CurtPalme.com Home Theater Forum

Spanky Ham · Joined: 22 Mar 2006 Posts: 5643 Location: Comedy Central

Were those filters Rec709?

aspec2 · Joined: 10 Apr 2006 Posts: 549

Which do you want, the dichroic or the jells. They are both Rosco and can be found at Rosco.com. I could go back to Avs and sort through posts back to 2003 or 4.

Walt

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

I used the Rosco gels when I did my experiment: https://www.curtpalme.com/forum_archived/viewtopic.php@t=5604.html

I stuck the gels to the front of the tube face, to avoid adding any internal reflections. The colors looked great, but that seemed to make the image a bit filmy, not as sharp. In retrospect, I realize the front of the tube face is very close to the focal depth of the phosphor layer -- what we actually focus on. So any optical imperfections in the film would be visible on the projected image.

I wish now that I had tried just taping the gels to the front of the lens barrel. It might add a bit more internal reflections and thus may have a very slight impact on contrast ratio. But it should do the color filtering without affecting the optical clarity of the lenses at all.

tschaeikaei · Joined: 08 Apr 2013 Posts: 490 Location: Germany/Saarland

@Gary: You mean you stuck the filter on the lens- side glas surface of the glycol aquarium,
not the tube face itself or am i getting something wrong here?
Regards, Julian

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

No, I had a Marquee 8500, which is an AC projector. No glycol tank, just the bare tube face and the lens.

So attaching the gel to the front of the lens barrel is probably the best answer for an LC projector.

tschaeikaei · Joined: 08 Apr 2013 Posts: 490 Location: Germany/Saarland

You are wrong in this case- every CRT projector has glycol in it. There is a flat glas box in front of the tube face which is filled with glycol.
The difference between AC and LC is that LC uses a concave glycol-tank front element (C- element).
Believe me, i just have to go downstairs and take a 8500AC tube out of the box. I have two 8500AC (and two AC NECs here).

edit: I understand why you wrote this. It's really hard to see that there is a glycol chamber.
Look closely onto the front and you'll see that there is a glass plate glued onto the aluminum housing
thats slightly bigger than the tubes edges in the background.
Many guys colored their AC projectors glycol in the past using ink or similar liquids. Thats even possible with the Marquee 8500.

Regards, Julian

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

Ack! You are right of course, I forgot about the glycol chamber in front of the tube face...

Which says that putting the gel on the front of the "tube face" actually did put it a ways in front of the focal point of the phosphor. Apparently though it was close enough to make a difference -- it didn't seem as sharp with the gel in there. But you couldn't do that with an LC projector anyway. Out at the front of the lens, it shouldn't make any noticeable difference to the sharpness. (You can stick your finger in front of the lens and barely see any difference on the screen.) It might affect the CR due to reflections, but I wouldn't think it would effect it much. Sure worth a try to see if you like the color results.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Many years ago I applied a Roscolux red gel filter directly to the face of the red tube of a Marquee 8000. I just used Windex to lay the gel on the CRT face, but I was extremely careful to trim the gel to shape without bending or wrinkling it. It helped the reds a LOT, and it stuck admirably well to the tube face. I had that projector for a few years and never got so much as a single bubble between the gel and the CRT face.

As for coloring C elements, has anyone given any thought to hydro dipping? Hydro dipping tends to leave a rather uniform film thickness, and so if you used the right shade of tinted clear lacquer, you might be able to successfully tint a C element this way.

tschaeikaei · Joined: 08 Apr 2013 Posts: 490 Location: Germany/Saarland

I could try that. I have had luck and found two original red C elements and i have some clear spares.
I also have a red LCP somewhere.
But this will be in some months, as i will complete the home theater first.
Best way to compare would be an original red C element. I can't use mine, because they're already
siliconed, glycol is filled in and they're mounted in the projectors.
If there is any interest in this, i could try in say spring.

Regards, Julian

digitalayon · Joined: 02 Mar 2009 Posts: 921

Is this at all necessary? I mean...dang!!! I robbed a 1292 of its red C a few months back in anticipation of swapping it out. I have yet to do it but I still think the picture looks good without. Perhaps I need to do the swap and see if I like the newer image.