Here's my thread about the pocket-thrower I built using a 501a and the DX aspheric:
https://budgetlightforum.com/t/-/6296#node-7345
Normal warnings about the suitability of the aspherics DX is selling now apply...
Testing this light with my cheap DX lightmeter showed 26k lux @ 1m, a hotspot intensity close to that of my 5x Q5 TR-1200...