Why Exposing to the Right (ETTR) is BAD!

Started Mar 30, 2013 | Discussions thread
Barrie Davis
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Re: Why Exposing to the Right (ETTR) is BAD!
In reply to schmegg, Apr 1, 2013

schmegg wrote:

Barrie Davis wrote:

In both cases the amount of light striking the sensor is identical... that is, an amount that is correctly exposed for 200-ISO. The fact that for one of the shots the camera happens to be set, not at 200, but to 400-ISO with 1 stop of overexposure for ETTR, alters NOTHING.

They are both 200-ISO exposures.

In other words, they are photographically the same, both exposed at 200-ISO, by means of shutter speed and aperture settings commensurate with that 200-ISO rating.

It is, after all,  shutter speed and aperture settings USED which determine which ISO was USED.

As you have stated yourself, the ISO on the dial means nothing, because what happens AFTER the 200-ISO's worth of light has been recorded by the sensor is neither here nor there. The ISO setting of the camera is indeed irrelevant to the strength of the exposure which has already been made...

... all it does is "position" the features of the histogram after the event with more or less amplification in firmware...

...or in SOFTWARE, if you are messing about with the tonal structure afterwards in a computer the way proponents of ETTR would have us do.

Now, does THAT make it any clearer for you?

Yeah - that's a much better reply - thanks for taking the time. I do appreciate it, as I'm sure others do too.

The only caveat I'd add - and you may disagree with, of course - is that, when the sensor is read at ISO 400, the readout signal will be treated differently to how it will be treated at ISO 200.

And this could, depending upon the particular camera, affect the final result - either in a good way or in a bad way. Though, as I said earlier, I doubt it would be particularly significant in most cases. Particularly in the case of adjustments made for ETTR.

I did tests with two different camera marques to find out what their responses were to processing via ETTR and subsequent tonal correction in Photoshop (ACR)..

...as compared with the USUAL WAY of invoking a lower ISO (!)... ;-)...

... and the results were so close to identical I was amazed at how different they were NOT. Indeed, I had expected to see some kind of difference -(well you would, wouldn't you?)- but despite looking as close as I could, if there was a difference, it was invisible to me. I do have some experience in evaluating photographs, it has to be said.

For this reason I feel completely vindicated in taking the stance that I do regarding the usefulness of ETTR.

However, that comment should be qualified. My conclusions extend only so far as the two cameras I checked... and that was six years ago.. (no, seven). If ETTR has gained validity in the meantime I don't know that it has, and suspect that it hasn't...

....but I have to admit that it is not impossible.

I ask, because for most people it doesn't, at least not usually. Most people just argue, and I'm not in the mood for that, I'm afraid.

Yeah - fair enough. I can understand that.

I would add though, that if you wish to make claims in these forums - particularly in beginners forums - you should really be prepared to explain them if people have questions. At least IMHO (for what it's worth).

No offence meant by that Baz - it's difficult to word the sentiment in a way that is not perhaps in danger of being perceived as insulting - but that is certainly not my intention at all!

The forums are really a place for people to share experiences and learn from each other. So your explanation is very much a good thing - and I'm sure it didn't really hurt all that much.

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Regards,
Baz
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"Ahh... But the thing is, these guys were no ORDINARY time travellers!"

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