CurtPalme.com Home Theater Forum

[Joust]

I agree.
Galen has an excellent solution. Works very well from what i read. Also Bjorns solution is great. The best way to build the proper part for the job.

The way to do it "correctly", is to make a mounting plate designed to accept the HD144. AND incorporate the other features of the barco design as the stock plate does.
I'm not knocking the other solutions. they are well done.

there are pros and cons to them all. IMHO the biggest con is COST! Lets face it. for most of us. $$$ speak volumes.
having to ship parts back and forth for modification adds a huge percentage of cost. especially lenses as they are both bulky and quite heavy.

What i want to do is a hybrid. My main goal is to keep the cost down. For those who want to have a solution that works out of the box, you will have to pay quite a lot for it. IIRC Galens solution is less expensive than machineing new plates from scratch, at $500 plus shipping ( I assume both directions). For what he is doing, I think that is cheap. No doubt he spends a lot of time on each one. I applaud his ingenuity. Not many could accoplish this as he does.

My thought is to make an adapter that requires the owner to do a little work themselves. This allows them to do some value added work that uses non-specialized tools. There is a lot of interest I can assure you. It definately is not the best solution, but by far the cheapest.
Maybe I'm wrong. PM me if you are interested. 5-10 guys would cover cost. Nothing in it form me really. I don't own a barco. I thought i'd just include you guys as a few Marquees guys/gals have benefited from this design (thanks to Chris).
Target price is $150. Same as for the Marquee.
Joust

[Alaric]

Hi There,

Must admit i've been interested in this project from the start, albeit that my front screen is a screen wall and as such can't be moved and i'd have fun moving the PJ as i have a *BIG* barco mount and installed joists for it, oh and then the hushbox which intersects with the back wall behind the PJ would be too short too....

However i'd like some decent colour filtering and sharper focus would certainly be a benifit on my BG808s. I think both Galen and Bjorns solutions are good, but both are high in cost.

I've always thought Galen could do with a stock of Hd144's that are modded and then sold on, but thats risk and investment and for a hobby, probably not worth it...As such i'd doubt there are many non-USA clients, as if you have that much money to waste, you'd probably go for a 9" PJ.

Bjorns loose lens flapping, which could be argued is not 100% required, however when playing with it on my BG808s, there is certainly a clearly visible change when altering the settings on my flat screen....How this compairs to a fixed solution i don't know, maybe i could try and set my lenses to a fixed plane with a set square and see (ie mimic a flat plane).... Barco certainly considered it to be a better feature - the manual doesn't say if you have a curved screen adjusting lens flapping may help, it gets you to adjust it regardless ????

I do like a cheapish DIY solution, i'd even like it, if i could make it myself - I run an aluminium/composites factory and we have a CAD/CAM router... i also have a spare BG808 on the floor with the lenses off if pics are needed !

cya,
Lee

[Spotmatic]

Lee,

Then you definitely should look at the following picture:

http://img120.imageshack.us/my.php?image=finaldrawingframemg0.jpg

Those are the drawings of Bjorn's adapters. He doesn't make then anymore, but maybe you can come up with something. I'm in for a cheap solution!

[Chuchuf]

[mp20748]

Spot,
I'm all for bargains, and i don't want to say anything against what some may be doing here at a bargain, because I know nothing about making things out of metal. So I can't really comment here on that aspect of this, but from what I received myself wit hthe plates that i got from Galen, they looked very well machined and were a perfect mate to the tube (distance) for the screen that I'm using. So when focused, the lens is near perfect 9very close) to the tube itself for the best results possible. Plus I recieved things in a kit, not just the plates.

I'm all for a bargain. but with the lens upgrade that I've made to my 8500, it's not just an 8" CRT projector that has a modified lens plate. It's now a very high end 8" CRT projector, and because it has the lens plate that performs so well, I'm not about to take it off the ceiling anytime soon. Which was not my plan. My initially plan was to use the 8" to show 1080P on an 8" machine. And from there I was going to remove my tubes from my 9500 and put them in that 8500 Ultra that I'm using now.

Well, the thing performs so well with the addition of the HD-145 lenses that I don't want to change anything. I'm even wondering if i could do better with 9" tubes..

[Ile]

[Alaric]

Hi Spot,

Curious. I've not seen a detailed drawing for them before....Shame its a jpeg rather than a proper cad format, i can convert dxf/dwg into instructions for my router which means dimensions are almost irrelivant...From this i'd have to transcribe it, but its still posible.

It is almost posible to mill in from one side which for my router is easiest, however there is a 5mm bevel, but that could be done later by jigging - I wonder what its end use is ?

