Has anyone ever figured out at what distance a "candy cane" on a single prism will disappear into the vertical crosshair of an instrument? We'll be starting a traverse soon that will have quarter mile to half mile legs. We don't have target plates for our single prisms. In the past I've seen custom made "candy canes" made out of one foot pieces of range poles. I thought that was a great idea!
There are a large number of missing variables here. Local weather and climate will have a huge impact.
Normally a half-mile shot here would be easy. Between the smoke and fog this week you'll never get a third of that. I wouldn't bet a few hours of billable time on theoretical visibility of a stick. Buy a few decent target and prism sets and add certainty (and quality) to your work flow...
Center your target between the double lines in you reticle - repeat - repeat - repeat ............
The vertical hair will appear with a width less than the rated accuracy of the instrument, and if a target feature disappears you can still aim to at least that accuracy. Averaging repeats will do even better. But as @tom-wilson said, if your reticle has a double line this issue goes away.
But consider that at a half-mile, a half inch is only 3.3 seconds of angle. You need something bigger to readily find the target, and then a fine feature to center on.?ÿ At that distance I would much prefer a typical target set to a candy cane with uncontrolled background and possible side-lighting bias.
Local weather and climate will have a huge impact.
Absolutely! Especially heat shimmer down here.
I only use the double lines as a rough sight, then I switch to the single line. I'll reconsider my method in this case.
@bill93?ÿ
I like your description "side-lighting bias" better than my description, which I call "the shadow effect." Did you get your description from a surveying textbook?
If I read it, I've forgotten where. That just seemed to describe the effect. I think I've seen it called "phasing" which I imagine is like the phase of the moon, but that term has too many other connotations for me.
long sights in the early morning.?ÿ
