DrewE wrote:
Gdetrailer wrote:
DrewE wrote:
Fixed link. Tempting gizmo.
If (or when) the $40 lamp on my $10 thrift store 8mm movie projector dies, I might see about cobbling something together based on this or something rather similar. It might even end up being brighter overall.
That little "pea shooter" isn't enough light to get an image to show on a 8mm projector..
I remain somewhat unconvinced that it would not work adequately for my purposes, though obviously it's entirely theoretical rather than practical on my side. I did just, out of curiosity, run a little experiment with a 5W Ikea Jansjö light; it made a quite dim but usable picture at short throw distances. The Jansjö does have the advantage of having a pretty decent optical focusing system already so there isn't too much wasted light out of it.
I'm not trying to light up a drive-in theater or anything like that....
I am not trying to light a "drive in" either, just a small screen area the size of a 8 1/2" x 11" sheet of paper to use a HD camcorder to capture the film correctly.
Under lighting the film causes a lot of digital video noise from your camcorder to show..
The problem is you are essentially trying to get 1000 to 1500 lumens squeezed through an opening of less than 8mm.. Takes a heck of a lot of light to accomplish this feat.. That is why there is a 80W-150W incadescent bulb in most 8mm projectors.
Additionally the incadescent bulbs have a very finely focused reflector behind the filament.. This concentrates a lot of light into that very tiny opening..
I ran into the fact that the "replacement" bulbs now days are junk.. First one I got the filament was so far out of square with the reflector the light missed 90% of the opening.. The result was a bright line at the bottom of the pix and a barely viewable rest of the screen...
The second bulb was better but still was not focused all that well, was a bit dark at the top otherwise useable..
I tried a 20W LED array and only had 50% of the light that I should have..
Tried a 30W array and better but still not as bright as the original bulb..
The 50W array proved to be the closest match and if the projector power supply could have provided a bit more power I would say the 100W LED would be the best choice.
To make a fair comparison for brightness I bought a digital LUX meter and used that to benchmark the brightness..
I also added a lens to the array, this concentrates the light from the array so more light gets through the opening.
I would highly recommend buying a LUX meter, get one that has the sensor separate from the meter readout.. Makes it a snap to remotely get your readings..