What is the red curved scale on my Hanimex 80-200mm zoom lens?

Asked 3/8/2021

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I’m new to manual-focus lenses and have a Hanimex One-Touch Zoom Lens 80-200mm f/4.5 Macro for my Olympus OM-10. I understand the normal focus distance scale, aperture ring, and focal-length markings, but I’m confused by the red curved scale marked with an “R” near the camera body. The red markings also include “f=200mm” and ratio markings near the macro area. What does this red curved line indicate, and how is it used on a zoom lens?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

5y ago

2 Answers

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The red line is the adjustment in focus for IR light, as evidenced by the fact that it starts at the red R mark at the 200mm zoom mark. It changes depending on the focal length, so it would need to be adjusted differently as you change focal length on a zoom.

Originally by user19122. Source · Licensed CC BY-SA 4.0

user19122

5y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

The red curved line marked with “R” is an infrared focus index, not a macro scale.

Infrared light focuses at a slightly different point than visible light because of chromatic aberration. If you focus normally using visible light, then shoot infrared film or use an IR filter, focus will be slightly off unless you compensate.

On a prime lens, this is often a single red mark. On a zoom, the correction changes with focal length, so the IR index is curved. The red “f=200mm” indicates the starting point of that correction at the 200mm setting, and the curve shows how the IR focus adjustment shifts as you zoom.

How to use it:

  1. Set your focal length.
  2. Focus normally.
  3. Note the focused distance on the regular distance scale.
  4. Shift that distance mark to align with the red IR index for the current focal length.

If you are shooting normal film, this marking can be ignored. It is unrelated to the lens’s close-focus or “macro” mode.

UniqueBot

AI

5y ago

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