Home Made Alignment Tool

[dr bob]

For those DIYSers, check out the following:

http://members.rogers.com/penate/ali...ment_tool.html

[Mongo]

I have to wonder why he went through the trouble of drilling through the mirror for the LEDs...wouldn't this have worked just fine with the LEDs, the wires, and the batteries all on the mirror surface? Also, rather than drilling a hole in the mirror for viewing, why not just scrape away the silvering from the center of the mirror and leave the glass in place?

Don't get me wrong...his solution is great...it just seems a bit over-engineered to me.

And as long as I'm picking nits....a mirror placed at a 45 degree angle to the hole would work as well as the pentaprism...just that the image wouldn't be upright so you'd have to mentally rotate it when you make the alignment changes to the enlarger.

[Neal]

Dear Mongo,

I must agree with you, he has a great solution.

If I had to guess, drilling a few holes is easier than building a frame to keep the diodes straight and it is easier to use a pentaprism than install a mirror at exactly 45° without a machine shop.

Now, how can the mirror be attached to the lens to align that?

Neal Wydra

[Loose Gravel]

Use mirrored plexiglass. It makes drilling the holes a whole lot easier.

[paul ron]

Mirrored plastic is not optically flat, the variations in the surface will not allow you to get proper parallelism<sp?> of the planes.

[lee]

I have a set of mirrors that are front surface and instead of drilling a hole we just scratched some of the silver off so we could see through it. We used these mirrors to optically alighn the copy boards with the film plane


lee\c

[Loose Gravel]

No, plexiglass is not optically flat. Optically flat is defined in fractions of a wavelength of light. I don't think anything in my darkroom is that flat and mirror tile is not optically flat either. Cast plexiglass has worked for years. It is 0.005"/ft flat. Probably as flat as mirror tile, negatives, lensboards, lensboard alignment, the edges of your enlarging paper, image flatness, negative holders, and the rest, all RSS'd together. This is photography, not laser interferometry.

[dancqu]

When all is said and done the trapezoidal method should
provide the most perfect alignment possible. I do not believe
the method can be faulted.

Not much is heard of the trapezoidal method probably
because it does not sell any equipment. Dan

[pwcphoto]

Seems like a lot of work, I don't want to think about how many mirrors were cracked in the process, that is a lot of bad luck at 7 years a crack! ;=] Pretty neat concept though.

I purchased a laser aligner at a trade show many years ago. It produces a laser beam that is perpendicular to the paper plane (easel) or baseboard. They supply a front surface mirror that sets in your negative carrier and one that fits in the lens board.

Basically you shine the laser up with the lens removed and adjust the negative carrier so that the beam falls back down on the emiiter, if you see it anywhere else you are out of alignment. The higher the enlarger head the greater the accuracy as the error is magnified. You do the same thing for the lens board and you have a nicely algined enlarger with all planes parallel. It is very fast.


I have a pair of Suanders LPL-4550XLG enlargers and I must say that out of the box, they are about the most accurate I have ever seen, almost no adjustment required. Can't say that for my Zone VI or Omega's.

Phil

[dancqu]

You do the same thing for the lens board
and you have a nicely algined enlarger with all planes parallel.
It is very fast.Phil

That very narrow beam of light is almost as small as one
of the infinite number of points which make up a plane.

The trapezoidal method is a more real world method as
it uses the carrier or a negative in the carrier and it's
projected image to make the alignment.

In a nut shell, a square in the carrier must project a
square and it be in focus across the entire plane.

Actually I think trapezoidal to be a misnomer. Dan