|
|
This topic comprises 2 pages: 1 2
|
|
Author
|
Topic: Lenses - What Have I Got?
|
Dave Bird
Jedi Master Film Handler
Posts: 777
From: Perth, Ontario, Canada
Registered: Jun 2000
|
posted 08-26-2000 12:28 PM
So many questions (more when I get back to working on my XL's in the fall). But today, I'm wondering what types of lenses I have, or more accurately, what they will be suitable for. They were in use at a drive-in previously:SCOPE : Baush & Lomb CinemaScope Projector Attachment I WITH Kollmorgen Optical Corp
BX241 f:1.9 4-3/4 in. E.F. (range around the B&L from 70 to 500) FLAT : G.T.S. G-2156 Can anyone tell me what these are and what kinds of throw/light/screens these might be suitable for in a range? The Scope lenses look very good save for dust/grease maybe. What can I use to clean without damaging them? The flat look OK on the outer lens, circular scratches on the inner from years of cleaning I'd guess. Why is there no "range" on the flats? Can lenses be re-ground and/or replaced? Of course, new lenses will be ordered for a public DI, but I'm wondering where (and how big) to make my backyard "test" screen. Thank you. ------------------
Dave Bird
| IP: Logged
|
|
|
|
|
|
|
|
Randy Stankey
Film God
Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99
|
posted 08-26-2000 06:56 PM
Have High School math ability? Do it by hand. Write out the equation, plug in the values for the lens, throw and screen you already have in operation. Insert the value for the aperture plate you use. If you don't know or can't look it up just measure as accurately as you can. (Your purpose here is just 'academic' so you don't have to be really accurate.) Once you have THIS one solved, plug in the values for the lenses you want to know about. You can compare things that way and you'll learn some stuff, too.It's all based on proportions: A lens that'll produce a 20 foot picture from 50 feet away will produce a 10 foot picture at 25 feet away. Cut the focal length of the lens in half, and you'll produce the original size picture again. (At 1/2 the original throw distance) Yes, I LIKE the lens calculator program. It comes in handy if you need accurate information or if you have to do a lot of them. It's also cool just to noodle around with just to learn stuff. I just think that too many people resort to computers and calculators too quickly these days. Back when *I* was in school, not only would my teachers holler at me the other kids would have seriously ridiculed me!
| IP: Logged
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
All times are Central (GMT -6:00)
|
This topic comprises 2 pages: 1 2
|
Powered by Infopop Corporation
UBB.classicTM
6.3.1.2
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.
|
Home
Printer-friendly view of this topic