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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 :)

Shutter Speed

I

Irri

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It's great that RED listen to their customers and have added the "relative" option, but find it a little confusing (this assumes I haven't made a mistake in my understanding of the relative shutter mode):

If I want to shoot 180 degrees, then it's easy. I just leave it at 1/50 (Europe).

If I want to do 50fps at 45 degree shutter then I have to work back from:
25 fps at 180 = 1/50
at 90 = 1/100
at 45 =1/200
The camera will compensate for 50fps and gives me 1/400

With the non-relative system I would have done:
50 fps at 180 = 1/100
at 90 = 1/200
at 45 = 1/400

So in a way, I'm still doing the same maths in my head, just in a different way.

I don't deny that thinking in terms of shutter angle is a little strange for a camera that doesn't have a rotating shutter, but a lot of people still think that way. I'm interested to know why RED didn't go with "absolute" and "cine" modes.
 
Relative and Normal Shutter

Relative and Normal Shutter

Irri said:
It's great that RED listen to their customers and have added the "relative" option, but find it a little confusing (this assumes I haven't made a mistake in my understanding of the relative shutter mode):

If I want to shoot 180 degrees, then it's easy. I just leave it at 1/50 (Europe).

If I want to do 50fps at 45 degree shutter then I have to work back from:
25 fps at 180 = 1/50
at 90 = 1/100
at 45 =1/200
The camera will compensate for 50fps and gives me 1/400

With the non-relative system I would have done:
50 fps at 180 = 1/100
at 90 = 1/200
at 45 = 1/400

So in a way, I'm still doing the same maths in my head, just in a different way.

I don't deny that thinking in terms of shutter angle is a little strange for a camera that doesn't have a rotating shutter, but a lot of people still think that way. I'm interested to know why RED didn't go with "absolute" and "cine" modes.
Click to expand...

Mainly because the math is the same whichever way you approach it, i.e. 180 degrees is half, 90 is a quarter, 45 is an eighth of the frame time so if shooting at 50 fps that would be 1/100th, 1/200th, 1/400th respectively.

For RELATIVE operation the camera just take your starting reference point and scales that by the ratio of the starting frame rate and the new frame rate. In NORMAL mode it just maintains the same exposure across all frame rates - if that is possible.

RELATIVE : if you were at 24 fps at 1/48th (= 180) and went down to 12 fps you would be at 1/24th (still = 180)

NORMAL : if you were at 24 fps at 1/48th (= 180) and went down to 12 fps you would still be at 1/48th (now = 90)
 
Hi Stuart,

It's a shame IMO it's so complicated, the shutter should be linked to the 'pull down' just like the film camera you are all trying so hard to replace.

Stephen

Stuart English said:
Mainly because the math is the same whichever way you approach it, i.e. 180 degrees is half, 90 is a quarter, 45 is an eighth of the frame time so if shooting at 50 fps that would be 1/100th, 1/200th, 1/400th respectively.

For RELATIVE operation the camera just take your starting reference point and scales that by the ratio of the starting frame rate and the new frame rate. In NORMAL mode it just maintains the same exposure across all frame rates - if that is possible.

RELATIVE : if you were at 24 fps at 1/48th (= 180) and went down to 12 fps you would be at 1/24th (still = 180)

NORMAL : if you were at 24 fps at 1/48th (= 180) and went down to 12 fps you would still be at 1/48th (now = 90)
Click to expand...
 
A suggestion how to solve the issue:

Either you choose the shutter speed in degrees (you could also say it's a percentage). In this mode, the shutter speed is always relative to the current fps.

Or you choose the shutter speed in ms (you could also display it as 1/n s). In this mode, the shutter speed is always fixed and not relative to the current fps. Of course, this value will be constrained by the actual frame duration because you cannot do overlapping exposures (yet).

What do you think?
 
Why not just use the same nomenclature used by other manufacturers? Sony and Panasonic both use "degrees" to reference a frame-rate-dependent film-style shutter, and "fractions" to reference a fixed shutter speed (regardless of frame rate).

So if you set an EX1 or HVX to 180 degrees, you know that you're going to get 1/48 at 24fps or 1/60 at 30fps, and regardless of what frame rate you select you're going to get the proper film-style exposure.

If you set to 1/48 you know you're going to get 1/48 of a second exposure, regardless of the frame rate.

Wouldn't that be less confusing?
 
