confused about sunrise / sunset

[dan.g]

Hello,

I've been using ML for almost an year now, especially for timelapses. While I have aquired some decent footage with your software, I was very happy when the bulb ramping feature was announced. Still, I think I need further info about it (I've read the built-in manual but it only helped to some degree). I  am still confused about a few things as I will mention below.

First:

If I try to make a transition from night (milky way should be correctly exposed) to day, it is my understanding that I should use the sunrise bulb ramping. The problems on my end are as follows

- how can I set the exposure I am looking for since the image that ML will aquire will be definitely underexposed during night time?

- should I meter for highlights or for shadows? From my trials and errors, I've learned that it's best to expose for highlights during sunset / sunrise, but I maybe wrong...

- what max ramp speed should I use? I've tried a few settings, but I always end up with serious flicker. Ok, it is manageable with manual deflickering or auto of some kind but it takes a lot of work, even when I'm shooting RAW. I understand that there ain't a simple answer to that, I'm just looking for some values that will produce the least flickering or some guide to understand the values in ML. For example: If the next day will be cloudy, the value of max ramp should be X. If it's gonna be a sunny day, the value should be close to Y. Same thing applies for the sunset option.

- How can I manage the interval between shots? The reason I'm asking this is because right now ML allows us to set an interval between beginning of shots which works fine during a day or during a night-only timelapse, but it's confusing which setting should one use if, for example, the milky way shots require a 30s exposure (more or less, depending on the lens, iso, camera, etc) and a sunset / sunrise should be done at lower intervals (1-10s, depending on whatever we want to aquire). I understand that "take pictures like crazy" maybe the only option right now, but this will quickly fill the card once the sun rises or sets. Not to mention the shutter, it's a little bit too much to take extra frames during the day time, just to dump them in post. Plus, during night time, I'd rather let the sensor cool for at least 4-5 seconds before exposing for the next shot.

- Is there a possibility to allow us to set an interval between the end of one shot and the beginning of the other? Or, is there a possibility to create key shortcuts for the interval? Like left arrow should lower the time and right arrow to increase the time?

- A better solution, but harder to implement, both for ML team and users, maybe the possibility to create a file beforehand in which we can schedule the timing of sunrise/sunset and which settings to use regarding the intervalometer. Example:

05:00am - interval = 30s
06:15am - interval = 20s
06:30am - sunrise - interval = 10s
06:45am - interval = 5s

This file can be created on the computer and transferred to the ML card before starting the timelapse.

One last question: is it possible to program in ML something like this: timelapse - move to movie mode and start recording for x seconds - stop recording - move back to timelapse? That would be a killer feature and it might lead to some creative uses IF at all possible.

Thank you,
Dan

[Roman]

I dont think it would work well to have ML automatically reduce or increase interval time based on brightness, as it could increase and decrease in unpredictable ways which means your video would speed up or slow down randomly.

The problem with specifying the interval at specified times, is how do you manage the transition in the video without a noticable jarring speed increase? Like the sun is coming up slowly, then BAM it takes off

Perhaps the simplest way to get a nice "interval ramping" would be to manually specifiy a % of change between frames.
So say 0.5% interval reduction per picture, so you'd get a predictable increase or decrease in speed rather than a harsh transition.

I guess the difficulty with bulb ramping is incorporating all of these possible scenarios without making it overcomplicated for first time users.

Another option could be to use something like Twixtor to interpolate frames in between, when you require more frames than what you've shot at. If you're downsampling your pictures from 18 megapixel to 1080p, it should be able to to a pretty good job of this without a noticable quality reduction.

A1ex has been doing some work on a script that pretty much eliminates flicker with RAW files:

http://www.magiclantern.fm/forum/index.php?topic=2553.0

[dan.g]

Thanks Roman for sharing your thoughts.

I dont think it would work well to have ML automatically reduce or increase interval time based on brightness, as it could increase and decrease in unpredictable ways which means your video would speed up or slow down randomly.

Not based on the overall brightness, but it would be nice to either have quick access to modify the interval during the timelapse, either to make a script beforehand in which one can specify the intervals based on time. We know at which hour the sun rises or sets.

The problem with specifying the interval at specified times, is how do you manage the transition in the video without a noticable jarring speed increase? Like the sun is coming up slowly, then BAM it takes off

actually, it will be a rather fast movement during night and just before sunrise or at sunrise the sun speed will BAM move even slower. Which isn't a bad thing at all.

[dan.g]

Meanwhile, I've shot another sunrise footage using the built-in timelapse intervalometer. I've had a hard time combining a few factors (bulb ramping, intervalometer, bulb mode and mirror lockup), but finally the camera began to shot from 4.00am to 9.00am.

Unfortunately, I have made an error, so I am posting this, maybe it will shed some light on others routine. Against my instinct, I have metered for shadows which proved to be a mistake. The camera was satisfied how the shadows were exposed, so all my night shots are severely underexposed. The algorithm didn't let the camera to bump up the iso up to 1600 or to 3200. All the night shots are made at 800 sensitivity. Pretty ugly, cannot do much in post with these shots.

Anyway, I will try metering for midtones also, haven't tried it yet. If I meter for highlights, the after-sunrise shots are a little bit too exposed for my taste, but a RAW workflow should allow a proper processing of these files. Better than underexposed night shots, anyway.

Still, is there a way to make such a timelapse, lets say at 10s interval, but allow the night shots to be exposed for 20-30s?

Thanks,
Dan

[a1ex]

For now, you can change the interval while the timelapse is running (and if the camera moves, use align_image_stack or some other similar tool).

You can also combine auto exposure with manual exposure, so night doesn't look like day, but a bit darker.

If you shoot RAW, it's probably very good to meter for highlights at 90% and deflicker in post; in theory, this should get very little noise, as all shots would be exposed to the right.

[dan.g]

If you shoot RAW, it's probably very good to meter for highlights at 90% and deflicker in post; in theory, this should get very little noise, as all shots would be exposed to the right.

Thanks, this is really a valuable information! Next time I'll try to use the built-in flash to expose some close object, just to get an image with lots of highlights to read the metering from!

You can also combine auto exposure with manual exposure, so night doesn't look like day, but a bit darker.

I'm sorry, I don't get this one. If I try to move the dialer during a timelapse, the intervalometer stops, or at least on my camera it behaves like this. Can you elaborate a bit, please?

[a1ex]

In bulb ramp submenu you have auto ramping (based on metered light) and manual ramping (blind). If you use both, it still meters and compensates for ambient light changes, but overall brightness will no longer be constant, but a ramp. You can configure it so at the end of the timelapse it's 2 EV darker (or brighter) than at the beginning, for example.

[Roman]

That's pretty cool!