Re: Polycarbonate bodies

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

On 23 Feb 97 at 22:42, Richard Lovell wrote:

> Hi all,
> 
> I have just shot my first roll of IR film (HIE) and have produced some
> really great images. So much so I can't wait to find new material to do it
> again- soon. However, I used a plastic camera body (Pentax MZ5/ZX5) which
> allowed a little IR leakage onto some of the frames which prompts the
> following questions:

Mmm....'some of the frames' excludes my first thought, that the 
camera uses an IR-LED counter instead of a mechanical 
counter....right?

 
> 1. Can I wrap the camera body in aluminium foil to make it impermeable to IR
> wavelengths? If the sun comes out this week I will try to measure the
> permeability of aluminium foil to IR wavelengths using a hand held
> radiometer, but until then any feedback would be great.

I doubt it is the back of your camera....can't exclude it, but many 
other cameras would suffer from it as well in that case. Even my 
Horizon body does fine.
Alu foil should be opaque to a wide range of near-IR, as it is 
already quite reflective to heat and opaque/reflective to visible.
 
> 2. My other option is to pick up a K1000 body and use my lenses. Recently
> various people alluded to the problems with the K1000's dimpled pressure
> plate. Can anybody confirm that this problem CAN be surmounted by using
> black tape over the dimples?

The suggestion in an UK mag was taping it with the paper backing of 
120.
I still ponder about what the effect would be if you taped it with 
IR-reflective alu instead of an IR-absorbing black material....the 
halo effect should increase, as a significant part of that effect is 
caused by back-reflection....

--
Bye,

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      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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