Thank you to all for your help with this question.
250swb- Yes, if I do buy another vintage rangefinder, it will have to have a manual. I presently own a vintage Saymon Brown rangefinder but without the manual I'm not understanding how to calibrate it. (It's slightly off.)
Regular Rod- I followed the link and it looks like a well-thought out device. However, with my way of working (meaning, I try to limit my "photo stuff" as much as I can!) I'm looking for a "1 item for all cameras push a button answer giver".
Basically, if I were better at remembering where my stepping rings and filters are, I would definitely consider this DIY device!
Thank you for the link!
Peltigera- Thank you for your responses. As it happens, it is from my testing of my Ikonta 520 that greatly lead to posting this topic.
Having recently taken out the Ikonta 520 for an initial test drive (on a tripod), my images came back with blurring in some images, but not in others. I need to be able to determine if, (A), my distance estimates are inaccurate, or (B), is the camera's focusing slightly off and I need to figure adjustments.
A trusted distance measuring device will allow me to take my distance estimates out of the equation and allow me to better determine any camera's possible focusing peculiarities.
Basically, if I know the distance is a true 18 feet, I need only to figure adjustments to the camera's focusing and move on.
Having now picked up the Brownie 3A, it seems like a useful item to employ with any camera that I might have to throw at it.
michr- "Accessory rangefinder". Yes, I was struggling with the term!
And thank you for the idea of a "laser distance measurer". I've not heard of this device. I think this is what will fit best for what I need and how I work.
I'm looking for as near exact distances as I can get (with price considerations). Whether this comes via a classical (or modern) analog rangefinder or a laser distance measurer is of equal value.
Once again, thank you to all for your responses.
And once again, APUG is a fabulous resource for us newbies who are feeling our way through.