BS: Cunning Device

Subject: BS: Cunning Device
From: Bryn Pugh
Date: 11 May 09 - 04:48 AM

The wealth of knowledge and wisdom which 'Catters have (most of you, any way :-) )leads me to start my query on the 'Cat.

There is, I believe, a device which, if yoiu put a picture in front of it, it puts an image of the picture on to a blanl sheet of paper at right angles - possibly using a prism.

Does any kind 'Catter

1.know what the device is called and
2.

Subject: RE: BS: Cunning Device
From: Bryn Pugh
Date: 11 May 09 - 04:50 AM

2. that's what I get for being too eager with the transmit button.

Does any kind 'Catter know what such a device is called (I think it's a camera summatorother), and where in the UK I might buy one ?

Kind regads to you all, Bryn

Subject: RE: BS: Cunning Device
From: mandotim
Date: 11 May 09 - 04:52 AM

Camera obscura?
You can get the same effect by using an old-fashioned portable overhead projector, called an epidiascope I think.
Tim

Subject: RE: BS: Cunning Device
From: s&r
Date: 11 May 09 - 05:10 AM

one of a number of episcopes

Camera obscura is a dark room with a hole or lens in one side which produces an inverted image onto the wall opposite the hole/lens. Used by artists to help their draughtmanship


Stu

Subject: RE: BS: Cunning Device
From: Jack Campin
Date: 11 May 09 - 05:36 AM

Camera lucida, not obscura.

There are some kinds of overhead projector that work that way - look in office supplies places.

Subject: RE: BS: Cunning Device
From: gnomad
Date: 11 May 09 - 05:52 AM

I have known them as epidioscopes, but alternative names seem to be accepted.

This Answers.com article concentrates on the antique (or near-antique) ones I remember.

It seems they are still made. Some modern ones for sale here, though I haven't seen a UK vendor.

Subject: RE: BS: Cunning Device
From: JohnInKansas
Date: 11 May 09 - 06:35 AM

In my grade school in the early 50s, it was called simply an "opaque projector." That may have been a generic term, or possibly was a "trade name."

In the common design, it had a fairly bright light shining down to illuminate the "platform" where an object (usually a picture/text on paper) was placed, with a 3 or 4 inch diameter convex lens to focus the reflected light from the object on a screen about 15 to 30 feet away.

A flat mirror above the lens "bent" the (focused) beam of light so that the object would lie flat in a vertical beam while the "bent beam" continued horizontally to the display screen.

The lens/mirror (and often the light source) were in a little "box" mounted on a vertical post with a rack/pinion to let you raise/lower the whole box to focus over a range of projector to screen distances.

A variant used more in later years has the light in a box below the object, with a glass surface (usually with a Fresnel "diffuser") on which a transparency could be laid. The rest of the assembly was identical to the "opaque projector" and in a burst of creative thought the local educators (and most business of the time) called it a "transparency projector."

In both versions, since the convex lens "inverts" the image and the mirror inverts it again, a right-side-up projected view required the "speaker" to stand in front of the projector to see the "object" right-side-up, and inept presenters were often "blinded by the light" but although it was bright, lasers hadn't been invented (or were not commonly used) so it was not necessary to invent the term "corneal burns" until sometime later; although I'm sure a few suffered retinal degradation.

John

Subject: RE: BS: Cunning Device
From: s&r
Date: 11 May 09 - 06:37 AM

Episcope for opaque images, diascope for transparent images, epidiascope for both.

Stu

Subject: RE: BS: Cunning Device
From: JohnInKansas
Date: 11 May 09 - 06:48 AM

Wiki entry.

A couple of links to "collections" show only rather complex ancient instruments. The commonly used configuration of the late 40s - early 50s (US) school rooms was very much simplified, probably through the more economical production of the 3 or 4 inch diameter single lenses with "adequate" accuracy.

The Wiki entry makes reference to "modern substitutes" but doesn't appear to be quite up to date on digital projectors now available fairly cheaply (or maybe just tried to "oversimplify" the descriptions.

John

Subject: RE: BS: Cunning Device
From: GUEST,.gargoyle
Date: 11 May 09 - 08:02 AM

Common in artist studios.

Multiple Variations - A Video Example - All price ranges
http://www.camera-obscura-lucida-shop.com/new-hardwood-camera-lucida.html

Sincerely,
Gargoyle

These used to be advertised in "Popular Mechanics" etc...usually with a drawing of shapely bathing-suit model posing for the male artist.

Subject: RE: BS: Cunning Device
From: Bryn Pugh
Date: 11 May 09 - 08:03 AM

Thank you, all, but in particular Jack Campin. His post above which named the cunning device. This has enabled me to find a supplier just a kick in the arse up the road from me, at just under a ton (£100 Sterling :-).

Again, thanks. Kind regards, Bryn

Subject: RE: BS: Cunning Device
From: s&r
Date: 11 May 09 - 08:15 AM

Cheaper?

Stu

Subject: RE: BS: Cunning Device
From: Naemanson
Date: 12 May 09 - 04:47 AM

When I was a kid (1960's) I had a Magna-Jector which was almost identical to the episcope shown in the clickie under gnomad's 11 May 09 - 05:52 AM post above. Mine was black and I used it for almost every school project I had to do. It's probably still in my parent's attic.

Subject: RE: BS: Cunning Device
From: Nigel Parsons
Date: 12 May 09 - 05:44 AM

In school (Circa 1966) we had an epidiascope in the geography room.
On its own legs, it had a 'book table' inside to provide the pictures to be projected, and a pointer on a gimble which reached through the wall of the machine to allow the teacher to point out sections of the book.
With its integral stand it resembled (in advance of its time) an AT-AT from star wars!

Subject: RE: BS: Cunning Device
From: Splott Man
Date: 12 May 09 - 05:59 AM

Perhaps that's what their prop department used, Nigel.