Quote Originally Posted by Dan Fromm View Post
We've discussed fettling and using shims to compensate for slight errors.
Sorry, Dan,

But you misunderstand.

ALL manufactured products have tolerances, from the simplest straight piece of wire to the Eiffel Tower.

Precision costs money. Making a part with a tolerance of +/- 0.001" is more expensive than +/- 0.01".

Every dimension of every lens element and metal component has a tolerance.
A complete lens cell has hundreds of dimensions, each with its own tolerance.
And the acceptable distance between the two cells likewise has a tolerance.

Custom assembly can be cheaper than making everything exactly right.
Lens makers must make a profit on a lens that can be sold at a reasonable price.

- Leigh