Can you crack the code?

Hi All,
I have a 16" mirror that came out of a M**de Dobsonian telescope. It has markings on the back (in Magic marker). They are a series of numbers printed in a vertical column as follows:
.3
-.7
.1
.1
.5
.7
There is a small 7.36 written next to the last .7

Any decoder rings out there?

Gary Pakalski

Sounds like zonal readings from a focoult test to me. The 7.36 is probably the radius of the outermost zone.

Jarad

I too suspect that they are test readings of deviation from optimum. If the numbers were .003 -.007 etc. I'd be much more comfortable in saying so.
This is a mass produced factory mirror - perhaps they set up their test apparatus for a +1 and -1 tolerance level and if all readings fit within these tolerances they pass inspection. Then you don't need an experienced optician to preform the test.
Just a thought.

Bob