Thomas A Davis
professor emeritus
Reged: 03/25/05
Posts: 738
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Decided to give the 2" Lumicon Deep Sky Filter a try I've
had laying around. I used a modded Canon XS at ISO1600
using a TMB80/480 at F/4.8 (TeleVue .8X reducer). 5x6m,
4x8m and 1x5m summed. Full frame rotated and reduced.
Tom
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Nils_Lars
Post Laureate
Reged: 01/04/08
Posts: 3459
Loc: Santa Cruz Mountains , CA
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Thats a super looking NA nebula , smooth and detailed with tight stars.
Great shot Tom.
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Erik
Orion Atlas Self Hypertuned (EQMOD)
Orion ED 80
Williams Optics VII reducer
Celestron 8" SCT
Orion Starshoot Autoguider
PHD guide
Canon 400D Hap Griffin Mod w/Baader filter
Astronomik clip-in LP filter and 12nm Ha
Stilleto CVF and Bahtinov mask
Tamron 75-300mm&28-80mm lenses
NexImage webcam
http://www.flickr.com/photos/31986095@N05/
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Skyshooter
member
Reged: 04/07/08
Posts: 48
Loc: S. Utah, U.S.A.
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A testament to that TMB scope. Those stars are miniscule and tight. Very, Very nice processing...
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C8 SCT, f/6.3 reducer, WO ZS66SD
Losmandy GM8, SSAG, Canon XS (stock)
Toshiba NB205 (field computer)
DSS, PS Elements 7, Bahtinov Mask
Plethora of eyepieces and lots of patience !
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s58y
Postmaster
Reged: 12/12/04
Posts: 5510
Loc: Eastern NY
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Very good shot -- the level of detail almost looks like what you get with narrowband H-alpha filters.
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Hutech 30D, SBIG ST-402 autoguider
SV80S, TV102iis
Old camera lenses: 800mm f/5.6, 180mm f/3.4
AP900, Barndoor tracker
http://www.pbase.com/s58y
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Thomas A Davis
professor emeritus
Reged: 03/25/05
Posts: 738
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Thanks. I was a bit concerned about using this filter due
to my experience with other Lumicon nebula filters I've had.
Most have had pretty badly distorted star images. This one
seems to work well. It does greatly reduce the background
brightness. To get to a 50% black level, I think it would
take about 15 minutes on the exposure time (took me 5
without the filter). It does increase the contrast quite a
bit.
Tom
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Thomas A Davis
professor emeritus
Reged: 03/25/05
Posts: 738
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Quote:
A testament to that TMB scope. Those stars are miniscule and tight. Very, Very nice processing...
The TMB80/480 is a really sweet little scope. Using the
TeleVue .8X reducer corrector with it, It is tack sharp
right to the edge of the frame. I really like this scope
for grab-and-go and imaging.
Tom
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Thomas A Davis
professor emeritus
Reged: 03/25/05
Posts: 738
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Quote:
Very good shot -- the level of detail almost looks like what you get with narrowband H-alpha filters.
The Lumicon Deep Sky filter really does block out a lot of
the sky glow. I was happy with the result. Only issue is
that the sky becomes greenish-blue with it. To get the
magenta appearance to the nebula some like is an issue, due
to the curves tool in PhotoShop pushing everything red when
you use the background to set it.
Here is the result done that way.
Tom
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Thomas A Davis
professor emeritus
Reged: 03/25/05
Posts: 738
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Quote:
the level of detail almost looks like what you get with narrowband H-alpha filters.
I went to the Lumicon website and looked at the transmission
graph for the Deep Sky filter. What I found interesting
was that the entire H-Alpha band is covered just the same
as a dedicated H-Alpha filter with a sharp cutoff between
540 and 640 nonometers. By shifting the balance to the red
channel in PhotoShop, I got this result. While not pretty,
it gives an idea how much H-Alpha is covered by this filter.
Note how much more nebulosity becomes visible.
Tom
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Thomas A Davis
professor emeritus
Reged: 03/25/05
Posts: 738
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This is processed using Gradient XTerminator with the
color balance background checked. The problem with this
filter is getting proper color balance, since the section
from 540nm to 640nm is completely blocked. This one is
about the best I can get. The HA component is very strong
on this filter (full HA spectrum pass, with a stronger HA
component that OII and H-Beta), and it has the effect of
creating a strong green-blue background. Not really sure
how to color balance with this, since using either white
stars (Maxim DL), or trying for a black background (PS CS4),
leaves something missing on either end.
Tom
Tom
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Mike Clemens
Post Laureate
Reged: 11/26/05
Posts: 4286
Loc: Wasilla, Alaska 61N
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All are nice but this last one really pops!
--------------------
historius apochromaticus
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Thomas A Davis
professor emeritus
Reged: 03/25/05
Posts: 738
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Thanks Mike. I'm trying to figure the best way to process
images with the Lumicon filter. It really does boost the
contrast, but getting color balance right is the issue. So
far, Gradient XTerminator seems to do this the best (don't
need it for gradient issues so much with this scope, but
it seems to have the best color balance function for this
filter). I'll gladly look at any other ideas out there.
Tom
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