There are no dims for the holes, but they could be guessed

25mm (1") is thick for aluminium plate....it would be almost classed as bar, but 200mm (8") bar is also wide. I can see just from this that the material cost isn't 'cheap'.

Actualy having another look at http://home.c2i.net/tomcat/ he didn't go for aluminium...Its some form of plastic/acrylic....Interesting - I'm half tempted to do a mock up

cya,
Lee

[Spotmatic]

Lee,

I've also asked Bjorn for that, but the Autocad DXF file was lost at the machine shop. Since he also doesn't sell them anymore... Well, that's the end of the story.

I'll try to recover what material he actually used. It was not aluminium but indeed some plastic. In fact, I've just found it: he used POM (polyacetal).

[Alaric]

Hi There,

http://en.wikipedia.org/wiki/Polyoxymethylene

A machining plastic that seems to have more names than any rose i've seen...What people will try to do to avoid a dupoint patent

So, is Bjorn happy for people just to copy/modify his design then ???

cya,
Lee

[Tom.W]

Here again are the two photos I received from Galen ...

http://i16.tinypic.com/4hn2seg.jpg Finished lenses

http://i12.tinypic.com/2ypfamq.jpg Photo of the adapters

Sorry about the size but the files were too large for image shack....

[zGman]

Polyacetyl - Also known as 'Delrin' - About as expensive as Aluminum.
Relatively stable (for a plastic), self lubricating, low thermal conductivity....

There's been some speculation about the need for schleimpflug.
The term refers to the relative tilt between the lens and the image/
focal plane. You can not achieve focus across the entire screen
without some tilt, because you are projecting at an angle to the screen.

You can minimize it in the vertical plane by projecting on-axis
at screen center - for most this is impractical for front projection.
Even for this setup however, there will still be horizontal tilt on the
red and blue since they are not on-axis.

Every CRT PJ I have seen has some provision for this adjustment,
it will either be static (washers or stepped rings behind lens) or
continously adjustable (BarcoGraphics, Marquee, G70/90, etc.)

Here's a brief explanation, about halfway down the page.

http://www.cameraontheroad.com/?p=222

Cheers,
Galen
144lens@bellsouth.net

[Spotmatic]

[Tom.W]

Too bad because the last I heard Bjorn had replaced his 1209s with a 909 or cine 9 . Wonder if he went digital

[Alaric]

Hi There,

Joust - You were looking for a picture of the mountings for the HD-8's, heres one from someone selling them from a BG808s, so it has the lens flapping

http://www.niktec.com/ebay/DSC02493.JPG

Galen - Thanks for that, though i can't say i find the explination that understandable..Or perhaps not in relation to CRT...I gather that a camera is basicaly a projector in reverse, ie the film=gun, screen=subject, and that the reference to 'view camera' is not your point and click, but a bellows style camera that you can tilt the lens in relation to the film (ie not just tilt the camera)...and as such tilting the two alows an plane of focus tending to infinity as the angles becomes more obtuse.... However, how quite this fits into our 3dimensional jigsaw puzle is still eluding me !

Does the lens flapping compensate for the toe in of the Blue/Red, if so why is it also on green - If its to compenate for the angle of the PJ to the floor in relation to the screen to the floor, ie if the tubes and screen are not paralel, can they not be set as such - Although doesn't that affect keystone (or lessen it).

And i thought physics and Optics was for the classroom !

Ta,
Lee

[zGman]

Hi Alaric,

The geometrical optics are the same for the camera and projector.
The "tilt" is in the lens relative to the image(tube face) and the focal
plane(screen).

The explanation is appropriate to CRT(or front projection in general)
because he is describing getting focus from an off center position -
esstentially the same as whem your projector is mounted on the ceiling
and thus not exactly centered on the screen. The drawing shows vertical
"tilt", however, there are two types of tilt, horizontal and vertical -
the red and blue will need more horizontal because they are mounted
off-axis, the green will only need horizontal when the projector is not
perfectly square and centered to the screen.

Hope that helps,
Galen

[Tom.W]

Heres an article on the subject . Think of a projector as a camera in reverse . The CRT face being the film .

http://www.trenholm.org/hmmerk/VuCamTxt.pdf

[zGman]

Thanks Tom,

That's a great find, I will save it.

G

[Spotmatic]

And here are some pics of my blue tube and the Scheimpflug hardware:











For those interested: this is a PT18-205 tube

[Joust]

Spotmatic, thats perfect. thanks
something to chew on..

do you have one taken appart? I'd like to see some pics of that tube mount behind the main plate by itself.
Thanks again.

[dc_pilgrim]

Here is the second pic from that auction Lee spotted, gives a back view:

http://www.niktec.com/ebay/DSC02494.JPG