As a personal project I bought a broken Argus C3 on eBay, and managed to completely clean and fix it, however it involved taking the lens apart since there was dead insects and dirt inbetween the lenses.

Now the camera is back together and I took a bunch of pictures, but they are blurry when using open aperture.

How can I properly calibrate the lens and camera back to infinity without having to go through a ton of films?

  • \$\begingroup\$ Typically, one makes marks on any two mating surfaces before taking them apart. Then matches the marks back up when reassembling... \$\endgroup\$
    – Michael C
    Oct 9, 2022 at 20:45
  • 2
    \$\begingroup\$ @MichaelC Well, now it's too late for that, but found a way to roughly calibrate it by creating a fake matte screen by taping a thin slice of paper to the back and making it transparent by making it oily, keep the shutter open in Bulb mode, and then using a different camera with macro lens to enlarge it on a monitor. It's already massively better but not perfect. \$\endgroup\$
    – Matty
    Oct 13, 2022 at 6:53

1 Answer 1


The Argus C3 is focused using the rangefinder.

These instructions are for rangefinder calibration.

Worth noting that by current expectations, the C3 may not be terribly sharp wide open. I mean if you are pixel peeping, don’t expect Sumicron results.

[edit] More Argus service manuals at Learn Camera Repair.

[edit] Typically a manual focus lens achieves infinity focus when the helicoid is fully retracted.

Which is to say infinity focus is when the lens helicoid is entirely unextended and closer than infinity focus is achieved by extending the lens in the helicoid.

However this assumes that the lens is the correct distance from the film plane and hence that any required shims are in place to provide the correct film to lens distance.

  • \$\begingroup\$ The range finder is calibrated to infinity, the lens itself is not as I had to take it completely remove and take it apart. \$\endgroup\$
    – Matty
    Oct 14, 2022 at 18:26
  • \$\begingroup\$ @Matty if the rangefinder doesn’t match the lens, normal procedure is adjusting the rangefinder to match the lens. \$\endgroup\$ Oct 14, 2022 at 23:21
  • \$\begingroup\$ @Matty if the lens is incorrectly assembled then reassemble the lens correctly and then adjust the rangefinder. If the lens is incorrectly installed, install it correctly and then adjust the rangefinder. \$\endgroup\$ Oct 14, 2022 at 23:23
  • \$\begingroup\$ That’s how the Argus (and most cameras) are designed. Good luck. \$\endgroup\$ Oct 14, 2022 at 23:24
  • \$\begingroup\$ The lens is assembled and installed correctly, and the range calibration of the range finder is independent from the lens. My issue is that I didn't mark down where the infinite point of the lens is when putting it back together, and I don't know how to calibrate the focus point of the lens. \$\endgroup\$
    – Matty
    Oct 16, 2022 at 6:42

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