Right Angle Mirror

[Neal Chaves]

I would like to have a right angle device to use on my view camera lenses for several reasons. 90* prisms were common when process cameras were in wide use, however, they are too heavy for my lenses and shutters. There have been novelty "spy lenses" available for small cameras for years but they are not large enough for my lenses and I am skeptical of the quality of their mirrors.

I am now making a right angle mirror box from 3/16" aircraft plywood to the same proportions as a Kodak prism (recently sold to anther member). Attached are some photos of my unfinished wood butchery. I will use a 67mm to 95mm step-up ring to attach to the two 67mm thread lenses I intend to use. The ring will be secured to the box by clips that can be loosened and tightened to adjust to the desired angle. I have purchased a high quality 100mm circular front surface mirror from the Surplus Shed that I will glue in the box.
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[vinny]

I didn't know they still made planes out of wood:)
I could think of a couple good uses for this.
What kind of things are you going to shoot with it?

[Dan Fromm]

http://www.ebay.com/itm/Spiratone-Mirrotach-Right-Angle-Lens-Attachment-With-Series-VII-55-Adapters-/171168120261

There are others on offer.

[Neal Chaves]

Some model planes are still made of wood. I bought the plywood in a hooby shop. I want it to photograph art forms in nature a la Karl Blossfeldt in the studio and in the field. This would enable me to photograph straight down with the camera horizontal. Could be used pointing up for astro photography and at any angle out the window or off the roof of a tall building.

The negative from these applications would have to be flopped in the enlarger to print in the correct orientation, however, direct positive prints made in the camera with materials like Ilford positive paper would be correct.

[Bob Salomon]

Not sure if it matters but I checked both the Linhof and the Wista Reflex Focusing Attachments that we have in stock and the mirrors are trapezoids which makes me think that a round mirror may not fully show all the corners.

[Jac@stafford.net]

Be sure you get a surface plated mirror.

[Neal Chaves]

I have a nice round first surface mirror from the Surplus Shed. It should be big enough, but if it is not I will cut one to fit the full size of the box. The mirrors in reflex viewers are trapazoidal, but I think that is because they have to reflect the image projected on the rectangular ground glass.

[Asher Kelman]

Neal,

I like the idea of reversing the image so that one can shoot direct positives.

Asher

[Drew Bedo]

Check e-bay for Spiritone. They sold a right angle attachment in the '80s I think.

[Neal Chaves]

Here's my completed right angle mirror attachment. I have had a chance to mount it on the 8X10 camera with two different lenses, a 250mm and a 450mm, which both have a 67mm filter thread. I don't see any evidence of cut-off or fall-off on the ground glass with either of these lenses at close-up distances (my main interest) or at infinity and the ground glass image is very bright and sharp. The image is, of course, reversed.

I am using a 67mm to 95mm step-up ring held in place by clips made from TV cable clips. The clips are mounted with 4-40 screws and blind nuts that came in a set from the hobby store. Then I use a 67mm polar filter ring with the filter removed to provide free rotation of the installed mirror. The whole rig weighs about 6 0z., making it quite practical for mounting on modern shuttered lenses.106756106757106758

[Neal Chaves]

Bob Solomon raised a good point about the coverage of the mirror. Here we are taking a 45* slice out of a cone of light rays. The ideal mirror would be eliptical in shape, and the same as that cone section. If we look at the commercial "spy lens" products now being offered, that is the way they are constructed, with an eliptical mirror at 45* inside a round tube or lens extension. As long as the mirror, regardless of its shape, is large enough to reflect the entire eliptical image there will be no cut-off.

[Curt]

Here's my completed right angle mirror attachment. I have had a chance to mount it on the 8X10 camera with two different lenses, a 250mm and a 450mm, which both have a 67mm filter thread. I don't see any evidence of cut-off or fall-off on the ground glass with either of these lenses at close-up distances (my main interest) or at infinity and the ground glass image is very bright and sharp. The image is, of course, reversed.

I am using a 67mm to 95mm step-up ring held in place by clips made from TV cable clips. The clips are mounted with 4-40 screws and blind nuts that came in a set from the hobby store. Then I use a 67mm polar filter ring with the filter removed to provide free rotation of the installed mirror. The whole rig weighs about 6 0z., making it quite practical for mounting on modern shuttered lenses.106756106757106758

Congratulations. This was devised in 1875 by Spencer, Sawyer, Bird, and Co. It consisted of a mirror formed by depositing a coat of pure silver upon a surface of plate glass, ground and polished to a perfectly true plane; this mirror is set at an angle of 45° in a well constructed mahogany box, which fits on to the front of the camera, and is kept in its position by very simple means. This "reversing mirror" offers the advantage of correct reading copies of maps, coins, and other documents in a single transfer carbon print.

Nice job on the construction of your "reversing mirror", a first surface mirror is a lot easier to obtain than making one from scratch!

[brighamr]

Hi Neal

I have a very heavy cooke prism and was a bit worried about mounting it on the end of any of my lenses
so instead I mounted it on the camera and put the lens on the end of the prism

seemed to work fine for the macro stuff i was doing

not sure if this is the "correct" way but it worked for me …

robin

[stawastawa]

I like the idea of using a small angled mirror with a pinhole camera for making direct positives =)

[Tracy Storer]

Nice. I used to use an 8"x10" front surface mirror for "straight down" table top work in the 20x24 studio. Haven't had a call for it lately, but it works great. (if you don't mind your L<>R)