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dvb
Carpal Tunnel
Reged: 06/18/05
Posts: 1922
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OK, still looking at the C11 v SN10 issue.
Someone mentioned that to get the C11 f/10 (without Hyperstar) down to the range of the SN10 f/4, the arrangements of Focal Reducers could result in vignetting.
My understanding is that the MFR-3, on its own, would yield F/6.3, and with one or more 10mm spacers, could get down to f/3.3. Am I right on that?
The Mallincam doesn't have a very big Field of View -- similar to an 8mm Plossl. So, is there really a likelihood of vignetting such a small FOV?
Clear skies,
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Skywatcher 10" f/4.7 Newt on Matilda
Skywatcher 10" f/4.7 Collapsible Dob
Meade 8" SN f/4
Celestron C8 SCT
Celestron C6 SCT
Skywatcher ED100
Skywatcher ED80
EQ6 Pro "Matilda"
AT Voyager
Skymaster 15x70
Mallincam HyperColor Plus
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richs
member
Reged: 01/21/08
Posts: 51
Loc: California, USA
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I use the mfr3 plus 2 10mm spacers almost all the time on my C11 with no vignetting. I'm more of a fill the screen guy as opposed to wide field views with the primary object being smaller as long as the image stays nice, this combination has produced very well for me. 
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RichS15" Obsession10" Meade LX200 GPS8" Celestron NexStar GPSCelestron Carbon Fiber C-11TEC 140 APODayStar .5a Ha Solar FilterCelestron CGEOrion AtlasMallinCam Hyper Color PlusSpeco 9" CRT monitorMarshall 4" LCD MonitorCelestron Sky ScoutDew Buster
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dvb
Carpal Tunnel
Reged: 06/18/05
Posts: 1922
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Thanks, Rich. Do you know what "speed" you are down to with 2 10 mm spacers? f/3.3?
--------------------
Skywatcher 10" f/4.7 Newt on Matilda
Skywatcher 10" f/4.7 Collapsible Dob
Meade 8" SN f/4
Celestron C8 SCT
Celestron C6 SCT
Skywatcher ED100
Skywatcher ED80
EQ6 Pro "Matilda"
AT Voyager
Skymaster 15x70
Mallincam HyperColor Plus
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richs
member
Reged: 01/21/08
Posts: 51
Loc: California, USA
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I've not calculated the f ratio but from past posts I would think around f3?
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RichS15" Obsession10" Meade LX200 GPS8" Celestron NexStar GPSCelestron Carbon Fiber C-11TEC 140 APODayStar .5a Ha Solar FilterCelestron CGEOrion AtlasMallinCam Hyper Color PlusSpeco 9" CRT monitorMarshall 4" LCD MonitorCelestron Sky ScoutDew Buster
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rmollise
Carpal Tunnel
Reged: 07/06/07
Posts: 1653
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Quote:
The Mallincam doesn't have a very big Field of View -- similar to an 8mm Plossl. So, is there really a likelihood of vignetting such a small FOV?
Clear skies,
Vidcam chips, Mallincam or Stellacam are far too small to make vignetting a worry. You'll need to get up to a DSLR APS size chip before the f/3.3 reducers become a problem.
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Uncle Rod
Watch for Rod's New Book:
Choosing and Using a New CAT--coming in December!
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dvb
Carpal Tunnel
Reged: 06/18/05
Posts: 1922
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Thanks, Rod!
--------------------
Skywatcher 10" f/4.7 Newt on Matilda
Skywatcher 10" f/4.7 Collapsible Dob
Meade 8" SN f/4
Celestron C8 SCT
Celestron C6 SCT
Skywatcher ED100
Skywatcher ED80
EQ6 Pro "Matilda"
AT Voyager
Skymaster 15x70
Mallincam HyperColor Plus
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