Film-Tech Forum ARCHIVE: Align-O-Tron -- Problem Solving

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Posted by Manny Knowles (Member # 1171) on 08-21-2002, 08:01 PM:

The "pyramid" device that comes with the fabulous Align-O-Tron does not fit* the reflectors in my Christie CC20-CH20 consoles, so I had to get creative and fashion a "plug" for my mirror openings. Here's what my tech and I came up with:

As you can see, that's a 2" core with just the right amount of film to make it fit into the opening in the reflector. We used the opaque side of a DTS snap-loc case (sorry, Karen) as the support backing. We applied Krazy Glue to the inner and outer diameters to secure the roll of film to the plastic backing and then we used those radiating lines on the core to locate the centre, drawing the "X" on the plastic backing with a Sharpie marker.

For anyone who is wondering what an Align-O-Tron is...it's a laser kit for doing optomechanical alignments. Your lamp house alignment to your aperture is a critical alignment. It used to be done with rods or string. This way is a lot more fun.

I had to make a pinhole aperture plate, too. The one I ordered from Kelmar has not arrived yet.

~Manny

*BTW, it was explained to me that the reason the Align-O-Tron "pyramid" doesn't come with "steps" for all of the existing reflectors is that some of the manufacturers did not (or would not) provide him with the specs on their reflector openings.

Posted by Gordon McLeod (Member # 33) on 08-21-2002, 08:18 PM:

Also there are far to many different reflectors out there and many permutations depending on vintage
I have made many plugs for various units out of ABS on the lathe
Also some units a centering plug has to be a taper to insert from the open end of the reflector as the back end is obstructed.

Also it is a good idea to have a flat mirror mounted on the back of the plug with the pinhole in its centre as it is important to be able to bounce the beem back to the source to ensure that the alignment is actually representing the complete optical centerline of the system

Posted by Manny Knowles (Member # 1171) on 08-21-2002, 08:38 PM:

Gordon: That's what I have to make tomorrow. But first, I have to go to the glass cutter and get them to make me up a small, round mirror (2" to match the core). At the moment, I have a 3" square mirror but I think it's too big to make an elegant plug.

Posted by Ken Layton (Member # 133) on 08-22-2002, 12:26 AM:

Manny:

I'm curious to know how much difference in light output you get after doing this alignment on the old Christies.

Posted by Pete Naples (Member # 761) on 08-22-2002, 02:41 AM:

I really need to get myself one of these gadgets!

I wander what shipping to the UK would come in at? OUCH probably.

Posted by Manny Knowles (Member # 1171) on 08-22-2002, 06:46 AM:

Ken, I get a lot more light. A whole lot more light. That's why I keep doing them; it's worth the time and effort.

But maybe I should first state that the difference is due to poor alignment (or no alignment) in the first place. We had really, really, REALLY dim screens prior to this. On one of them I actually thought perhaps the dowser wasn't fully opening up. I was going to have to do these alignments with a string kit until I saw the Align-O-Tron mentioned here on Film-Tech. I thought, "gee [i]that/i] method looks way more fun."

I buy gadgets all the time and some only look good on paper, but this one turned out to be a worthwhile investment. Seriously, you shoulda seen these screens before the alignments were done. I still have a few more screens to go. I'll see if maybe a photo can do justice to "before" and "after."

One day (soon) I'll have aligned all 20 of my lamphouses. I have some ORCONs, too. They are scattered over three different islands and so I would have to schedule some trips to get them all done. For right now, I'm getting my technique (and, as you can see, my accessories) in order.

~Manny.

"The first casualty of war is innoncence." -- Tagline for "Platoon."

Posted by Greg Mueller (Member # 17) on 08-22-2002, 11:24 AM:

Gordon is right about there being a zillion or so hole sizes in the reflectors. When I did the pyramid gizmo, I called all the manufacturers I could think of and got as many dimensions for openings as I could get. One manufacturer simply said "We don't know what the opening size is" others were happy to give all the info they could. Anyway I'm always on the look out for feed back from the field and If you have some sizes that I could add to the pyramid I'd like to accomodate you. On the other hand I get such a bang out of seeing peoples problem solving techniques it's probably more fun to see ideas like Manny's.
Another way you could make a bull's eye is to trace the opening on a piece of cardboard and using a compass (not the magnetic kind) figure the center of the circle and put an "X" there.

Peter shipping to the UK is around $25

Manny try a dime store for inexpensive round mirrors. I stole one out of a makeup compact of my wife's (don't tell her). The one I used in the picture on the web page was a cheap bathroom portable mirror that I busted the plastic frame off of.

------------------
Greg Mueller
Amateur Astronomer, Machinist, Filmnut http://www.muellersatomics.com/

Posted by Gordon McLeod (Member # 33) on 08-22-2002, 12:24 PM:

One problem I found with the cheap dime store compact mirrors they are not often flat and as such when taped to the back of the plug they will sometimes bend the beem

Posted by John Pytlak (Member # 331) on 08-22-2002, 12:37 PM:

Edmund Optics has mirrors speced for optical flatness:
http://www.edmundoptics.com/IOD/Browse.cfm?catid=320&FromCatID=40

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Posted by Pete Naples (Member # 761) on 08-22-2002, 12:58 PM:

Greg, that's a whole lot less than I thought!

What would the total price be, including shipping? Email me like.

I've used the Strong laser with great success, but it's quite pricey, and I'd really like to get one of my own.

