Re: [APML] tech pan revisited

[steve banbury <banburys@sonic.net>]

Scott---Murphy was an optimist!

:^} Steve

Scott Hammonds wrote:

> 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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