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

Started by RenatoPhoto, May 25, 2013, 07:24:06 PM

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budafilms

Write short, please. Too much emotional thinkings. Thanks.

Audionut

There's no better way to learn, then getting out into the field and trying things.

I would suggest you take the knowledge you currently have, and try some some practice.

tetsusaiga

Sorry for the long posts, but I didn't know how to explain things without going into the nitty-gritty details.  I'll do my best not to make it long.

I just went outside to my backyard to try and shoot a timelpase while the sun was setting.  I wasn't sure if AutoETTR was working because the exposure wasn't automatically changing as the sun was setting.  In other words, the sky was getting darker, and so was the pictures.  It didn't seem like AutoEttr was exposing to the right.  Here are my settings:

1) AutoETTR with the following parameters:
      - Trigger Mode = Always On;
      - Slowest Shutter = 16 second;
      - Exposure Target = -0.5EV;
      - Highlight Ignore = 0.1%;
      - Midtone SNR Limit = 6EV;
      - Shadow SNR Limit = 2EV; and
      - Link to Dual ISO = On;

2) Post Deflicker with the following parameters:
      - Sidecar File Type = UFRaw;
      - Deflicker Percentile = 50%; and
      - Deflicker Target Level = -4RV;

3) Intervalometer with the following parameters:
      -Take a Pic Every = 20 seconds;
      - Start After = 3 seconds;
      - Stop After - Disabled; and
      - Manual Focus Ramp = Off.

With these settings, I took a few test shots and was able to see what was being overexposed via the zebras in Live-View.  After the test shots, I enabled the intervalometer and let the camera do its thing.  I stood next to it the entire time and was checking the image preview and Live-View after each shot.  As the sun was setting and the sky getting darker, the ISO and shutter speed didn't change at all.  Then my battery died, which meant that it was game over for the night.  What did I do wrong?

dmilligan

I would recommend not using LV for timelapse (probably why your battery died). Also did you have the quality set to raw? Did you hear the beeps from AETTR? Did you see the expo messages from AETTR? Did you see any errors, specifically "Raw Error"? Did you see the other raw overlays during QR, like the histogram(assuming you had them enabled)? Finally, what camera are you using (there have been reports of issues with AETTR not working correctly on certain cameras that aren't as well maintained)?

tetsusaiga

dmilligan:  I think I can answer only some of your questions. 
1)  I thought I need to use LV to use AutoETTR? Guess not, after your comment.  Not sure why I thought I had to us LV, but I will try again tomorrow without using LV.
2)  The Canon and ML setting is set on RAW.
3)  I didn't hear any beeps from AutoETTR at all.  Didn't know I had to hear beeps actually.  What do the beeps mean?  And what do I need to do to hear the beeps?
4)  I didn't see the expo messages from AutoETTR.  What are the expo messages supposed to say? And what do I need to do to see the expo messages?
5)  I did not see any errors or "Raw Errors."
6)  I have the zebra and Raw Histogram enabled under the Overlay tab in ML.  I only see zebras and the Raw Histogram.
7)  I'm using a Canon 600D (T3i).  I might have the wrong ML/TL nightly build installed on my camera.  A while back, I installed TL [600D]NewMem.zip, which probably doesn't have a properly working AutoETTR.  Which ML or nightly build should I be using on my camera?

Thanks again for the help.

Update:  I just downloaded the most recent ML nightly build and it makes the beeping sounds and shows the messages you were talking about.  I'll give it another try tomorrow after work and hopefully I'll be successful this time.

tetsusaiga

Sorry guys, but I was given a big project at work and didn't have time to test out the AutoETTR and other ML features in a timelapse.  I'll get right on it when things at work die down a little.

tetsusaiga

Hi guys.  I was able to find some time last night to shoot a day to night (sort of) sequence.  Right off the bat, there's a lot of flicker, although it seems that AutoETTR has been working well after I downloaded the latest Magic Lantern Nightly Build.  Here is the link to the timelapse:  https://www.youtube.com/watch?v=NCNcF8tdY1g&feature=youtu.be.  Below are my settings for this sequence:

1) Modules:
      - raw_rec = On;
      - deflick.mo = On;
      - dual_iso.mo = On; and
      - ettr_mo = On.

