Re: [MF 3D] MF viewer lighting

[Richard Rylander <rlrylander@xxxxxxx>]

Greg Erker wrote:

> ...  Do you have a photo or drawing
> showing the configuration of your LEDs and
> reflector?
> ...
>   Basically I measure about EV12 on my Dr T's
> Red Button viewer (2.5V 0.8A clear bulb). And
> in my MF viewer with Cabin Light panel measure
> between EV11 and EV12.5 depending on input
> voltage.
>
>   Do you have an EV measurement for your
> CCFL lit MF viewer?
>

The [pair of] reflectors for the twin 35mm viewer are acrylic mirror pieces
forming truncated pyramids with square bases 1.5 in. on a side (the diffuser
side), square tops 7/8 in. on a side (where the 4 LEDs are mounted in the
corners), and a 1 in. height between the base and top.  This will evenly
illuminate full frame 35mm slides in landscape or portrait mode.

The CCFL backlight I made for the Saturn viewer measures 11.8EV @ ISO 100 through
the eyepiece.  The inverter draws 285mA @ 5.9V (~1.7W) when powered from a wall
transformer.  Keep in mind that the 35mm twin viewer is only illuminating a total
of 4.5 square inches of diffuser, while the MF viewer illuminates about 14 square
inches of diffuser.

Compared to white LEDs, CCFLs are (for now) the best bet for lumens/$ and
lumens/W.

Richard Rylander