[APML] M51 & M97

[Matt BenDaniel <matt@starmatt.com>]

Brian,

Great shots! Comments below...

>-----Original Message-----
>From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
>Behalf Of Brian Lula
>Sent: Sunday, April 28, 2002 9:26 PM
>To: astro-photo@seds.org
>Subject: [APML] M51 & M97
>
>
>Hi,
>
>Tony's M51 was an inspiration to all imagers to go deeper than usual to
>extract as much
>info as possible in the image field. I was intrigued to see how deep I could
>go in my
>moderately light polluted area near Worcester MA. Limiting magnitude is
>4.9 - 5.0 at my
>site in the area of M51 reducing to about 3rd mag  25 degrees above the
>horizon in the
>south. Seeing was about 6 the night I took these images with transparency
>about 8. I took

The M51 shot is very impressive, but considering the sky conditions, it is 
amazing.

>the images just after Tony posted his luminance image I but it took me a
>long time to get
>my M51 image to a half decent point and post today.
>
>M51 and M97 are both (L)LRGB's with 90:24:24:30 minute respective total
>exposures using
>10 minute individual exposures for the L frame in 1x1 bin mode and 5 minute
>individual
>exposures in the RGB frames in 2x2 bin mode. The L and RGB's were combined
>in MAXIM
>using average and bicubic resampling for each set.The luminance for M51 was
>also slightly
>DDP'ed ( custom setting of 20) and 0.8 gamma stretched before importing into
>PS6for
>further curve work. Both images were (L)LRGB' in Photoshop using the double
>layering
>techniques that Rob Gendler prepared on his website with considerable
>lassoing,
>feathering, curve adjustment and star shaping ( thanks Matt!) techniques
>used to enhance
>local features.
>
>M51 is almost a full field image using a Finger Lakes IMG6303E CCD (2K x 3K
>x 9 micron
>pixels) camera on my 20" homemade F/4 Newt while M97 is a subframe.

That's a nice set of equipment.


>I tried the "Mike Cook" technique on both images today to reduce the "fat"
>stars using the
>radius at 1 and adjusting the fade to somepoint between 40% and 70% but
>noted it also
>eroded finer detail in the spiral arms and eliminated faint stars. Bloated
>stars are one of my
>biggest challenges in imaging and I was hoping for a silver bullet fix. Are
>these effects
>expected or did I do something wrong in the execution?

If the seeing spreads the stars out on the chip, then you have to use 
"artificial" means to make them smaller. Try selecting the stars and using 
minimum with no fade.


>You will note some astigmatic effects in the stars images on M51 from the
>cooldown
>problems with the 20" pyrex Galaxy primary as it chased thermal equilibrium
>all through
>that particular night.
>
>The new images are at:
>
>http://www.heavensgloryobservatory.com/Color_Jpegs/m51FRGB04-6303Eweb.jpg
>
>and
>
>http://www.heavensgloryobservatory.com/Color_Jpegs/m97FRGB01-6303Eweb.jpg
>
>M97 shows additional faint galaxies through the nebula in addition to the 6
>stars that form 2
>distinct triangles.
>
>I had considerable problems to remove the magenta from the HII regions in
>M51's arms.
>Any ideas how to accentuate these with more "accurate" color?

I think they are great just the way they are. In fact I think the color 
overall in both images is exemplary. However, you can do anything you want 
to the HII regions by selecting them manually, feathering, then applying a 
curves layer.
--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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