OT: white LEDs

Tony Duell ard at p850ug1.demon.co.uk
Fri Feb 26 13:54:17 CST 2010

> Tony Duell [ard at p850ug1.demon.co.uk] wrote:
> > OK, I can't grind lenses,
> Oh please! Herschel managed in the late 1700s so I don't see what
> possible excuse you can have :-)

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.


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