Posted by Kenneth Wuepper (Member # 1174) on 08-22-2002, 03:34 PM:

Mirror:
You might get the best results with a "first Surface Mirror" of the type used in making Kaleidoscopes. The silver is on the front side of the mirror, not protected by the glass and usually very flat.

A Kaleidoscope is an instrument with three surface coated mirrors inside a tube. The viewer's eye is placed near one end and a variety of objects are placed near the other end. As the objects are rotated, the viewer sees endless rotating and geometric patterns from reflections within the mirror lined tube. (Enough of the old teacher coming out!)

The Delphi Glass catalog shows front surface mirror as # M5397 in one size fits all 12" x 16" for the cost of $21.95 plus shipping.
http://www.delphiglass.com

This same glass was used in rear projection 16mm and television projectors. We had an old film chain with these mirrors to place the RCA TP-16 image into the camera.

KEN

Posted by Manny Knowles (Member # 1171) on 08-22-2002, 06:49 PM:

As it says in the instructions (on the website) you do not really even need a mirror. I used the clear plastic from a CD jewel case (as suggested) and it worked just fine. My only concern was flatness. I felt the plastic was too prone to flexing. I got a 2" circular mirror cut at the local glass factory. Cost me $5 and was ready in less than 5 mins.

Posted by Gordon McLeod (Member # 33) on 08-22-2002, 06:58 PM:

The only way that you can insure that the complete system is in a straight line is with the mirror mounted on the back of plug

Posted by Greg Pauley (Member # 503) on 08-22-2002, 07:14 PM:

Why not a pyramid gizmo for the snood opening? You could have the front of the lamphouse out of square and still hit the opening on the rear gizmo. Just wondering if anyone has thought about this or had something made up for the snood opening. I've been using a donut fitted on the anode support for alignment, but I think a snood gizmo would produce a more "square" alignment of the phyical lamphouse. Whada think?

Posted by Gordon McLeod (Member # 33) on 08-22-2002, 07:25 PM:

The snood doesn't matter at all the tow important items are
The optical axis of the reflector is in line with the optical axis of the lens/apperture
The lamp is on the optical axis of the same system

Posted by Tim Reed (Member # 137) on 08-22-2002, 07:50 PM:

quote:
The snood doesn't matter at all

The heck it doesn't. Try getting light out of a console with both the reflector mount and projector shifted to one side. I've always thought alignment kits should come with a means to find the center of the front of the lamphouse.

Also, the front of the reflector should have the center defined as well, to ensure a true alignment. The mirrors in the plugs do this, if they're exactly perpendicular to the reflector optical axis (bumps and flash in the coatings can prevent this), but not all kits have mirrors.

------------------
Better Projection Pays!

Posted by Gordon McLeod (Member # 33) on 08-22-2002, 08:07 PM:

Snood doesn't matter the optical train does
The size of the hole in the bulkhead is usually larger than the cone of light.
Reflector and snood do not always fall in line
I have come across many older systems that when the snood lied up with the projector there was crap light put the optical train in line lots of light and the snood was about 1/2 off

Posted by Rick Long (Member # 213) on 08-24-2002, 11:21 PM:

"Close dowser before servicing, snood" was on our Christie lamphouses. Always thought they were insulting me.

As Gord says, we did visit a theatre with a light problem (ORC 4K). He found the front end of the lamphouse about a half-inch low, even tho the snood lined up fine with the Vic. 8. Correcting for optical height improved the light dramatically.

In theory, if properly assembled, the lamphouse snood should be in alignment with everything else, but who is to say that the mirror assembly hasn't been disturbed in the past?

I guess the three basic components of any projection system, (bulb, reflector and lens) all have to be in the same vertical as well as horizontal alignment if decent light is to be expected.

Posted by Tim Reed (Member # 137) on 08-25-2002, 01:22 AM:

No, Gordon, it can and does matter. Only the extent depends on the size of the beam and snood. I'm not talking about just the projector and the snood - the entire optical train. You stated, unequivocally, that the snood didn't matter. When in fact it does, because it's in the path. It vignettes.

I've gotten extremely high light readings after correcting these kinds of misalignment. If you've had lamphouse openings more than large enough, projectors lining up with the snood from the factory (automatically making a reflector-to-projector alignment correct), or reflectors slow enough, you've just been lucky. Otherwise, the center of the snood (opening) IS part of the optical train.

If the opening didn't matter, it wouldn't be large at the rear and small at the front.

Naturally, aligning the reflector with the projector will give an increase, that's like saying water is wet, but it's important that ALL the centers coincide - not just the front and the back elements.

Quick test with a string from the outside of the reflector, all the way around, going to the respective corners of the aperture. If anything is in the way, the string will hit it.

Posted by Gordon McLeod (Member # 33) on 08-25-2002, 09:50 PM:

I have had many lamphouses right from the factory that the optics are not in alignment through the snood. Often I end up just removing it and puting in some duct

Posted by Greg Pauley (Member # 503) on 08-25-2002, 10:36 PM:

Gordon are you saying that the factory is just picking a spot in the general area and knocking out a 6" opening? Maybe someone from Strong or another manufacturer can fill us in on the alignment of the snood opening.

Posted by Gordon McLeod (Member # 33) on 08-26-2002, 07:50 AM:

No but in a lot of cases equipment is pulled from other locations and in a case of one manufacturer I doubt if they were very carefull