looking at a feature at 1000x you should be able to detect +/- 1 minute.
If only this would work at this price and this accuracy.
It is rise over run and number of pixels/3. This ignores the lens and those pin/barrel problems plus the part is round.
The plastic lens on these guys are not flat field by any stretch of the imagination. Yes I do use them and super handy.
Turns out this a tad hard to do.
High mag is of no help since you have poop for view size. Lower mag better and you do best fit line not two points.
I for sure get how it makes common sense in video or machine vision. But, but, but.... so many buts.
At this surface finish matters. A lathe will make cusp and forms even on the cut off end. Do we do tips, valleys or middles
Not to say this is hard to make or hard to check. Plus zero minus 15 is sort of standard to me so we set at 7.5 as close as we can and that alone is problem on a simple carbide insert.
Welcome to WTF in measuring. Not once but 6 times unbiased or diffenrt people on differnt days making the measurement.
The customer is always right but they may check it one way and you check it different.
Right, wrong or off .....Make those who send the check to be cashed so happy campers that they will come back for more.