So before NARAM60, I had zero experience in dealing with altimeters. After NARAM60 I have mostly bad experience. I'd like to try and figure out what I'm doing wrong. I had four flights with normal, very straight boosts to altitude, but three of those reported altitudes in the 30-50 meter range (using two different MicroPeaks). I don't think I was the only one having this problem, as I counted about 20 flights in the results with qualified flights but similar unlikely low altitudes. There may have been more, as there were some reported as 'TL' or not returned. (But I also don't know how many of those were MicroPeaks.) Along the way, I heard a couple of comments in the nature of: "People are having trouble with MicoPeaks." I don't have any reason to think that there is a particular failure in the MicroPeak altimeter, but I do think that there is some procedural problem with the way I, and perhaps others, are using it. The instructions say to turn it on, wait for it to report the prior altitude, then after a delay of one minute for prep time, it will be ready to detect a launch. The problem that I had with this is that after prepping, checking-in, getting pad assignment, setting up the tower and piston; easily thirty minutes could have elapsed. 'De-prepping' the model to recycle the altimeter before launch would have been difficult and wasn't built into the process. Perhaps it should/must be? Vent holes. Per some threads and comments here I'd assumed that vents wouldn't be necessary. But on a second flight, a vent was added with the same low reading result (utterly certain the altimeter was on). Thoughts on vents re this problem? Finally, I've heard about a 'light-sensitivity' problem, but no information on the nature of this problem. Does exposure cause low readings/no readings/failure to detect launch/ what? Is light exposure a bad thing before, during, or after a launch? Anything else I'm missing or should/shouldn't be doing? TIA.