This post was last modified: 2015-06-25, 12:32 by yannick_c.

An other test, same place, nearly same settings as before but for on a day to night timelapse this time. Didn't really edit too much the sequence as I was not really happy with it (too underexposed so I can't really get things back as I wanted and didn't like the sky cut in half on the night part), so I don't even delete the paragliders. But it's a good exemple for high dynamic range ETTR and the problems that you can find in those conditions.

[Video: https://www.youtube.com/watch?v=jH7kHFKfrFc]

Gear :
Camera : Canon 550D/T2i
Lens : Canon EF-S 10-18 mm f/4,5-5,6 IS STM
Tripod : Manfrotto 055XPROB
Head : Manfrotto 804RC2

Camera and Lens Parameters :
Focal Length : 12mm
Aperture : f/5.6 (could have gone wide open, but wanted to test better sharpness like you can see here on the sharpness - field map tab)
Maximum ISO : 1600 (1600 is not good on a 550D, will stick with ISO 800 later)
Image Review : On, 2sec

Parameters in Magic Lantern
Interval : 7sec

ETTR Parameters :
- Trigger Mode : Always On
- Slowest Shutter : 2 sec
- Exposure Target : -0.5EV
- Hightlight Ignore : 0.5%
- Midtone SNR Limit : 6 EV (default value)
- Shadow SNR Limit : 2 EV (default value)
- Link to DUAL ISO : OFF

Here is LRTimelapse luminance curve before editing :

Reference set to all picture
   

Reference set to the botton part (it's way too dark)
   

LRTimelapse did a really great job deflickering it (as always).

With those settings, the highlights are not clipped (only 0.5%) but the foreground is too underexposed and gets noisy really fast when you want to edit it (you can see it on the start and the end of the sequence). The video is also speed up 2x. On the next exemple that will come soon (not fully edited yet), I went to a 14" interval to win some stops before the ISO start moving up and I adjusted the Midtone and Shadow SNR limit to get more light on these areas (but loose some hightlights).

Last test on that spot. On this one, I tried not to underexpose too much the moutains to keep some light info for postproduction. I increased the highlights ignore value to 3% and I played with the Midtone and Shadow SNR limits. I've increased these values by 1EV to get the exposure I wanted without cliping too much highlights. I've done it while in Live View Mode, so I was able to see the new overall exposure and the highlights clipping in real time for each change (you can't do it if you start at night, cause the Live View won't be able to display real preview with long exposure).

You can see the magic of LRTimelapse to smooth everything

[Video: https://www.youtube.com/watch?v=w8XDRGAXwEI]

Gear :
Camera : Canon 550D/T2i
Lens : Canon EF-S 10-18 mm f/4,5-5,6 IS STM
Tripod : Manfrotto 055XPROB
Head : Manfrotto 804RC2

Camera and Lens Parameters :
Focal Length : 10mm
Aperture : f/5.6
Maximum ISO : 800 (best compromise with high ISO and not too much noise on my 550D, for new camera you can go to 3200 easily I think)
Image Review : On, 2sec

Parameters in Magic Lantern
Interval : 14sec

ETTR Parameters :
- Trigger Mode : Always On
- Slowest Shutter : 10 sec
- Exposure Target : -0.5EV
- Hightlight Ignore : 3%
- Midtone SNR Limit : 7 EV
- Shadow SNR Limit : 3 EV
- Link to DUAL ISO : OFF

There is still some problems I need to correct, like the sun jumps at some times. I needed to loose some highlights to get the exposure correct on the shadows, that's why I got those clipping bumps. But I think I can tweak that not by getting highlights back (cause it's impossible due to the clipping) but by adding some gradual brightness in the sun between HG keyframes, will try some things on it, maybe someone have good tips on that.

I've also found a good way (long but undestructive) to erase the paragliders. I couldn't do it automatically (the auto erase bird technique doesn't work if the things you want to erase are not dark enough). I've used the paint tool in after effect, it's quite impressive. You can paint some areas and tell it from where in space and time you want it to copy the content. So you choose the previous frame (or the next one), align it if you need to (usefull if clouds, or waves change between 2 frames wich is the case with a 14" intervall), and paste content to erase the area you want. The good thing is that if you want to edit your source (like I did), you don't need to do the erase process again like you would if you've done it in photoshop. Quite usefull if you have to erase more than 1500 paragliders in the all sequence.

For the SNR limits, is quite complex to understand how that works (at least for me), here are some explanations from one of the creator of this module a1ex :

For midtones it's easy: the median "brightness" gives you the signal level, so we can use the SNR. So, when I say the midtone SNR is 5 EV, this means half of the image has a SNR less than 5 EV, and the other half has a SNR higher than 5 EV. Pretty easy and statistically robust.

For shadows, I've chosen the 5% percentile. So, in this context, the shadows having a SNR of 3 EV means 5% of the image pixels have a SNR lower than 3 EV, and the other pixels will be brighter than that.

Keep in mind that 5% is bigger than you may think, since it refers to image area, not linear size. The linear percentage is roughly 22% (1/4.5).

So, you can choose 2 noise limits, one for midtones and one for shadows, and the image will not get noisier than that (but you may lose some highlights). This setting has the highest priority, so it will sacrifice highlights even if you disallow clipping from the other settings.

Last usefull tip for now, the "Ghost Image" in Magic Lantern. You can add a ghost picture of your choice in the Live View, that way, you can align 2 timelapse shots quite precisely. I've done it with that shot and the one with the clouds I posted some days ago in that thread. With some blend work in After effect, i will be able to mix them quite smoothly.

Hope some infos will be usefull for someone. I've done the HG sequences I needed for my project, so I don't think I'll post more exemples too soon. Feel free to post yours. Next step may be to test the Dual ISO feature, to gain some dynamic range but it seems to alter the vertical resolution (not good for a 4K project).

Hi Yannick

I'm trying magic lantern on canon 6D. I usually use Qdslrdasboard but I've got too many crashes...


Magic lantern works fine with ETTR option BUT do you know if it is possible to ramp ISO setting by 1/3 values ?
Shutter speed vary with 1/3 value but ISO only with entire value... 100 - 200 - 400 - 800 etc
Sometimes  jumps are too big to have very smooth results.

In Magic lantern user guide they say: "Only full-stop ISOs (100, 200, 400 etc) are used (because you are supposed to shoot RAW). "

No way to change this ?

Thanks !

stef

qDslrDashboard should work fine with the 6D too, I've been working with a 6D for several months and it was always stable. Maybe something work your smart device? Or you did something wrong? You should give it another try. Here are some useful tips: http://forum.lrtimelapse.com/Thread-how-...holy-grail

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