Re: lens 'recipes'


"Phil Hobbs" wrote

snip

3. Measure the focal length of the lens (crack doublets apart for
measurement purposes, assuming you have several identical ones--use a
knife and a soggy hammer, and wear safety glasses).

You crack me up! :-)

What's a soggy hammer? You mean a mallet?
I love the safety glasses part. You forgot the cold chisel I assume.

You actually separated a doublet using your method without chipping
the individual lenses? If so congratulations on your dexterity and luck!

The method to separate a doublet is to immerse it in a solvent and
let it soak overnight, or as long as it takes (which may be several days).

Sometimes the separation is impossible.
Especially with modern UV curing cements or bonding agents.

Sometimes the separation proceeds half way and then stops.
Then good luck on being able to reuse the doublet.

The sovent depends upon the cement that was used.

For old lenses "Canada Balsam" was used in which case hot water may do the
trick. Raise the temperature slowly as the doublet may shatter.

If using a solvent put the container in a fume hood.
Solvents have often disagreable features (toxicity, flameability etc.)





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