Long Exposures

[Chad Shillady]

Ok so I dropped down to 6K and all the frame averaging options because available. Thank you for pointing the 8K issue out. So now I’m at 1 FPS 1/16 SS 360°. If I select 8 frames in averaging what values would I select in the time lapse screen to try to get light trails of cars passing by at sunset? These values are confusing me, I don’t think I’m looking at them the right way.

 

[Thomas B.]

Hi Chad,

This seems to be a difficult question - I mean, almost one week over and no help so far...
this question must have caused many headaches... :shocked:
First of all, I don't own a RED yet, nor any other cinema camera, so the "shutter angle way of thinking" is still unusal for me. (...and maybe with DSMC3 and global shutter, this way of thinking might disappear in the long run)
But I have taken several timelapse shots with DSLR's in the past and so I try to help.
According to RED's DSMC2 OpsGuides, your camera's longest exposure time is 1 second and the minimum frame rate is 1fps.

And here's an important notice out of the Operation Manual:

When in Frame Summing mode or Frame Averaging mode, the current integration time is applied to each frame.
This means if the integration time is not the entire frame time (or 360°) there are gaps between the images used to create the combined frame.
This may lead to unexpected motion artifacts.

I don't think the mentioned reduced noise is worth dealing with unwanted artifacts. Maybe the gaps would be too long. Better you try 1 second exposure or 1/16th SS at 16fps (16 frames averaging), so there's just the gap between your 1fps framerate and the frame interval.

BTW wouldn't it be a lot easier to shoot this scene (long streaks of car lights at sunset) with a DSLR and ND filter (maybe adding up in the scene)?

Generally, with longer exposure, the timelapse scene looks smoother, but of course, it all depends on what you shoot (slow or fast moving objects). In this case, how fast the cars are driving by, your distance to the cars (relative speed the cars are passing the FoV), the angle of view (are the cars passing by from left/right :auto: , up/downwards / diagonally /
low angle almost from behind/front :driving: , etc.). This is determing how long the streaks of light will get, and therefore you would be a lot more flexible with a DSLR, in case you would have to make a long exposure (longer than 1 second).

If I understand the OpsGuide correctly, with your setting, the camera would take a single frame every second
with 1/16th s exposure time, after 8 seconds you'll get your first averaged frame, but it might look strange, because of the gaps. You won't get a usual 8 second exposure out of this setting, nor a 1/16th s exposure, even if the exposure value of the final image equals to a 1/16 SS frame. But it might look interesting or pleasing, too, honestly I don't know.
Would be great if you could post an averaged frame after your try.

In the end all this is subjective and everyone will have to try and choose the settings for themselves to get the exact look they want.

By the way, I don't know how you can achieve a shutter angle of 360° when setting an exposure time of 1/16th of a second at 1fps, but as I already mentioned, I'm new to this shutter angle way of thinking.

Don't know how your "Internal TimeLapse Timer Screen" looks like (I'm reading the OpsGuide), but I guess they all offer about the same settings to select.
You have set the values how the single frame will look like in the frame averaging menu, and in the timelapse screen, you can select how slow/fast, smooth/stuttery the final timelapse scene will look like, and of course how long the final scene/clip will be. (this also might need some testing, but luckily, your mentioned scene happens every day)
For this, you have to know your final project time base, let's say 24fps. If you set the frame interval to 1s (if even possible, due to averaging processing time), your final playback speed of the clip will be 24x the normal speed which already looks quite fast but not too smooth due to 1/16th s SS, frame averaging and possible motion artifacts.
With frame averaging, you probably get unwanted, additional time loss between the recorded frames.
Therefore I guess a 1 second exposure would be better.

If you would set a longer frame interval, lets say the camera takes a picture every 4 seconds (remember there are driving cars), it get's even worse.
The slower the playback speed/project time base/less fps, the longer you will have to expose to get a smoother look (but then, the objects get blurred), and if you choose a longer time interval for shooting frames, I'd also suggest to set a longer exposure time for most moving subjects, except you want to shoot a "miniature world" looking scenery or blooming/withering flowers stuff, etc.
...but as I already mentioned above, it's all a matter of taste and depends on what you shoot. Therefore you should try different settings and choose the one you like the most.

