[Aavso-photometry] Johnson Filters

[arne]

Walter MacDonald wrote:

> I see that Optec is selling off its 1" Johnson filters for US $50 
> each.  That's a good deal if you're looking for one of those filters! 
> (Page is here: http://www.optecinc.com/optec_036.htm )
>
For B and V, this is a good deal.  However, all readers should realize
that Johnson R, I are not the same as Cousins R, I.  All professionals
use Rc and Ic, not Rj and Ij.  The Schuler/Astrodon Rc/Ic filters are
about the same price and do meet the wavelength specs to match the
standard system.
Arne