Coronado diagonal mirror issue

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Carbon60
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Coronado diagonal mirror issue

Post by Carbon60 »

I thought I'd share this with you.

I'm a bit OCD with regularly cleaning my camera sensors and lenses. This morning I disassembled my Coronado BF15 diagonal (one used on my Lunt 60) and was shocked to see the state of the mirror. I hadn't seen this before, although I must admit this particular piece of kit hadn't been inspected for at least 12 months.
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On close inspection the issue is on the rear face of the mirror (being visible through the glass). I'm assuming that the mirror works by reflecting off the front face, which is clean, but if so why isn't the mirror metallised on the front face? Anyhow, my concern is that if the mirror is reflecting off the back face (through the glass) then I've got a problem.

I'll be writing to Mead Instruments (Coronado), but wanted some thoughts from anyone else who knows about this sort of thing. I have another Coronado diagonal body with a better mirror, but one of the threaded parts is of a larger diameter to the one shown here and I can't use it (interestingly one body has Coronado written in white and the other in black). I could swap the mirrors and I might end up doing so if this is worth the risk.

I'm hoping it is nothing to worry about (I'm optimistic that it isn't), but wanted to bring it to anyone's attention who owns a Coronado diagonal.

Stu.


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Re: Coronado diagonal mirror issue

Post by rsfoto »

Hi Stuart,

That does not look right to me. I have a dust collecting BF15 and will take a look at the mirror. First I need to open it. Both round parts look like they are welded into the triangle.


regards Rainer

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Re: Coronado diagonal mirror issue

Post by rsfoto »

Hi Stuart,

I am back after opening the shiskebab. Your mirror is more or less dead ...

Look how mine look like.

You can get a new one free of charge. As far I know they have lifetime warranty ... OK, it will take a few months until youget a new one :lol:

:mrgreen:
SM40_BF15_Mirror_01.jpg
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regards Rainer

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Re: Coronado diagonal mirror issue

Post by Carbon60 »

Thank you for taking the trouble to take a look at your mirror, Rainer. I really appreciate it.

Mead UK don’t really want to know (just importers/sellers) and have passed me on to Mead in the US suggesting I might need to send the whole assembly back to the US to be refurbished. Clearly I won’t be doing that.

I’ll write to Mead US and see if they will send me a replacement mirror. Wish me luck.

Stu.


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Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
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Re: Coronado diagonal mirror issue

Post by rsfoto »

Carbon60 wrote: Fri Feb 11, 2022 7:12 pm Thank you for taking the trouble to take a look at your mirror, Rainer. I really appreciate it.

Mead UK don’t really want to know (just importers/sellers) and have passed me on to Mead in the US suggesting I might need to send the whole assembly back to the US to be refurbished. Clearly I won’t be doing that.

I’ll write to Mead US and see if they will send me a replacement mirror. Wish me luck.

Stu.
You are welcome


regards Rainer

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North 22° West 101°
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Re: Coronado diagonal mirror issue

Post by Highbury Mark »

[quote=Carbon60 post_id=322764 time=1644606752 user_id

Mead UK don’t really want to know (just importers/sellers) and have passed me on to Mead in the US suggesting I might need to send the whole assembly back to the US to be refurbished. Clearly I won’t be doing that.

[/quote]

:lol: :lol:


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Re: Coronado diagonal mirror issue

Post by Highbury Mark »

I have seen this with other Coronado blocking filters Stu so would hope there was some Meade representative (in Europe at least?) who could send you a new mirror.


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Re: Coronado diagonal mirror issue

Post by Carbon60 »

The plot thickens..... [email protected] has automatically rejected my email (twice), so I'm not sure what's going on there. Back to Meade UK for an answer.

Stu.


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Re: Coronado diagonal mirror issue

Post by marktownley »

Will your mirror clean up like Rainers looks Stu?


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Re: Coronado diagonal mirror issue

Post by Carbon60 »

marktownley wrote: Sun Feb 13, 2022 6:54 am Will your mirror clean up like Rainers looks Stu?
Hi Mark,
Unfortunately it is on the rear face of the mirror as seen through the thick front glass. Had it been on the front surface I might have had a chance.
I'm assuming that light from the objective passes through the glass and reflects off the rear (in my case, mottled) reflective surface, but it could be the case that light reflects off the front (glass) surface in which case the condition of the rear face is not so important.

I only opened the diagonal up to inspect the mirror because my Ha images somehow lacked the sharpness I'd expected to see. At first I was putting it down to the time of year, seeing and general weather conditions, but now I'm not so sure.

Anyhow, I have replaced my mirror assembly using a spare one from another BF15. This is in perfect condition, so when we see the Sun again I'll give it a run and see if things have improved.

Stu.


H-alpha, WL and Ca II K imaging kit for various image scales.
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
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Re: Coronado diagonal mirror issue

Post by marktownley »

Have you removed the mirror from the black plastic back piece?


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Re: Coronado diagonal mirror issue

Post by Carbon60 »

marktownley wrote: Sun Feb 13, 2022 8:04 am Have you removed the mirror from the black plastic back piece?
No, not yet. I was holding out in case I needed to send this piece off in exchange for a replacement. I’ll see how I get on with Meade and then investigate the issue further if this becomes a truly redundant part.

Thanks for the suggestion though.

Stu.


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Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
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Re: Coronado diagonal mirror issue

Post by marktownley »

Ha ha ha! I'm taking things apart to quickly here :lol:


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