[LargeFormat] Turner Reich Orange Filters

[Clive Warren]

Some time ago we discussed Turner Reich 4x5 lenses - some people love 'em 
some have had bad experiences....

Think it was Ken Hough who has great things to say about them.  It seems 
that bad experiences may have been due to the fact that the lenses need to 
be refocussed when stopped down and that they should (always?) be used with 
an orange filter which was supplied with the lenses when new.  This is when 
using both lens groups together in addition to single lens groups for the 
longer focal lengths.

Hardly an APO lens - however apparently capable of excellent performance as 
they are a protar design with an additional element to avoid being sued I 
guess .......

If  Ken is listening then perhaps he can enlighten me - or maybe someone 
else knows - would like to find out the Wratten number equivalent of the 
original orange filter.  Can anyone help?

Cheers,
             Clive