Hoya R72 InfraRed filter

[danzig@xxxxxxxxxxxxxx]

ello mates ! ;)


Finally after waiting for a full year I've got my first opaque IR filter ( 
things move slow on this blasted island )

It's the Hoya R72 InfraRed filter, & what I want ask is does anyone 
have any idea what the filter factor is ?

If any can be derived from something that cuts all visible light out, 
that is. I'm not even sure how to conduct an experiment as to how 
to posibly expose for images.With a deep red filter you can pretty 
much use the recommended exposure of the meter.

But on an opaque filter what assumptions should I make ? What 
ISO should I set my lightmeter to ? (Minolta 4F ) 

Another question, in Hoya's catalougue, I saw 2 infrared filters, the 
R72 & the M90. I'd suppose the M90 lets in less light than the R72. 
Only question is, what exatcly is it supposed to let in & what is it 
meant for ? 

Could it possibly be used for solar photography ?
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