RE: [APML]: August Photos

[Chris Cook <ChrisCook@platsoft.com>]

The Astro-Photography Mailing List
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Philip,

The Cocoon shot is quite good.  Nice job!

Regards,

Chris


> ----------
> From:         Philip Perkins[SMTP:philip@astrocruise.com]
> Sent:         Tuesday, September 15, 1998 1:58 PM
> To:   astro-photo@nightsky.com
> Subject:      [APML]: August Photos
> 
> The Astro-Photography Mailing List
> ------------------------------------
> 
> Amidst the impenetrable gloom of English skies I managed to find a few
> semi-clear nights last dark period. Compared to southern France the
> transparency was pretty abysmal, but hopefully there may be something of
> interest in these new photos.  I partially overcame the transparency
> problem by double and triple stacking..
> 
> http://www.astrocruise.com/cocoon.htm
> Cocoon nebula - triple stack on hypered PJM-2, 2850mm with GEG at f/11.2  
> Nothing too unusual about this shot except that the scope went out of
> focus
> during one exposure and trailed slightly during another.. :)  The very
> thin
> negatives mean that graininess shows, even with a triple stack.
> 
> http://www.astrocruise.com/skull.htm
> 'Wolf Skull & Pelican's Eye' ('Wolf Skull' is my own description:)  Stack
> of
> three 2.5 hr exposures on hypered PJM-2, 2850mm with GEG at f/11.2  This
> shot would have been much better with a filter but I specifically omitted
> the filter to try to capture the true emission line response of hypered
> PJM-2.  One of the exposures trailed quite alarmingly (this shows on the
> photo) with what looks suspiciously like field rotation (I thought that
> polar alignment was quite accurate).  If anyone would care to help with
> the 
> diagnosis I would be happy to mail this image.
> 
> http://www.astrocruise.com/veil.htm
> Complete Veil nebula with Nikon 400mm f/3.5 (at f/4) + Lumicon DS filter.
> Stack of two 50 minute exposures on hypered PJM-2.  You will find this
> version of the Veil resplendent in beautiful yellows and greens! :))  I
> have
> a theory that the yellows and greens are due to use of the DS filter. I
> know that in theory the DS filter should not modify the film's response to
> OIII, however I have only ever seen these colours when using the DS
> filter. 
> I believe that there would be a big difference if I was to photograph the
> Veil again without DS filter (maybe I should try to do this). 
> 
> The images may also be accessed from the front page of my web site (link 
> below).
> 
> Here's wishing for clear skies in the current dark period...
> --Philip
> 
> Philip Perkins  --  philip@astrocruise.com
> 51 27'N 1 36'W  --  Wiltshire, UK
> 43 54'N 5 32'E  --  Luberon, France
> Astrocruise     --  http://www.astrocruise.com
>