8mm Forum: PROBLEM WITH SCOPE

This is topic PROBLEM WITH SCOPE in forum 8mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=000994

Posted by Martyn Bennett (Member # 263) on January 15, 2005, 07:25 AM:

Hi everyone this is my first posting, i have been reading with interest the postings on this forum for a few months and have picked up a lot of useful info.
To put everyone in the picture (no pun intended) i am in the process of converting my garage into a cinema.
Having just bought a scope lens i find the projected image is too wide for my future screen, i am using a standard ELMO ST1200 zoom lens.
Is there an alternative primary lens i should be using? i need a scope image of approx 7 foot projected at a distance of 17 foot.

Posted by Bob Pucci (Member # 8) on January 15, 2005, 08:05 AM:

Hi Do you have your zoom lens set for the smallest picture.I have a ST 1200 with a scope lens and at a 17 foot throw I get a 7 foot wide picture.

Posted by Martyn Bennett (Member # 263) on January 15, 2005, 08:20 AM:

Hi Bob, yes zoom is set to minimum, projection distance is 18.5 foot.Just measured it.

Posted by Adrian Winchester (Member # 248) on January 16, 2005, 07:43 PM:

I use a GS1200 with a slightly longer throw, and when projecting in scope, I'd also like a slightly smaller picture than the smallest I can get. I guess the range of the zoom is more geared towards flat films. I know there is an Elmo long-throw zoom lens that would give a smaller picture, but they are very hard to find.

Posted by John Clancy (Member # 49) on January 17, 2005, 02:48 AM:

Sounds like you need an Elmo 1.4 zoom lens.

Posted by Jan Bister (Member # 332) on January 17, 2005, 08:17 AM:

Another, somewhat obvious, possibility would be to move your projector closer toward the screen... Now I realize that probably puts it smack in the middle of the garage where the audience is intended to sit, and you don't want anybody knocking the machine over during a feature *shock, horror* :-) But I'm thinking, maybe you could build some sort of platform suspended from the ceiling on which to place the projector? It's an idea, at least.
BTW - maybe I'm misunderstanding the "Elmo 1.4 zoom lens" part here, but I'm not entirely sure how a slower lens is going to help get a smaller image. (No insult meant - purely ignorance on my part.) [Cool]

Posted by Alan Rik (Member # 73) on January 17, 2005, 09:24 AM:

Hello. I believe the 1.4 Elmo is the 25-50mm lens. Good for auditorium use. Im not really sure though. I use to own the super sharp 1.2 25-50. Great lens but I had to be to close to fill the screen!

Posted by Tim Christian (Member # 48) on January 17, 2005, 10:42 AM:

Data giving lens focal length, screen height and distance can be found in

this article

Note that the screen height is used so that both Academy and scope formats can be derived. (For full 'scope, 7' wide is 2' 7 1/2" high; that height is given by a 25 mm lens at 17'.)

HTH. Tim.

Posted by Mike Peckham (Member # 16) on January 17, 2005, 11:36 AM:

Classic Home Cinema; http://valueservices.org/classichomecinema/ had one of the auditorium lenses for sale recently, might be worth checking with them [Smile]

.

Mike

ps. Welcome!

Posted by Martyn Bennett (Member # 263) on January 17, 2005, 03:50 PM:

Thanks everyone for the replies, i have now got plenty of info to go on.
PS the projectors are in a purpose built projection room that i have built on the rear of the garage so moving them closer to the screen is not an option for me, and i do not want to move the screen closer, my garage is too small.

Posted by Chris Quinn (Member # 129) on January 17, 2005, 04:00 PM:

Hi Martyn,
Nice to see you made it on here at last.
I think the f1.4 long throw is your only way out, i have seen them come up on ebay from time to time but it is rare.
Keep an eye on the german site you stand a better chance getting one there, may take time but do come up.
Im sure you had a F1.1 lens of me on one of the ST's you bought, make sure this is the one your not using, although more light output which is what you want, it is a shorter throw lens than the f1.3

Chris.

UBB.classic^TM 6.3.1.2