At 07:03 PM 3/23/2009, David Beierl wrote...

>>2) 80 cp sounds way to high as a minimum for a stop bulb. The 1156 is
>>a common US stop light bulb, and puts out 32 CP.
>
>I thought so too, but look at the values they allow for front turn
>signals that are near headlights!  Could it be a mistake in
>units?  Note that U,D,L,R,H in the figures mean Up, Down, Left, Right,
>Horizontal.  As I understand it, Figure 1a refers to fixtures, whereas
>1b refers to the actual lamps.

I think that when they say "candlepower," they really mean effective
mean spherical candlepower, which is really flux (lumens), but in
Imperial units.

A bulb which puts out 32 CP could certainly provide 80 effective MSCP
on-axis in a lamp, since there's a reflector (a perfect reflector with
a cutoff of 180 degrees would double the effective MSCP in the
illuminated hemisphere), plus lens.

In any case, even with #93 bulbs in Vanagon running lamps, brake lights
are easily noticed due to the design (I upgraded brake lamps to #1295
bulbs, which have 45 CP).