OT: white LEDs

OK, I know how to grind lenses and mirrors by hand (using onepiece of glass against aonther with suitable abrasives between them, and the fact that by doing this all you cna produce is spherical surfaces (which are not the right surfaces for lenes, but until quite recently, it's all that could be accurately made). But as you and I well know, to grind a lens take a lot of practice. Since I can't get the optical glasses easily anyway, I find it more sensible to buy second-hand lens assemblies. For the sort of cameras I have, the faults in them are likely to be mechancial, mostly gummmed up grease. I am capable of dismantlig diaphragm or a focussing mount and cleaning/rebuilding it). Lens griding would be an intereting thing to try, sure, but there are only 86400 seconds in a day... This does not contradict my earlier comments that IMHO people who want to do electronics as a hobby, or restore classic computers, should learn to solder. Notice I haven't said that everybody should learn to solder. There are plenty of people who persue other interests for which soldering is not necessary. -tony