J. Lamar King IMPOSTOR Posted February 24, 2005 Share Posted February 24, 2005 This is one those questions I should know the answer to but I don't. Are square wave flicker-free ballast's flicker free at any speed? Can I shoot at 32 and 48fps at 180 shutter and not worry? I've been getting two different answers on this. Link to comment Share on other sites More sharing options...
Premium Member Adam Frisch FSF Posted February 24, 2005 Premium Member Share Posted February 24, 2005 (edited) Supposedly, yes. But I've gotten flicker on both straight tungsten and Kino's at strange fps/shutter angles, so there's really no telling. In ASC's manual there's a chart where one can kinda tell if you're in the danger zone. Might be useful in your instance. Edited February 24, 2005 by AdamFrisch Link to comment Share on other sites More sharing options...
J. Lamar King IMPOSTOR Posted February 24, 2005 Author Share Posted February 24, 2005 Thanks Adam, that's exactly what I've been hearing from other people. Some say no problem others have said they still flicker. Link to comment Share on other sites More sharing options...
Premium Member Laurent Andrieux Posted February 26, 2005 Premium Member Share Posted February 26, 2005 (edited) I had the pb : different answers about this same question. Here's the diagram in the asc manual. It's from the 80's edition. It may not take account of flicker free disposal, but if you're good for standard, you'll be good with flicker free. The problem is always, what happens if it doesn't work properly. I've seen non flicker free flickering at 25 fps 50 Hz. If a flicker free doesnt work properly, it may be better to respect the diagram... Are you at 50 Hz or 60 Hz ? http://l.andrieux.free.fr/hmi.htm Edited February 26, 2005 by laurent.a Link to comment Share on other sites More sharing options...
Premium Member Laurent Andrieux Posted February 26, 2005 Premium Member Share Posted February 26, 2005 The diagram actually doesn't tell you anything about 32 et 48 fps.. I would consider 48 fps is fine at 144° but many people here said 180 ° was ok at 60 Hz 24 fps... assuming you are at 60 hz, I would recommend 30 fps better than 32 if avaible... Link to comment Share on other sites More sharing options...
J. Lamar King IMPOSTOR Posted February 27, 2005 Author Share Posted February 27, 2005 Thanks for posting that chart Laurent. I got a look at one before the shoot. I was just a bit worried about flickering because I realized I've never overcranked with HMI's. I've always used tungsten units or straight sunlight before. I had a discussion with the Gaffer and he assured me that we would not get flicker with our ballasts, shooting at 32 or 48fps. We just wrapped today and the TK is set for Tuesday so I guess I'll know for sure then. There was really only one setup where the HMI was the main source of light anyway. The rest were mixed with sunlight. Link to comment Share on other sites More sharing options...
Premium Member Laurent Andrieux Posted February 27, 2005 Premium Member Share Posted February 27, 2005 Let us know ! Link to comment Share on other sites More sharing options...
Gilbert Posted March 2, 2005 Share Posted March 2, 2005 This is one those questions I should know the answer to but I don't. Are square wave flicker-free ballast's flicker free at any speed? Can I shoot at 32 and 48fps at 180 shutter and not worry? I've been getting two different answers on this. <{POST_SNAPBACK}> You will not get any flicker or flutter at any speed with a square wave HMI ballast when the unit is working properly. The only time you will get flicker or flutter with a square wave ballast is when you have a defective ballast, defective power source or a bad globe (usually old, to many hours). I hope this helps, Link to comment Share on other sites More sharing options...
Premium Member Laurent Andrieux Posted March 2, 2005 Premium Member Share Posted March 2, 2005 (edited) Gilbert, Funny your signature is three times your post's size ! :) You see, that's what I ment... How d'you know the ballast or lamp isn't working properly... before the daylies ! :D I say that because a flickering-because-non-workering-properly one is not that rare, unfortunatly... Edited March 2, 2005 by laurent.a Link to comment Share on other sites More sharing options...
Gilbert Posted March 2, 2005 Share Posted March 2, 2005 Gilbert, Funny your signature is three times your post's size ! :) You see, that's what I ment... How d'you know the ballast or lamp isn't working properly... before the daylies ! :D I say that because a flickering-because-non-workering-properly one is not that rare, unfortunatly... <{POST_SNAPBACK}> Have it serviced to make sure it is working properly! They can tell the age of the globe and check the output power (square wave) of the ballast to make sure everything is working properly. Just like a car you want it serviced once in a while, correct? By the way, I like my signature 3 times the post. Best Regards, Link to comment Share on other sites More sharing options...
J. Lamar King IMPOSTOR Posted March 3, 2005 Author Share Posted March 3, 2005 Well, it turns out we got no flicker at 32fps and intermitent flicker at 48fps. Nothing we couldn't cut around. I guess if it were a more critical shot it would be prudent to use a cine speed meter or something to double check them. Link to comment Share on other sites More sharing options...
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