Re: IR fogging

[Patrick Magee <pmagee@xxxxxxxxxxxx>]

On Mon, 21 Feb 2000, David Lee wrote:

> 
> 
> > >
> > > > I have shot numerous sheets of HSI with my Leonardo pinhole camera.
> > > Plywood
> > > > may not be the best material to use with infrared, but pine
> > > seems to have
> > > > worked well enough for me.
> > > >
> > > > george
> > > >
> > > > ---
> > > How thick is the wood?
> >
> > The Leonardo uses 1/2" thick wood.  Pine isn't exactly one of the better
> > choices when shooting IR pinhole - actually, it's one of the worst - but I
> > believe that the thickness helps.
> >
> > george
> >
> I suspect that the thickness is the important factor here, although the type
> of wood may be a factor, too. As I mentioned in my previous post, the
> mahogany plywood that I used is only 3/16"thick (and of course the mahogany
> part is only 1/3 of it.) I wouldn't think that IR would get through 1/2"
> plywood of any sort (although I didn't expect it to get through 3/16"
> either.) One of the reasons I made my pair of wooden 4x5 cameras was to be
> light (since I am carrying 2 of them). A single camera of this sort weighs
> no more than a Rolleicord, but with 1/2" thick wood they would have been
> much heavier.
> 
> David Lee
> 
Another factor to look at is the number of plys in the plywood. Since
virtually all plywood has voids in some of the plys, the more plys there
are the lower the chances of getting overlapping voids which can make the
thickness, as seen by IR, very thin. Of course voids can occur in
different places in different cameras. Some cameras may have none, others
may have multiple voids in the plys. I guess testing is the only way to
determine the IR capabilities of your camera.

Pat

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