(Auto) ETTR (Exposure to the Right): -- History & Beginners Guide

[vk4tnt]

Hi there
I am a new ML user and a bit lost in regards to versions and modules loaded.
RenatoPhoto wrote in his post on 2013-05-26, 03:24:06
>>>>
Are you ready for the easy stuff now?

ETTR in RAW images -  Camera Options available

This functionality has been ported to all of the supported cameras. 

PLEASE BE ADVISED THAT THESE MODULES ONLY WORK IF YOU HAVE ENABLED THE BOOTFLAG IN YOUR CAMERA.

If your camera has these features then you will find them here:

In the Expo Tab (Exposure Menu of ML) you will find Auto ETTR.  For this to work you must be in Manual mode and also the ISO must be in manual.  If you meet these requirements you will be able to enable it by pressing the Set button (depends on camera).
<<<<<

Am I right in assuming that a daily build after Magic Lantern v2.3 has to be loaded to actually display ETTR functions in the Exposure Tab?

Thank you in advance

[Stedda]

You are correct.. you must use a Nightly build after ML 2.3. Copy the nightly files over and you'll be good to go.

[pru]

[...]

     RAW histogram on the bottom right is a small graph.

a. Inside this histogram you may see near the top-left of the graph, in white lettering, the letter E followed by a number which represents how far you can go, in EV numbers, to reach ETTR, i.e E1.2
[...]

I did a quick test on 6d and I cannot see the 'E', only R/G/B are there. I used TL zip from NOV09, any hint?

[vertigopix]

You must load the module and shoot in RAW !

[pru]

You must load the module and shoot in RAW !

OK - must be full RAW mode, not M-RAW/S-RAW.

[mgrant]

I extracted the info in the forum threads and added documentation on Auto ETTR to the dokuwiki:

http://wiki.magiclantern.fm/ettr

Feedback welcome!

[a1ex]

Nice!

Probably a good idea to have a page like this for most major modules (maybe also for smaller features like zebras?).

Maybe even split the user guide into pages, and then having a master page that collects them all?

(just thinking out loud)

OT: about the image with zebras... how did you get that 3.4GB overlaid on it? (that thing should have been reported as bug)

[kitzie]

Hey guys, long time lurker here, just wanted to say the hugest thanks to all the developers on this project, it really is a thing of beauty to see so many people collaborating so selflessly for the benefit of the film-making community.

I'm still trying to wrap my head around ETTR, and can't find an answer anywhere on here -

- When I do auto ETTR by pressing the set button it changes my shutter speed from 48 to 53. Any idea why / how I can keep my shutter speed at 1/48?

If you could shed some light on this, I'd really appreciate it!

Jeb

Edit - I've fixed this with the shutter tweak!

[D.Stasinos]

Hey guys! I just tested the ETTR feature on my 5d mark iii and i get a "Raw error" message. Sorry if this has been discussed but i found nothing about this. It doesn't happen always but at least 6/10 times i take a photo with ETTR.

ML last version for 5d 1.2.3
Raw enabled from Canon menu
ETTR Always on (i didn't change nothing else, just followed the instructions)

*In cases that ettr works and i don't get the "raw error" message, the photos get about 3 stops overexposed and all highlights get blown out. Any ideas?
Thanks in advance.

[a1ex]

I took around 10000 pictures on 5D3 after upgrading to 1.2.3, most of them with ETTR, and I have yet to see this error message during actual use. A video showing the error and the settings should help.

Overexposure may happen if SNR limits are too high, or - with "always on" outside LiveView - when moving from a dark scene to a bright one, until it converges.

[Marsu42]

Hey guys! I just tested the ETTR feature on my 5d mark iii and i get a "Raw error" message.

Do you also have jpeg enabled next to raw? That's the culprit on 6d.

[D.Stasinos]

Do you also have jpeg enabled next to raw? That's the culprit on 6d.

No, only raw is enabled.

I took around 10000 pictures on 5D3 after upgrading to 1.2.3, most of them with ETTR, and I have yet to see this error message during actual use. A video showing the error and the settings should help.

Overexposure may happen if SNR limits are too high, or - with "always on" outside LiveView - when moving from a dark scene to a bright one, until it converges.

A1ex thanks for your feedback. And by the way thanks for all the nice tools you brought to our hands! The first time i got the "raw error" message was when i moved the camera outdoors (i moved from a dark place to a bright one). I am trying to find a certain way to reproduce this cause its a bit random. LiveView is always enabled on my tests.
And a quick question: when i half press the shutter button, is this the moment when ETTR needs some time (3 secs as RenatoPhoto pointed out) to make proper calculations about the exposure?