EDIT: what Big Lebowski proposes is exactly how it's done on the other cameras (but not as a percentage, as an actual 0-360 degree setting).
 
Barry Green EDIT: what Big Lebowski proposes is exactly how it's done on the other cameras (but not as a percentage, as an actual 0-360 degree setting).

As I see it, in the REDONE is a digital shutter that is working (with a CMOS,etc) , it will be great if they have translation to degrees, but the camera will be a rolling shutter anyway, it wan´t convert by a miracle in to a mechanical shutter so it will be just easyer to compare but we will be having the same effect, actualy with the relative shutter you will have pretty much cover and when you want to change the 180 traditional you just have to aply the math. Check the formula in the red manual they have been as helpfull as always putting it there.
Jon Corcuera
 
I don't see the point of using degrees in a camera without a mechanical shutter other than you know it's compensating when you select different frame rates.

Otherwise, if the electronic shutter shoots in fractions of time, that's how it should be displayed and input, etc. When shooting film, I'm always having to convert degrees to actual shutter speeds anyway (like trying to figure out the degrees needed if I'm shooting at 24 fps and need a 1/50th shutter speed to shoot under 50 Hz lighting -- it would be a lot easier if I could just select 1/50th!) My meter doesn't have shutter angles as a selection option. Or the 200 degree shutter on the Panaflex -- what is that, an extra 1/6th of a stop more exposure over 180 degrees? I'd have to do some math to figure that out.

I just want to know the frame rate and the actual per-frame shutter time. Working in degrees just seems like some archaic holdover. I dread using digital cameras that still have shutter angle settings.
 
In case you missed it, I had a thread up a while back with conversions......

http://www.reduser.net/forum/showthread.php?t=8741

This lists all of the available shutter speeds RED offers in addition to a shutter conversion and the resulting f-stop increase or decrease based upon that speed.

All conversions are based on a 24fps frame rate.

+/- F-stops are based on a baseline 320 ASA with 1/48th (180°) shutter.

Please keep in mind that a few of the +/- f-stop conversions are rounded off to the nearest angle.

1/24 - 360° +1 f-stop
1/30 - 288°
1/32 - 270°
1/40 - 216°
1/48 - 180° Baseline
1/50 - 172°
1/60 - 144°
1/96 - 90° -1 f-stop
1/100 - 86°
1/120 - 72°
1/125 - 69°
1/192 - 45° -2 f-stops
1/200 - 43°
1/250 - 34°
1/400 - 22° -3 f-stops
1/500 - 17°
1/696 - 12°
1/800 - 11° - 4 f-stops
1/1000 - 9°
1/1200 - 7°
---N/A - 6° - 5 f-stops
1/2000 - 4°
 
Angles etc

Angles etc

Also the Operations Guide provides this simple math to converts any Angle to Shutter Speed or back..


To Convert an Angle to an Equivalent Shutter Speed

Equivalent Shutter = 1 / ( Frame Rate x 360 / Angle )

e.g. = 1 / (24 x 360 / 180 ) = 1 / (8640 / 180) = 1 / 48



To Convert Shutter Speed to Angle Equivalent

Equivalent Degrees = (Shutter Speed x Frame Rate x 360)

e.g. = (1/48 x 24 x 360) = (8640 / 48) = 180
 
Whether you want degrees or not, it's just seems counterproductive (if not plain silly) for the camera to report 1/48 when the actual exposure time is not, in fact, 1/48 (and that's what happens in the 'relative'" mode).

It is good to have both absolute and relative modes, yes. You can go in and force an absolute exposure at any time, and it reports that exposure, properly. But the relative mode is where the issue is. I'd rather put in the angle, and have the camera report back the actual exposure time that it's currently employing. So, at 24fps, I select 180d, and when I exit the menu it says 1/48. Then if I change the frame rate to 30fps the shutter display would now read 1/60 (instead of how it currently does, which is that it will still say 1/48!) That's just wrong no matter how you slice it.
 
Barry Green said:
Whether you want degrees or not, it's just seems counterproductive (if not plain silly) for the camera to report 1/48 when the actual exposure time is not, in fact, 1/48 (and that's what happens in the 'relative'" mode).

