Re: why using #87 and #87C filters?

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

On 13 Jul 98 at 19:36, Jaap Los wrote:

> Hi all,
> I installed #87 and #87C sheetfilters between the filmrails of my
> Nikormat EL camera. After having shot some films (HIE) with each filter
> I wonder what the advantage of using these filters is! I compared them
> with the always good results I got from a #25 red filter (Cokin 003
> red). I noticed following nasty properties of the sheetfilters:
> 1. Sharpness is less.
> 2. Contrast has completely gone. 
> 3. Parts in the shade do not reflect IR so they appear almost blanc on
> the negative. Shots made at overcast sky are useless.
> 4. It is very difficult to get good negatives, they are always of a much
> lower quality than the #25 filter negatives.
> 5. I see hardly any or no difference in the 'wood-effect' as compared
> with the #25 filter.
> For processing HIE, see my homepage. It's possible, that I do not
> profit  from the special quality of these sheetfilters. Maybe there is
> something I have to change. Please let me have your comments. What are
> the experiences of other LIST-members? 

Jaap, some comments/questions:

- - where did you find that bright sunny day in the last couple of 
weeks? The ones I saw can be counted on the fingers of one hand, and 
AFAIK, we still live in the same country....8-))
While #25 might still get you a decent image, #87C relies on
IR-only, and it simply isn't there on anything but a bright sunny
day....even though some people might have a use for this effect, the
lack of contrast makes me depressive....

- - did you remove the protective cover from the #87C material? (the 
thick, 0.4mm foil)

- - did you use the same focus correction as you did with #25?
#25 doesn't need half the correction as #87C does, just like Konica 
requires half that of Kodak....


- -- 
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'!]
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End of Infrared-Digest V0 #679
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