Michael Morris
Member
Reged: 01/05/05
Posts: 1518
Loc: Worcestershire, UK
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I'm wondering how people image coloured double stars?
I can see three viable methods; all with disadvantages:
Webcam - sensitivity too low
CCD - too affected by poor seeing at high magnification
Film - too affected by poor seeing at high magnification
Drawing - too subjective.
What works best for you?
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Michael Morris
8" LX200 classic with piggy-backed Orion 80ED and Revelation 66mm Apo
Skywatcher HEQ5 Pro (portable mount for Orion 80ED and Revelation 66mm Apo)
Observatory Almira Observatory Website
Co-author of NightCal Astronomical Observing Calendar Software http://www.nightcal.co.uk
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novbabies
Postmaster
Reged: 06/05/05
Posts: 15678
Loc: Northern Georgia!
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Low tech me, I snap with a digital camera. Albireo works fine, Later this year, I'll see how Almach works. 24 Com seemed OK too.
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Good Seeing!
Mark
Orion 12" XTi f/4.9
VERY old Edmund 6" f/8 reflector
Assorted binoculars
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sdbodin
super member
Reged: 02/04/07
Posts: 131
Loc: Eastern Washington State
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Color video camera. The Malincams will work, but pricey. I use a color starlight camera from Mintron, sold by Polaris in Atlanta for $250 as a DX8263SL model. But I think they upgraded to a DX9263SL model number.
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Steve
Meade 16 LX200 GPS UHTC
Meade 4 107D SCT
AstroTech AT80LE
Orion Express 80
Coulter optics 17.5 DOB
Orange tube dual motor C8
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RLTYS
Post Laureate
Reged: 12/18/04
Posts: 4267
Loc: New York (Long Island)
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Michael
I'm "Old School" drawing. I feel visual is more accurate for observing color on most doubles.
Clear Skies.
Rich (RLTYS)
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10" F4.8 Refl.
4" F5 Refr. (Genesis)
3" F4 Celestron FirstScope
50mm F12 Refr. (Tasco #6TE-5)
12x63 and 10x50 Binoculars.
"I want to do more then just look."
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Michael Morris
Member
Reged: 01/05/05
Posts: 1518
Loc: Worcestershire, UK
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Quote:
Color video camera. The Malincams will work, but pricey. I use a color starlight camera from Mintron, sold by Polaris in Atlanta for $250 as a DX8263SL model. But I think they upgraded to a DX9263SL model number.
Has anyone tried one of the cameras produced by DMK for imaging doubles?
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Michael Morris
8" LX200 classic with piggy-backed Orion 80ED and Revelation 66mm Apo
Skywatcher HEQ5 Pro (portable mount for Orion 80ED and Revelation 66mm Apo)
Observatory Almira Observatory Website
Co-author of NightCal Astronomical Observing Calendar Software http://www.nightcal.co.uk
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Dennis_Oz
sage
Reged: 08/20/06
Posts: 335
Loc: Brisbane, Australia
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Quote:
Quote:
Color video camera. The Malincams will work, but pricey. I use a color starlight camera from Mintron, sold by Polaris in Atlanta for $250 as a DX8263SL model. But I think they upgraded to a DX9263SL model number.
Has anyone tried one of the cameras produced by DMK for imaging doubles?
Here are some examples taken with an Imaging Source DBK 21AF04. Hopefully the http links will survive the “copy & paste” and will not wrap!
Antares, Grafias, Sabik & Tau Oph
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/1703789
Xi 1 Lup, Eta Lup, Graffias, HR 6426 Sco
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/1698885
Zeta 1 Aqr, Gamma PsA, Eta PsA & 53 Aqr
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/1670661
HR 6780 Sgr, 36 Oph, 94 Aqr & HR 6106 Sco
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/1670657
41 Aqr, V915 Sco, Omicron Oph & Beta PsA
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/1668771
Cheers
Dennis
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Michael Morris
Member
Reged: 01/05/05
Posts: 1518
Loc: Worcestershire, UK
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Dennis
Fantastic shots. Would I be correct in assuming that you are using a filter wheel and RGB filter set?
What sort of frame rates are you using?
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Michael Morris
8" LX200 classic with piggy-backed Orion 80ED and Revelation 66mm Apo
Skywatcher HEQ5 Pro (portable mount for Orion 80ED and Revelation 66mm Apo)
Observatory Almira Observatory Website
Co-author of NightCal Astronomical Observing Calendar Software http://www.nightcal.co.uk
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Dennis_Oz
sage
Reged: 08/20/06
Posts: 335
Loc: Brisbane, Australia
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Hi Michael
I'm using the DBK which is the colour version of the DMK, with the Bayer matrix.
DMK = Mono.
DFK = Colour with built in IR non-removable filter (not recommended for astronomy).
DBK = Colour with no IR filter (user fits their own e.g. Baader IR/UV cut filter).
From memory, stars down to Mag 3 or 4 can be imaged at 30fps (max rate for DBK) and 1/30 sec exposure, Gain set to between 400 and 800, Gamma = 10 (slider hard left).
To get down to Mag 7 and if you are lucky, Mag 8, I’m shooting at 5fps, 1/9 sec exp, Gain between 900 and 1000 (max=1023) and Gamma at 16 or 18 (max=22).
The jet stream winds of 150mph+ have been parked over Brisbane for the last 3 to 4 months, so the seeing has been quite poor, around 3 to 5/10, resulting in only between 3 and 150 frames being usable from most of the AVI’s of 1600 frames.