Let's get back to the settings menu:
If you already know how long your clip has to be, you can multiply the clip duration (seconds) with the project time base (playback time) to get the number of frames you have to take.
Then, if you want to know how much real time the whole take will take, multiply the number of frames with the frame interval (the time between every recorded frame).
When using frame averaging multiply this result with the amount of frames you have set for frame averaging.
(divide the total through 60 for minutes or 3600 for hours)
For example, a 30seconds/24fps clip needs 720 frames, x 8 frame averaging = 5760 frames or 5760 seconds because you shoot 1fps : 60 = 96 minutes of recording.
Or just select the maximum frames you can select and stop the recording manually whenever you want.
Choose the interval (between 1 second and 1 hour) and start recording / waiting.
Is your camera setup able to hot swap batteries? Just in case you shoot a scene with a longer frame interval one day...

I hope this helps. :smilewinkgrin:

Thomas

 

[Alex Lubensky]

1fps - 360 shutter - frame averaging set to 16. (RED Scarlet MX, iso 1600, 4k UHD)

By setting a shutter of 360 with any desired frame you end up without any gaps. If you set your shutter to 180, you'll get gaps in moving objects due to iteration time (camera collects 1 frame from 16 different images recorded one after another, not depending on your timelapse trigger settings)

 

[Thomas B.]

Thank you, Alex, for showing an example. Looks nice.
With your setting, you get a 16 second exposure in one frame (exposure averaged from 16x 1s exposures).
That's almost what I suggested in my post...to get no gaps. I just didn't realize that you can add as many images as you want.
Nice feature, indeed. But you can't record 1fps with an exposure time of 1/16th second and a shutter angle of 360°, right?
If you set 1fps and a 360° shutter angle you expose for 1 second, or am I wrong?! Chad's infos confused me quite a bit... :banghead:

 

[Mike P.]

The 16/1 only comes into effect with Frame Summing I believe. With Frame Averaging, it remains 360deg, and then combines 2-16 360deg shots and averages them (reducing noise in the process)... I'm not sure if this means it's the equivalent of a 2-16s long exposure/shutter while retaining "360deg brightness" though (but that'd be easy to test).

In Frame Summing, it'd be 16/1 shutter (as it adds the 2-16 frames together increasing brightness)...

...I think.

There's also this (not that it makes it any clearer): http://docs.red.com/955-0192_v7.2/R...nus/1_Settings/Recording/Frame_Processing.htm

OH, if no one has mentioned it, you'll need to do a black shade at 1fps/360deg shutter, otherwise it'll be a friggen mess.

 

[Alex Lubensky]

Thank you, Alex, for showing an example. Looks nice.
With your setting, you get a 16 second exposure in one frame (exposure averaged from 16x 1s exposures).
That's almost what I suggested in my post...to get no gaps. I just didn't realize that you can add as many images as you want.
Nice feature, indeed. But you can't record 1fps with an exposure time of 1/16th second and a shutter angle of 360°, right?
If you set 1fps and a 360° shutter angle you expose for 1 second, or am I wrong?! Chad's infos confused me quite a bit... :banghead:

To be exact - in frame averaging mode set by 16 you get - 16 frames of motion mixed to 1 frame with the exposure of 1 second each, while the overall exposure of them all gets averaged to the same 1 second. Thus your images does not multiply in exposure, if you record 1 frame without frame averaging at exposure of 1 second the brightness of the image will be exactly the same as if you do averaging of 16 frames, but the motion recorded into the image will be only 1 second, while with averaging you get 16 seconds of motion recorded to 1 frame.

In frame averaging mode most of the time (speaking of timelapse) you want a 360 degree shutter if you record motion - if you set lower you are going to see gaps in motion blur.

If you want a brighter image by multiplying frames you should set frame summing. For stars you might want setting frame summing - BUT it’s not going to be as good as bulb exposures on dslr. For stars I find much more comfortable shooting on a dslr.

*also you seem not to understand what shutter angle is. Shutter angle is a relative term, which in case of 180 degree example is /2 the fps. If you record 24 fps with 180 deg shutter you get 24/2= 1/48. If you record 100 FPS - you get 100/2=1/200. If you record 1 FPS = you get 1/2 shutter speed. So 360 deg shutter is dividing FPS by /1, 180 deg shutter is /2, 90 deg shutter is /4.

 

[Thomas B.]

*also you seem not to understand what shutter angle is. Shutter angle is a relative term, which in case of 180 degree example is /2 the fps. If you record 24 fps with 180 deg shutter you get 24/2= 1/48. If you record 100 FPS - you get 100/2=1/200. If you record 1 FPS = you get 1/2 shutter speed. So 360 deg shutter is dividing FPS by /1, 180 deg shutter is /2, 90 deg shutter is /4.

