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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Question: capture lightning with Scarlet / Epic

Hi Todd. I like your lightning stills. I had a question regarding them. I read the thread and was wondering if you used 4K, 1 fps, 360 shutter in order to correct the flash artifacts or you were still getting the artifacts on some frames and not on others (a mix)? I shoot lightning quite a bit on CCD and my Arri 35-3 which (of course) produce no flash issues. They shoot lightning very well. I shot some lightning last week for the first time with my Red-X and was getting the artifacts which I call flash banding. Actually, not as terrible as my Sony EX-3 CMOS camera, but they were there. I can see how shooting a long duration frame every second, or two seconds 'might' get around the rolling shutter, at least sometimes. Of course, when played back it would be time lapse, but might make for some good stills. Hmmm. I'll try your method the next storm. Otherwise, perhaps the Red Motion Mount may be the best answer.
 
I just skimmed trough this thread so maybe allready mentioned. But the best way to get around rolling shutter is actually to shoot quite high speed and 360 shutter. Then you can use different transfer modes to your liking to "frame sum" or "compound over frames" in post. Basically If you shoot for example 25fps you can do the following:


Compound over 25 / 360 frames so that you actually get 1 fps result. Set your compound curve so that the first and last frame in the compound only blend with a few procent and then the 12 frame is mixing to 50% then you actually get a really nice sine wave 1 second exposure that has 25 steps of exposure. This is something that to my knowledge is very unique to the RED's as most other cameras are not doing a pure 360 exposure. If you want more samples in your sine wave exposure you can just up the framerate.

if you don't have a compound plugin then it's quite easy to set up something similar in AE or such. Simply explained it works like this:

Take the first frame, then take the second frame, blend the second frame onto the first with 50% transparency, then take the 3rd frame, blend it ontop of the other two with 75% transparency, then take the 4th frame and blend it ontop of the stack with 88% transparency, then take the fifth frame and blend it on with 94% and so on... That is then a linear transparency. There are plugins that does this with functions so you can do it nonlinear and also use different transfer modes as additive mix, screen etc.

To me it's a really cool way of doing time-lapse as it is such nice way to stay out of over or under exposure. Shoot like 12 fps 360 with slightly low exposure then in post I can blend with a sequence that is compound to 1fps that is pure mix, no altered exposure and a sequence that is made with additive which then gives me 12 times the exposure.

So I think fiddling with the above would make the scarlet/epic the best lightning catcher there is, especially with the pre record function.
 
i agree with bjorn, although there's also the motion mount which effectively does what he's talking about in camera.

this was 360degree shutter or frame summing/averaging if i'm not mistaken...
there may have been a frame somewhere that got cut short, although i don't think that part is included below.
and if you do get cut short, it's pretty easy to photoshop a frame or two for motion (or stills)

http://player.vimeo.com/video/74626051?autoplay=1&loop=1
 
Thank you Björn ! Actually the method you posted was what I thought should theoretically work and that was what I was trying to shoot. Well mostly : shoot higher speed to capture lightning instead of exposing it longer in the get go. I just had no idea how to work it from there. The other bad thing about it is the banding I got during the lightning. I can't see how these frames would blend. Now I'll just need another thunderstorm to do more tests :)
 
the key for shooting is 360 degree shutter. you should really look into the motion mount for this kind of work as well, to avoid...

tearing, you've got to run triage on the broken frames...
copy from another one, do an isolated color correct and/or paint it.
or just drop/blend the frame.
 
Thanks Paul. Will do that - as soon as I have footage worth doing it. I'll check on the older stuff in the morning and see if there's anything worth for trying it out on.
 
No motion mount is probably not so good, it actually does not do it. All it does is at best is a .9ND during "redraw frame period" and a sine wave while all the photo sites are capturing at onces. So for example heavy lightning will expose through the ND of the mouton mount as it is not a complete global shutter only a heavy ND during the sensor redraw. It will for sure help and get away with some but not a complete solution. frame summing and such in camera also limits the results heavily as you can not set your exposure afterwards and such as you can when using compound. Also with the new ADD it's even more valid to frame sum in post after noise reduction.

The banding you got was from not having 360 shutter. The stepping comes from the missed degreses of exposure, the motion mount does not do 360 it only do 360 minus the sensor redraw time, if you do not use it as a normal ND but thats not usually needed when the thunder hits :)
 
Good example of rolling shutter


13939626075_fe43dcdaa3_c.jpg
[/url]A002_C029_0701W8 by mdharrington1, on Flickr[/IMG]

Shot this at 96 FPS 5k 360 shutter....

Got lots of usable footage, with about 10 rolling shutter artifacts to fix .....the one above would have to be hand painted in PS/AE as the next frames usually have an overlap in the luminence difference...i.e. a simple mask wont do it when the brightness change is this much.

The next 2 images are 1 frame apart

13940072764_5b4876860b_c.jpg
[/url]A002_C029_0701W8 by mdharrington1, on Flickr[/IMG]
13916521172_dd4f40737a_c.jpg
[/url]A002_C029_0701W8 by mdharrington1, on Flickr[/IMG]
 
Bjorn, could you link an example of a frame sum or compound plugin?

I googled this unsucsessfully...
 
exactly, mike. although when your camera is stable it can be alot easier to find similar frames to roto/paint from - whether you're doing it in photoshop or compositing software. sometimes you can get away with a simple mask that refers that area to the frame before/after, or a similar frame somewhere else. keep in mind there are some lightning effect generators, like the ones in ae, which can be a quick element to use for trying to match/fill in pieces of lightning. otherwise, copy or paint some happy lightning (:

you will not get these kinds of tears with the motion mount.
 
i'm not sure there are any plugins available, at least not for video, so you'll probably have to do it manually. check out 'frame averaging' it's essentially the same concept with a different blending mode. it wouldn't be too difficult to write something for nuke, aftereffects, virtualdub, or something else, but i'm not sure it'd get used much. if you're just trying to get a still, it's just as quick to do it by hand. if you're shooting this method for motion and want realtime, you need to shoot fairly high framerates @ 360 degree shutter, and that does give you a buncha control over exposure. alternatively, don't forget about hdr-x...

probably the easiest thing that might get you close is to just animate an echo effect or similar in after effects.
 
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