Film-Tech Forum ARCHIVE: Help with lenses for 1.37

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

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » Help with lenses for 1.37

Author

Topic: Help with lenses for 1.37

Dave Cutler
Master Film Handler

Posts: 277
From: Centennial, CO
Registered: Jun 2000

posted 09-26-2000 10:55 AM

I have just found out that I could very possibly be running a classic horror film series in the month of October. While very cool I don't have a lens for the 1.37:1 that the films were filmed in. I will be (hopefully) running films like Dracula, Murders in the Rue Morgue, and the Mummy (Original). Am I right on the aspect ratio?

Anyway, how can I show these films? Where can a get a lens for 1.37? I have three Schnieder lenses currently and none of them will work. I have a 70mm, a 35mm (Flat), and a Integrated Anamorphic.

Any help (recomendations) would be appreciated.

| IP: Logged

Phil Connolly
Film Handler

Posts: 80
From: Derby, England
Registered: May 2000

posted 09-26-2000 11:10 AM

To project 1:1.37 you use a flat lense with a 1:1.37 aperture plate. A scope aperture plate will work at a pinch. Depending on the throw you would proberly need a different flat lense, using your current flat lense the image would be same width as normal flat print, but it would be too high.

| IP: Logged

Dave Cutler
Master Film Handler

Posts: 277
From: Centennial, CO
Registered: Jun 2000

posted 09-26-2000 12:36 PM

I thought about it some more and talked with one of the guys I work with and we came up with this idea...

Flat lens with NO apeture and masking on the portglass.

I work at a large format theatre so a taller image isn't a problem and the 35mm won't fill the screen either way.

Any ideas, suggestions? Good idea or bad?

| IP: Logged

Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 09-26-2000 12:54 PM

If screen masking isn't an issue, the 1.85 lenses will work fine. Not getting proper aperture plates is cheesy, though. What kind of projectors do you have? If they're Simplexes or Centurys, you can order pre-cut (to SMPTE spec) Academy plates for about $10 each. You could order under-cut plates and file them yourself, but it would be difficult to get the edges sharp if you don't have masking.

| IP: Logged

Dave Cutler
Master Film Handler

Posts: 277
From: Centennial, CO
Registered: Jun 2000

posted 09-26-2000 02:29 PM

Does anyone know the higth and width for a 1.37 aperture? What would you be looking for with RP-40 to achieve 1.37:1?

Thanx

| IP: Logged

John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 09-26-2000 02:53 PM

A "old ratio" aperture plate is 0.600" x 0.825." That is what you would see projected with 35PA (RP-40.)

An old trick is to take the anamorphic adaptor off of the existing 'scope lens, and use it. It not exactly correct, but is close. If you would like us to figure out what the correct lens size you need, tell us the screen size and throw.

Scott is right; aperture plates are usually cheap and get you close right away. Otherwise, some elecrical tape on the port window will mask it off; which will be important, since I assume ther will not be any masking at the screen,

| IP: Logged

John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 09-26-2000 03:04 PM

Dave Cutler asked: "Does anyone know the higth and width for a 1.37 aperture? What would you be looking for with RP-40 to achieve 1.37:1?"

Standard SMPTE 195 specifies the projectable image area for 1.37:1 to be 0.825 x 0.602 inches (20.96 x 15.29 mm). The SMPTE 35-PA (RP40) film has fiducial lines outlining this format, as well as 1.85:1, 1.78:1, 1.66:1, and 2.39:1 anamorphic.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

| IP: Logged

Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 09-26-2000 05:34 PM

Dave,

How about you tell us the projector model, the screen size (that which it would be in 1.37) and the distance to the screen? Give us that and we can figure something. Otherwise we're taking a blind shot in the air at this. If you have something like a Century projector, those plates are indeed very cheap and would be worth the price of a ticket. I'm assuming these projectors do not have turrets?

| IP: Logged

Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 09-26-2000 07:21 PM

Re Dave Cutler's original post - the only thing which occurs to me not covered in subsequent replies is that some of the films he mentions may not be Academy ratio. I raised this point in another thread on ratios - between the introduction of sound-on-film in 1927 and the standardisation of the Academy ratio, some films were shot with silent cameras (e.g. a full-gate aperture), then the soundtrack area was masked off in printing.

This 'early sound special' ratio (is this what John Walsh calls the 'old' ratio?) is about 1:1.15 - the 1931 'Dracula' was was certainly made this way; I remember from showing it. The frame area is very nearly the same as 'scope (i.e. a lot taller than Academy), only the picture is not anamorphic. Use a 'scope backing lens and plate without the anamorph to project it. You will see a little bit of matte line on the top and bottom but hardly any. Anyway, it's much better than showing an early sound film in 1.37, which will result in a lot of cropping.

For more info on the early sound ratio, see John Belton's book 'Widescreen Cinema' (Harvard Univ. Press, 1996).

| IP: Logged

James Wright
Film Handler

Posts: 1
From: Williamsville, NY 14221
Registered: Aug 2000

posted 09-27-2000 01:23 AM

Let me know the focal length of your 1.85 (flat) lens. Also does this (flat) lens fill the proper height of your screen.. Being the full .446? Do yo have common width or common height picture? To many unknown factors here. It is very simple to figure.

Side masking will also have to come in for 137.. Regaurdless..

| IP: Logged

Dave Cutler
Master Film Handler

Posts: 277
From: Centennial, CO
Registered: Jun 2000

posted 09-28-2000 12:33 PM

OK, screen size isn't really an issue, my screen is 56' tall and 76' wide. I don't want to fill it, and would destroy any film is I did. It's a large format silver screen, and there is NO masking.

Flat lens has a 30mm focal. Throw is 61' from center. 35mm projector is 10'6" off center to the left, so yes there is some serious keystoning. Projector is a Simplex 35/70 combo without a lens turret.

So I figure the flat lens will be OK, but aperture plate I may need to cut.

| IP: Logged

John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 09-28-2000 01:03 PM

Dave: That 30 mm lens with a 61-foot throw will give you an 1.37:1 image size of 43 x 31 feet with the standard 0.825 x 0.602 inch projected image area.

I'd stay with that lens if it's a good one. Trying to get a bigger image with a shorter focal length lens is likely to have more "focus flutter", especially with B&W prints that absorb more infrared. Shorter lenses have less depth of focus, and are less forgiving of "focus flutter" with high powered lamps. Keystoning is more severe too.

| IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

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.