Scotty claims:
The difference between 1/25 sec and 1/4 sec is 2-2/3 stops, 6.25x as many photons falling on the sensor. That's the reason for the slight reduction in noise.

Again, Selmslie tries to obfuscate with bad math...no wonder he has problems with photographic calculations:
1/25sec ...1 stop > 1/12 sec...one stop > 1/6 sec ...one stop > 1/3 sec ... 1/3 stop >1/4 sec.

That is, in fact, 3 and 1/3 stops

He'll have to think on it a bit more; but, with effort, it should come to him!

I can't believe no one else has corrected him !

There have been numerous posts promoting the use of ETTR/EBTR (expose to the right, expose beyond the right) based on a ten year old concept developed by Michael Reichmann of the Luminous Landscape. The idea originated when Reichmann observed that his existing camera was not taking full advantage of its dynamic range (DR) thereby missing an opportunity to suppress noise and use the full DR of the sensor in capturing images.

A lot of progress made in the past ten years has widened the DR of modern sensors and found ways to suppress noise that were not part of the cameras that Reichmann originally used. By the time Reichmann passed away earlier this year he had stopped promoting the concept of ETTR/EBTR because modern sensors have pretty much eliminated the need for it.

However, there are still die-hard users of the technique who promote its use, in the absence of any remaining logical need for the convoluted process.

Today's cameras support DRs of over 14 Ev at base ISO, far exceeding the DR in the vast majority of scenes encountered by the photographer. In those rare cases where the scene's DR is too wide for the sensor, HDR can be used to combine multiple exposures.

The signal to noise ratio (S/N) is also highest at base ISO. For situations that call for the use of a higher ISO (lower S/N) there are many solutions for removing unwanted noise from the image.

ETTR/EBTR has been promoted as a way to maximize the use of the camera's DR by increasing exposure. That claim is misleading. All you need to do to accomplish that is to lower ISO and thereby increase the recommended exposure - slow down the shutter.

It has also been suggested that ETTR/EBTR can reduce S/N, noise. That is also not true. What reduces noise is the additional exposure (signal) from slowing the shutter speed. You can also get there by reducing the ISO and slowing the shutter.

Nowhere in the promotion of ETTR/EBTR has it been suggested that you can get the most out of a camera’s dynamic range by simply lowering the ISO and increasing the exposure time. Neither is it suggested that reducing the ISO and increasing the exposure is a simple way to increase S/N and reduce visible noise.

Nowhere in the promotion of ETTR/EBTR is the dynamic range of the scene compared to the dynamic range of the camera at any ISO. That would expose a critical piece of missing information – that the maximum dynamic range of the camera is only available at base ISO.

In fact, I have posted a complete list of disadvantages to the use of ETTR/EBTR. Here are just a few:

- Determining the ERADR (Extra RAW-Accessible Dynamic Range) for your camera requires careful research since it is not a constant. It is less at higher ISO settings.
- Setting up the exposure for an image is not simple since you need to look at the histogram, possibly after attempting a test image, and then calculate how much exposure you can get away with adding.
- Once the final image is captured, you often cannot review the results on your camera because the resulting JPEG representation may be washed out.
- There is always the danger that the histogram is inaccurate and that you might go too far to the right, blowing highlights.
- There may be highlight and shadow details in which you are not really interested. This complicate the interpretation of the histogram.

So not only are there significant disadvantages to the use of ETTR/EBTR, it is clear that there are no demonstrable advantages.