RE: filmscanners: LED Illumination for Film Scanners

["Austin Franklin" <darkroom@ix.netcom.com>]

> >>
> >> 1000 hours MTBF can't be right, Austin.
>
> Didn't the word humility crop up in a message I sent you about a year
> ago? ;-)

This issue isn't about humility at all.  I was merely citing directly from a
manufacturers data sheet!  I did not make up the number, nor did I say I
liked it, and I certainly had no plans on spending this inordinate amount of
time on such a simply absurd discussion!  I posted the URL of a scan of the
data sheet to show that I didn't just make it up, as it appears some people
are assuming.

> Also, I'm guessing LEDs made in 1987-88, when your Range Rover was
> likely put together, were not the same ones used today, about 12
> years later

You could very well be right.

> Austin, this is why it sometimes is helpful to engage your obviously
> very capable brain rather than relying totally on written "fact".  I'm
> sure given a little thought, you'd have recognized the silliness
> of the 1000 hr number, considering how often we replace incandescent
> household light bulbs.

Of course I thought it was quite low.  I never said that I liked that
number, it was the number the manufacturer stated in their specs.  I used
that number as a point of data showing that LEDs DO have MTBFs that CAN be
quite low.  But...since, as I've said before, this is all speculation, since
no one here really knows what LEDs the Nikon scanner uses.

> I think Rafe gave
> some good examples of the huge number of devices we use which rely upon
> LEDs to sense locations, positioning, actuation or switching (how about
> most computer mouses, for instance).

Again, that all has nothing to do with my point, as I said above.  We all
know that LEDs CAN have very high MTBFs, that is not, and never was, under
dispute.  They also can have very low MTBFs too.  You have to KNOW what the
particular parts used are before you can pin down what the MTBF REALLY is
instead of speculate.

> Tell you one thing, I'm not buying any Stanley LEDs! (they must have
> gotten a great buy on these!) ;-)

Me either!  I'll try to use those billion hour ones that Rafe cites are used
for traffic signs.  They might be a bit large for my type of projects
though...