2) AutoETTR with the following parameters:
      - Trigger Mode = Always On;
      - Slowest Shutter = 32 seconds;
      - Exposure Target = -0.5EV;
      - Highlight Ignore = 0.1%;
      - Midtone SNR Limit = 6EV;
      - Shadow SNR Limit = 2EV; and
      - Link to Dual ISO = On.

3) Post Deflicker with the following parameters:
      - Sidecar File Type = UFRaw;
      - Deflicker Percentile = 50%; and
      - Deflicker Target Level = -4EV.

3) Intervalometer with the following parameters:
      -Take a Pic Every = 35 seconds;
      - Start After = 3 seconds;
      - Stop After - Disabled; and
      - Manual Focus Ramp = Off.

Although I enabled post-deflicker, I didn't use the sidecar file in this timelapse.  I think this is a little too advance for me right not.  I'll revisit post-deflicker when I get the basics down first.

So, I followed LRTimelpase (Gunther's) holy-grail tutorial but, as you can see, there's a bunch of flicker in the timelapse.  Also, I'm not sure what that blip was around the 2 to 3 second mark of the timelapse.  Is there something wrong with my settings?  Any help to remedy this issue would be great.


dmilligan

If you don't use the deflicker sidecars, you're going to have lots of flicker. The whole point of the sidecars is to remove the flicker we're expecting to get.

If you're using Lightroom, then you need to use XMP sidecars not UFRaw. If you use the XMP sidecars, you should pretty much automatically end up with a deflickered sequence when you load it into LR.

The sidecars simply contain a correction/adjustment to the exposure, all you need to do to deflicker is to apply this correction. LR (ACR) automatically applies develop settings stored in XMP sidecars. You'll notice that the exposure slider has been moved around in all your images. All LRTimelapse does is create these sidecars with exposure corrections that it computes, so the workflow is basically identical, except the sidecars are created in camera by ML and you don't have to run a third party tool (you also don't have to pay for said tool).

Also, if you have Adobe Bridge, you can use my script that does basically the same thing (generates XMP sidecars with exposure corrections):
http://www.magiclantern.fm/forum/index.php?topic=8850.0

tetsusaiga

dmilligan:  Thanks for the input.  I'm going to switch the deflicker to XMP.  So let me get this straight, I basically import the Raw files from my SD card and LR will automatically deflicker the Raw files using the XMP files?  I'm going to give this a try in a few days.  Thanks again.

tetsusaiga

Can some teeach me how to synchronize the XMP files with my raw files? I think I need to save the raw and XMP files onto my hard drive and then import the raw files into LR5. does the XMP files automatically get applied to the raw files upon import into LR5 from my hard drive?

dmilligan


tetsusaiga

thanks, I'll give it a try when the weather gets better here.

tetsusaiga

I have time over the weekend to try and shoot a sunset-holygrail timelapse.
This time I'll be enabling the deflicker module with sidecar XMP file.
But I have a questions about the XMP files created by the ML deflicker module.
So I basically save the CR2 file and ML XMP files onto my hard-drive.
Then I import both the CR2 files and XMP files into Lightroom.
I'm assuming this will change the exposure to reduce any flicker, right?
After this, I would be using LRTimelapse to create the timelapse video.
In this instance, can I actually use the deflicker program in LRTimelapse to do additional deflicker-ing? Or will this not work?
Thanks.

tetsusaiga

I'm trying to shoot a holygrail timelapse right now. When I take a test shot, the next picture comes out extremely under exposed. So I increase the highlight ignore to 3 and everything looks fine. But now it's getting dark out and the pictures are too bright - I.e., the pictures are way brighter than it really is outside. Did I do something wrong?

