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From: More Info on 25 Oct 2009 17:42
On Sun, 25 Oct 2009 16:15:36 -0500, Peabody <waybackNO746SPAM44(a)yahoo.com>
wrote:

>
>By the way, I've found that every old Polaroid Pronto,
>One-step, and Sun camera contains a trapezoidal mirror in
>it which reflected the image coming through the lens down
>to the film plane. And the mirror is front-surfaced, so
>nothing goes through glass - no distortion of any kind,
>even at an angle. I'm using one for my piano study so I
>can get views where my camera won't fit. A handy thing to
>have I think. You just need to get up close to the mirror
>because it's small, and so any dust won't be visible.
>

If I recall, the mirrors in Polaroid SLRs had a super-fine fresnel lens
engraved into the surface of them. Not unlike how the condenser lens in an
overhead-projector consists of a large fresnel lens. Unless the Pronto is
not one of the camera's I'm thinking of. (I have the model (SX1?) stored in
a box somewhere, but ... where.) This allowed them to focus the light more
accurately without any vignetting over such a short and wide field.

Is there any evidence of that on your mirror? If so, it might alter the
view of your subjects when bounced off of it.

If looking for inexpensive fs-mirrors, try <www.sciplus.com>. I think I
bought something like six 8"x10" mirrors from them for only $10 once. I
still have some that I cut pieces from when needed for various optics
projects.

I see on checking just now that they have some 77mm x 194 mm (3" x 7.6")
for only $2.00 each, in case you need to go looking for other fs-mirrors.
(Item # 4112)

<http://www.sciplus.com/category.cfm/subsection/21/category/190>

They are surplus dealers and stock constantly changes.

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