Solar scope nomenclature

[Lee]

Hi all....
I'm looking at a solar scope, but am a little confused about what some of the nomenclature used to describe them means....
Can anyone offer explanations on some of these terms??
double stacked
pressure tuning
etalon
blocking filter

Any buying advice around $2k?? Would mainly be for casual visual observing, but would want to be able to image through also at times.....

TIA
Lee

[h0ughy (David)]

Lee give me a call

[frolinmod]

Originally Posted by Lee

Any buying advice around $2k?? Would mainly be for casual visual observing, but would want to be able to image through also at times.....

I'd recommend the Lunt LS60THa/B1200/PT.

[Paul Haese]

Lee and for anyone else.

Double stacked- a solar scope can be either a single stack which is around 0.7A (Angstrom). This shows detail on the surface and prominences. The detail on the surface is hard to see when you first look in but it becomes more visible as your eyes adjust to the light. If you add another module called a double stacking module this give you a more contrasted look and the view is around 0.5A. There is slight more detail visible but the surface detail is more prominent and makes for really nice viewing. It is not absolutely necessary for imaging.

Pressure tuning - is the way Lunt scopes tune the etalon to see the Ha detail. It has a really large knurled knob which you turn one way or the other and that increases the pressure in the tuning vessel.

Etalon - is the device that gets tuned to 656.28 nanometers.

Blocking filter - is a necessary component to stop the damaging radiation and is usually found after the etalon in a diagonal (made by the solar scope company; it is not a normal diagonal).

You can buy several scopes for that price range. I recommend a 60mm Lunt with double stacking for that price range. Bintel has prices listed on their site.

[John W (John Wilkinson)]

Hi, Since you are just getting into solar astronomy, you should buy a copy of the book, New Eyes on the Sun (published by Springer) - get from online shop (Amazon best price). It is useful for amateur astronomers and is reviewed in the equipment/books section of IIS. Good luck.

[asimov (John)]

Well, you won't get a DS 60mm from BINTEL for 2K..It's closer to 3K & you may as well go the BF15 making it 3.3K.

[Lee]

Thanks Dave, Paul, Johns....
Tossing up between Solarmax II 60 BF15 and Lunt 60THa B1200....
any specific pros/cons/contrasts between these??

[Poita (Peter)]

I have the Lunt 60 THa and it is very good, I have also owned the coronado and the Lunt gave better views with less banding issues and feels better made.

However, after using the pressure tuned Lunt 60 at a friend's house, spring for it, much easier to adjust to see all of the detail and better photos from it.

Also, Lunt were very good with a warranty claim I had recently.

[John W (John Wilkinson)]

I have a Solarmax II 60 mm scope and have had no problems with it. Works great visually and photographically (with DSLR). Best to stick with single stack for brighter image esp. if new to the game. Whichever scope you get Lunt or Solarmax II you will have a good scope.

[Merlin66 (Ken)]

Lee,
All Ha solar telescopes work on the same principle:
An ERF (Energy Rejection Filter) to reduce the total energy into the system - Usually at least a red filter. The better ERF's (Baader D-ERF etc) are actually broadband Ha filters which suppress most of the UV, Visible and IR wavelengths.
The Frabry-Perot etalon - a very expensive interference filter ( two pieces of 1/100 wave reflective plates very close together) which produces a "comb" of light - each "tooth" is usually 0.7A wide and about 10A apart. This "comb" covers the whole spectrum.
By slightly tilting the etalon (or in the case of the Lunt pressure tuned system, the density of the air in the filter) the mid wavelength can be "moved" +/-2A -this allows the Doppler shift to be seen/ recorded.
To isolate the Ha wavelength a blocking (BF), or sort filter is used. This has a bandwidth of around 8A and is tuned to allow only the "tooth" at Ha wavelength to get through.
The ERF/ etalon/ BF are mandatory components. You can't observe or image in solar Ha without them all being in place.
Hope this helps.

[Lee]

Another question on this one to the solar guys....

Blocking filters - the Coronado has BF5, 10 and 15.... what is the difference between these??

[Merlin66 (Ken)]

The "number" - 5 -20-15 is the size in mm of the solar disk covered....close to 1/100 the focal length.
The BF5 therefore is suitable for fl<500mm
BF10 <1000mm
and the BF15 <1500mm