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Author Topic: Welding plate as ERF?  (Read 4071 times)

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Offline JohnM

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Welding plate as ERF?
« on: 00:07:35, 06 May, 2011 »
Has anyone ever heard of this? I read someplace about a guy using one, but now can't find where it was.
Probably to get away from the high cost of something like a Baader. Would have had to be a #14 or 15 I'd think, but I can't imagine how it would work because of the optical quality of those plates. He had some photos which were pretty spectacular.

Offline Merlin66

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Re: Welding plate as ERF?
« Reply #1 on: 06:49:20, 06 May, 2011 »
That would be a good link to find.....
I wouldn't have thought for ha type work that it would be much good. As you say the optical properties would be suspect.
Never come across a similar reference.....
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline JohnM

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Re: Welding plate as ERF?
« Reply #2 on: 13:30:30, 06 May, 2011 »
Hmm, figured some one here had probably seen this.
This cam from Germany and there was a brief write up bu my German is really poor any more.
I wanted to try and send him an email and then lost track of where the article was.
I'm going to spend some time trying to find it again.
One of the problems of the internet, so much out there, but it's too east to lose track of it.

Offline Nomis Elfactem

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Re: Welding plate as ERF?
« Reply #3 on: 14:13:46, 06 May, 2011 »
There's actually quite a few suppliers of glass that would do the job. I got a quote from these guys in the summer of '09 (http://www.uqgoptics.com/) and they would do a one off round K3 glass at 80mm for £180. They would also do three for £70 each.  I didn't go ahead as they couldn't guarantee the quality of the finish which I guess is why the Baader filter costs so much.  I might still give one a go but would ideally want a spectrascope to check it worked before sticking anything of value behind it !
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline JohnM

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Re: Welding plate as ERF?
« Reply #4 on: 14:37:44, 06 May, 2011 »
I've been searching around this morning, but since I don't remember the name it's pretty hopeless.
All I remember was that it was a refractor of 250mm and had a number of Baader components at the back end.

Offline Merlin66

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Re: Welding plate as ERF?
« Reply #5 on: 15:52:38, 06 May, 2011 »
Simon,
If you want anything spectroscopy tested, just let me know.
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline Nomis Elfactem

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Re: Welding plate as ERF?
« Reply #6 on: 20:30:23, 06 May, 2011 »
Cheers Ken  :thumbup:
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline swashy

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Re: Welding plate as ERF?
« Reply #7 on: 01:04:26, 07 May, 2011 »
Three for £70 each, I may be willing to contribute to a consortium on this?
Ade

Imagine...  above us only sky!

Offline Nomis Elfactem

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Re: Welding plate as ERF?
« Reply #8 on: 11:15:38, 07 May, 2011 »
I think it needs a bit of investigation first Ade.  Looking at the transmissions graphs I'm not sure it will work as the cheaper glass lets a whole lot more bandwidth through verses the Baader D-ERF (which may also go someway to explain the price difference) so not sure it will do a good enough job.

UQG actually do a 50mm x 50mm off the shelf for £30 so I may order one and take Ken up on his offer to do a bit of testing.  I'm guessing the first test is to stick a thermometer in a focused beam to make sure it stays cool ?!

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline Merlin66

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Re: Welding plate as ERF?
« Reply #9 on: 16:17:33, 07 May, 2011 »
That KG3 glass looks like a UV-IR cut-off; combined with a good quality Red wratten #29 filter the combined curve would look very much similar to the Baader.
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline JohnM

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Re: Welding plate as ERF?
« Reply #10 on: 16:36:30, 07 May, 2011 »
So, a good UV/IR filter of correct size plus wratten #29 would perform similar to the Baader D-ERF?
Could be a way to set up for imaging only?
I found 2 names I recognized, but neither were the ones who had brought up the idea of using a welding plate.

Offline Merlin66

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Re: Welding plate as ERF?
« Reply #11 on: 17:24:10, 07 May, 2011 »
Yes, the UV-IR plus Wratten #29 is where I started a couple of years ago. Works 100% and is perfectly safe for both visual and imaging.
BTW the Daystar "ERF" is more more than a #29 filter!
The problem is getting good optical quality filters of a large enough diameter. You could have a full aperture UV-IR folloed by a subdiameter #29 or vice versa.
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline swashy

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Re: Welding plate as ERF?
« Reply #12 on: 18:12:38, 07 May, 2011 »
Interesting stuff indeed, what price does the 80mm Baader filter cost?
Ade

Imagine...  above us only sky!

Offline JohnM

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Re: Welding plate as ERF?
« Reply #13 on: 18:22:29, 07 May, 2011 »
It looks like here where I live a 70mm D-ERF would run about 340USD, no listings given for an 80mm for some reason.
To find good UV/IR and wratten filters would be expensive too in large diameters.
I have the 40mm and 60mm PST, I'd really like to mod an excellent 152mm achro I have, stopped to 127mm.
But any route I chose would be terribly expensive.

Offline Nomis Elfactem

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Re: Welding plate as ERF?
« Reply #14 on: 20:52:43, 07 May, 2011 »
A 90mm Baader D-ERF cost £355 euros (http://www.teleskop-express.de/shop/product_info.php/language/en/info/p3246_Baader-D-ERF-90mm-Energieschutzfilter-fuer-Sonnenbeobachtung.html) so depending upon exchange rate is currently £310.

UQG does colour filters too... so I'll have a look.

One problem I see is that the K3 only had 66% transmission at Ha which is a bit disappointing.  I see a test coming on.....

S.
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

 

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