Re: [APML] Sh2-119

["tan@home.com" <tan@home.com>]

John,

	Yes, you're right, mine has an additional circular plate added to the
top of the film holder. Together with the filter, the film is reasonable
well protected although it is definately not air tight. The Wratten
filter is too flimsy to stop air from seeping thru the sides.
Nevertheless it is better than not having it. Sorry I would have
suggested this as a possible source of your mottling problems but I had
always thought that all the 8" Schmidts had the same roll film holder. I
had posted images of my film holder before but no one mentioned this
difference. 

Loke


"John C. Mirtle" wrote:
> 
> Thanks Loke;
>         My film holders are very different on both Schmidts, the outer edge of the
> body pretty much ends at the edge of the screw head. It almost looks like
> yours has had a plate added to the top of the stack, with the threads part
> of this plate. All my film holders are 2 pieces only. A machined aluminum
> back piece, and a black anodized top piece. Yours appears to have an
> additional top piece, which looks like a brilliant idea! A really big
> advantage that I see is that it would completely seal off the film from
> humidity during exposure - something like this might clear up my mottling
> problem. :-) Thanks!
> 
> John Mirtle
> Calgary, Ab. Canada
> 
> -----Original Message-----
> From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
> Behalf Of tan@home.com
> Sent: Thursday, October 11, 2001 9:05 PM
> To: astro-photo@seds.org
> Subject: Re: [APML] Sh2-119
> 
> John,
> 
>         Here is a picture of the film holder again.
> 
> http://www.starryscapes.com/tmp/film_holder.jpg
> 
> The two center screws mount a circular plate onto the film holder. This
> circular plate is threaded on the inside as can be seen in this picture.
> If you can find the maker of this circular plate, you could probably get
> in mounted onto your Schmidt's film holder. I do not know if it was
> Epoch who did this. Don't you also have an Epoch upgraded Schmidt? I
> would think that yours would have this feature as well if it was Epoch
> which was responsible for it. I am kinda curious now. I had thought all
> the 8" Schmidt film holders were like this.
> 
> Loke
> 
> "John C. Mirtle" wrote:
> >
> > Great shot Loke, another interesting field for my hit list! Your film
> holder
> > sounds interesting, and is probably much easier to use than the stuff I
> had
> > to build to enable filter swapping. There are 2 8" Schmidts in town, both
> > are early model Celestrons. Both have the simple 'click-on' filter
> holders,
> > which are designed to have a single filter glued into place. Do your
> filters
> > screw directly onto the film holder? Perhaps this is one of the Epoch
> > modifications...
> >
> > John Mirtle
> > Calgary, Ab. Canada
> >
> > -----Original Message-----
> > From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
> > Behalf Of tan@home.com
> > Sent: Thursday, October 11, 2001 10:56 AM
> > To: astro-photo@seds.org
> > Subject: Re: [APML] Sh2-119
> >
> > Kent,
> >
> >         I did not discover this until recently but it appears that the
> film
> > holder's means of accepting filters come in two flavors. Mine is
> > threaded in the front to accept standard photographic 52mm filters and
> > there is another type which is not threaded. This is certainly news to
> > me.
> >
> > Loke
> >
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