Audionut

Quote from: tetsusaiga on October 04, 2014, 12:38:23 AM
I'm trying to shoot a holygrail timelapse right now. When I take a test shot, the next picture comes out extremely under exposed. So I increase the highlight ignore to 3 and everything looks fine.

Post a CR2.  You probably don't want highlight ignore set to 3, unless you have a large amount of specular highlights.

Quote from: tetsusaiga on October 04, 2014, 12:38:23 AM
But now it's getting dark out and the pictures are too bright - I.e., the pictures are way brighter than it really is outside. Did I do something wrong?

If there is no overexposure, then you probably got the correct ETTR results.  If you still have highlight ignore set to 3, you probably want to revisit that setting.

tetsusaiga

Audionut, thanks for replying.  I'm still out trying to shoot the timelapse.  I'm going to try and process the sequence through LR5 and LRTimelpase and see how the end result is like.  I'll post a CR2 file after. 

As an aside, the reason why I set highlight ignore to "3" is because the sun was in my frame, and I think ML was trying not to overexpose the sun, which made everything else really dark. 

Audionut

Yes, you will need to do that for the sun (never mind the cr2).  I'm not sure how the guys transition from sun in frame to darkness with autoETTR.

I've bugged dmilligan previously about having highlight ignore as a rampable feature in his module.

dmilligan

use a wide enough angle lens and the sun is small enough it doesn't matter :P

tetsusaiga

dmilligan: LOL...thanks for that, I'm actually working on getting my hands on a wide angle lens; I need to save up some money first though.  The 24-70 standard lens on my crop sensor is not capturing enough of what I want in the frame.

I just got home from the beach and I want to process the timelapse, but I ran into a problem already. 
I used the deflicker and AutoETTR modules in ML, which gave me a bunch of XMP and CR2 files. 
I imported the pictures into LR5 and the exposure of each picture is different, so I'm assuming the XMP files that ML created for deflickering works.  But I'm stuck from this point on. 
If I use LRTimelapse, the first thing I need to is "initialize."  But if I do this, the exposure for each picture is set to zero, which means all the XMP deflickering files created by ML is useless.
Does anyone have a workflow for this?

By the way, how do I post a CR2 file so that you guys can download?

dmilligan

If you want to use ML's deflicking, then just export the CR2s to JPG or TIFF in Lr and compile those into a video. If you want to use LRT, it sounds like you'll have to throw out ML's derflicker and start from scratch and let LRT do the deflicking (you can always backup the XMPs from ML in case you need to use them later).


tetsusaiga

Thanks to dmilligan, audionut, pauljbis, the ML team, Gunther from LRTimelapse, and everyone else that helped me with learning how to make a timelapse.  I shot a sunset timelapse last night using Auto-Ettr and Deflickering modules, and it came out better than I expected (I was expecting a lot of flickering or over/under exposed timelapse).  Here's my short timelapse clip (5 secs), which I'm sure can be improved, which I'm striving for:  https://www.youtube.com/watch?v=QiwjuJS5Eto&feature=youtu.be

tetsusaiga

By the way, do you guys think setting my highlight ignore to 3 or 4 EV was the right move? Maybe I should have set it to 1 or 2 instead?

Audionut

The highlight ignore parameter is a percentage of pixels in the frame, not an EV.

Use raw based zebras.  Increase the highlight ignore value until wanted details in the scene start to overexpose.  In other words, until something other then the sun is overexposed.

tetsusaiga

audionut...I have the raw histogram and zebra enabled. So are you saying I should over expose some things in my frame other than the sun? I set my highlight ignore to 3 or 4 because the default settings made the next picture really dark. I played around with highlight ignore until I was happy with the exposure of the next picture. Is this the correct way to do this? I might try again tomorrow.