Cheers
Dennis
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sdbodin
super member
Reged: 02/04/07
Posts: 131
Loc: Eastern Washington State
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Quote:
To get down to Mag 7 and if you are lucky, Mag 8, I’m shooting at 5fps, 1/9 sec exp, Gain between 900 and 1000 (max=1023) and Gamma at 16 or 18 (max=22).
Dennis, I have been looking at these firewire cams too, maybe as a replacement for my video setup. BUT, just 3-4 mag at 30fps?? WOW really slow. Maybe I will reconsider. I'm getting to 13th mag in the bigdog at 30 fps f20, and an easy 11 in my C8. Goes to 18th at 2 sec integration.
Bright stars, like Porrima, 1/250sec with the gain at zero at f20.
Jet stream a problem with imaging here too!!
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Steve
Meade 16 LX200 GPS UHTC
Meade 4 107D SCT
AstroTech AT80LE
Orion Express 80
Coulter optics 17.5 DOB
Orange tube dual motor C8
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Dennis_Oz
sage
Reged: 08/20/06
Posts: 335
Loc: Brisbane, Australia
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Hi Steve
13th mag! Wow - that is awesome. With the 180mm F12 Mewlon and a Vixen x2 Barlow (F24 efl), my limit is around 7th to 8th mag and that is really pushing it. Even if I plugged in the more sensitive mono DMK to replace the colour DBK, I would still be struggling at Mag 8.
At mag 6 and less, with the DBK, I need to drop the frame rate to 15 or 7.5 fps, the exposure to 1/15 and sometimes 1/9 second, with the Gain and Gamma almost maxed out. With these settings, the image is quite grainy (noisy) and the slow speeds smear the stars into blobs.
Cheers
Dennis
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sdbodin
super member
Reged: 02/04/07
Posts: 131
Loc: Eastern Washington State
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Quote:
At mag 6 and less, with the DBK, I need to drop the frame rate to 15 or 7.5 fps, the exposure to 1/15 and sometimes 1/9 second, with the Gain and Gamma almost maxed out. With these settings, the image is quite grainy (noisy) and the slow speeds smear the stars into blobs.
Dennis,
That is my concern. My setup, with the hi-sensitive video cam, allows freezing of the seeing. On my typical 4-5/10 seeing I can get 20-30 good images out of 200-300 video frames. These stack into a fine image that can be measured. One minor plus is that no computer is needed for capture, only a VCR. Nice for field work as a camcorder will do the job. Attached my closest to date:
Clear skies
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Steve
Meade 16 LX200 GPS UHTC
Meade 4 107D SCT
AstroTech AT80LE
Orion Express 80
Coulter optics 17.5 DOB
Orange tube dual motor C8
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Dennis_Oz
sage
Reged: 08/20/06
Posts: 335
Loc: Brisbane, Australia
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Hi Steve
That is a very impressive split at 0.35”. Hmm…maybe time for me to move up to a larger aperture ‘scope! LOL.
Undoubtedly your Meade 16 inch with a DMK or DBK will allow you to image much fainter doubles that I have managed, although you will need a Firewire capable Notebook computer. I also use an external 300Gig hard drive as I typically capture around 50G to 100G of AVI’s.
Sometimes I ache for the relaxed simplicity of visual observing!
Cheers
Dennis
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sdbodin
super member
Reged: 02/04/07
Posts: 131
Loc: Eastern Washington State
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Quote:
Sometimes I ache for the relaxed simplicity of visual observing
Yes, but I do observe visually; not by contorting my head to an eyepiece, but by sitting back and watching my TV set adjusting the color and contrast to what works for the seeing. Even inside my house if it is too cold outside in the winter.
It is the new eyepiece for the 21st century.
Clear skies
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Steve
Meade 16 LX200 GPS UHTC
Meade 4 107D SCT
AstroTech AT80LE
Orion Express 80
Coulter optics 17.5 DOB
Orange tube dual motor C8
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lunator
sage
Reged: 01/08/05
Posts: 231
Loc: London
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Mike
I used a £100 compact digital camera held on an orion Steadypix.
It can get down to 9th mag and split down to 1"
Cheers
Ian
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jgraham
Postmaster
Reged: 12/02/04
Posts: 11575
Loc: Dayton, Ohio
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I had pretty good luck using a Meade LPI; sharp images and good colour, though you're limited to fairly bright doubles (down to about magnitude 10ish). I'll be trying my DSI for imaging doubles when I get a chance later this fall.
Although I enjoy imaging, double star observing is one of those areas I found visual observing to be much more rewarding. The subtle colour and contrast are difficult to capture and close doubles that push the edge of resolution are very, very difficult to image well.
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-John
The best advice on imaging I've ever been given... don't forget to look! 
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sdbodin
super member
Reged: 02/04/07
Posts: 131
Loc: Eastern Washington State
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Quote:
close doubles that push the edge of resolution are very, very difficult to image well.
Well, I have found that doubles at and below the limit are actually easier when imaged and processed. Sometimes they do not present themself in realtime, due to the seeing, but post processing will split the pair. This extends my double observing to those cloudy and rainy days, as I can review the videotape and capture to a computer.
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Steve
Meade 16 LX200 GPS UHTC
Meade 4 107D SCT
AstroTech AT80LE
Orion Express 80
Coulter optics 17.5 DOB
Orange tube dual motor C8
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jgraham
Postmaster
Reged: 12/02/04
Posts: 11575
Loc: Dayton, Ohio
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Steve; hmm, you could be right, I'll have to add this to my to-do list. I think some of the problems I was having was either with doubles with large differences in brightness, where the primary overwhelms the companion, or working too hard trying to take a pretty picture with background and surrounding stars. I bet if I concentrated just on the target double I'd do better.
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-John
The best advice on imaging I've ever been given... don't forget to look!
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