pick an exposure setting that encompasses them all. This avoids having to mix reflected and incident reading.

[Rense]

nope,
take a quick reading at this link where I talk about the zone system.

[Worm324]

I just wanted to add this picture to show how P mode saved me last night I was at my friends bachelor party and we were inside Dave & Buster's so the lighting conditions were pretty unknown for me Also your not allowed to take pics in there and I had several cocktails, so I had to be quick.

The flash comp was set to -1 in Av mode, so I'm not 100% sure if that carried over to P mode. But I just let the camera do it's thing on full auto and it came out with this.


I think thats pretty good exposure wise considering the conditions and the lens I was using. If I had the 580ex or something with a diffuser I bet it would look a lot better, but for a stock rebel on auto I was happy Some PS work and this will look really good IMO.

Best,
Jay

[cyclohexane]

You may have a bit of noise in the shadows, but the midtone noise is going to be hard to see IMO

Depends on your sensor's noise response, too. The D2H looks ugly as fast as 1/3 stop of lightening.*

*this could just be the photo gods' way of telling me I should buy a newer camera

[Worm324]

This image was a little more in my area of experience lighting wise so I set the camera how I though it should be and fired with the flash comp on -1.

I knew we were all sweating from hiking down to the river and I also new my head is really shinning and loves to blow out in pictures

I decided to purposely underexpose this a little bit by exposing at 0 exp comp. My camera on default seems to be 1/3 stop dark so +1/3 is IMO true 0.

Also based on the tests Kelly has been doing I knew my flash comp should be higher in order to fill in the my eye sockets, but I also knew the flash would probably blow out are sweaty faces.

Anyways, here is the result right off the camera. You can see me (middle) and the guy to camera rights heads are just about blown, but not. and the eye sockets are dark. A total compromise, but I would rather recover the she shadows in the eye area than have a blown out head Gatta love the self timer mode also


Thanks again Kelly for keeping this thread going!! and to everybody thats contributing

Best,
Jay

[Brooks]

Originally Posted by KellyL

Here are larger snapshots of N-5 and N+3. Three stops over, and it looks like I am losing serious detail. I have lost a lot of detail in N-5, but some detail is still discernable. At N+4 all detail is lost. Why is more detail kept in the N-5 image? Is it because it is a white subject?

Kelly,

There's no real information in either your N+3 or N-5 exposure. What you do have there is a barely discernable texture which is just a transition from a textured shadow/highlight to a blown shadow/highlight.

If you look at the Zone Ruler you posted earlier, you can see that your real textures shadow is N-2 and your real textured highlight is N+2 which is a 5 stop (N-1, N-1, N, N+1, N+2 ) dynamic range. I say N-2 and N+2 are "real" textured zones because there is information in those zones that can convey a usable amount of detail and texture in an image. A 5 stop dynamic range is typical for a small 6 mp sensor.

[KellyL]

Kirk asks why I make this so hard.

A beautiful blue sky. White clouds. Subject in front of sun. Want to take a lasting picture where the sky is blue and the subject is well illuminated. Exposing for the subject blows out the sky, exposing for the sky and the subject is in the dark.

Have the subject turn around and face the sun! Forget it. Squinty eyes do not make a beautiful picture.

So...get a grip on the five stop dynamic range of the camera. Doing the test helped me to visualize what five stops look like. If I meter for the highlights, I have to be willing to accept that anything two stops below the highlight will be lost. If I meter for the mid tones, I have to accept blown highlights because the dynamic range of the camera can not withstand the dynamic range in reality.

So to create that beautiful blue sky, open sun picture, I have to learn to mix my flash with ambient light. That is what this thread is all about.

It has been suggested along the way to just put the camera on auto and fire away. When I tested that idea, the results were better handled by the camera than when I tried to take matters into my own hands.

Jay, I have noticed that when I have my flash on and in P mode, the camera automatically sets to 5.6 1/60, which is what Mark McCall uses to create much the same shot you did here. Your camera opened up to 4.0, which allowed a bit more ambient light in.

Your hiking picture looks pretty good. I wonder what it would have looked like without the flash. Was the camera close enough that the flash had an effect?

Rense: I'll check out that link. I am still trying to figure out the importance of this zone system. The two latest books I have read both refer to the system. Exposure and Lighting for the Digital Photographer Only and SKIN both bring up the zone system and the dynamic range issues.

And why is it that the 30D IS only a 6 mp camera. It should have been 10. With a greater DR.

I have also read in book, after book, about how difficult exposure is for digital capture and that many folks struggle with it. So I know I am not alone.

So...why make it so difficult? Because, without thinking I want to:

1. Create a shot outside with a beautiful blue sky and a subject well lit.
2. Create a shot outside with a beautiful blue sky and subject in shade well lit.
3. Create a shot outside when it is partly cloudy and have colors look fully saturated.
4. Understand how to take a shot outside in the evening and have the background exposed properly as well as the foreground.

