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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 :)

Ramping Bug

Trevor Meier

Trevor Meier

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I've done some ramping tests, with a GPIO trigger and On-Record, and have run into a rather nasty bug.

Tests from 24-48 fps work fine. But go any higher (60, 120, etc.) and things start getting weird on playback. The ramp occurs as it should, either starting from record or from when the trigger is hit and landing at the target frame rate. But then, after a few seconds the clip starts speeding up, dropping down to what looks like around 12fps.

Again, this is only on speed ramps above 48 frames (23.98 timebase).

Any ideas?
 
... you can do time ramping with RED? Explain, please?
 
Varispeed frame rate ramping - so, ramping a shot from 24fps to 120fps as you are rolling.
 
Ramps

Ramps

Which Build Trevor ?

Edit. We did a fair amount of work on internal ramp control on Build 16, so this is likely to me much better now
 
Stuart English said:
Which Build Trevor ?
Click to expand...

I had serious issues on build 15 with this. 16 seemed to be a lot better, but I have had ramps that failed with 16. What happens to me is usually the ramp stops before target frame rate. There's some recipe of total ramp time and total FPS distance that causes more problems than others.

The problem with just choosing a faster frame rate and ramping in post is you don't get smeary slow shutter effects on slower frames if you want that effect as part of your ramp.
 
Trevor Meier said:
I've done some ramping tests, with a GPIO trigger and On-Record, and have run into a rather nasty bug.

Tests from 24-48 fps work fine. But go any higher (60, 120, etc.) and things start getting weird on playback. The ramp occurs as it should, either starting from record or from when the trigger is hit and landing at the target frame rate. But then, after a few seconds the clip starts speeding up, dropping down to what looks like around 12fps.

Again, this is only on speed ramps above 48 frames (23.98 timebase).

Any ideas?
Click to expand...

If you don't mind me asking what device are you using as your GPI trigger? (Not that I think it has anything to do with your problem mind you, just curious.)
 
Do you need a GPIO button to do ramps??? And can you do several ramps or just keep ramping during a take. Say go from 2 or 3 fps to 48 and back at the click of a button and push it again to go back to 48 over and over. Of corse setting up that the ramp is to be timed at say 2 or 3 seconds.???
 
Just one ramp per roll. You can do ramps on record-start if you don't have a GPIO trigger, but that's of limited usefulness...
 
Depends whether you're maintaining exposure with an iris pull or constant exposure time (variable shutter angle through the ramp). If you're doing an iris pull, yes, shooting 48 won't help. If you want the equivalent of ramping shutter angle along with framerate, then shooting 48 and doing the ramp in post will look the same.
 
Your wrong! 2 FPS at 360 shutter looks extreamly different than 48 FpS. The amount of movement is 20 times more. Its like looking at a smeary water color painting or a crisp digital still. To rapidly go between the two looks like going from 200 mph to a crawl.
 
I'm wrong, eh? Re-read my post. If you want constant exposure time (variable angle - "normal" shutter on the RED), doing it in post will look identical. If you want to do an iris pull and maintain shutter angle (in your case 360º) then no, doing it in post won't help.
 
We have a start stop from our handle to the third lemo down on the right front of the body. can that make a ramp or does the contact closure go to another lemo?
 
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