cweinhei
sage
Reged: 01/14/06
Posts: 253
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I see there are two kinds of H-alpha filters: narrowband (~7nm) and broadbande (~13nm). I'm planning on buying one to use with my DSLR. Which one should I buy or do I really need both?
Which brand do you guys like?
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Orion Atlas EQ-G w/ EQMOD
8" F/4 LXD75 Schmit-Newt (Flocked)
JMI NGF-55D Focusor
Hutech Canon Rebel 350 XT (Clear filter)
DSI Pro (for guiding)
Shoestring USB Shutter Control
Shoestring Focusor Control
HNSky,PHD,DSLRFocus,WCS,Iris
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Tonk
Post Laureate
Reged: 08/19/04
Posts: 4324
Loc: Leeds, UK, 54N
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I would like to know this too ...
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Televue 85, GM-8/Gemini, Canon 40D (unmodded), Canon 450D (modded w/Astronomiks clip-ins - UV/IR, OWB)
Coronado SM60/BF10, Baader Herschel Wedge
Leeds Sky Clock Ripon Sky Clock
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Rankinstudio
sage
Reged: 04/05/08
Posts: 377
Loc: Salt Lake City, UT, Lake Powel...
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I third that, would be neat to see some examples...
Cheers
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Freddy WILLEMS
Carpal Tunnel
Reged: 11/13/05
Posts: 2523
Loc: Hawaii, Honolulu
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I had the 7nm with my unmodded D10 and was not happy with it, I sold it !
Now I have a modified D40 and want an H Alpha filter again.
The 7 nm took long exposure times before getting any results. I would try a 12nm or 13 nm again before buying a 7nm.
I'm not an expert in the H alpha field !, but I did see a lots of great results taken with DSLR's and 13 nm H Alpha filters.
Just my two pennies here.
I'll try to dig out some webpages. I saved a bunch of websites about DSLR and H Alpha, but my computer crashed and all the information was gone. I think if you google DSLR and H Alpha you're getting close.
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Freddy
Meade 14" LX200 GPS UHTC GPS on permanent pier
Celestron C 14" Peltier cooled for planetary imaging.
Meade 10" LX200 & TITAN 50:1 mount Gemini 'go to'
Meade 127 mm f/9 APO & TITAN 50:1 mount Gemini 'go to'
W/O 102 mm f/7 APO doublet
Orion 80 mm f/7 ED
DFK 21AU04.AS
ToUcam 840 II pro
Canon 10D Unmoddified
Canon 40D Hutech moddified
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Igor
super member
Reged: 04/20/06
Posts: 124
Loc: Croatia
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In my opinion the narrower the better because H-alpha line has wavelength of exactly 656.28nm, everything else is LP. Recently I bought Astronomik 12nm Ha filter because its cheaper 
Some time ago there was discussion on this subject but I could't find it.
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GSO 250/f5 dob
Skywatcher Explorer 130p @ EQ3
Baader modified 350D and bunch of old M42 lenses
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gavinm
scholastic sledgehammer
Reged: 08/26/05
Posts: 796
Loc: Auckland New Zealand
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Theoretically, deep sky objects will exhibit enough spectral line broadening that a filter that is too narrow will miss a sizeable portion of signal, so wider might be better. Fortunately there's not too much light pollution around this wavelength.
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Gavin
Mt Albert Grammar School Observatory
Auckland, New Zealand
http://www.mags.school.nz/astronomy/index.html
12" LX200R F6.8 AP
SBIG ST7-XME + CFW10
Moonlite SCT focuser w/ temp
Skywatcher Equinox ED80 Pro (ADM dovetail)
+ other stuff
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Coliwabl
scholastic sledgehammer
Reged: 01/01/05
Posts: 834
Loc: Dallas, Oregon, USA
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I've been using the Astronomik 13nm Ha filter with my Canon 20Da and have gotten fair results. I've attached a photo of the filter as well as a shot of IC434 as an example using it. Good luck!
