Re: [APML] OT (sort of) Collection of widefield images from Pentaxmediumformat lens/ccd camera

[George Anderson <tillerman1@videotron.ca>]

Hi Richard

The images are great (as usual).
What is the website for the Schuller (sp) filters that you are using?

George Anderson
Montreal Canada

Clear skies and good health

> Richard Crisp wrote:
> 
> I assembled a collection of widefield images I have taken over the
> past few months using Pentax medium format lenses of various focal
> lengths (90mm, 150mm and 200mm) with slight variations in the system
> configuration. All but one of them were shot using my ST10XME camera.
> 
> The first configuration tried used a separate guide scope and guide
> camera mounted on a Losmandy side by side dovetail plate arrangement.
> I used an AP80/900mm guidescope which is longish and because of that
> there was noticeable differential flexure in that system that
> manifested itself in elongated stars in the corners.
> 
> the next configuration tested was the same setup but with self
> guiding used via the ST10XME camera. So long as the camera is self
> guided that is a potentially workable solution but I found with
> Halpha and other emission line filters that the attenuation of the
> guide star was so great that sometimes guidestar integrations of 15
> to 20 seconds was needed.
> 
> at a short focal length that is OK except for the time lost in
> reacquiring the guidestar after image download and aiming dithering.
> It usually takes 4 to 8 cycles of guiding to reacquire good tracking
> and that was taking several minutes in some cases. Still I managed to
> take
> a few nice images with that arrangement, one of which was selected as
> an APOD
> on Feb 14th of this year.
> 
> the third configuration tried was using a custom made frame that
> permits a solid mounting of the guidescope and will also allow the
> imaging camera to be rotated to any angle from horizontal to
> vertical. This gave the functionality I needed to use a separate
> guider without introducing differential flexure and also let me
> optimally frame my object by rotating the camera to an optimized
> angle. One of the first targets taking advantage of this camera angle
> adjustment was the Antares/Rho Ophiuchus area
> 
> I arranged the images in order of most recent first (they are the
> better ones) to oldest last.
> 
> http://www.narrowbandimaging.com/widefield_page.htm
> 
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