Re: Flash and IR filters and Konica 750

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

On  4 Feb 98 at 20:24, Clive Warren wrote:

> At 3:28 pm +0000 3/2/98, Willem-Jan Markerink wrote:
> 
> >On  3 Feb 98 at 13:42, Clive Warren wrote:
> >
> >> Further to my flash filter experiments using Konica 750 with no filter in
> >> the dark.
> >>
> >>
> >> Well after having a closer look at an article by Andrew Davidhazy :
> >>
> >> http://www2.ari.net/glsmyth/articles/filter.htm
> >>
> >>
> >> it seems that two sheets of unexposed, processed Ektachrome produce a sharp
> >> cutoff starting at 750 and finishing at 800 nanometres.  This may explain
> >> the lack of any image on my Konica 750 film.
> >
> >How long did you expose?
> >Konica will work up to #87 (not #87C), and that is quite a bit darker
> >than the processed-E6 solution AFAIK [0% @ 740nm, 50% @ 795nm]....
> >You just have to adjust your exposure times....you might end up with
> >fractions of ASA, but noone said this would be an easy hobby....;-))
> 
> 
> Uhhhh....  it was a flash exposure Willem-Jan and it was dark.  To satisfy
> your curiosity I used 1/125 on a leaf shutter.

Oh well, just increase exposure no matter how!....:-))
 
> Take your point about requiring more light though.
> 
> The flash was on auto, but close enough to rate at 50ASA - no filter on lens.

Dangerous thing....I once did this with HIE, and both a #87C on the 
flash and BTFR....my shots didn't show much differences, although I 
bracketed like hell, from 6 ASA to 400 ASA.
And with the OTF sensor, light then passes a #87C 3x before it is
measured....while I don't even know whether IR *reflects* much from
the film in the first place! The OTF sensor is calibrated for
visible light and normal film, but for IR all bets are off....8-))
My flash could have spit out the full capacity each time....or the 
minimum capacity in your case....

> What is required now is someone else to waste a frame or two - I'm running
> out of money ;-)  Have beautiful darkslide Ektachrome shots for anyone
> willing to take part in this flash extravaganza......

Something in the name of IR science/art can't be a waste!....:-))

 

- -- 
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 #384
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