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SkyWatcher Pro EQ-6 w/Skyscan
SkyWatcher 180mm MAK
Meade LX200 8" GPS SMT
Meade 80mm 5000 ED APO
WO 66SD + Flat-2 Focal Reducer
Orion Starshoot Autoguider
Astronomik Ha,OIII,and SII Canon cmos clips
Canon 20Da
Registax 5.0
Photoshop CS4 Extended
Images Plus 2.8
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Coliwabl
scholastic sledgehammer
Reged: 01/01/05
Posts: 834
Loc: Dallas, Oregon, USA
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Here's a shot of IC434 I took using the filter.
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SkyWatcher Pro EQ-6 w/Skyscan
SkyWatcher 180mm MAK
Meade LX200 8" GPS SMT
Meade 80mm 5000 ED APO
WO 66SD + Flat-2 Focal Reducer
Orion Starshoot Autoguider
Astronomik Ha,OIII,and SII Canon cmos clips
Canon 20Da
Registax 5.0
Photoshop CS4 Extended
Images Plus 2.8
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justabob
Carpal Tunnel
Reged: 05/05/07
Posts: 1636
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I use the 13nm clip in. There are several examples in my gallery.
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http://www.pbase.com/rkn/astro&page=all
Vixen Sphinx SXW
Meade sn6
Canon EF 200mm f/2.8L II USM Lens
Hutech 1000d
Self modded 350d
DSI PRO II
Bob
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justabob
Carpal Tunnel
Reged: 05/05/07
Posts: 1636
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Ha and rgb
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http://www.pbase.com/rkn/astro&page=all
Vixen Sphinx SXW
Meade sn6
Canon EF 200mm f/2.8L II USM Lens
Hutech 1000d
Self modded 350d
DSI PRO II
Bob
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cweinhei
sage
Reged: 01/14/06
Posts: 253
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Wow. Love the Ha+RGB shot of the horse head nebula. Ha+RGB is my primary motivation for getting one.
Why did you guys choose the clip in version vs. the 2" screw on filter? Is the 2" filter easier to change? If I recall, I think the price is about the same isn't it?
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Orion Atlas EQ-G w/ EQMOD
8" F/4 LXD75 Schmit-Newt (Flocked)
JMI NGF-55D Focusor
Hutech Canon Rebel 350 XT (Clear filter)
DSI Pro (for guiding)
Shoestring USB Shutter Control
Shoestring Focusor Control
HNSky,PHD,DSLRFocus,WCS,Iris
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Nils_Lars
Post Laureate
Reged: 01/04/08
Posts: 3260
Loc: Santa Cruz Mountains , CA
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I also went with the 13nm clip in so I could use it with lenses or scope and it is another barrier to dust getting into the camera.
I have had good results using it to enhance my RGB shots with another layer and I love having to option to shoot something when the moon is out.
I am still not sure if using it to shoot objects heavy in Ha is better exclusivly with the filter or as a combination with RGB or RGB only and making a greyscale out of the red channel.
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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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KevinUK
Vendor (DSLR-AstroMod)
Reged: 08/22/07
Posts: 709
Loc: N 51'53 W 00'25
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Another thumbsup for Astronomik clip, either 6 or 12nm forall the reasons mentioned above.
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DSLR AstroMod
DSLR filter removal and replacement packages
http://www.dslrastromod.co.uk
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s58y
Postmaster
Reged: 12/12/04
Posts: 5473
Loc: Eastern NY
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I have the 13nm Astonomik and 7nm Baader H-alpha filters. At first I tried the 13nm, but ended up with fuzzy stars or haloes, for some reason (and apparently not because of no IR blocking). Also, on nights with a bright moon, the sky background was still noticeable.
