120fps @ 180 degree shutter?

[caseybramall]

Is there a way to get 120fps @ 180 degree shutter? It appears that the "shutter angle", (I use quotations because it's not really working as a true shutter...), changes as the FPS is changed... is it possible to lock in both the shutter angle and the fps that is desired? If so, how?!! If not, why?!! Any help would be much appreciated!

Thanks!

Casey

 

[Alex Carr]

If you set the Shutter mode to Relative it will be 180 at 120fps, or 1/240th of a second.

Watch out for Magnetic Ballast HMI's, or you will have to use off shutter speeds

 

[caseybramall]

ugh... am I missing something???

ugh... am I missing something???

From what I can tell there isn't a 1/240 = 180 @ 120fps, it appears the only preset close is 1/250th = 208 @ 120fps, basically it appears that the shutter angle is only a representation of the closest exposure time available. Maybe I'm not getting it, but if you could explain how it's possible to dial in any shutter angle at any frame rate, specifically a 180 degree shutter at 120 fps, that would be great, because from what I can work out, dialing in the degrees isn't possible, you can only get "close" Help?

 

[caseybramall]

ok is this right?

ok is this right?

So. Ok... 1/48 @ 24fps = 180 degree shutter, sooo, in "relative" mode, all I need to do is to set the cam at 120fps, and the shutter changes from 1/48 to 1/240 by itself, to make a 180 degree shutter? If this works, why can't the camera be set to 1/240 in the presets? I hope this is correct... brain starting to hurt...

 

[Matt Redmond]

Right...

Right...

So you want to shoot 180 degrees at 120fps?

First, you can either display your shutter as degrees or fractions of a second.
SYSTEM » SETUP » DISPLAY » SHUTTER

To be honest it doesn't matter, just as long as you comfortably understand what's going on.

But caseybramall is right - 1/48 @ 24fps = 180 degree shutter.

Next, go to the shutter menu and change your shutter MODE to RELATIVE. Why Relative over Normal?

Normal means, no matter what frame rate you are at, the chip will be "EXPOSED" for that period of time (1/48th of a second generally if you're running at 24p).

Relative means, what ever frame rate you select the shutter will automatically adjust to keep the same motion blur characteristics in those "off speeds" as they would appear at, say 1/48th of a second shutter at 24p.

So, if you want 180 degrees at 120 frames per second, first set your "BASE." In other words set the camera to 24p and the shutter to 1/48th OR 180deg. Set the shutter mode to relative. Now set your new frame rate and you will notice on the LCD or in the Viewfinder that the Shutter (now displaying in yellow as opposed to white) will do 1 of two things.

If your shutter display is set to degrees it will stay at 180 degrees. Yay.
If your shutter display is set to fractions of a second it will vary as you change the frame rate. Again...yay.

NOTE: The back LCD on the camera will display your BASE settings only (24p 1/48th shutter, etc) no matter what frame rate you go to.

 

[caseybramall]

thanks! problem apparently solved.

thanks! problem apparently solved.

Ok, went to build 17... seemed to correct the issue I was having with the shutter angle. Can now shoot in relative mode at 180 degrees, at 120 fps! Still not sure why you have to use relative mode to get a 240 degree angle, seems like there should be a lot more presets for degrees in the camera natively... maybe that's just me. Another thing: Can now ramp from 24 fps to 120fps in relative mode @ 180 degrees... almost like a film camera, except not. nice effect, love it. Thanks for your responses, and help, its appreciated!

 

[Dominic Jones]

This is the clasic problem with Red´s implementation of shutter type selection and readout. I´ve said it before and no doubt I´ll say it again - it´s very confusing and really should be changed at some point.

Essentially, as you´ve probably worked out by now, you can change the shutter viewing mode between angles and fractions of a second without changing the shutter mode from absolute to relative, and vice-versa. The thing is, it just doesn´t make any intuitive sense to either those used to working on video or those used to film cameras. I´ve had problems explaining this to literally every AC I´ve worked on the camera with, many of them very experienced and certainly not stupid!

It would be much better, imho, if they just had one selection - relative or absolute shutter mode - where absolute reads out as a fraction of a second and relative reads out as an angle.

FWIW, the number of "preset" absolute speeds selectable for the Red is greater than almost any other video camera I´ve worked on - the problem with having all of them available is that it then takes you forever to dial in a high shutter speed, or move back down to a low one. Normally, a shutter speed that´s fairly close will do with a slight compensation in the iris (safe speeds at high framerates is a different issue, of course), but perhaps in future a "fine tune" control could be added for those who really don´t want to use angles...

 

[Stuart English]

Shutter Speeds

Shutter Speeds

Why can't the camera be set to 1/240 in the presets?

You can. Select the closest SPEED that you can find - for example 1/250.

Now go to MODE and set it to SYNCRO

Now adjust SYNCRO and you will see the 1/xxx value changing.

At SYNCRO = 52 you will have 1/240.3.

Stop there, and now shoot your 1 - 120 fps slow motion ramp.


By using this method you will keep the same 1/240th exposure throughout the ramp.

If you want a film camera style ramp with a constant percentage of exposure - i.e the exposure decreases as the frame rate increases, pick a reference point - for example 1/48 at 24 fps, and set the shutter mode to RELATIVE. Now as the frame rate increases the exposure will halve i.e at 120 fps it will be 1/240th.


As has been stated, the choice of 1/xx as a display or angles as a display has NOTHING to do with the capabilities described above.

 

[AntonyCASAFilms]

Relation between Framerate and Timebase

Relation between Framerate and Timebase

I am not clear how the settings of Framerate and Timebase affect each other.

If I want to shoot at 120fps (at 2K), then what difference will it make whether the Timebase is set to 24, 25, or 50 ?

 

[Jason Ing]

You can. Select the closest SPEED that you can find - for example 1/250.

Now go to MODE and set it to SYNCRO

Now adjust SYNCRO and you will see the 1/xxx value changing.

At SYNCRO = 52 you will have 1/240.3.

Stop there, and now shoot your 1 - 120 fps slow motion ramp.


By using this method you will keep the same 1/240th exposure throughout the ramp.

If you want a film camera style ramp with a constant percentage of exposure - i.e the exposure decreases as the frame rate increases, pick a reference point - for example 1/48 at 24 fps, and set the shutter mode to RELATIVE. Now as the frame rate increases the exposure will halve i.e at 120 fps it will be 1/240th.


As has been stated, the choice of 1/xx as a display or angles as a display has NOTHING to do with the capabilities described above.

Is there a chart that lists the conversion, rates, etc.? And did I miss this instructions/explanation in the R1 manual?