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...
Post Reply
User avatar
tafig
The Sun?
The Sun?
Posts: 6
Joined: Mon Mar 25, 2019 2:04 pm
Location: Poland
Has thanked: 3 times
Been thanked: 1 time
Contact:

Telescope with etched mirrors

Post by tafig »

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.


User avatar
marktownley
Librarian
Librarian
Posts: 42272
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 20435 times
Been thanked: 10243 times
Contact:

Re: Telescope with etched mirrors

Post by marktownley »

Greetings Tafig! By etched do you mean the coating has been removed from the mirror?


Image
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!
User avatar
tafig
The Sun?
The Sun?
Posts: 6
Joined: Mon Mar 25, 2019 2:04 pm
Location: Poland
Has thanked: 3 times
Been thanked: 1 time
Contact:

Re: Telescope with etched mirrors

Post by tafig »

Hello! Exactly


skyhawk
Ohhhhhh My!
Ohhhhhh My!
Posts: 83
Joined: Tue Feb 26, 2019 1:14 pm

Re: Telescope with etched mirrors

Post by skyhawk »

tafig wrote: Mon Mar 25, 2019 7:11 pmHello! 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

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"
skyhawk
Ohhhhhh My!
Ohhhhhh My!
Posts: 83
Joined: Tue Feb 26, 2019 1:14 pm

Re: Telescope with etched mirrors

Post by skyhawk »

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"
User avatar
marktownley
Librarian
Librarian
Posts: 42272
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 20435 times
Been thanked: 10243 times
Contact:

Re: Telescope with etched mirrors

Post by marktownley »

I think using with a uv/ir cut filter is not a bad idea.


Image
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!
bart1805
Almost There...
Almost There...
Posts: 636
Joined: Mon Feb 06, 2017 9:04 pm
Location: The Netherlands
Been thanked: 1 time

Re: Telescope with etched mirrors

Post by bart1805 »

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.


User avatar
marktownley
Librarian
Librarian
Posts: 42272
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 20435 times
Been thanked: 10243 times
Contact:

Re: Telescope with etched mirrors

Post by marktownley »

skyhawk wrote: Thu Mar 28, 2019 3:10 pm
tafig wrote: Mon Mar 25, 2019 7:11 pmHello! 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.


Image
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!
User avatar
tafig
The Sun?
The Sun?
Posts: 6
Joined: Mon Mar 25, 2019 2:04 pm
Location: Poland
Has thanked: 3 times
Been thanked: 1 time
Contact:

Re: Telescope with etched mirrors

Post by tafig »

During the solar eclipse. O III filter in the eyepiece
Zaćmienie Słońca.jpg
Zaćmienie Słońca.jpg (167.95 KiB) Viewed 4505 times


christian viladrich
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 2150
Joined: Sun Jun 14, 2015 4:46 pm
Location: France
Has thanked: 1 time
Been thanked: 2713 times
Contact:

Re: Telescope with etched mirrors

Post by christian viladrich »

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
Co-author of "Planetary Astronomy"
http://planetary-astronomy.com/
Editor of "Solar Astronomy"
http://www.astronomiesolaire.com/
Post Reply