CurtPalme.com Home Theater Forum

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

Hey, does anyone have experiences on how to color a clear C-Element?
I'd need two reds, but afaik they are rare and expensive.
So what i thought is this: Mix some clear lacquer with red and spray it on the lens- side of a clear C- element.
Opinions?

Regards, Julian

gjaky · Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary

If you could spread the lacquer evenly -as you don't, AND keep the proper color of the filter it would be a good idea.
You'd better paint the tubeface directly.

justin_f · Joined: 27 Nov 2010 Posts: 51 Location: Australia

could you apply some type of 3m film instead?

garyfritz · Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

I've already thought that spraying might not be the best idea- but what about thinning the paint and dip the c element
into the paint? Sure the backside (convex) should be protected with a foil or something.
I'm not sure if the paint thinner (which already is in the paint without further thinning it) will damage the acrylic.
I guess they are made of acrylic... does anyone know for sure?

The advantage of painting the lens-side would be: If i put the tube back together, fill glycol and mount it in the pj..
if the thing with painting doesn't work, i'd only have to remove the paint using a cloth and thinner.
Should be pretty much failsafe if i think right.

Regards, Julian

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

Ok, if it is acrylic, it will solve in paint thinner. Not the right way to go.

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

This was talked about a couple of years ago. The best option would have been new correct colored c-elements. There was a guy in San Diego that thought he could do it, but declined when someone mentioned the design was proprietary to 3M.

I haven't tried, but I would think it would be a lot harder to spray the inner curve of the element than the outer. Unfortunately, you need a paint that doesn't desolve in glycol.

Another option might be to color the lenses. It has already been done for AC. Why not LC?

gjaky · Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary

garyfritz · Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO

It does definitely affect the brightness (contrast), at least with the gels I tried. You had to recalibrate after adding the gels. But it worked really well.

I'm kicking myself now, because when I tested it, I adhered the gel to the tube face with a bit of water (just for testing). I didn't like it because it added a bit of filmy distortion to the picture. At the time I didn't think about the "tube face being at focal point" issue, duh.

I suspect a gel in front of the lens would work well, color-wise. BUT it's likely to introduce internal reflections... Now that I think of it, that's probably why I stuck it to the tube face. No (or almost no) additional reflections that way.

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

@gjaki: do you have more info on those color filters?
@gary : what do you mean by gels? do you have an example link or sth?

Thanks, Julian

ecrabb · Posted: Sun Oct 11, 2015 9:42 pm Post subject:

stefuel · Posted: Sun Oct 11, 2015 11:30 pm Post subject:

I am not suggesting that you do this................BUT, I have taken HD-10's apart out of desperation. They got wet in shipping.
If I were getting back into CRT front projection, I would look for the correct tint of red and green film and put it inside the lens pack. Trust me when I tell you, this is not for the faint of heart. It's like brain surgery and you should have no other choice before you attempt it. Your work has to be absolutely clean and dry. The film needs to be protected but as far away from the gun side of the tubes phosphor coating as practical. The gun side of the tubes phosphor coating IS the preferred electron beam focal point, not the tube face. What do I know? I'm just a useless HVAC guy Wink

garyfritz · Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

@Gary;
So you say there is two options on green.
Which one would be best for P43 fast phosphor?
Just curious, i have two dark green c elements, but i'm not absoltely sure they are the best choice for P43.
I've got one brighter green C-element, too.
And: http://www.stagelightingstore.com/4490-CalColor-90-Green
Both other numbers end up in finding green filters, too.
Maybe you could check again, please. Seems a good and cheap way to go.
I've got the tubes on the bench anyways and could decide between filtering in front of the tube face inside the glycol or in front of the lens, which is surely possible everytime.

The crazy thing about color filtering is (like i wrote in another thread before):
On my silver screen, the unfiltered colors from the M8500 looked ok, if not perfect.
I've not measured, but compared to how it looked before (white screen, same projector) it was way better.
Grayscale itself wasn't good, little pinkish shiny sh*t, but over all, watching a normal picture or movie, it was great.
Just had to say that...

garyfritz · Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO

tschaeikaei · Joined: 08 Apr 2013 Posts: 489 Location: Germany/Saarland

As i'm changing glycol in the 1209s tubes ... is it really necessary to remove the C-element for filling it?
I can't believe it... what are the fill screws for? Worst is: I've already drained and refilled two of them, but can't get the air bubbles out.
Regards, Julian

CIR Engineering · Posted: Fri Oct 16, 2015 4:56 pm Post subject:

I have measured clear, G90 light green celements, and dark green celements on P43. By for the best for REC709 is the dark green celement. It moves green much closer and away from yellow. That said, even with the dark green celement, the P43 is still quite under saturated while the standard green phosphor is almost perfect for REC709 with dark green.

Furthermore, the dark green celement cuts the already diminished light output from P43 phosphor by a lot. It cuts more light than on standard green phosphor because the P43 has less of the green that can pass through the dark green celement. So with the dark green celement you get the best color, but the tube gets rather dim.

If I were going to permanently install a P43 in my own system I would most likely use the G90 light green celement as a compromise. But I would always be unhappy with the color too. It's a compromise and personal preference will by the key factor here.

craigr

CIR Engineering · Posted: Fri Oct 16, 2015 4:59 pm Post subject:

http://www.curtpalme.com/forum/viewtopic.php?t=25790

With my spectroradiometer (lab grade) the green was not as good as the graph, but you get the idea. The GetragMacBeth Eye-One has it's worst acuracy on green so...

craigr

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

I have a thought about tinting a clear C element. I'd suggest picking up the small diameter C elements out of an old CRT rear projection TV set for practice before committing a useful C element to the experiment.

You've heard of water transfer/dipped finishes, by now, I'm sure.

Suppose you were to do this in transparent red or green lacquer.

It should give a uniform film thickness. Or fairly uniform, in any event.

It'd be worth experimenting but I can't guarantee satisfactory results. Tint uniformity is pretty critical.

aspec2 · Joined: 10 Apr 2006 Posts: 549

I remember the color filter threads on Avsforum..KBK said we should be using Dichroic glass filters. I bought a red and tried it. Cost me $65.00 and was worthless. Big bright spot in the middle and dim around the edges. I sent it to KBK and never heard back. I ended up with KennyG's suggested filters. It was easy to ignore the slight focus issues and enjoy the better color. I think the green was a Rosco 4460 but I forget what the red was. The green was a compromise between color and light output the 4490 was a better green the 4460 allowed more light. Wow...that was probably 13 years ago and I can't remember what I had for lunch yesterday.

Walt