What is this back for?

[Wenbiao Liang]

Hi,
I bought a 8x10 camera today on ebay, and there is back on the camera.
(I assume it is a 5x7 by the scale of the back)

From the picture, it seems the frame can slide left and right? but what is the point? since it does not seem it can rotate ?
http://imagehost.vendio.com/bin/imageserver.x/00000000/codyy/bbc4.jpg

Thanks!
Wenbiao

[Robert Oliver]

It's a sliding back that allows you to shoot two verticle 4x5 portraits on a single sheet of 5x7 film.

Move it all of the way to the left shoot a picture. Move it to the right. Shoot a second picture. two images for the price of one.

[Wenbiao Liang]

Thanks Robert!

[cyrus]

I think you mean two 4x5 on a single sheet of 8x10 not 5x7

[Donald Qualls]

No, two 3 1/2 x 5 on a 5x7, reduced from the original 8x10 camera format.

Basically, a film saver, like a format masks that were often sold with MF folders from the 1920s until the early 1960s.

[wfwhitaker]

The film back should remove from the carriage and allow you to place it in a vertical orientation. The carriage doesn't rotate; only the 5x7 back

[Robert Oliver]

You can turn this one vertical looks like. It should give you two 4x5 horizontals on a single 5x7 sheet of film.

My 5x7 sliding back on my 5x7 can't go vertical.