Re: IR filters

["Keith Zimmerman" <zz_ir@xxxxxxxxxxx>]

----- Original Message -----
From: "Clive Warren" <Clive.Warren@xxxxxxxxxxxxxx>

> At 4:03 pm -0600 25/2/01, Keith Zimmerman wrote:
> >Thanks to phillip and chaz for their responses to my earlier query.
Their
> >info will help me make a decision about new filters to add to my toolbox.
> >
> >Also,thanks to those who spent the time to do the testing and presenting
it
> >in a manner that made it relatively easy to make educated decisions.
> >
> Did I miss some posts?  Can't seem to find other replies apart from
> WJ's which I have just read......
>

Clive, I will cut and paste the content of their messages below and include
also my thanks to you and everyone on the list that responded.  I have a lot
of resources to check out so I can make a decision as to the filter(s) to
add to my toolbox.

Phil's reply:
gelatine filters come in many  colors of red, but tend to be expensive
because
they wear out, and fade after several years, they aren't waterproof and are
very
fragile. They can't be cleaned other than blowing off dust. You have to buy
a device to
mount them on the lens or do it some where behind the lens.

polyester filters only come in a few shades of red, they can be cleaned,and
are waterproof.
while more durable than gelatine , they still scratch and in my opinion, are
not as clear.
same mounting problem

resin filters are a better choice than polyester, but you have the same
limitation on shades of red.
same mounting problem except you can't put them behind the lens except on a
view camera.


glass filters , depending on whose you get are the most durable.
Tiffin glass filters are gelatine sandwiched between glass and are probably
prone to fading.
Other companies make filters out of solid color glass.
The price has more than doubled on the IR filters made by B+W in the last
two years.
The filters from HOYA are the most reasonably priced.


> 3.  Which material works best?  Or are there instances when one material
is
> better suited than another?

glass or resin are better if you plan on using more than one filter in front
of the lens,
like an red and a polariser
also better if you shoot in dusty locations.

> 4.  Which filters would be candidates for inclusion in my new IR toolbox?
I
> currently own a 25.

29, 89b, 88a

phil

Chaz's reply:
Don't know how much this will help but you can try these web sites:

Wratten filters for Infrared- & UV-Photography
http://www.a1.nl/homepages/markerink/irfilter.htm#comparison

A comparison of B&W infrared films
http://www.pauck.de/marco/photo/infrared/comparison_of_films/comparison_of_f
ilms.html

Infrared transmitting Filters
http://www.artzone.gr/filterzone/infrared.htm

A Comparison of Infrared Filter Absorption Plots (near the bottom of page)
http://www.photo.net/photo/edscott/ir000020.htm

Chaz

>
<<<<<Date: Sat, 24 Feb 2001 20:35:26 -0600
From: "Keith Zimmerman" <zz_ir@xxxxxxxxxxx>
Subject: Filter questions

I'm planning for the up-coming release of this year's Konica by
increasing my tool inventory of filters.  I have a couple of quick
questions.

1.  Can someone discuss the optical pros and cons of the various
materials; polyester, gelatin, resin, and glass.

2.  Is there a site anywhere that has this type of information?

3.  Which material works best?  Or are there instances when one material
is
better suited than another?

4.  Which filters would be candidates for inclusion in my new IR
toolbox?  I currently own a 25.

Hopefully, this information will allow me to make a more informed
decision on the type of filters to buy.  Thanks in advance.>>>>>

Keith Zimmerman
zz_ir@xxxxxxxxxxx





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