Great Site about close-up diopters / achromats

[kds315*]

http://fuzzcraft.com/achromats.html

[LucisPictor]

Thanks.

[estudleon]

Thanks. USEFULL!!!

Rino

[sichko]

A nice site. Thanks.

[kds315*]

I found that quite helpful to figure out a needed diopter.

So if for instance an old lens has closest focus 2 meters, this is equiv. to 0.5 dioptries for the lens itself.

Add a diopter with 0.5 dioptries 1/(0.5 + 0.5) gets you close to 1 meter (focus range is 1 - 2 meters),
one with 1 dioptries (+1) gets 1/(0.5 + 1.0) = 0.67 meters (focus range is 0.67 - 1 meters),
one with 2 dioptries (+2) gets 1/(0.5 + 2.0) = 0.40 meters (focus range is 0.40 - 0.5 meters)
and so on...

Btw. diopters from +1 onwards should be achromats, not just simple meniscus lenses or you will see
terrible CA (as shown in that link I posted above)!!

[martinsmith99]

Bookmarked - Thanks for that!

[Minolfan]

Nice find, thank you!

[Abbazz]

Thank you Klaus, very useful link. Those achromats can be a very good solution to explore macro photography without committing huge lumps of hard earned cash. A Raynox DCR-150 or DCR-250 achromat will clip on any consumer telephoto zoom turning it into a rather good quality macro lens. Contrary to extension tubes or bellows, an achromat will not decrease the aperture of the lens (or only by a very little amount due to transmission loss): a 80-300/4-5.6 zoom will retain its F/4-5.6 aperture range while allowing quite spectacular reproductions ratios when used at the 300mm marking.

Cheers!

Abbazz

[ChrisLilley]

[Abbazz]