Re: Is it possible to get an 88A?

[Clive Warren <Clive.Warren@xxxxxxxxxxxxx>]

At 12:22 am +0100 17/8/99, Willem-Jan Markerink wrote:

>On 16 Aug 99 at 7:25, Jim Bisnett wrote:
>
>>
>>  Is it possible to buy an 88A filter anymore?  if so where? and what
>> brand?
>
>In glas/screw mount, only Heliopan has an equivalent (Schott RG715).
>
>Resin/Cokin-P is possible too, but I have found the darker colors to
>be quite inaccurate/inconsistent....to the point that some batches
>of a #87C show the same 'opaque-ness' as an official Wratten #88A or
>even #89B.
>
>Last but not least: even though Kodak doesn't make all the
>inbetween-types anymore, I still can provide you with a thin-foil
>gelatine quality. Mail me if you want more details.
>
>--
>Bye,
>
>Willem-Jan Markerink


Willem-Jan,

I was interested in your comments on the accuracy and consistency of
optical resin Cokin "P" size filters as I sell them!

The most difficult filter to manufacture in the IR range is the 87C.  This
is associated with the "dyed in the mass" process and how particular dyes
react with the optical resin when hot. It is much easier to make thin foil
filters whether they be gelatin or polyester.

The CoCam optical resin 87C filters are accurate to the Wratten 87C
standards.  The manufacturers reject a high proportion of their 87C filters
which are then destroyed.

The higher cost of the filters is due to the materials costs, rejection
rate, and low volume.

I am currently out of stock of the 87C filters and am waiting for new stock
to arrive.  This is a significant investment for me. Following a tour of
the filter factory I am satisfied that the manufacturers have the highest
possible quality testing standards and adhere strictly to the Wratten
specifications.

The drive to source my own filters and indeed to set up a company to supply
them  was as a result of a trip to the USA last year where I needed a "P"
size IR filter for a particular camera and could not find one anywhere.
This resulted in no IR photographs on the trip and I was determined that
this would not happen again.

I would be happy to answer any questions on CoCam filters however please
mail me off the list.





All the best,

             Clive   http://www.cocam.co.uk
                     Photographic Services, Filters and Equipment
                            http://clive.bel-epa.com
                            Adventures in Cyberspace - Digital Art and Photos


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