It is good to have both absolute and relative modes, yes. You can go in and force an absolute exposure at any time, and it reports that exposure, properly. But the relative mode is where the issue is. I'd rather put in the angle, and have the camera report back the actual exposure time that it's currently employing. So, at 24fps, I select 180d, and when I exit the menu it says 1/48. Then if I change the frame rate to 30fps the shutter display would now read 1/60 (instead of how it currently does, which is that it will still say 1/48!) That's just wrong no matter how you slice it.
Click to expand...

Thank you Barry Green, I've been waiting for you to join these forums and raise this entirely too important point.

Stephen Williams said:
Hi Stuart,

It's a shame IMO it's so complicated, the shutter should be linked to the 'pull down' just like the film camera you are all trying so hard to replace.

Stephen
Click to expand...


Thank you Stephen as well, as always, quite properly worded.
 
There you go again Barry.... Making things easy to use again. :)

No, Seriously. Here is where video and film collide in digital cinema. I prefer the degrees path as it heralds back to my SD and HD roots. I know this is wrong to some. So why not make it a setting in the menu and leave it at that? Choose the one you want. WHat do you think Stuart?
 
I think I generally work out in my head what the shutter angle is and also what the exposure time is. I see David's point about knowing the actual exposure time being more important. There are a lot of DoPs who just think in shutter angles though.


Stuart English said:
Also the Operations Guide provides this simple math to converts any Angle to Shutter Speed or back..


To Convert an Angle to an Equivalent Shutter Speed

Equivalent Shutter = 1 / ( Frame Rate x 360 / Angle )

e.g. = 1 / (24 x 360 / 180 ) = 1 / (8640 / 180) = 1 / 48



To Convert Shutter Speed to Angle Equivalent

Equivalent Degrees = (Shutter Speed x Frame Rate x 360)

e.g. = (1/48 x 24 x 360) = (8640 / 48) = 180
Click to expand...

This is exactly the maths I don't want to be doing on set and exactly what I thought the relative mode would take away. I actually wish there wasn't a relative mode because it doesn't solve the shutter speed to shutter angle conversion issue and it adds the danger of making a mistake. To have the camera report that it is shooting at 1/50 when it is actually shooting 1/100 is scary, especially when it is able to report 1/50 and shoot 1/50.

I could understand if in relative mode there were options for 1,1/2,1/4,1/8 etc.
 
RELATIVE Shutter

RELATIVE Shutter

Barry Green said:
Whether you want degrees or not, it's just seems counterproductive (if not plain silly) for the camera to report 1/48 when the actual exposure time is not, in fact, 1/48 (and that's what happens in the 'relative'" mode).
Click to expand...

No question, and that issue is being addressed. Same reporting issue if you select SYNCRO shutter mode.
 
big lebowski said:
A suggestion how to solve the issue:

Either you choose the shutter speed in degrees (you could also say it's a percentage). In this mode, the shutter speed is always relative to the current fps.

Or you choose the shutter speed in ms (you could also display it as 1/n s). In this mode, the shutter speed is always fixed and not relative to the current fps. Of course, this value will be constrained by the actual frame duration because you cannot do overlapping exposures (yet).

What do you think?
Click to expand...

Having read all your comments I must come back to my suggestion from above. I still think this is the solution for everything.

There is two kinds of starting points when it comes to choosing a shutter speed:

a) You want a certain kind of look, speaking of motion blur. The easiest way to do that is by setting a relative shutter speed, relative to the frame duration. Historically it's done in degrees but you could use a percentage as well. 180 degrees = 50 %. These are values you can remember easily and they are absolutely independent of the frame rate. Why should we have to do math on the set in order to make our choice of motion blur?

b) You want to avoid flicker with a certain kind of light/displays etc. Here you know or guess the flicker rate and want the shutter speed to reflect that. So you go for an absolute value. This could be set as a duration (20 ms) or a fraction (1/50 s).

The display should always reflect our choice in our words: either "180°"/"50%" (and there's no need to update the value with overcranked or ramping shots) or "1/50 s" (and it actually IS 1/50 s, no matter what fps you currently use).
 
Angles and 1/xx conversion

Angles and 1/xx conversion

David Mullen ASC said:
I think someone whose nickname is "Workflow Wizard" is going to find making calculations in the field easier than I do... :huh:
Click to expand...

Our mission is to serve our customers, so we'll take the feedback on-board - although our experience with high end projects to date has been closer to David's comments. Meanwhile, the math explanation may allow someone in the RED community to generate a Widget or i-phone applet?
 
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