I know that shutter angle is the "exposure time" relative to the frame rate. But "shutter speed" or "exposure time" are the same, specified in (fraction of) seconds, while shutter angle is specified in degrees; so if Chad writes "So now I’m at 1 FPS 1/16 SS 360°", I assume that SS stands for Shutter Speed which can't be true/possible; when he has set a shutter angle of 360° at 1fps, his shutter speed or exposure time is or must be 1 second. This is what confused me.
But it was interesting to read your experience with frame averaging/summing, thanks a lot for that.
I'm sorry Chad, for writing about you in the third person, but since you've been so quiet...
...would be glad to hear from your experience and if your scene worked out.

 

[Alex Lubensky]

I know that shutter angle is the "exposure time" relative to the frame rate. But "shutter speed" or "exposure time" are the same, specified in (fraction of) seconds, while shutter angle is specified in degrees; so if Chad writes "So now I’m at 1 FPS 1/16 SS 360°", I assume that SS stands for Shutter Speed which can't be true/possible; when he has set a shutter angle of 360° at 1fps, his shutter speed or exposure time is or must be 1 second. This is what confused me.
But it was interesting to read your experience with frame averaging/summing, thanks a lot for that.
I'm sorry Chad, for writing about you in the third person, but since you've been so quiet...
...would be glad to hear from your experience and if your scene worked out.

oh, my bad, wasn't quite into what whas discussed before. I guess what was meant - he's recording 1fps with frame averaging of 16 at a shutter angle of 360. When you set frame averaging to 16 your camera shows frame rate of 1/16.

 

[Thomas B.]

Ah, okay, sorry....how could I know...all good. :cheers2:

 

[Mike P.]

Just got an email saying this week's Solidary Series will be covering time-lapse and record modes... with any luck it might cover long exposure too!

 

[Mark A. Jaeger]

DSLR time-lapse (T-L) and RED T-L with frame processing have few things in common with respect to the mechanics. Obviously the basic principles of T-L shooting apply equally but the "doing" is different with frame processing. The comments below are based upon my DSMC2 Monstro. Here are some things to consider:
a) As Chad found above, shooting 8K with frame processing is not possible on the present DSMC2. The information highway has a speed limit. If you want the full range of 16 frames processed, you'll need to go to 5K. This means an effective focal length change.
b) Frame processing is applicable to continuous shooting and Internal Timelapse Timer Mode.
c) On my Monstro I can select 1 second shutter and 1 fps. I don't know why 1/2 second was stated as the maximum in David's post above. The 1fps + 1 second shutter is the most light you can get to the sensor (that I am aware of) without frame processing.
d) Fast Glass is really important to low light shooting with RED. You want f/1.4 or T1.5 glass. I also use the low light OLPF as it gives a small additional benefit. What would be easy-pie on a Nikon D850 is not so simple with RED.
e) Within Frame Processing there are two choices: Frame Summing and Frame Averaging. Both have applicability to low light work (e.g. Astrophotography). For either FS or FA you can select 2, 4, 8 or 16 frames to process.
f) In the case of FS, the summing increases the brightness, respectively, about 1, 2, 3 or 4 stops. With FS, the noise is also summed. As such, it is my experience that 2 or 4 frame frame summing is about all I want to do because of the noise build-up.
g) In the case of FA, the frames are averaged. There is no appreciable increase in brightness. Noise is nicely reduced as the averaging will greatly reduce non-repeating anomalies.
h) When you shoot FA with a 1 second shutter and 1 fps, the DSMC2 will force the fps to roughly 1 divided by the number of frames to process. If, for example, you select 16 frame FA, the resulti will be 1/16.15 fps.
i) motion blur can be an issue. My goal is to NOT have star trails. There are calculations to determine for a given lens and sensor pixel pitch how long the exposure can be before you have pixel crossings. It is way shorter than the Rule of 500/600. A 30 second astro shot will result in slightly sausage shaped stars. If you want star trails, you need to work it within the limitation of a 16 second exposure.
j) With f/1.4 lens, 1 fps, 1 second shutter, ISO800, and no frame processing I find that nice Astro shots are possible. With a higher ISO, I use 4 frame FA. If the light is just not enough I have used 4f-FS on several occasions with discernible but acceptable noise.
k) As Thomas points out, 16f-FA will take awhile to capture frames. 16 seconds per frame is a lot of time compression (1 : 384 @ 24 fps viewing). Four frame FA yields what I think is an acceptable 4-second interval.
I hope this helps.

 

[Thomas B.]

Mark,
Thank you so much for sharing your experience. Let's hope that Komodo will also have a time lapse (FS/FA) function.