I could keep making that list.

But I want to make sure that I have all of these things practiced and nailed so that I don't have one bit of guesswork to do and can be more creative and at ease with my subjects.

[KellyL]

Good tips from mr. Rodgers.
In the weekend I will share some more tips. For now remember the golden rule:
film: expose for the shadows, develop for the highlights
digital: expose for the highlight, develop for the shadows.

This is the first step on to the path of a good exposure (and by the way also the first step to the zone system (don't be afraid)).

B/W also affects composition and you can play tricks with light by using filters.

boy this sounds like a 5day course.

Rense

Rense, Jay and I both just decided that we were going to underexpose the midtones a bit. To me, that is exposing for the higlights.

[Worm324]

Kelly, Thanks for the comments

I just wanted to re-iterate how valuable this thread is to me and I'm sure many others. I felt like I had a good understanding on how to get a good exposure when this thread started, but now I feel I have a 10x better understanding!

As you said, adding the elemts of sky, Sun and Flash is a lot of variables so trial and error/ practice is also a big part. If you scroll back to the beginning of this thread and look at your pictures, then look at the most recent picture you posted, the improvements are monumentally!

As far as my shot goes, I was using the Sigma 10-20mm @ 15mm so the camera was a bout 8-10 feet away. So I think the flash did a lot IMO. I'm not sure what it would look like without the flash, but my guess would be much more underexposed. The people anyway.

Here is the edited version. This took about 15 minutes or so.




Best,
Jay

[kgphoto]

Originally Posted by KellyL

Kirk asks why I make this so hard.

A beautiful blue sky. White clouds. Subject in front of sun. Want to take a lasting picture where the sky is blue and the subject is well illuminated. Exposing for the subject blows out the sky, exposing for the sky and the subject is in the dark.

Have the subject turn around and face the sun! Forget it. Squinty eyes do not make a beautiful picture.

So...get a grip on the five stop dynamic range of the camera. Doing the test helped me to visualize what five stops look like. If I meter for the highlights, I have to be willing to accept that anything two stops below the highlight will be lost. If I meter for the mid tones, I have to accept blown highlights because the dynamic range of the camera can not withstand the dynamic range in reality.

So to create that beautiful blue sky, open sun picture, I have to learn to mix my flash with ambient light. That is what this thread is all about.

I have also read in book, after book, about how difficult exposure is for digital capture and that many folks struggle with it. So I know I am not alone.

So...why make it so difficult? Because, without thinking I want to:

1. Create a shot outside with a beautiful blue sky and a subject well lit.
2. Create a shot outside with a beautiful blue sky and subject in shade well lit.
3. Create a shot outside when it is partly cloudy and have colors look fully saturated.
4. Understand how to take a shot outside in the evening and have the background exposed properly as well as the foreground.

I could keep making that list.

So Kelly,

Answer your own questions above. it is easy! You have already received the information. It has been done on transparency film for decades in commercial work. Don't believe everything you read, even in books. Sometimes they like to make a big deal out it just to sell their book.

I bet you can answer those questions yourself. Try it. If you get stuck read my old posts and Brooks. It is all there.

[Max@Home]

Originally Posted by Worm324

I just wanted to re-iterate how valuable this thread is to me and I'm sure many others. I felt like I had a good understanding on how to get a good exposure when this thread started, but now I feel I have a 10x better understanding!

Question: would having a live-luminance histogram that followed your settings have helped with this shot?

- if yes, we have just found a(nother) useful tool for LiveView on the 40D (& others ??), when in LiveView, and 'LCD simulates exposure' is set, pressing INFO button twice brings you a live luminance histogram

...€0.02 and a bit...

Kindest regards!

Max@Home

[Worm324]

Yes it would have definitely helped take the guess work out this shot for me! That 40d is a nice upgrade or sure IMO.

I could have also went back and chimped the histogram in playback mode, and retook the shot with some ajustments (more flash) But, I only took 1 image and it was a spontaneous throwaway I thought. It came out a little better than I though it would so I worked it the best I could

Best,
Jay

[KellyL]

It is the thread that would not die.....

Always looking to improve exposure. Of course, this was on AV so Camera did LOTS of work for me. A good lesson learned.

Wish I would have had his face sharp.

[Max@Home]

Originally Posted by KellyL

It is the thread that would not die.....

... yeah, makes you think: Now What ??

Always looking to improve exposure. Of course, this was on AV so Camera did LOTS of work for me. A good lesson learned.

Wish I would have had his face sharp.

...exposure looks purty dead-on to me

...and how did you take focus? which mode, which AF-point ?? ...if you selected the appropriate AF point & didn't recompose and/or move, your lens seems to backfocus ??...

...just *my* €0.02 worth...

Kindest regards!

Max@Home

[KellyL]

I always use the center AF point, but I was trying to get this picture in a hurry. I could have very easily missed the target.