Re: Night lights again

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On  4 Oct 99 at 10:05, Clive Warren wrote:

> At 6:15 pm +0100 1/10/99, Willem-Jan Markerink wrote:
> 
> >On 29 Sep 99 at 11:27, Clive Warren wrote:
> 
> Big snippety snipletson
> >>
> >> My point was that even WJ had no Cokin "P" size filters available in May
> >> last year -
> >
> >Not the one you were looking for, #89B....at least not in stock at
> >that time. And although that was the result of erratic production
> >and demand, it got complicated by problems with accuracy of the
> >darker colors, when compared to Wratten....I can't accept a '#87C'
> >where you can see much more than just the filament (not just the
> >entire lamp reflector, but even the reflection on a table)....8-))....no
> >matter what 'Wratten-accuracy' the manufacturer claims. Haven't had
> >this inconsistency with foil quality filters....
> 
> 
> Wiilem-Jan,
> 
> You have mentioned your problems with manufacturers previously.  Agree with
> you that such "out of spec." filters would be unacceptable.
> 
> I would be happy to supply you with professional quality CoCam Infrared
> filters in Cokin "P" size if your suppliers are unable to provide
> consistent products :-)

You better check yours too by comparing them with Wratten 
filters....the inconsistency itself wouldn't be that bad, if the 
manufacturer acknowledged there was a problem, and also informed 
previous customers of this problem. I felt, and still feel, like talking 
into the desert....any manufacturer claiming 'better than Wratten 
accuracy' should take such a problem a lot more seriously, including 
information to previous customers.

So there are probably dozens, if not hundreds of these filters
circulating among other photographers/scientists, bought previously
and afterwards (two very different batches of off-spec filters delivered
to me only can't be exceptions....I suspect off-spec colors every
other batch, if they do spectral checks inbetween at all)....without
them knowing about this problem. And from an academic/photographic 
standpoint, that stinks the most. IR gives enough erratic results as 
it is....8-))

So I hope you have a set of Wratten originals in your posession, and 
a tungsten/halogen lamp to compare....never trust manufacturers....;-))

Btw, I did get correct-spec #87 and #87C from them in the past....so 
I haven't given up yet....also because they claim they can do #87B 
and #87A....

--                 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
*
****
*******
******************************************************
*  To remove yourself from this list, send:          *
*         UNSUBSCRIBE INFRARED                       *
*       to                                           *
*         MAJORDOMO@xxxxx                            *
*----------------------------------------------------*
*   For the IR-FAQ, IR-Gallery and heaps of links:   *
*  http://www.a1.nl/phomepag/markerink/mainpage.htm  *
******************************************************