my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Scrims for lamphouse to change f stop

Author Topic: Scrims for lamphouse to change f stop Bernie Anderson Jr Master Film Handler Posts: 435 From: Woodbridge, New Jersey Registered: Apr 2000 posted 05-07-2009 07:10 PM                        I was presented with an issue today. I'm updating a booth for a lab in NYC , they asked me today about scrims for the lamphouse/projectors to cut back the f stop. They are doing something with a picture a 1/4 of the normal 1.37 aperture size which would increase the brightness (I have no idea what that's about). They do not want to defocuse the bulb or use filters, but they want to be able to swap out this "scrim" to change the stops by half or by 1. Is this a manufactured item? They're using a variable iris Schneider lens for their normal projection, but this job will require a different lens, for which they don't want to spend the money. Understandable. I know there was one post about f stops, but not specifically using scrims. Any thoghts?  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 05-07-2009 10:03 PM                     I'm not sure other than through experimentation how you would calibrate a series of scrims. Stainless steel screen could be used but it may eventually deterioate causing the light level to wander. If this is a smnall lamp... say 1kw or under then they'd probably last a long time... but larger lamps would take theor toll on the screen material. Iris's are really the best way and can also provide a bit of extra depth of focus at the same time. Can be a big advantage. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 05-07-2009 10:50 PM                     I usually make them from stanless steel window screen material and mount them in the front of the lamphouse  |  IP: Logged Bernie Anderson Jr Master Film Handler Posts: 435 From: Woodbridge, New Jersey Registered: Apr 2000 posted 05-08-2009 04:29 PM                        So nothing is really manufactured for such a job then? Just trial and error. Thanks Bernie  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 05-08-2009 04:40 PM                     I made up many different ones over the year for various labs and shouts to match what they want and it was a trial and error process  |  IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.