Why Exposing to the Right (ETTR) is BAD!

Started Mar 30, 2013 | Discussions thread
Tan68
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Re: Why Exposing to the Right (ETTR) is BAD!
In reply to schmegg, Apr 1, 2013

schmegg wrote:

... You still have not commented on this though - instead you seem to simply imply that I don't know what I'm talking about - which I find to be a cop out and, most likely, an avoiding tactic.

"Avoiding tactic" is generous.  I thought to make a comment a few hours ago.  At that time, I thought the fellow had a little trouble with his explanation.  If you have explained things countless times yet no one understands, maybe it is worthwhile to re-evaluate the explanation.  etc.

Of course taking a picture at two different gains/ISO aren't the same.  What he means, though, is that the end product will look pretty much the same.  The ISO 400 shot with one stop of ETTR will be brighter than the ISO 200 shot 'properly' exposed.  When the brightness of the ISO 400 shot is reduced one stop in post processing, the two images will have very similar characteristics with respect to noise and etc.  So, effectively, the image taken at ISO 400 + 1 stop ETTR is the same as the ISO 200 picture.

Taking two pictures with different gain settings are not the same.  Most people will not see it as the same because there is a different camera setting involved.  That is simple and obvious.  In trying to explain a concept to people it is worthwhile to not create a point of confusion and instead admit that the settings on the camera are different but the end product, the final result will be the same and here is why.  That is a way to explain things to people.  The fellow you are dickering with has chosen another way to explain things.

For some cameras, it actually isn't the same to use two different gain settings.  This gets more technical and it is not something I can explain very well... One camera may have basically the same read noise at both ISO 200 and 400.  Another camera may have less read noise at ISO 400 than at ISO 200.  For this first camera, to say "ISO 400 + 1 stop ETTR = ISO 200" is pretty much right.  For the second camera, to say  camera, to say "ISO 400 + 1 stop ETTR = ISO 200" is not entirely correct.  Why cameras some have different read noise at some ISO and not at others and other cameras have the same read noise at different ISO, I don't know.  Hmm, I think it is read noise at issue.  In any case, the scenarios I have described exist.  Still don't know why.

So, in trying to help people understand a concept, it is sometimes better to see things from their point of view, explain you understand their point of view, and then explain how things can be looked at differently.

Telling someone two different gain settings are the same when what is meant is that the end result may be the same is another way of explaining things.

Telling someone that two different gain settings with the higher gain receiving +1 stop, will produce the same result isn't always true.  The results vary by camera and by the particular gains/ISO being used for each camera.

Anyway, I hope this helps you understand that I think the fellow is trying to explain that the end result is the same and this is once the brightness of the ISO 400 +1 has been reduced to match that of the ISO 200 +0.

I believe this will be true for most cameras.  It is not true for all cameras and it is not true for all cameras for all available ISO's...  The differences may be more or less..  But this is a thread about very particular exposure so the small differences should be considered.  If you want to be particular...

I think, out of hand and finer points set aside, that what the fellow is telling you is a fine rule of thumb.

PS - I have read even a few more posts!  Shortly after your post that I replied to, you mentioned different read out noise and etc.  So, I needn't have mentioned all that to you.  I am glad things are approaching fusion between you and the other fellow.  It seemed a singularity was approaching...

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