Re: [APML] Pentax 67 purge port........NOT!<g>

[Tim Povlick <potentate@home.com>]

Hello Phillip....

Philip Perkins wrote:

> Hello Tim,
>
> >I was curious about purging so here goes some questions:
> >
> >When one drills either the 67 or 67-II, for daylight use
> >would you have to plug the hole else light will get in?
>
> Highly unlikely but I keep a blob of sticky tack in the tripod hole just in
> case.  Of course when the camera is mounted (using the tripod socket) or
> when using the gas nozzle then the hole is blocked anyway.  The hole is
> very small and for light leak to be at all detectable one would have to be
> shooting a dimly lit object while at the same time with a very bright light
> shining towards the base of the camera.  Now, if one was shooting a dimly
> lit object with a camera like the Pentax 67 one would have to use a tripod
> anyway, so you can see how unlikely this is.  If using the camera handheld
> in anything like normal lighting I am sure that light leak would never be
> an issue, even without the blob of tack in the hole.
>

A very good point....

>
> >In a desert environment, say  15% humidity is a purge
> >system necessary for hypered film?
>
> That is very dry - I would say no.  In exposures of up to 30 minutes I have
> not detected any film movement or other problems without using a
> purge.  The RH was about 45% at the time.  Problems will start to creep in
> with longer exposures in humid conditions.  But 15% is so dry that I am not
> sure you would notice any real difference without a gas purge, provided
> that the RH is maintained during the night.  But even so you might decide
> to purge as a safety feature in case the RH increased during the night.
>

It would be nice to avoid bringing  a high pressure cylinder of N2 along.
The air is so dry one sees a graphic example of why to wind the film slowly
in the camera or risk a 'lighting streak' on the film.  When I was digging into
a plastic bag, I saw many flashes of electrical discharge from the static.

>
> >If you have some accessory before the camera, say a
> >field flattner that can be drilled, is this an acceptable
> >place to drill?
>
> Some people have done this successfully with 35mm cameras but I couldn't
> answer for the Pentax 67.  The void that has to be filled is much larger in
> the case of the 67 but if the flow is increased to compensate then it
> should all be the same.
>

Darned, just checked my FF and I really don't have to room for a purge.

>
> >Since oxygen (as well as H2O) seems to be the enemy
> >of hypered film, it would seem a nitrogen purge is better
> >than a dried air purge.
>
> This is the view that I hold.
>
> --Philip
>

Thanks for the info both to you Philip and Bobby.  I'll dive slowly
into this  HYP arena.  You guys (and many others out here) do
some astounding work.


Tim Povlick
San Juan Capistrano, CA


>
> Philip Perkins - philip@astrocruise.com
> Wiltshire UK & Luberon France
> Astrocruise - http://www.astrocruise.com
>
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