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# Thread: fat max laser plumb

1. First check with a square to confirm that it is
a rectangle.
You can verify that it's a rectangle by comparing the diagonal measurements. They should be the same.

2. I keep several laser alignment tools on my belt!

3. Originally Posted by BetterSense
You can verify that it's a rectangle by comparing the diagonal measurements. They should be the same.
Let's assume that we have the trapezium ABCD and AB, CD are the parallel sides. If angles A=B and C=D, then the diagonals AC, BD will be equal!

4. Correct. That certainly works. But you need an angle-measuring device to measure the angles and see if they are the same. You can compare all four sides of the quadrilateral as well as the diagonals with only a length-measuring device. And since you are only comparing them for equality, it doesn't even have to be accurate (a piece of string etc.).

I don't even have a square around here, but I certainly have something I can mark with a pencil to compare lengths with.

5. Oh, you missed my point. I didn't suggest to measure the angles. I just wanted to point out that you can have equal diagonals, without having 4 90 degree angles. If you're going to use diagonals, you need to make sure they bisect each other. In any case, comparing lengths seems the best choice for me.

6. Originally Posted by Anon Ymous
Parallelogram, or did you really mean trapezium?
The most common misalignment should produce that.

Can you misalign an enlarger and get a rhombus
from a square frame?
Well you mentioned "the parallel sides" in your post
so I went with that. Rhombus, trapezoid, from the
four sides of the negative I can't say how many

I've an Issue of Camera and Darkroom wherein
an article describes a method of alignment which
makes use of the trapezoid as part of the
alignment procedure. Dan

7. ## Quick Check for Alignment

Originally Posted by BetterSense
But you need an angle-measuring device to measure the
angles and see if they are the same.
A square or triangle, draftsman's or grade schooler's, is
needed. Ninety degrees is THE angle. Only TWO checks of
the internal angles need be made. If the object projected
is a rectangle and the projected image tests square at
two corners the enlarger is well aligned.

The same test will do to confirm progress when actually
working to align an enlarger. After all, the finale proof
of alignment is on the baseboard. Dan

8. Originally Posted by dancqu
A square or triangle, draftsman's or grade schooler's, is
needed. Ninety degrees is THE angle. Only TWO checks of
the internal angles need be made. If the object projected
is a rectangle and the projected image tests square at
two corners the enlarger is well aligned.
That's true! And the OP should be more that happy to spend his \$100 buying more film and paper IMHO.

9. You guys would over think an orgasm.

10. Originally Posted by raucousimages
You guys would over think an orgasm.
ROTFLMAO!!

Steve

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