In my work I have relied on optical intstruments, first I used a David White 8300 builders transit/level since the 1970's. Very useful as a level, over short distance, but limited for precision in angular layout, 5 minutes of arc read off from a stamped vernier scale, in a layout test I could achieve + or - 3/8" in fifty feet for angular accuracy. So a tape check and readjust is normal.
Seven years ago, at auction, I bought a Lietz transit, a Brunson dumpy level, two tripods and a surveying rod for $400. The transit is an American pattern instrument all mechanical, no electrics, vernier scale reads to 20 seconds of arc, has upper and lower horizontal movements so repeating techniques can raise precision, if needed, and the scope can be inverted for cross checking and averaging readings. The proverbial gnats ass is clearly in sight.
The Brunson levels vial is calibrated to ten seconds per 2mm division compared to two minutes per 2mm division on the David White.
Using the old pattern instruments is satisfying, productive and accurate. The adjustments and techniques are easy to learn from any old surveyors manual. No electonics to go bad. Perhaps I was lucky at auction or older instruments are not favored in the marketplace but great lasting value is available.
