Re: [APML] 1805 Redo with Mike's technique

[Philip Perkins <philip@astrocruise.com>]

Thanks Roland, I really appreciate that explanation.  I had wondered
for a long time about the strange blue flaring in that shot..  It's
interesting because it came from using a standard Nikon lens on a
standard Nikon camera.  It's possible that it was caused by the use
of a Lumicon Deep Sky filter on two of the shots (although no filter was
used for the remaining four shots of the stack).  In the case of the
300mm f/2.8 lens it is a drop-in filter, so it would be strong
candidate.  If I can dig out the original scans it would be
interesting to check which ones have the blue flaring.

--Philip


> Flare
> is the used to describe extraneous light from poor baffling, shiny lens
> mount surfaces and internal reflections/ghost images caused by poor
> coatings. What you have there is classic lateral chromatic aberration
> (i.e. the blue image is slightly smaller than the red image). This means
> that the 3 colors don't quite register accross the frame. This may be
> fixable if you can extract the blue channel in Photoshop, increase its
> dimensions ever so slightly, and re-paste it back as a blue channel of
> the proper dimensions to fit the red channel. I notice that the red is
> also slightly different than the green. For a more perfect result, you
> might need to match the size of red to green and blue to green. 
>
> Roland Christen

Philip Perkins - philip@astrocruise.com

Wiltshire UK & Luberon France

Astrocruise -
http://www.astrocruise.com