K
kkx
Guest
If you're using a model like mine.... In reality the mag power is the focus , regardless of how it's marked. The actual mag power is a function of the distance so moving your nozzle to the focal point would work, if you had the same focus in each image, it doesn't appear that you do.
Idk your setup exactly or anything, more just trying to relate it to what I've attempted to do with mine. Which I've not been able to measure one nozzle, switch to the next, then go back to the first and get the same measurement, something almost always goes off kilter.
You may be getting better results than I am... Idk... Maybe I'll have to work on my setup.
I have this guy,
https://www.amazon.com/Portable-Mic...t=&hvlocphy=9010174&hvtargid=pla-570926080938
Mine is similar: https://www.amazon.com/Veho-VMS-004...ocphy=9031921&hvtargid=pla-406644941415&psc=1
Same operating principle, the magnification is just focusing. But I guess if the magnification is wrong, then the absolute measurement will be off, but the relative diff should still be ok (if the result is repeatable). I am able to repeat the measurement with consistent results even after a few days (where everything has moved).
I try to position the nozzle so that the lib of the nozzle is sharp, I guess that is what matters the most, that my focus plane is always on the lib since I am measuring the size of the hole on that plane. Which photo do you think is off focus? My eye is not as sharp as it uses to be, so I could get it wrong. But sometimes when I repeat the trials, I get lazy and didn't get thing in perfect focus (it is hard and take a lot of concentration and steady hand), I get fuzzy nozzle lib, that makes placing the measure point a bit of a guesswork, but even then, the result is within 0.02mm.
I also did one more rough sanity checks, I try to measure an 1mm mark on a ruler using the same setup to verify that I the measurement is correct. 1mm is too big so I have to find a 1mm mark that have a mark in the middle and do the measurement in two parts, this make the reference less acurate. But the two part did sum up to 1.04mm. See attached photo (and this also is repeatable).