Re: Filters!?!?

["Richard L. Butler" <rbutler@xxxxxxxxxxxxxx>]

Pedro Luís wrote:

> Hi I've bought a IR film and I'm taking the first steps towards trying
> it out. I came to this impasse.In the catalogue of one of the filters
> I have appears an IR filter that stops visible light from getting into
> the camera.But I haven't been able to find that filter yet.Are the
> differences significant? Cause what I really want is to explore that
> absence of depth of field that I see in some IR photos. Best
> regards,PedroL _________________________________________________________  Visita
> a página da Juventuna Rebelde em:
>   http://juventuna.cjb.net

Well, Luis, there are two different filters which block light--one
absolutely black (B+W 093--SchottRG 830--Wratten 87C) and one red (B+W
092--Schott RG 695--Wratten 89B), but so dark it is vitually impossible
to see light through it.  The black blocks 100% of all visible light
while the red blocks all visible light 650 nm.  There is also the B+W
099--Schott OG 550--Wratten 12 which blocks the blue and blue-green
portion of the visible spectrum up to 520 nm.  However, most
photographers are happy using either a Wratten 25 or 29 red lens.

Happy photography.

Richard Butler

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