On Sep 27, 2021, at 2:34 PM, Robert Chozick via groups.io <rchozick@...> wrote:

Thanks Roland. Someone had already suggested to me that it could be a need for extension of the secondary by about half an inch. I have used the scope many times and this is the first time this is happened. I think there was a bright star nearby. The iris is close to one of the main stars in Cepheus.   

Robert 

On Sep 27, 2021, at 1:14 PM, Brian Valente <bvalente@...> wrote:



you might try extending the baffle a few inches (or experiment) and see if you can eliminate it?

I had a similar issue on my cdk20. After I isolated the cause using paper baffle extensions, my solution was to 3d print a baffle extension and attach it 

Problem gone. 

Brian

On Mon, Sep 27, 2021 at 10:55 AM Emilio J. Robau, P.E. <ejr@...> wrote:

Robert,

I have been fighting the same thing on my 12"GSO RC for years.   I have a truss system.   If you find a remedy, please let me know.  Recently I placed protostar flock on the tube portion of the scope to make it even darker, but I doubt it will help.  It seems to happen when my scope is pointed between 10 degrees and 30 or so degrees, and is less frequent when I am pointed more towards the zenith.  I think it also happens when there is a bright star nearby.

--

Brian 

Brian Valente

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