Welcome to our community

Be a part of something great, join today!

Log in
  • 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

-edit-

That last line might be confusing.

180 is half a circle. 90 degrees is a quarter. 45 degrees is an eighth.
At 24 fps we take 24 frames every second. That means that the longest each frame could be is 1/24th of a second.

At 180 degrees we have only half of each frame so one half of 1/24th is 1/48th. At 90 we have a quarter of 1/24th which is 1/96.

If we were shooting 48fps then the longest we expose a frame for would be 1/48. 180deg gives us half that which is 1/96th of a second.

Sorry if I'm writing stuff you know already know.
 
Deanan said:
If the shutter is spinning 48 times a second at 360 degree shutter, you will get the same motion blur as 1/24th at 180deg shutter. Motion blur is related to exposure time and if the shutter is spinning twice as fast for 48 fps, then 180 degrees will be open shutter for half the time (or 1/96th sec).
Click to expand...
Yep, thats what I expected...
Irri said:
180 is half a circle. 90 degrees is a quarter. 45 degrees is an eighth.
At 24 fps we take 24 frames every second. That means that the longest each frame could be is 1/24th of a second.

At 180 degrees we have only half of each frame so one half of 1/24th is 1/48th. At 90 we have a quarter of 1/24th which is 1/96.

If we were shooting 48fps then the longest we expose a frame for would be 1/48. 180deg gives us half that which is 1/96th of a second.

Sorry if I'm writing stuff you know already know.
Click to expand...
That's fine Irri... like I said, long time since I've shot, and then it was mainly mo-con, timelapse, or fx-plates, and all on film.. doesn't hurt to verify the thought process.
You're both saying what I'm thinking...

As I said earlier, my notes (as read from the LCD info) tell me that for:

clip A001_C001 we shot 48fps (varispeed ON - "Relative" selected) 180 deg (1/48th) 3k 2:1 and we were @ T16
Metadata through RedCine shows:
A001_C001_metadata.jpg


clip A001_C005 we shot 48fps (varispeed ON - "Relative" selected) 90 deg (1/96th) 3k 2:1 and we were @ T11
Metadata through RedCine shows:
A001_C005_metadata.jpg


What am I missing here (probably something simple?) ??

(cont'd next post)

~~~~~~~~~~~~~~~~~~~
 
pt2

pt2

... and just to make sure I'm not going crazy... I powered up the camera and loaded a CF card from the shoot, and the LCD is showing all the data I expected.. (see photos below) yet the Metadata from the last clip on the card shows as:
A019_C003_metadata.jpg


(cont'd below)
 
Thanx Irri... i expected this too.
 
Chris, I think the meta data is wrong.

The calculation it makes for reporting the shutter angle is probably based on the project frame rate rather than the actual frame rate.

So in clip A001_C001 it takes the 1/96 exposure time and the project frame rate 24fps (instead of the actual frame rate 48fps) and reports 90deg instead of 180. This is a guess, but it seems quite likely.

Nick
 
Im pretty sure of it...thats right Irri
 
Thanks guys... so the question is... how do I verify the data-rate/conditions that was actually recorded if I can't trust the Metadata?
I mean, I'm looking at flames.... it looks like its probably 48fps... but I'd like to be able to convince the VFX sup that it was definately a 180deg shutter....

Chris
 
Work it out from the shutter speed and fps:

fps x shutter x 360 = shutter angle
e.g.
48 x 1/96 x 360 = 180

I think that is right.
 
This is for people with patience.

Can somebody, very simply, give examples of scenes where one might want to use different shutter speeds? :nerd:

Thanks:biggrin:
 
You must log in or register to reply here.
Back
Top