Film-Tech Forum ARCHIVE: Pre show stills Projector - 5x5 glass?

This is topic Pre show stills Projector - 5x5 glass? - Blacktown in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Adrian Hauser (Member # 4723) on 06-18-2008, 06:22 PM:

HI Can someone please tell me what type of pre show stills projector I may be describing here. The Blacktown Drive-in has a pre show slide projector that apparently takes 5x5 cm (ish) Glass slides.
Im told the image mounted within the glass slide is about 3cm in width which almost
would be a 35mm slide, but apparently not.
Im having to make up some slides for this projector and require some definative
measurements.
Thanks for your help,

Adrian Hauser
Sydney

Posted by Stephen Furley (Member # 1277) on 06-18-2008, 06:45 PM:

'5x5 cm (ish)' sounds like modern slides. These weren't always 24x36, there were all sorts of sizes, up to the 4x4 cm 'superslides', in this size of mount. Traditional cinema type glass slides were much larger, I can't remember the exact size, but it was about 3.5 inches square. There were larger sizes of 'modern' slides too, 2.75 inches square was used for 6x6cm medium format slides for example.

Glass slides would be unusual in a size as small as 5x5cm, though slides were sometimes mounted between glasses, and the edges bound with tape, my father was still mounting slides this way in the '60s.

Ask the place to specify exactly what is required, overall size, maximum image area and minimum and maximum thickness. '5x5 cm (ish)' really isn't good enough, you need to know exactly. They could have anything from a Kodak Carousel, which can take glass-mounted slides, at least the thinner ones in the 80 slide magazines, to a Brenograph.

Posted by John Wilson (Member # 269) on 06-18-2008, 08:17 PM:

I would have thought they were more like 8cm x 8cm run on a Cinemeccanica 'pop-up toaster'. Give Val Morgan a call and ask them as they used to do the slides...not sure if they still do. Of course, just because they are 5x5 or 8x8...that doesn't mean image area so you'll need to get those measurements too.

And you'll need to make a few copies...about 15 seconds is enough on these before the glass will crack from heat stress.

Posted by Richard Fowler (Member # 893) on 06-18-2008, 08:17 PM:

Sounds more like a medium format slide mount which tends to be 6cm x 6cm......Gepe or Wess slide mounts come to mind....
If the advertising projector is the Toaster (or large circular endless belt for mounts)like described, Cinemecanica, Veronese and other European based made those beasts [Smile]

Posted by Phillip Grace (Member # 2262) on 06-19-2008, 01:37 AM:

Hi Adrian.
There are two common sizes for glass plate slides as used in cinemas. 3 1/4inch square and 3 1/4 inch by 4 1/4 inch. If the slide machine is one of the Cinemeccanica automatic types, the slides will be the 3/14 inch square type. More commonly in drive-ins the old manual machines would use 3 1/4 by 4 1/4 inch. The slide itself is a photographic glass plate with a hi-contrast b/w emulsion with a cover glass taped around the sides, Colour was introduced by staining the emulsion with coloured dyes. Later slides just had a transparency sandwiched between two glass plates. There were standard image areas for the plates, according to the required aspect ratio, but I cant remember the details now. You should measure the existing aperture mask and see if the result will suit your purpose. The extreme heat at the gate is a major consideration. Slides will crack (after 15-20 seconds exposure) and/or fade pretty quickly in that sort of situation. Maybe consider a theatre type Scene Projector, such as a Pani for the job. (larger image area and longer exposure times)

Posted by Stephen Furley (Member # 1277) on 06-19-2008, 01:39 AM:

Richard,

The overall size of the mounts for 6x6 and 6x4.5 cm slides was 7x7cm (2.75 inches). There was also a larger size foe 6x7 cm slides, I think these were 3.25 inches; they were slightly smaller than the old cinema lantern slides.

Did anybody see the projectors which were used in the main concourse of Grand Central Terminal? I've seen them there twice, but I don't know how often they are used, since I'm not there very often. They were installed close to the ticket windows, and projected onto the opposite wall. They used a roll of film which advanced automatically every few seconds. The film was about 5 inches wide. They looked quite modern, and were much smaller than other large former slide projectors which I've seen. I don't know who they were made by.

Posted by David Kilderry (Member # 142) on 06-19-2008, 02:53 AM:

Blacktown used to have Cinemeccanica GPR 3/4 gattling guns with either 1.6 or 2.5 k vertical xenons. The slide, as Phillip says, is a 3 1/4 inch square (83mm x 83mm). The safe area for projection depending on their lens and aperture masks would be around 60mm x 38 mm. It was designed as a w/s format slide as opposed to the 3 1/4 x 4 1/4 which was a scope ratio slide.

We used the same set-up at our drive-in until Val Morgan dropped the advertising slides. These slides will last anywhere from 25 seconds to several minutes on screen depending on the darkness of the slide and if film is sandwiched between the glass or black lettering on a clear slide is used.

David

Posted by Bill Ryan (Member # 2814) on 06-19-2008, 07:16 AM:

Hi All, Absolutely Philip and David 3 1/4" X 3 1/4" Glass slides with a Cinemechanica gatling gun slide projector. At least that's what they had when I worked there.

Posted by Scott Norwood (Member # 30) on 06-19-2008, 08:12 AM:

Where does the 3 1/4" square format originate? A standard medium-format (120-size) slide would be 2 1/4" square (possibly wider). The next larger format would be 4x5", though I've never seen mounted 4x5" transparencies. Is the extra space just for the mount? Mounted 35mm slides are 2" square, so maybe that explains the extra space.

Posted by David Kilderry (Member # 142) on 06-19-2008, 10:24 AM:

Scott, here is Australia the 3 1/4 square format slide goes back to at least the early sound days of the early 1930's and perhaps even earlier. Almost every cinema here ran both advertising and coming attraction slides, mostly in this format, until the mid 1980's when 35mm transparancies in carousel projectors took over in multiplexes.

All of the automatic slide machines (gattling gun style) for glass slides that I know of were manufactured in Europe, I guess the format was popular there too.

David

Posted by Hugh McCullough (Member # 1542) on 06-19-2008, 11:10 AM:

Glass slides could be of any size, and often were, until the Victorians standardised the magic lantern glass slide at 3.25ins square.
Why this odd size was decided upon is a mystery.
This size was naturally used by the early cinema, when they wanted to show slides, as magic lantern low intensity arc projectors were readily available.

Posted by Bill Enos (Member # 440) on 06-19-2008, 09:01 PM:

Our Master Brenograph Model F7 can handle 8x9 inch slides,
4 x 3 1/2 inch and 35mm slides. The 8 x 9 slides go in a slot on the front of the lamp house, the 4 x 3.5 slide go in a holder that flips down into the center of the 8 x 9 holder and the 35mm slides go in a factory supplied holder that goes in the 4 x 3.5 holder.