Now, I use a 7nm Baader filter. The stars are better, but still slighty fuzzy, compared to shots with a Hutech IDAS or Astronomik UHC filter. Maybe this is normal with H-alpha filters? For some reason, the haloes always seem elongated in the horizontal direction of the DSLR.
The sky background is darker with the 7nm. On his website, I believe Samir Kharusi recommends 6 or 7nm filters, if you have really severe light pollution.
One problem with the Baader filter is that the mounting ring is too wide to fit inside my old Nikon 800mm telephoto lens (rear filter slot). The astronomik and IDAS filters fit OK.
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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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cweinhei
sage
Reged: 01/14/06
Posts: 253
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Have you tried a 7nm or 13nm H-alpha filter in combination with a Hutch IDAS filter? Does that help get rid of the halos?
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Orion Atlas EQ-G w/ EQMOD
8" F/4 LXD75 Schmit-Newt (Flocked)
JMI NGF-55D Focusor
Hutech Canon Rebel 350 XT (Clear filter)
DSI Pro (for guiding)
Shoestring USB Shutter Control
Shoestring Focusor Control
HNSky,PHD,DSLRFocus,WCS,Iris
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s58y
Postmaster
Reged: 12/12/04
Posts: 5473
Loc: Eastern NY
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Quote:
Have you tried a 7nm or 13nm H-alpha filter in combination with a Hutch IDAS filter? Does that help get rid of the halos?
I never tried combining two filters to suppress haloes.
Let me show you examples of these "haloes" - maybe it's just "star bloat", and this is normally seen with H-alpha images?
Here are 3 test images, taken in 2006 at a place with light pollution readings of about 20.3 on the original SQM. They were taken with a Canon 30D at f/4.9 with a SV80S telescope + unmatched TRF2008 reducer. Mount was a G-11 and autoguiding was used. The target is NGC7000 -- North America Nebula.
These are full-frame, uncropped single subexposures of either 5 or 10 minutes. Usual dark+flat+bias calibration was done in Images Plus. Post processing with Photoshop involved extracting the red channel and replacing the blue + green channels with the red. A single gamma adjust from 1.00 to 2.20 was done using the Photoshop levels function. No other processing was done, except reduction to 750x500, conversion to 8-bits and then JPEG conversion with quality = 9.
1st shot has no filters. 5 minutes, ISO 400, new moon:
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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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s58y
Postmaster
Reged: 12/12/04
Posts: 5473
Loc: Eastern NY
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Second shot is with the Astronomik 13nm filter, 10 minutes, ISO400, 27% moon.
Note that the stars are larger than on the first image, despite being dimmer. Note: It's hard to focus an H-alpha shot, since only the red pixels respond well in the small star image used for focusing. You see a checkerboard pattern with mainly red pixels.
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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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s58y
Postmaster
Reged: 12/12/04
Posts: 5473
Loc: Eastern NY
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Third shot is with the 7nm Baader H-alpha filter. 10 minutes, ISO800, 59% moon. Note the background is actually brighter, because of the ISO800 + much brighter moon. The bloated stars are smaller than the 2nd image, but still larger than the first.
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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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s58y
Postmaster
Reged: 12/12/04
Posts: 5473
Loc: Eastern NY
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BTW, here's what a finished narrowband shot with the 7nm Baader looks like:
(note: This was taken from a darker site in 2008).
finished shot
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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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justabob
Carpal Tunnel
Reged: 05/05/07
Posts: 1636
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Interesting. What filter is on your Hutech 30d? Clear or astronomic ir cut? I ask because I noticed much more in the way of star halo effect with my self modded 350d "no filter replacement" than my new 1000dh with the mild ir cut, when using the ha filter. My 80ed also seemed to cause more bloat and halo than my meade sn6 reflector or a quality camera lens would.
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http://www.pbase.com/rkn/astro&page=all
Vixen Sphinx SXW
Meade sn6
Canon EF 200mm f/2.8L II USM Lens
Hutech 1000d
Self modded 350d
DSI PRO II
Bob
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