Problem with reflections when I use barlow lens with my Coronado 90

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shadowchaser
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Problem with reflections when I use barlow lens with my Coronado 90

Post by shadowchaser »

Hi everyone!!!
I recently changed my Coronado Solarmax II 60mm for a Coronado Solarmax II 90mm BF15. When I capture images with my ASI 290MM placed directly on the diagonal, I have no problems. But when I use a barlow lens or an extender, a reflection appears and I cannot remove it.
What can cause this problem? I tested with a Barlox Cemax 2X, with a 2.5X Powermate and with a Explore Scientific 3X. With these same accessories and my Solarmax 60 I had no problems.
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marktownley
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Re: Problem with reflections when I use barlow lens with my Coronado 90

Post by marktownley »

Is the inside of the nosepiece bare metal on the bf15 with the 90?


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shadowchaser
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Re: Problem with reflections when I use barlow lens with my Coronado 90

Post by shadowchaser »

marktownley wrote: Thu Aug 22, 2019 6:30 am Is the inside of the nosepiece bare metal on the bf15 with the 90?
The inside of the nosepiece is black painted metal.
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marktownley
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Re: Problem with reflections when I use barlow lens with my Coronado 90

Post by marktownley »

What about the other end of the diagonal?


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Re: Problem with reflections when I use barlow lens with my Coronado 90

Post by shadowchaser »

marktownley wrote: Thu Aug 22, 2019 2:59 pm What about the other end of the diagonal?
It is also painted black
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marktownley
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Re: Problem with reflections when I use barlow lens with my Coronado 90

Post by marktownley »

It's a reflection from somewhere, just from the shape of it and that your imaging off the edge of the sun. My suspicions would be somewhere higher up the OTA then from the blocker...


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Re: Problem with reflections when I use barlow lens with my Coronado 90

Post by pedro »

Try using a Halpha filter (e.g. Baader 35nm or 7nm) in the nose piece of the camera. It worked for me


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Re: Problem with reflections when I use barlow lens with my Coronado 90

Post by marktownley »

Does your reflection come off the top and bottom of the sun? I get it (with my sm90) with all but 2 of my barlows.


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