RE: [Cameramakers] Laser alignment tool
I guess I wasn't very clear. My idea is that the laser is attached to the base and the laser its base are rotated on the enlarger baseboard. Something like the following: | reflection point on mirror --+-- - mirror \ - laser at angle attached to a plate \ --+-+- - alignment fixture base ^ target spot for laser -- - enlarger baseboard Turn this around 180 degrees and get: | reflection point on mirror --+-- - mirror / - laser at angle attached to a plate / --+-+- - alignment fixture base ^ target spot for laser -- - enlarger baseboard When you rotate the fixture, if the base of the fixture and mirror are parallel, the spot stays on the same target on the laser fixture. The spot does move on the enlarger baseboard, but since the base of the laser pointer fixture is also rotating with the laser, it doesn't matter. You don't need to measure a circle or anything. There would be some trial and error adjusting the enlarger since every adjustment would move the laser spot (maybe use a postit). Once the mirror and baseboard are parallel, the angle of the laser could be adjusted (with the right fixture) so that the target is coincident with the laser itself, but this isn't strictly necessary. John -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of J. Wayde Allen Sent: Monday, January 14, 2002 11:19 AM To: [EMAIL PROTECTED] Subject: RE: [Cameramakers] Laser alignment tool On Fri, 11 Jan 2002, John Sparks wrote: You don't actually have to align the laser at all. Mount the pointer on a fairly large base at a slight angle. Put a mirror in the negative carrier or whatever. The reflected beam should hit a point on the base. Mark this point and rotate the whole thing on the enlarger baseboard. When the reflected beam always hits the same spot on the base as you rotate the base, the enlarger baseboard and mirror are parallel. If your laser pointer mount is adjustable, you could then use the parallel baseboard and mirror to align the pointer to be perpendicular to the baseboard (reflected beam is coincident with laser). If you don't adjust the mount, you will get a different point on the base for different enlarger heights. Very interesting idea of using the laser for self alignment. I think that there are some real possibilities here, but there do seem to be a few difficulties too: - The laser spot reflecting from the mirror will hit the baseboard providing the angle of incidence isn't too great. However, since the angle of reflection is equal to the angle of incidence, simply rotating the base will change the direction of the reflection. Hence your spot won't stay in one place, but rather will scribe out a circle when the system is in alignment. You would only get the beam to hit the same spot if you rotated the enlarger head/mirror rather than the tilted laser on the baseboard. - The rotation of the laser on the base requires that you get a pure rotation with no translation. Shifting the laser in any lateral direction will also shift the spot and cause a measurement error. - Since rotating an angled laser draws a circle on the baseboard, rather than creating a fixed spot, you'd need to be able to measure how perfect the circle is that the laser draws on the baseboard. The catch is that it may be more accurate and simple to align the laser once and look for a perfect reflection. That creates a fairly fixed source of measurement uncertainty (the alignment uncertainty). If your measurement depends on the stability of rotating the laser on the baseboard you have a very operator specific uncertainty. I'd also think that determining the concentricity of the scribed circle would be problematic as well. - Wayde ([EMAIL PROTECTED]) ISART 2002 International Symposium on Advanced Radio Technologies http://www.its.bldrdoc.gov/meetings/art/index.html ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
RE: [Cameramakers] Laser alignment tool
On Mon, 14 Jan 2002, John Sparks wrote: When you rotate the fixture, if the base of the fixture and mirror are parallel, the spot stays on the same target on the laser fixture. The spot does move on the enlarger baseboard, but since the base of the laser pointer fixture is also rotating with the laser, it doesn't matter. Ah ... OK, I did indeed miss the point about the base moving with the laser - very clever! - Wayde ([EMAIL PROTECTED]) ISART 2002 International Symposium on Advanced Radio Technologies http://www.its.bldrdoc.gov/meetings/art/index.html ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Enlarger Alignment
William, I will give your idea a try, sounds simple enough and I don't have to buy anything. Thanks for the good idea. Phil William Nettles wrote: My Bessler 4x5XL enlarger was never in alignment and I don't think it ever could. I made an adjutable lensboard by making a parallel board to hold the lens below the regular one that plugs into the enlarger. The gap is filled with a piece of foam rubber insullation and the adjustment is made by tighting the long 8-32 screws holding the two together. How I aligned them was to make a pattern on the computer with dotted lines and print it out on to transparency material. I also printed out on photo glossy paper the same pattern scaled up to 8x10. The pattern consists of 3-4 concentric circles, and a grid about 1 apart. It's important to beable to tell which line is which. The paper one is inserted in the print easel. The Trans goes in the neg stage. Rougly align the neg stage and the easel with a level. Then with the neg in place begin focusing and aligning. The scale between the two patterns should line up exactly. Focus shift is caused at the lens stage, alignment shift--you can see this if your circles down't line up. Takes a little time and you have to be able to think three dimensionally. A friend brought over a ZIG Align (which is a much quicker way to accomplish this but it cost about $150) and my alignment was right on the money. Good luck. ---William Nettles [EMAIL PROTECTED] Nettles Photo / Imaging Site http://www.wgn.net/~nettles ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
Re: [Cameramakers] Enlarger Alignment
At 04:56 PM 1/14/02 -0500, you wrote: William, I will give your idea a try, sounds simple enough and I don't have to buy anything. Thanks for the good idea. Phil William Nettles wrote: My Bessler 4x5XL enlarger was never in alignment and I don't think it ever could. I made an adjutable lensboard by making a parallel board to hold the lens below the regular one that plugs into the enlarger. The gap is filled with a piece of foam rubber insullation and the adjustment is made by tighting the long 8-32 screws holding the two together. How I aligned them was to make a pattern on the computer with dotted lines and print it out on to transparency material. I also printed out on photo glossy paper the same pattern scaled up to 8x10. The pattern consists of 3-4 concentric circles, and a grid about 1 apart. It's important to beable to tell which line is which. The paper one is inserted in the print easel. The Trans goes in the neg stage. Rougly align the neg stage and the easel with a level. Then with the neg in place begin focusing and aligning. The scale between the two patterns should line up exactly. Focus shift is caused at the lens stage, alignment shift--you can see this if your circles down't line up. Takes a little time and you have to be able to think three dimensionally. A friend brought over a ZIG Align (which is a much quicker way to accomplish this but it cost about $150) and my alignment was right on the money. Good luck. ---William Nettles [EMAIL PROTECTED] Nettles Photo / Imaging Site http://www.wgn.net/~nettles William, I have the same enlarger and when I first tried the mirror alignment tool I found it adjustable at every axis with shims and existing adjustment screws. It wouldn't stay aligned though because moving the head up and down or swapping heads changed the center of gravity enough to throw things off. I strapped the top of the frame to a concrete wall with a couple turnbuckles to cure that. I would guess that any enlarger would benefit from a good strapping. Your projection technique sounds like a good idea because you can have a check grid in all your neg holders. AZ Maker of Lookaround panoramic camera. www.geocities.com/soho/gallery/8874/ or keyword.com lookaround ___ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
