Aye, they can be a real pain in the ass when you're surrounded by HPS light and fans are blowing all over the place. By the time I start using one of these, I'm getting pretty damn close to harvest, so I'll usually clip a small piece from the bud in question and take it out of the room, then examine it there. Much easier to focus on the right spots this way. Then, as an added bonus, you get to dry and smoke your experiment when you're done!

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"In order to become "old & wise", you must first be young & stupid." -?
"Switch to 24/0 light schedule and don't worry... about a thing... every little thing... gonna be all right." -StinkyAttic
"It can be a fine balance between 'ok...I need to water later today' and 'shit...I should have watered yesterday.'" -Rusty Trichome
"I know it was just a typo, but you wrote "Marital Arts," instead of "Martial Arts," and that makes for a very hilarious paragraph!" -Dragonrider