Loupe magnification

How strong of a loupe is good for checking my tricomes?

Start out with 10x, that should suffice unless you have really poor eyesight. Above 10x you start to see distortion around the edges. Although, you're not grading diamonds, so the distortion isn't really a problem. Bring the loupe right up to your eye and then move in close to the bud. Test it out on something else first to get a feel for it. The loupe will be nearly touching your eyelashes, as well as the object you are magnifying.

They're cheap get one that has a variable magnification range and a light. The stronger the power the harder it is to see, and it can fuck with your eyes.

I use a 40X loupe to check trichomes

You only need a good 10X loupe to grade diamonds

By all means, use what works best for you. You have to get right on top of the crystals with a 40x and the focal distance is much shorter than the 10x. I find the 10x easier to use and it allows you to see more triches at once to get a better idea of what percentage are clear/cloudy/amber. I have a lighted loupe with both 10x and 30x(?) lenses, but rarely use the 30x because its a pita to keep in focus for more than a second, plus you see far fewer triches at once, so you're constantly moving, finding focus, etc...just to get an idea of what percentage of triches are at which stage.

I have a lighted loupe that has 30x, 60x,and 90x ... really difficult to get focused on using 90x but the 60x seems to be perfect for me. 30x is OK but I can't seem to get a close enough look to see trichomes colors with it. Could just be that mine is cheap and not good quality of it may have to do with the fact that I wear strong glasses lol

I use 90x with my electronic one.
handheld one for outside is 60x.

I bought & used many 10x, 30x, 60x, and 100x, all of them not as good as taking a high resolution pic of the bud and viewing it on your screen.