To ETTR or not to ETTR...?

Started 3 months ago | Discussions thread
FingerPainter Senior Member • Posts: 7,779
Re: ETTR rules

Jeepit wrote:

FingerPainter wrote:

From the first article:

... this means that you should bias your exposure towards the highlights, and the right side of the histogram. But, it definately [sic] doesn't mean blowing the highlights. [emphasis in original]

Since you seem to have difficulty understanding the use of "bias" in this context, let me re-phrase this for you:

You should use the highest exposure that doesn't blow desired highlight detail.

Obviously, people usually want to do that without clipping things too much, and it's always a matter of trying to get a good balance,

Not with ETTR.

Thank you for your are you saying ETTR is not needed?

That's not what I am saying. ETTR is the method to minimize noisiness in an image.  Because using ETTR involves adjusting aperture and shutter, these adjustments can have other effects on the image. Sometimes these other effects are of little consequence or may even be beneficial. In those cases, use ETTR. Sometimes the other effects are unacceptable. In those cases, avoid ETTR.  And then there are cases between both extremes.

Widening the aperture decreases DoF and if you widen it wider than the sweet spot, will reduce lens sharpness, though widening it only up to the sweet spot increases lens sharpness. Slowing the shutter increases motion blur.

For landscapes, it is rare that using ETTR will slow your shutter so much that motion blur becomes visible. This is due to the common use of relatively short focal lengths (and tripods) leading to little risk of camera motion blur, and the static nature of the scene avoiding subject motion blur. So ETTR is often advisable for landscapes.

With ETTR it is not about balance, but rather about a limit. The limit is the highest exposure at which desired highlight detail is not blown. With ETTR the idea is to reach that limit.

Which I understand ETTR is to reach the limit.

Yes, though you are still better off from a noise point of view if you adjust exposure only part of the way to that limit as opposed to not adjusting it at all.

but when people say that rather than trying to get a good balance in general, they're "exposing to the right" it means to me that they're obsessed with trying to maximize the exposure and they risk clipping or degrading the quality of highlights more than someone who simply practices sensible exposure based on the conditions and requirements of the shot.

It only means that to you because you do not properly understand what ETTR is about. It is about getting the maximum exposure that does not blow desired highlights.

how does one not ‘blow the desired highlights if one is over exposing with the EC?

I don't think you use "over exposing" the same way I do. I'll guess that you mean making an image lighter than the lightness targeted by the camera's autoexposure system. Whereas I'd mean using an exposure high enough to blow desired detail.

Depends on the tonal range of the scene. It is quite possible to blow highlights without using any positive EC at all, if there are light details in good light. And it is also possible to find scenes at have multiple stops of headroom above the lightest detail in the scene.

Unless your camera is metering only for highlights, you should not assume that the highest tonal value in the image at the lightness the camera chooses is jus below blowing. It could be above or below that point.

Imagine you are photographing samples of slate on an 15% grey background. If you spot meter on the background you will get an image lightness that matches the scene, but  you may have 3+ stops of highlight headroom because nothing in the scene is lighter than middle grey. IF yo take that shot as metered, Your slate will be noisier than it needs to be. I don't call that correctly exposed. I call it underexposed.

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