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Dob secondary mirror help

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4 replies to this topic

#1 Altair91

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Posted 15 January 2020 - 11:40 PM

Not sure if this is in the right forum, but my question pertains to a dobsonian scope. I've been in the hobby for 3 or 4 years as a casual observer and photographer, so my knowledge base is somewhat limited. I bought my nephew a 12 inch dobsonian Meade starfinder. While cleaning the secondary he not only managed to wipe away the silvering, but also dropped it leaving a rather large chip in it. Tough lesson for a 16 year old. My question is, will any Newtonian secondary work for his scope as long as it's the same size as the original? Or am I better off scouring the reaches to find another identical Meade starfinder secondary? Thanks y'all.



#2 Mark Strollo

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Posted 16 January 2020 - 12:24 AM

Size matters. It does not have to come from a Meade Starfinder. 


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#3 havasman

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Posted 16 January 2020 - 01:03 AM

A standard GSO secondary of the same size will likely be very much like what came with the scope and work fine. A 1/14th wave secondary of the same size from Antares or Astrosystems would likely be a noticeable optical upgrade.

 

For a startup scope I'd likely go with the GSO.

 

A 12" Dob is a very powerful scope.



#4 TOMDEY

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Posted 16 January 2020 - 03:19 AM

It's almost always easier to replace it with similar, rather than trying to repair it.    Tom



#5 Oberon

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Posted 16 January 2020 - 03:21 AM

And tell him never to touch the secondary again. Why was he cleaning it? In 30 years I’ve never needed to clean a secondary. Generally the surface faces down and doesn’t even collect dust.


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