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Old 14-03-2013, 08:03 PM
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John K
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Baader Multi Purpose Coma Corrector

Hi guys,

I have a 12.5" f/5 newtonian and Canon DSLR for my imaging set up and considering getting a Coma Corrector to improve the level of pinpoint stars that I am getting with my set up.

Although I have not yet fully nailed my guiding at the focal lengths I am shooting, and the OMI mirror that I have is second to none, I am wanting to get sharper stars across my images with my set up.

I am not really that interested in using the coma corrector for visual stuff as I hardly do visual stuff these says but if I can do this with my 32 mm Televue Plossls or other eyepieces in the future it could be good but not a necessity.

Have plenty of back focus with my set up.

Just wondering on the experiences that others have had with the Baader or equivelant coma corrector which looks like great value for money (around $200 US) and the benefits I am likely to see in terms of star sharpness improvement from the set up I am using.

Also, do coma correctors assist when guiding off axis?

Thanks in advance and clear skies.

John K.
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Old 14-03-2013, 08:10 PM
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multiweb (Marc)
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Hi John, a MPCC wil do a world of difference to the field of your newtonian. Because the corner stars will be sharper and rounder they will be easier to pick up in the OAG prism. You can't go wrong with a Baader MPCC. I've had mine for years and just bought the mark III. Highly recommended.
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Old 16-03-2013, 04:10 PM
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alistairsam
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Hi John,
Yep, I have the mpcc and it works really well on my 8 and 10inch F4's
This was taken with a mark2 mpcc at 58mm distance which is not the correct spacing, but it has still corrected it across
Minor elongation is more due to other issues not coma
http://www.astrobin.com/full/24613/?mod=none

I just sold the mark2 and got the mark3 as it has 44mm aperture compared to 38mm of the mark2
Would definitely recommend it for imaging

As for guiding without a cc, I have done a 20min sub with a TS oag, lodestar and a 10inch F4 without a cc, and it came out perfect, although the stars in the guidecam were eagles, not seagulls due to the coma of the F4 without the cc. So using one would only aid not deter as the oag uses the edge of the field where coma is more pronounced.
most guiding software would work fine even if they're not round as they measure the pixel values of a certain area to get the centroid.

Cheers
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