Re: 4x5 halo (was: 4x5 camera suggestions

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

On 14 Feb 97 at 18:33, Robert Long wrote:

> On Fri, 14 Feb 1997 00:36:00 GMT, you wrote:
> 
> |I pondered about that some time ago....assuming it lacks the=20
> |anti-halo layer for the same spectral reasons as 35mm (and 70mm?=20
> 
> Spectral reasons?  You mean there's a *reason* it lacks an
> antihalation--aside from the "status quo at all cost" attitude of U.S.
> Government procurement policies?

I believe the official reason is that the antihalation layer cannot
be made IR-proof, just like the argument that the damn paper backing
of 120/220 cannot made IR-proof. Though the latter is a lousy
argument, as the paper backing is only needed for cameras with
film-counter windows. OTOH, handling film outside the camera is a practical 
argument, as 70mm comes in IR-light tight cannisters....

As for the antihalation layer not being IR-proof: Somehow this
collides with the results of Ektachrome IR, but I realize that this
is comparing apples with oranges (or pears if you are Dutch).

--
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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