I was gifted some vintage gear. I'm estimating the Vivitar lens in question is from the mid-80's; I believe my relative bought it to supplement an Olympus OM-PC. This lens has color coding on the stops, and the stops are printed several times in different places; I think I need an education about this, I'm pretty new to photography.
So the specific sub-questions I'm looking to answer are:
- Are the color-coded f-stops an industry standard or vendor specific?
- Why is the 2.5 stop red?
- Why is the 5.6 stop orange?
- What is the red line pointing to "16" on the right?
- Why are the f-stops printed twice?
- Why are the f-stops mirrored under the focus ring?
- What is the green set of f-stops? Note that the ring doesn't even turn that far.
- What does the little circle mean above the last f-stop?
- What is the L/O switch near the camera side of the lens? I'm guessing (L)ock and (0)pen, but I can't figure for what. It has a little button, but I can't tell what it does, doesn't move anything in the mount. This is not the mount lock, BTW, those are two other buttons. (UPDATE: this was stuck but finally started turning. I figured out it unlocks and removes the OM mount, I'm guessing to allow other branded mounts)
Note that I have used this lens on a 35mm Olympus OM-PC and adapted to a D3400 so it's working properly, just want to know about the seemingly extraneous f-stop labeling and colors.
Edit 04/MAR 2019: This is a Vivitar TX series lens which has interchangable mounts. I did not realize this at the time of posting but have learned a lot since then.
(I had a picture of the lock ring, but apparently I'm too new to new to post "more than 2 links"...er...images... ;P )