RE: [APML] New California Nebula

[Alen Koebel <alen_koebel@yahoo.ca>]

Thanks. 

Re the Dual III, I've never used another film scanner
before, so I have no reference by which to judge it.
After experimenting with the focus and exposure
controls, and trying out the multi-sampling (decided
I didn't need to use it), I settled on taking 16-bit
linear scans. Given I'm using Picture Window Pro 
right now, which can do everything in 48 bits, that
seemed the easiest course of action with no real
penalty (except for computer memory and processing
time). Because of this, I can't really say how
effective the rest of the DiMAGE software is for
scanning using the techniques Jerry Lodriguss
described in his S&T article. (Effectively I'm doing
much the same things in PWPro on the "raw" 16-bit
data, but after the fact.) But I can say I saw no
conclusive evidence of the flaring problem described
here with one particular older Minolta model (maybe
it's there to some degree but I missed it). And no
evidence of the streaking that is described in some
other reviews of the Dual III for "regular"
photography. 

The scanner seems to be sharp to the edges. The 
California Nebula shot I posted is of the full 35 mm
frame (downsized 1/4), with no cropping. Although it's
not very obvious at this scale (at least to my eyes),
in the full-size image there is some elongation of
stars in the corners (due I believe to coma) but they
still look reasonably sharp. And in the version prior
to smoothing, I can see the film grain plainly across
the entire image, which I think is a better test of
whether the scanner was focusing well. (Sharp stars 
are rather a test of *my* focusing at the telescope.)

-----Original Message-----
From: Chris Schur [mailto:cschur@cybertrails.com]
Sent: Thursday, April 17, 2003 8:15 AM
To: Discussion of Film Astrophotography
Subject: Re: [APML] New California Nebula


Very nice shot. How do you like your Dimage scanner?  
is it sharp to the edges?

Chris Schur

----- Original Message -----
From: Alen Koebel <alen_koebel@yahoo.ca>
To: APML <astro-photo@seds.org>
Sent: Wednesday, April 16, 2003 4:52 PM
Subject: [APML] New California Nebula


> This is my second posted image to APML. It's not
> really a "new" shot since it was actually taken last
> August (kinda hard to find this object now <g>). But
> it's a new scan of the slide (2,820 dpi, 48 bit) and
> the first time I've image-processed the scan.
>
>
http://www3.sympatico.ca/the.koebels2/Astronomy/california.htm
>
> Please critique the image. (As if I have to ask!
<g>)
> Things I know about already: One, it's not in the
> usual orientation of North up. I tried flipping it,
> but for whatever reason I preferred it this way.
> {The framing, OTOH, was the choice of my off-axis
> guider: I take whatever is reasonable to find a
> suitable guide star!) Re the processing, the
brighter
> stars are clipped and hence bloated a bit. And, I
> applied some gaussian blur in Picture Window but I
> haven't yet tried SGBNR, which I suspect would yield
> better results.
>



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