The 35mm SLR Camera is a relatively simple piece of machinery.
The light enters through the lens, passing through the aperture, and is reflected by the mirror [...]

The single-lens reflex camera, more commonly known by the abbreviation SLR, uses a mirror placed between the lens and the film to project the image seen through the lens to a matte focusing screen. Most SLRs use a pentaprism to observe the image via an eyepiece, but there are also other finder arrangements, such as [...]

A brief potted history of photography. Covering ancient times through 16th, 17th, 18th, 19th and 20th century milestones. Please feel free to comment any additions, [...]

Based on: 35mm film, 50mm lens,

f/stop
Focus at (ft)
DoF start to infinity

3.5
78.1
39.05

4
68.4
34.2

5.6
48.4
24.4

8
34.2
17.1

11
24.9
12.45

16
17.1
8.55

Multiply feet by 0.3048 for meters
Note:

In this posting, I’ve put some data tables for help when using the fully manual Argus C3.

This is a clockwork self timer, that came in a blue Bakelite case with instructions. Another useful addition from ebay.