Did you feed the pets?

Started Jun 15, 2003 | Discussions thread
OP Lothman Senior Member • Posts: 1,092
achromatic close up lenses - Tutorial

ANON-A-TOM wrote:

Lothman, whats the difference between an achromatic close up lens
and any other type. I,ve had a look at the close up lenses sold by
Jessops and they dont note whether the lenses are achromatic or not.

By the way, excellent photo.

Thanks ANON-A-TOM,

achromatic close up lenses are made of to lenses "glued" together, therefore they don't show chromatic aberration as single element lenses do mostly in the corners. I strongly recommend achromatic close up lenses it's woth the money.

you find a survey on achromatic close up lenses here:
http://www.angelfire.com/ca/erker/closeups.html

Here some further links which explain the principles of achromatic lenses.
http://www.yorku.ca/eye/chroaber.htm
http://www.oriel.com/homepage/down/pdf/09023.pdf

You can build your own achromatic close up lens using an old binocular. The front lens there are usually achromats and also coated (see pic). This one I got from ebay for 10.- Euros.

High quality binoculars often have lense wich can be unscrewed but on the cheaper ones they are glued. So I saw them off, be carefully not to saw in the glas. Then I did very carefully an axial cut to open the housing and to clip out the lens. Attention the lens can be easily damaged with the saw, so use hand tools to feel and heard what you are doing.

You can see the two lenses. And to check the madnification put it before a paper board. Mine is +6 the binocular was 7x50 labeled with "Bresser".

All you have to do is to glue this lens in an empty filter ring or in an stepup ring to mount it to the 602. Therefore I used silicone because it is elastic (glas) and can easily fill gaps.

Regards
Lothman

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