Macro lenses and close up filters

[OzzieTraveller]

G'day othrelos

Not meaning to pick on you at all here - your info is 'good' although may I offer you a response to one aspect of your post above

A "filter" is [mostly] a flat piece of glass, usually coloured, but being flat will NOT create an image
A "lens" is [usually] glass though it may be another element, it is curved AND will create an image

Thus we can have "close-up lenses" we do not have "close up filters"

There are many people [and shop staff] who see the close-up lens screwing into the "lens-accessory-thread" on the front of the lens, that thread usually used for filters, and who then call the close-up lens a "close up filter" ... ie: incorrect

Equally, I have seen the plastic boxes that filters come in, when they contain a closeup lens, the cover still says eg: 'maker-name' filters, but the box contains a lens. It does not help we users when the maker is too lazy to use correct labelling

Hope this helps
Regards, Phil

[Othrelos]

A "filter" is [mostly] a flat piece of glass, usually coloured, but being flat will NOT create an image
A "lens" is [usually] glass though it may be another element, it is curved AND will create an image

I don't disagree with your definition of what is a filter and what is a lens. Though I believe your definition could use some refinement. For argument's sake, a close up lens while capable of forming a coherent image cannot be used for photography on it's own without being attached to the filter thread of a lens. The close up lens has the effect of increasing the minimum focusing distance of the lens it is attached to, so technically it is an auxiliary lens. I agree it isn't a filter, I was merely using the layman term "filter" for clarity.