What do the aperture colors and extra markings mean on a Vivitar 135mm f/2.5 TX lens?
Asked 3/21/2017
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I’m new to vintage lenses and was given a Vivitar 135mm f/2.5 TX-mount lens. It works on an Olympus OM body and with an adapter on a Nikon DSLR, but I’m confused by the extra aperture markings and colored numbers.
What do these markings mean?
- the color-coded f-stop numbers
- why some f-stops are repeated
- the mirrored f-stop scale under the focus ring
- the red line near the right-side “16”
- the green set of f-stop numbers
- the small circle above the last f-stop
- the L/O switch near the mount
I later learned this is a Vivitar TX lens with interchangeable mounts.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
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Why are the f-stops mirrored under the focus ring?
It's a scale that shows you approximate depth of field at the selected aperture. So if you select f/16, you can look at distances on the focus ring at the two lines marked 16 to get an idea of the nearest and farthest distances that will be in focus.
What is the red line pointing to "16" on the right?
I think it does double duty as the DOF scale marking for f/16 and also the infrared focus indicator. When shooting with IR-sensitive film, you'd focus manually and then move the point on the focus ring that lines up with the normal focus index line (red line with dot, dead center) over to the IR focus indicator.
Why are the f-stops printed twice?
What is the green set of f-stops? Note that the ring doesn't even turn that far.
Best guess: those marks are for use when the lens is adapted to a different camera system.
Why is the 5.6 stop orange?
Might indicate the sharpest f-stop.
Originally by user4262. Source · Licensed CC BY-SA 4.0
user4262
9y ago
0
Generated from our catalog & community — verify before relying on it.
Most of these markings are normal vintage manual-focus lens aids rather than anything specific to Olympus.
- The repeated/mirrored f-stop numbers around the focus ring are the depth-of-field scale. After focusing, the pair of matching numbers shows the approximate near and far distances that will look acceptably sharp at that aperture.
- The red mark near the right-side f/16 is likely doing double duty: it’s part of the f/16 depth-of-field marking and also the infrared focus index. With infrared film, you’d focus normally, then shift focus to that IR mark.
- The color-coded f-stops are not an industry standard, and may not even be consistent across one brand’s lenses. They were mainly visual aids.
- The green aperture numbers are likely a secondary reference scale tied to lens operation/DOF markings rather than a separate usable aperture range.
- The L/O switch is for the TX interchangeable mount system: it locks/unlocks the mount so it can be removed and replaced with a mount for another camera system.
The small circle marking isn’t clearly identified from the answers provided.
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