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Reply With QuoteYou use a focal reducer to get below 6.3?
I'm surprised you don't get serious vignetting as well
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Thread: Secondary mirror in image
- 06-09-2012, 03:07 AM #1
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Secondary mirror in image
Hello
I have an Meade LX200 classic F6.3 253mm . My problem is whenever I attempt to use a focal reducer I cannot obtain proper focus without a shadow from the secondary mirror showing up in the image. This happens weather I use a DSI , modified web cam or digital camera attached.
Any suggestions will be greatly appreciated.
Thanks
Tom
- 06-09-2012, 06:32 AM #2
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Meade LX90 ACF 8" Canon 450D (Rebel XSi) 18-55 and 75-300 lenses
4000 lens kit .Antares 6.3 focal reducer. Meade Wedge. Orion deluxe off axis guider. Orion Starshoot Autoguider.
230mm Concrete/plastic/steel pier
10ftx10ft shed that passes as an observatory
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tom1n (06-17-2012)
- 06-09-2012, 06:58 PM #3
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I agree with Jennifer -- you already have a "fast" SCT telescope.
Clear skies!ETX 125PE, Stellarvue 80mm BV & Televue TelePod tripod, LX90 8" LNT, 10x50, 15x70mm binoculars, Stellarvue binoviewers, solar filters for all three telescopes. Ham radio call sign - W1XWX
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tom1n (06-17-2012)
- 06-17-2012, 09:58 PM #4
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Re: Secondary mirror in image
Thank you Jennifer and Joe. I suspected this was my problem. I also get the "shadow" in an image when I use a 25mm on my Fuji S700.
I am thinking about going to a DSLR for imaging. Would using prime focus help with this matter?
Thanks
tom
- 06-17-2012, 10:32 PM #5
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Re: Secondary mirror in image
Not really - the problem is that the cone of the focal plane is too small for the sensor.
Meade LX90 ACF 8" Canon 450D (Rebel XSi) 18-55 and 75-300 lenses
4000 lens kit .Antares 6.3 focal reducer. Meade Wedge. Orion deluxe off axis guider. Orion Starshoot Autoguider.
230mm Concrete/plastic/steel pier
10ftx10ft shed that passes as an observatory
Editor of Event Horizon Ezine (Southern Astronomical Society's newsletter)
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tom1n (06-17-2012)
- 06-24-2012, 03:08 PM #6
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Re: Secondary mirror in image
Hello again
One quick question . Would I have a problem using a DSLR set up at prime focus on my F6.3 scope? No focal reducers.
Not a lot of info out there on this subject. any information or references will be greatly appreciated.
Thanks again
Tom
- 06-24-2012, 11:59 PM #7
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Re: Secondary mirror in image
Depends onthe DSLR - there's several sensor sizes - 1.6 crop (23mm diag) will probably be fine for most work - it'll have some vignetting, but not too much and it will be 'negotiable' with a graphics prog -
A full frame (35mm diagonal) will give you more severe vignetting and you'll probably have to crop the result back to get a decent pic.Meade LX90 ACF 8" Canon 450D (Rebel XSi) 18-55 and 75-300 lenses
4000 lens kit .Antares 6.3 focal reducer. Meade Wedge. Orion deluxe off axis guider. Orion Starshoot Autoguider.
230mm Concrete/plastic/steel pier
10ftx10ft shed that passes as an observatory
Editor of Event Horizon Ezine (Southern Astronomical Society's newsletter)
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tom1n (06-25-2012)
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