[a1ex]

Today I was in a short trip, so I used ETTR always on in LiveView. I've got "raw error" 3 or 4 times, but I've narrowed down all of them to the changes from this branch, which is not included in the nightly builds. So, if you were using the nightly, I still have no clue about how to reproduce the error (it means the raw backend was not available for some reason).

When you press the shutter halfway, ETTR finishes the current iteration and then it gets paused. You will notice a big slowdown if you use the "zoom on half-shutter" option, but I'm going to speed it up.

[sweetpie]

Hello everyone, another ML first time user here!  I've installed it mainly to play around with ETTR.  I have a couple of beginner questions; if you can be patient with me as I have not been able to find the information through a search of the forums:

1)  It is possible to disable the beeps?  (I am thinking of discreet situations when shooting from the hip and trying not to attract attention)

2)  Am I right is thinking that this only works in Liveview, i.e. it is not possible to replace Canon's default metering algorithms outside of liveview?

I'm having a lot of fun playing around with ML, so thanks for all the hard work!

[Walter Schulz]

Top of page -> User Guide -> FAQ and User Guide.

[sweetpie]

Top of page -> User Guide -> FAQ and User Guide.

Thanks, but there is nothing in neither the user guide nor the FAQ about disabling beeps in ETTR.  I guess I should clarify by stating that I am referring to the two methods of using the SET button or the half-press to ETTR.

Please correct me if I am wrong.

[Walter Schulz]

I'm running ML on 650D and 7D. First one doesn't give sound with ETTR, second does.
Would be fine to have sound confirmation optional.

[sweetpie]

Good point - I should have said that I am running ML on the 5D mk ii.

[Walter Schulz]

Try Audio tab -> Beep, test tones -> Enable Beeps -> OFF

[sweetpie]

Try Audio tab -> Beep, test tones -> Enable Beeps -> OFF

Ah, brilliant - thanks!  I was just reading the instructions for the ETTR part.  Sorry for the bother.

[Quentin]

I used AUTO ETTR, Always ON.
Auto Exposure was also ON and I realized that both could not coexist.
When I disabled Auto Exposure, Auto ETTR was working perfectly.

I think this should be handled by ML.

[dmilligan]

I think this should be handled by ML.

Since these are both modules, they don't "know" about each other. Perhaps something like a "Conflicts" tag could be added for https://bitbucket.org/hudson/magic-lantern/pull-request/407/module-tags-ratings-wip That could also be used for mlv_rec, raw_rec.

[pjburnhill]

Right, I've tried searching the forums having no luck.

Having read this thread, my understanding on ETTR is that it really shines when recording RAW (highlight recovery etc.) but if the sensor is linear and most colour information is captured at the bright end of the sensor, surely ETTR should be used with H.264 recording as well? Or am I missing something here?

I saw someone commenting that editing H.264 in post is destructive, which of course is the case, but wouldn't using ETTR still produce better results than 'correct' exposure (providing no clipping, or acceptable clipping occurs)? Wouldn't this yield better SN ratio and thus less noise in the shadows for the H.264 too?

And on another note, should ETTR be used if recording to higher bitrate codec (i.e. ProRes 422 HQ) through HDMI?

I mostly shoot video in very controlled environment so knowing this would be helpful.

Thanks,
PJ

[dmilligan]

The concept of ETTR should be used with H.264, of course, but this ETTR module and it's specific implementation uses the raw histogram and raw data to calculate the clipping level and other things (like SNR levels). If you are doing H.264, that means that the calculation will be incorrect => something that isn't clipped in the raw data, might very well be in the h.264 data.

So, if you're shooting H.264, yes you should "ETTR", you just wont be able to use the AutoETTR module to do that for you automatically. You can do it manually with any of the non-raw exposure aids (like zebras, histogram, spotmeter, etc.)

[a1ex]

In H.264, I'd say you should use ETTR only if you find the footage noisy. The exact exposure choice for H.264 can be different from RAW though (you mentioned it - editing 8-bit data after compression is not going to be funny).

A good option would be to ETTR just as you would do in RAW (to maximize the SNR of the input data), then use ML digital ISO (the one from image fine-tuning) to get something close to your final look. In RAW, the digital ISO is ignored (you apply it in post), so ETTR ignores it completely. But for H.264, digital ISO is essential, because it's like an editing step done before the conversion to 8-bit.

A good rule of thumb is to set a full-stop ISO from Canon menu, and set your digital gain of around -0.3 or -0.5 EV. Darkening more than that will create pink highlights (but if you don't have any, or if you can fix them easily in post, just go ahead and darken a little more).

One thing to be aware of - Canon does not use any highlight recovery for JPEG/H.264 (so, depending on your white balance, around 1 stop from red and blue will get clipped). So, the exposure choice for H.264 may have to be a little darker than with RAW.