Telescope with etched mirrors

Frankenscope? Let's see it!***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
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tafig
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Telescope with etched mirrors

Post by tafig » Mon Mar 25, 2019 3:00 pm

I'm the Coordinator of the Polisch Solar Observation Section. For my observations I use a 114 x 900 telescope with etched mirrors. Such equipment transmits about 0.8 to 1.4 beams of sunlight. I'm inserting an OIII filter into the eyepiece. The question is this.
Does this filter adequately protect against infrared radiation? I have not found any answer to this and I use this equipment for visual observation of the Sun. Greetings.

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marktownley
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Re: Telescope with etched mirrors

Post by marktownley » Mon Mar 25, 2019 7:04 pm

Greetings Tafig! By etched do you mean the coating has been removed from the mirror?
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tafig
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Re: Telescope with etched mirrors

Post by tafig » Mon Mar 25, 2019 7:11 pm

Hello! Exactly

skyhawk
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Re: Telescope with etched mirrors

Post by skyhawk » Thu Mar 28, 2019 3:10 pm

tafig wrote:
Mon Mar 25, 2019 7:11 pm
Hello! Exactly
The comment Hello ! exactly sounds rather a RUDE comment and not needed

I hope I am wrong but it sounds dangerous what you are doing, I certainly would not want to be the one to use it :shock: :shock: :shock:
Just for info, if I ever come over as "blunt" or upset it is not intentional, I am AUTISTIC, I have Aspergers, and ADHD, Autism, so my apologies if I ever sound, unintentionally confrontational. Thank you

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skyhawk
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Re: Telescope with etched mirrors

Post by skyhawk » Thu Mar 28, 2019 3:13 pm

Such equipment transmits about 0.8 to 1.4 beams of sunlight

What does this mean ??????????
Just for info, if I ever come over as "blunt" or upset it is not intentional, I am AUTISTIC, I have Aspergers, and ADHD, Autism, so my apologies if I ever sound, unintentionally confrontational. Thank you

Esprit 120mm triplet refractor
Celestron Evolution Edge HD 8"
72mm Ed Skywatcher for Solar

SkyTee 2
Sky-Watcher SolarQuest
Gitzo Systematic Series 5

ASI 178MM
Daystar Quark Ha
WO Binoviewers
Many eyepieces 2"

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Re: Telescope with etched mirrors

Post by marktownley » Thu Mar 28, 2019 5:06 pm

I think using with a uv/ir cut filter is not a bad idea.
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Re: Telescope with etched mirrors

Post by bart1805 » Thu Mar 28, 2019 5:57 pm

If both mirrors are etched about 4% of 4% enters your eye. OIII normally does not block above 1000nm. I would follow Mark's suggestion.

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Re: Telescope with etched mirrors

Post by marktownley » Thu Mar 28, 2019 6:19 pm

skyhawk wrote:
Thu Mar 28, 2019 3:10 pm
tafig wrote:
Mon Mar 25, 2019 7:11 pm
Hello! Exactly
I hope I am wrong but it sounds dangerous what you are doing, I certainly would not want to be the one to use it :shock: :shock: :shock:
It's perfectly safe, there are quite a few people who have done it now. The uncoated mirror reflects a similar amount of light as a solar wedge transmits (assuming only the primary is uncoated). Therefore additional ND filtration is required to bring things down to a safe visual level, if imaging is the only consideration the more light the better as exposures will be shorter.
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http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!

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Re: Telescope with etched mirrors

Post by tafig » Thu Mar 28, 2019 7:07 pm

During the solar eclipse. O III filter in the eyepiece
Zaćmienie Słońca.jpg
Zaćmienie Słońca.jpg (167.95 KiB) Viewed 173 times

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Re: Telescope with etched mirrors

Post by christian viladrich » Thu Mar 28, 2019 7:17 pm

OIII filters are not all the same. Photographic OIII filters give more protection than visual OIII filters. Still they usually block up to 1100-1200 nm.
Here is the example of the Astronomik CCD OIII :
Image

So, as said before, it is better to associate the OIII with a neutral density filter, and if possible to an IR filter (KG3 or equivalent), in order to have blockage beyond 1100 nm. A good IR filter is the Beloptik IR filter.
Christian Viladrich
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http://www.astronomiesolaire.com/

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