Rollei lens ball

[belgiumreporter]

Don't know if it should be called a filter or lens,but for some time now rollei has been selling so called "lens balls" available in different sizes ranging from 60 to 110mm. These can be fun to work with, but the novelty will wear of quickly so unless you're into this creative sort of photography the question is if it is worth buying one...

Now i happened to have a cristall ball in my minerals collection, it is larger than the rollei versions (160mm), but usable non the less if the +3KG weight isn't an object.

These balls need to be handled with caution as they work as a strong burning glass, i once left the ball on a marble table in the sun and whitin a few minutes the plastic coating of the table was melted on the spot where the focal point of the ball was concentrated.


Some fun outside



Crazy Possibilities inside when doing table top just add a colourfull or graphic background.

[philbirch]

Ive seen pics with these. Its a one trick pony. Gets boring after a while.

[paulhofseth]

A terminology "complaint":

Filters in past vocabulary were suppposed to be meticulously madde planeparallell glass (Or in the case of Asahi two same-radius convex surfaces so as to avoid reflections)or even cheap plastic bits; all with closely specified spectral transmissivity so as to correst colours or block some rays.

These are usually confused with front mounted close-up lenses chich may be achromatic doublets with specific diopters and sometimes happen to be matchded to a specific lens.Many experimenters peersist in calliong them filters when they make attempts to avoid sensor problems with wideangles.

Effects attachments like star-burst prisms, vignetting discs and straightforward dabbing vaseline on the front lens element or looking through objects deserve to be be more precisely named than just being called filters.

Theere is even one rare tarnsparent filter fulfilling a particular role as part of the design of of a catadioptic lens (the end filter), it was even designed to be made of a tightly specified type of glass.(I suspect low dispeersion since it is not supposed to have any refractive purpose, merely to let light through, or as its siblings, to reduce light by a specific amount.)

p.