Originally Posted by Reagan
I love this idea. It's been in my head for a few months now.
Help me out on some issues/questions, please. Are these statements correct?
1. From what I can tell you wouldn't even have to buy the 67 inch Samsung, the 61 incher would do the job. Same internals.
2. The 1080p DLP chip in the Sammy is wobulated.
3. Light output is going to be low, so a high gain screen and a dark room are mandatory to get, say a 100 inch diagonal image.
4. The current generation of Sammys can correctly display a 24p image. If I understand correctly, they operate on at 120hz. All frames in 60fps signals are doubled and all frames in a 24fps signal are displayed 5 times.
5. New lens needed to handle different throw distance and focus.
6. And most importantly, a direct front projection of the image straight out of the lens would result in a backwards image (left/right flopped).
Just found this thread... does anyone still have any interest?
This is a project I've been actively (more or less) working on for a few months... bought up all the parts to make a complete "guts" for the 3rd gen model (with a few spare parts).
First comments... I hate losing the "Cinema Smooth" mirror that shifts the entire image vertically 1/2 pixel, to fill-in the inter-pixel gaps... it really does work.
To retain this "moving mirror", you have to retain a folded projection path... in fact, the "best case scenario" would be to add a fold, and use all the original optics... just in a slightly different manner.
Currently the image path leaves the DLP chip, goes through the main Lens assy (est. 4-5 elements, with focus), then through a circular cropping aperture (eliminating DLP "off-mode" spill), then bounced off the moving-mirror upwards at about 60°, then through the upper-half of the super-wide-angle lens assembly. This is where it leaves the Light Engine, and 'normally' reflects off the FS mirror, and onto the rear-projection screen.
I've been trying to figure out if it's possible to:
a) measure the original length of the light-path from the primary lens, to the wide-angle lens assy - this needs to be exactly the same post-mod
b) For the moving-mirror - move it closer to the primary lens assy, and change the reflected angle to 45° -
c) bounce image up to an additional small fixed 45° FS-mirror, reverting the light path back to the original direction as when it exited the DLP/main lens
d) remove shield from original wide-angle lens, and use it in a more traditional (not so much image shift) mode, but yet allow some image shift for a downward throw.
The goal is to place the projector (in it's new enclosure) flush with the ceiling, about 24" in front of the screen... whatever distance it takes to fill the screen (120" in my case)
Now... about brightness... I will likely need to swap out my existing Da-Lite Cinema Grey for a gain-type screen... the room allows for a narrower viewing angle, so I'm good there.
Preliminary tests at full-white show around 300-350 ANSI (9-point) lumens.
Not enough you say?... I think it is... the contrast in this thing is wonderful, and the saturation is incredible. My HT room (basement) has excellent ambient light control, so with full lights out, it looks absolutely great.
Alternative plan - use a different lens altogether. I bought a 'surplus' lens from a Runco 720p DLP projector, but it has too small a glass diameter (and "f-stop") for my flavor.... and not enough zoom range at the "Wide" end. I've not spent enough time with that lens yet though. First test with it gave only around 250 ANSI lumens under the same conditions.
With this "alternative lens" method, you lose the "Cinema Smooth" moving-mirror... so you will see some SDE... and the Samsung DLP pixels are rotated 45°... like a diamond... I had never heard of this DLP style before... maybe it's a custom for Samsung to take advantage of the 'moving-mirror' smoothing.
BTW - I have tried the original lens both with & without the Cinema Smoothing ("SP Actuator" in service menu) - and though the effect is not "huge"... even on my 120" screen, it's nice... but I seem to always be looking for nits to pick.
I need to learn more about the service menu - I'm not sure my LED's are cranked up 'all the way' - not going to mess with them until I learn. May be some mode I should be in to get maximum color correct brightness... but I tend to think the Test Patterns in the service menu would be at full brightness.
About "wobbulation"... can anyone verifiably confirm these 3rd gen models use this?? In my estimation... they don't. Maybe I'll find something in the service manual that indicates otherwise... but nothing yet... it seems to be full HD, with pixels rotated 45° from what I'd consider 'normal'.
Anyone with questions or comments, feel free!