To ETTR or not to ETTR...?

Started 3 months ago | Discussions thread
FingerPainter Senior Member • Posts: 7,792
Re: ETTR rules
4

Adielle wrote:

TN Args wrote:

Adielle wrote:

XRF wrote:

Adielle wrote:

TN Args wrote:

Adielle wrote:

Clipping / squeezing highlights is the worst thing to do in MFT as far as I've seen. True for GX8, E-M1 and G6, so I'd expect it to be similar in other models. Far better to be careful and slightly underexpose than to overexpose.

ETTR is the art of NOT clipping or squeezing desired highlights. Once you understand it, that's obvious.

Level 1 ETTR: JPEG histogram.

Level 2 ETTR: raw histogram. Once you learn to do this, best IQ in terms of noise and colour is attained.

Cheers

When people say "expose to the right" I understand it as having a bias towards possibility of overexposing than towards underexposing, and I believe that's what is actually meant. I don't support this bias at all, and I'm saying that it's far better to have a bias towards underexposing, because any obvious loss of quality is much less likely in that situation.

ETTR is maximizing the exposure without clipping any highlights, and setting brightness in post. Technically, reducing exposure to avoid clipping can be considered ETTR if you intend to bring brightness back up in post.

Any mirrorless camera (I don't know about all DSLRs) already aims to do exactly that, by default, when the exposure knob is centered: maximize the exposure without clipping highlights. That's obviously not always the desired setting, because sometimes some highlights lower the average exposure too much, and sometimes you actually want to lower the average exposure and retain highlights better, and sometimes it's actually not enough exposure for whatever reason, so the exposure compensation option is provided (as well as various auto exposure settings). I don't see "ETTR" as having anything to do with "maximizing exposure without clipping" but as having a personal bias towards maximizing the average amount of highlights (getting a histogram with lots of highlight content) in any situation (manually).

You evidently don't understand it. That's why I explained it for you. It has nothing to do with personal bias.

A couple of useful tutorials, 1, 2.

cheers

No, I understand it perfectly,

It doesn't seem so.

it has everything to do with personal bias.

I take it English is not your first language. The use of "bias" in these articles has nothing to do with personal bias. It has to do with tending to adjust towards a higher exposure. However since the limit of the exposure is defined in ETTR to be the highest exposure that does not blow desired highlight detail, this can actually result in using a lower exposure than metered when the scene has a high end to its dynamic range.

The bias has nothing to do with objective decisions. From that tutorial, "opportunity of biasing the exposure toward the brighter tones" - like I said, this is all about attempting to get as far as possible with biasing exposure "to the right".

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. 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.

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.

By the way, obviously, in many situations, if you're totally obsessed with "exposing to the right", you're never gonna get the shot, because the shutter speed required for it is way too low.

Well that's where balancing finally does enter the picture. You have to trade off the benefits of reduced noisiness against the benefits of motion blur control and aperture effects (DoF and lens sharpness). That's not a balance within ETTR. Rather it is a balance between the benefits of ETTR and the benefits of other approaches to controlling aperture and shutter.

So a way to take that into account, while accounting for ISO setting is to say:

Use the widest aperture that gives you acceptable DoF and lens sharpness, and the slowest shutter that gives acceptable motion blur, without blowing desired highlight detail. If that combination of aperture and shutter leaves highlight headroom at base ISO, increase the ISO until the headroom is used up or the ISO reaches the setting at which the camera becomes ISO invariant.

The writer of that tutorial (#1) seems completely oblivious to the fact that even in rather bright surroundings, in many cases "ETTR" would mean unacceptably low shutter speed.

In EV 15 (@ISO 100) light and a scene with two stops of highlight headroom, with ETTR you'd use an exposure of f/8 1/125. A shutter of 1/125 is more than adequate for landscapes and outdoor portraits, which are the sorts of shot that benefits from ETTR. One typically doesn't doesn't use ETTR for sports or wildlife shots because that sort of shooting doesn't usually afford one the opportunity to meter each shot carefully for the highlights.

It's all a matter of balance and it is in fact all about personal biases.

Balancing may be, but balancing is not part of ETTR itself.

An auto "ETTR bias mode" may be a nice thing to add to cameras, but it's absolutely not a proper replacement for the normal auto exposure modes.

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