selmslie Loc: Fernandina Beach, FL, USA

It has been established that a reduction in noise is accomplished only by increasing exposure - the combination of aperture and shutter speed. A constant exposure results in no change in the level of visible noise in an image, regardless of ISO (see the next post for links to evidence).

The examples in those posts also demonstrate that the histogram for an underexposed image can be moved to the right by as much as 3 Ev after the raw file has been copied to the computer to recover shadow information with no visible detriment to the image so long as the histogram in the raw conversion program does not move past the right end of the display.

The opposite is more risky. Depending on how much the image is overexposed, it cannot always be moved to the left on the computer to recover highlight information. This is because the highlights in an overexposed image might be blown.

But why would you need to do either – underexpose or overexpose an image? Modern cameras have much wider dynamic ranges (DR) than most common scenes. Allowing the camera to select the exposure seldom has a down-side if you are capturing the information in a raw file and developing later on your computer. All you need to remember is, “Don’t blow the highlights.”

The only time you might want to take evasive action is when the scene has a much wider DR than the camera can naturally accommodate. In that case you might want to reduce the exposure to protect the highlights, assuming that there is something in the highlights you want to keep in the image.

What am I asking for here is for you to post any evidence of a scene where ETTR/EBTR can solve an exposure situation better than the simple caution expressed by, “Don’t blow the highlights.”

The challenge is to demonstrate the value of using ETTR/EBTR vs. simply avoiding the blowing of the highlights. This is going to require a scenario where the DR of the scene is wide but not so wide as would actually require the use of multiple exposures combined into an HDR image.

So far the proponents of ETTR/EBTR have presented descriptions of the method, what it does and how to go about doing it. What has never been presented to date is any visible evidence (with and without ETTR/EBTR) that it is any better than exposing normally. In other words, what benefit does ETTR/EBTR provide that you can't get simply by remembering, “Don’t blow the highlights?”

selmslie Loc: Fernandina Beach, FL, USA

For additional information, see:

Is ETTR/EBTR a Concept Whose Time has Passed?
What is the Camera's Dynamic Range?
What is the Camera's Dynamic Range? - Part 2

imagemeister Loc: mid east Florida

Lots of people pay lots of $$ to have ETTR shoved down their throats ....as well as raw.

selmslie Loc: Fernandina Beach, FL, USA

Your images clearly show that thoughtful center-weighted exposures work and that JPEG is perfectly fine for your chosen subject matter - wildlife in daylight.

In fact, almost all daylight conditions, especially overcast, will work well with JPEG and simple metering. Only minor tweaks to brightness and contrast are usually all anyone would need.

It makes sense to concentrate your attention on the center of the subject's dynamic range because that is where most of the final image is going to end up - middle gray +/-2 Ev.

Having a raw image as a backup can rescue an undexposed image as I demonstrated in Don't Give Up on Dark Images.

johneccles Loc: Leyland UK

I use bracketing on my camera, I set the exposure to +/- 0.7 plus a normal shot, I usually find the under exposed shots the best for PP, the other thing that can be done is to blend the three shots as in HDR

selmslie Loc: Fernandina Beach, FL, USA

Close counts in horseshoes and hand grenades ... and exposure.

From what I found running my tests (see links above) a lot more information can be recovered from an underexposed image than from one that is overexposed.

In the future if I need bracketing I will probably use -2, -1, 0 because one-stop increments are probably close enough.

imagemeister Loc: mid east Florida

I now "meter" with the exposure comp using the EVF .... and, what am I looking for ? - The highlights ! and let the shadows fall where they may - no guessing and no chimping !

selmslie Loc: Fernandina Beach, FL, USA

That's probably what most successful photographers do whether they are using JPEG, raw or both. Probably more than 99% of them don't bother with ETTR/EBTR or may not have even heard of it.

The use of ETTR/EBTR without knowing the relationship between the camera's dynamic range and the DR of the scene can be a waste of time and effort.

big-guy Loc: Peterborough Ontario Canada

Seems to me that ETTR and "don't blow the highlights" are basically the same thing. ETTR allows one to walk right up to the door without going through whereas DBTH is on the other side of the door and doesn't allow anyone through. Regardless of DR.

selmslie Loc: Fernandina Beach, FL, USA

They are not the same thing.

ETTR is when you increase exposure (slow down the shutter) until the histogram just reaches the right end of the display.

EBTR is when you increase exposure (slow down the shutter) until the histogram goes beyond the right end but not beyond the ERADR (extra raw accessible dynamic range).

"Don't blow the highlights" does not compel you to increase the exposure at all. To the contrary, it suggests that you be mindful and if necessary reduce the exposure (speed up the shutter) to move the histogram to the left to reduce or eliminate the highlight blinkies.

imagemeister Loc: mid east Florida

And the best/fastest way to accomplish this is using an EVF and shooting JPEG - IMO .

big-guy Loc: Peterborough Ontario Canada

So what you're saying is that ETTR takes the histogram to the right without going beyond the right and DBTH allows the histogram to be anywhere as long as the highlights don't go beyond the right.

selmslie Loc: Fernandina Beach, FL, USA

That sums it up.

Of course it does not mean that you should expose recklessly. Average or matrix metering with minimal exposure compensation is a good place to start.

rmalarz Loc: Tempe, Arizona

Why are you only referencing shutter speed? Using a larger aperture, or a combination of aperture and shutter speed, will also increase exposure. I alluded to, some time ago, that taking a photograph is, somewhat, of a system management problem. There are trade offs. If one wants to capture motion, one might have to sacrifice depth of field. If depth of field is important, some motion might be blurred. If both are critical, higher ISO may be necessary. I can understand your not wanting to raise the ISO, but aperture also figures in as a method to increase exposure.
--Bob

selmslie Loc: Fernandina Beach, FL, USA

The same argument applies to aperture. If you can open the aperture you can also reduce the ISO and expose normally.

Once you reach the widest tolerable aperture, the only way you can continue to increase exposure is to lower the shutter speed so we are back to - if you can reduce the shutter speed you can reduce the ISO and expose normally.

Either way you increase the exposure will reduce the noise until you get it below your goal.

The process continues until you have reached the widest aperture, the slowest shutter speed and the lowest ISO that still works. At that point the remaining work is up to you and your raw editor.

Of course, if you start with base ISO, noise may not be an issue. Then it's just a matter of getting the desired DOF an a shutter speed to stop undesired blur. You may need a tripod or image stabilization.

PS: Once you have reached the maximum aperture and slowest shutter speed you can tolerate, your total exposure and noise is set. Changing the ISO only moves the histogram back and forth by changing the gain.