Re: (Fwd) Re: Color UV?

[Zoe Paddy Johnson CIRT CSOS <pjohnso@xxxxxxx>]

Our ancient filter book says that a 47 is all called a C5.  It is 
described as tricolor blue for direct color separation and from Kodak 
Extacolor Film for dye transfer.  Contrast effects in commercial 
photography and tungsten and white-flame-arc tri-color projection.

There are also 47A, light blue used for medical photography and
47B which doesn't sound much different than a plain 47.

The transmittance diagram shows light being transmitted from 350nm to 
515nm, so a lot of blue is getting through.  

The 47A is from 280nm to 560 nm with a secondary lobe at 660nm extending 
into the infrared.

The transmittance diagram for the 47B is from 360nm to 500nm.

For comparison, the 18A, the "uv filter" transmits from 305nm to 400nm 
with secondary transmission starting around 700nm.
zoej

On Sun, 26 Jan 1997, Russell J Rosener wrote:

> Speaking of Ultra Violet photography, I found an old Wratten # 47 filter
> in my filter box last night. It's a deep indigo blue, so I wonder if this
> is some kind of Ultra violet filter which could be used to take images in
> the UV spectrum?
> 
> Russ Rosener
> Washington University
> St. Louis
> 
> 
> 
> 

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