RE: [APML] tech pan revisited

["Scott Hammonds" <shammonds@creatorsview.com>]

Chuck, Jim, Don,
Thanks for the replies. I am truly baffled by this one.

Chuck, 
I am using a dry air purge and only shooting here at my house. Moisture
is present, but the scope, camera, etc are not wet with dew. Humidity
here in the southeast is always a problem, but during the winter it is
much lower and I had this problem back in January. I have used several
different rolls, the first was from Lumicon. Jim offered to hyper some
fresh tech pan for me and I had the same result.

Jim,
I was very careful loading and unloading the film. I need to try the OM1
again to verify it created the same effect. Frustrating...

Don,
I have been thinking along the lines you said about emulsion cracking.
It did not happen on unhypered tech pan. My camera does roll the
emulsion side out. I've used old and new(fresh) film, same result. 

I'm heading out to try another few shots once the moon descends a little
lower. Murphy be ...


Scott 

-----Original Message-----
From: astro-photo-bounces@seds.org [mailto:astro-photo-bounces@seds.org]
On Behalf Of westergren
Sent: Wednesday, September 03, 2003 8:43 PM
To: Discussion of Film Astrophotography
Subject: Re: [APML] tech pan revisited

Scott,

Looking at you picture of the CA nebula with the vertical lines in it
shows
that the spacing between lines is variable.  So here are a couple
questions
and comments.

1. Did the lines also show up on the rest of the leader rolled up in
your
camera?
2. Does your camera reverse roll the leader (with the emulsion facing
out)
or roll the film the same direction as in the cassette?
3. How old is the film and how was it stored before and after hypering?

What I'm guessing here is that the film emulsion is cracking by becoming
brittle when flexed during roll up on the camera spool.  I've never seen
this happen, so it's only a wild guess.  If this is the case, then it's
probably from aging of the film (another wild guess), and the solution
would
be to try absolutly fresh film.  Maybe even try developing some
unhypered
tech pan run through your camera to see if it's somehow the hypering
process.

I don't have the same cameras you do, but my Nikon F winds the film
reversed.  I have used hypered tech pan, hypered at 50°C for 96 hours
after
vacuum at 28 in. Hg without this effect.  If Jim is using a hard
(mili-torr)
vacumm, maybe the extreme drying out is causing brittleness.  It can't
be
the temperature, since people all over the world are hypering it at
50°C.

I hope the cause can be found.  I'm really curious about what is going
on.

Don


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