a question about CaK Filters

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thedoci
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a question about CaK Filters

Post by thedoci »

Well i have several questions to which i have not found a straight answer.

- Could the LS152's CaK Hershel wedge be used on some other telescope with smiler specifications? I ask this, based on the CaK module looking like a standard Lunt Hershel wedge with a CaK filter on top. If this is literally all it is then i could theoretically use it on some other 6" Refreactor. If there are some corrective optics, then could a normal Lunt Hershel wedge be modded with the CaK filter from the LS152's CaK module?

- Could a (probably modified) Lunt CaK filter (straight type) be used with, say a C14 with Baader Photographic solar Film on the aperture? If not the lunt, then could the DayStar CaK / CaII-H etalon be used? And no, i do not own a C14, but i have access to one in a observatory, and yes i already spoke with the observatory director about using the C14 for solar imaging. He actually liked the idea, and wanted to see how the C14 Performed.

And yes i will be starting out with a Coronado PST, and this is just some questions for the not so distant future.


Gear: GSO 150/750mm Newton, Old 68/1200mm Refractor, Baader Solar Film, Baader Continuum Filter, Baader L filter, Baader Q-turret Barlow, Sony A350, Sony HX-20, Point Grey Scorpion 13FFM, Point Grey Grasshopper GRAS-03S3M-C, Grundig FA85 I (CCTV camera that im having a play with)

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Re: a question about CaK Filters

Post by grimble_cornet »

Once again, from my limited recent experiences....

I bought a Lunt 60 scope plus a CaK1200 filter (which is a superb bit of kit) with the intention of using it on my 80mm and 120mm Equinox refractors.
The bad news - both Equinox scopes have a step in their focus tube which prevents the long tube of the CaK1200 going in more than half way so they won't reach focus. :cry:
Be sure to check that any scope you hope to use does not have the same problem. I recently bought a relatively cheap Tal 100RS which works very well with the CaK1200. :P

The 152 CaK unit is different - I know that Pedro recently started to use one of these so he might chip in with his much greater knowledge :oops:

The good news - because of the nature of the short wavelength of CaK, a simple refractor often works better than more expensive/complex ED or triplet scopes AND it is amazing how much detail can be resolved by the small Lunt 60.
If you look at some of Mark Townley's post you will find that we have discussed this in some depth recently but this will give you some idea of what the 60mm can do in the hands of a relative novice:
Lunt 60 CaK Grasshopper 3 2014 1608 0840 ut coloured.jpg
Lunt 60 CaK Grasshopper 3 x2_5 2014 1608 0850 ut coloured.jpg
Good luck,

Mike


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Mike Garbett

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Re: a question about CaK Filters

Post by swisswalter »

Hi Lukas

I second what Mike said. I do not see a reason why we could not use the LUNT152 CaK module on an other scope. You need the right FL , an additional ERF and an adapter.

A mirror type system works with the KLUNT filter, we (Mark T.) have just done the proof of principle on a decoated 8" mirror on sunday. A baaderfoil up front of the C14 will cut most probably too much light.

The Daystar CaK Systems need longer focal lenght (f/20) and then they work, in combination with a baader foil, you will not have enough light.


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thedoci
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Re: a question about CaK Filters

Post by thedoci »

Well in terms of finding a near identical Telescope, i managed to find a scope with the exact same Specs as the LS152. Its called the TS Individual large field refractor 152/900mm. It even looks almost like the LS152.

Also what kind of ERF dose the LS152 use for the CaK filter, i assumed it was using the Hershel wedge as the ERF, as to my knowledge the standard ERF's don't transmit the CaK wavelength.


Gear: GSO 150/750mm Newton, Old 68/1200mm Refractor, Baader Solar Film, Baader Continuum Filter, Baader L filter, Baader Q-turret Barlow, Sony A350, Sony HX-20, Point Grey Scorpion 13FFM, Point Grey Grasshopper GRAS-03S3M-C, Grundig FA85 I (CCTV camera that im having a play with)

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Re: a question about CaK Filters

Post by Valery »

thedoci wrote:Well in terms of finding a near identical Telescope, i managed to find a scope with the exact same Specs as the LS152. Its called the TS Individual large field refractor 152/900mm. It even looks almost like the LS152.

Also what kind of ERF dose the LS152 use for the CaK filter, i assumed it was using the Hershel wedge as the ERF, as to my knowledge the standard ERF's don't transmit the CaK wavelength.
Every fast refractor has a huge spherical aberration (SA) at 393nm wave length ( CaK). If you like to have clean sharp images at this wave length at high resolution, then you need a SAFIX - the device for SA canceling. Otherwise you will be limited to only Full Disk (FD) imaging or may be middle scale imaging with huge aperture stop of your telescope. But in this case you don't really need such a telescope. 80mm F/11 will be enough.

6" mm telescope at 393nm (CaK) will deliver the angular resolution same as a 10" telescope at 656nm (Ha) and the details just amazing.


Valery.


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