Sorry lele, I missed your last post
I love my new uvb meter. It really is a neat little toy. After reading your post, I took my dog out and brought the solarmeter. It is partly cloudy outside, but I was able to get under a patch of clear sky. I Was getting readings up to 210 (Texas May 23 12:30PM). Under clouds or tree shade I was getting readings between 20 and 120.
After seeing all the well documented tests at
uvguide.co.uk, I did not see the need to immediately order a bunch of lights for testing. I do have a zoo med 10.0 and 5.0 for comparison, and there is a definite difference between the two. I also have a few old 5.0 bulbs, one of which disturbingly shows a very low reading. I have not tried the powersun or any other bulbs besides those mentioned above, but probably will in the near future.
One thing I really want to do is learn the specific uvb gradients panther chameleons in Madagascar are exposed to. I assume this could differ depending on the locale and time of year. I have not had a chance yet to look into this, but when I do learn more I will post about it.
Is it worth the money? I think it is, especially if you are caring for multiple chameleons or other reptiles. If you go through a lot of bulbs throughout a year, knowing exactly when to replace those bulbs could save some money over time and eventually pay for the meter. It is also very nice knowing the true levels of uvb your cham is getting. I bought a 5.0 bulb about a year ago for Ezhno, my panther chameleon. I used it for about a month and put it away for a new and slightly larger 5.0 bulb. This old bulb is now showing a uvb reading of 2 from 6" away

This is much lower than it should be and had only been used for a month (2max). The
graphs at uvguide.co.uk are a great reference. One thing I do lack is a way to make sure the meter is correctly calibrated. The meter says it is accurate to within 10%.