[photo-3d] Viewer Review - 3 - Illumination

["Dr. George A. Themelis" <drt-3d@xxxxxxx>]

Continuing with the Ekeren 5XR review.

--- CHAPTER 3: ILLUMINATION

The ingenuity of the design is reflected in the 
"illumination" device.  First, it is the way the 
two parts come together.  A pair of quick-snap 
retaining clips are used so you can take the 
illumination device in and out really fast.  
You can also reverse the illumination device and 
have the on-off switch from the right upper side 
to the lower bottom side (whatever is convenient 
for the user, the device is otherwise symmetrical 
and the fit is perfect both ways).

Illumination is based on one halogen 5.2V @ 0.85A
bulb, powered by 4 rechargeable NiMh (Nickel Metal 
Hydride - the latest in rechargeable battery 
technology) cells, rated 4.8V @ 1300mAh capacity.  
By simple calculation (1300/850 = hours of operation) 
we conclude that the light will be on for 1.5 hours 
of continuous operation.  This translates to over 
1000 slides viewed for 5 seconds each which can last 
from one day to months, depending on how often you 
use the viewer.

A universal 100/220 AC charger is provided that will 
fully charge the batteries in about 5 hours (at 300mA).  
The batteries are "memory free" which means that you 
can recharge them any time you like, without having 
to run them down first.

The switch is a nicely sounding push button microswitch 
for flicker-free operation.  (My son loves to click it... 
it's a game for him :))

Now, here is the burning question:  How can a light 
source based on one single, centrally located halogen 
light bulb provide even illumination from side to side 
in an area which is 40mmx2 wide (yes, wider than a 
full-frame slide)?  And how can this unit which also 
houses the batteries and the switch be made to be ONLY 
1.5 inches long?  

(For comparison, the illumination part of a Realist red 
button viewer is 4 inches long and, based on a centrally 
located light bulb it is physically IMPOSSIBLE to provide 
even illumination across an area 36mm wide x 2 - even 
though I do my best in the viewers I recondition).

I had to take the unit apart to find the answer:  The 
centrally located halogen bulb is surrounded by two 
pieces of plexiglass.    Each piece of plexiglass is 
covered by a thin sheet of plastic.  Light from the 
halogen bulb is transmitted through the plexiglass and 
distributed evenly along the surface of the plastic 
sheet.  So, this very clever design, based on light 
transmission (instead of reflection) results in even 
illumination while it occupies only a fraction of an 
inch.  Wow!

I understand that the same exactly illumination unit 
is used in more Ekeren viewers and it is sold separately 
from the viewers.  For more details please confirm with 
Jon.

One alternative illumination source used in some custom 
viewers today is fluorescent light.  I have tried both 
and must confess that I am personally attracted to halogen 
bulb illumination which is slightly warmer than FL but 
still cooler than typical AC bulb illumination in viewers 
like the Kodaslide and Realist green button.  

One advantage of the particular design is that it is open 
to experimentation.  I can see how one could replace the 
halogen bulb with other sources of light (LEDs?) to reduce 
weight and energy consumption even further or one could 
attach two small light blue filters to provide a more 
white light, or whatever.  These changes are easy to make 
if you are inclined to do so.

Finally, when viewing on a bright daylight environment 
you can always remove the illumination unit and point 
the viewer towards the sun or out of a window for example.  
If you want to impress an innocent bystander who wonders 
why your camera has two lenses, show him a slide in this 
viewer in daylight.  3d might gain a new adddict!

This completes the main body of the review.  I hope to
upload a few pictures in my web site soon.  After all,
this is a new toy for DrT.

I will continue for a few general thoughts and ideas...

George Themelis