The trichomes are a good way for people learning to grow to detect ripeness but I haven't look through any of my microscopes for a very long time. If this isn't your first harvest and you're familiar with what a ripe bud actually looks like then I'd suggest going by the overall look of the bud. I look for key signs such as the pistils "folding in" each calyx and the majority of the hairs turning brown. Sometimes if the buds were heat stressed or contaminates such as the oil on your fingers or dust in the room touches the buds it will force the hairs to be brown very early. In these situations you really want to focus on the length of the pistils, the shape of the pistils, the swelling of the calyx, etc. If you've had a harvest or two it will be obvious. Each calyx should really start to look like a flower with multiple petals surrounding each one. This is what gives you the illusion that the pistils are retracting into the bud but in reality it's the bud itself swelling around the pistils making them appear shorter.
The trichomes can fool people because they grow in many different stages. They start out by sitting flat, then they grow their little stem, then they swell on the end into a ball. Sometimes the flat ones turn amber at unpredictable stages and the bulbous ones won't turn amber for a very long time, even after the bud is acceptably within the harvest window. If the bud starts foxtailing this can really start to throw a beginner in a loop because they will be waiting for a very very very long time and incorrectly assume that it's not ripe.
