Arri Sr Pressure Plate
Posted 21 June 2011 - 07:31 PM
Posted 21 June 2011 - 08:23 PM
The top of the plate should exert around 200 gram-force or 2 Newtons, the bottom half that (100 gram-force). Also important is the centre plate pressure (a separate spring), which should exert 10-15 gf.
If these pressure values are off, the film may not be guided properly through the gate, causing possible steadiness issues, focus breathing or scratching. It sounds like the large spring that controls the entire pressure plate force (top and bottom values) might be slack.
It's an easy adjustment for a tech with proper tools, but if your footage is coming out OK maybe not an urgent repair. If you have other mags, I'd use them for critical footage.
Posted 23 June 2011 - 08:44 PM
Posted 23 June 2011 - 10:44 PM
That can then cause issues as the film passes through the gate. Make sure you clean the gate regularly, as that sticky stuff could build up in there. Maybe also clean the guide rollers. If you can have the feed and take-up tensions checked that would help.
I haven't found a solution other than stripping and repainting them, which is more time than the mags are worth. It sometimes helps to leave the mag somewhere warm and dry with the doors open, and let it air.
Posted 24 June 2011 - 12:35 AM
Posted 24 June 2011 - 02:47 AM
Chances are your footage is fine. It's just something to be aware of - air the mag before use, take care loading, check the gate regularly, listen out for scraping sounds.