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The Baader 2" safety cool Herschel Prism

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#1 Jethro7

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Posted 03 March 2021 - 12:59 AM

Hello Cners,

I am not new to the hobby, but will be new to Solar observing and would like opinions on using a Baader 2" safety cool Hercshel  prism diagonal. Besides using this diagonal is there anything else that I need to know?  I will be using this either with a AT102ED or a Altair 102ED F/11. 

 

THANK YOU AND KEEP LOOKING UP Jethro


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#2 noisejammer

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Posted 03 March 2021 - 01:59 AM

The only crucial point is that you use either a neutral density, a rotatable polariser or a solar continuum filter after the prism. I find the solar continuum filter (540nm) gives the most detailed view but the image is bright yellow-green.

 

Herschel wedges can be used with refractors only. I use mine with a TOA150.

 

I have used my Tak 1.6x extender before the prism without difficulty. This is probably not recommended but I locate it well inside focus (roughly 8") so the illumination is not too extreme. I have had no issues.

 

You may want to get yourself a solar finder. I find the Televue Sol-Searcher works quite well. You can also try the ScopeStuff offering - I have an older version which I secure using a bit of bungee cord.


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#3 sg6

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Posted 03 March 2021 - 02:24 AM

The wedge will have to have an ND3 filter installed - not a case of either/or. You have to have one.

Will say I would expect the Baader to have a permanent one installed - giving you no choice or option but keeping your eye safe.

 

After the wedge you can put in a variable polarizer if you wanted to reduce the intensity down more - it would be at around 1/20,000 of the incoming at this stage. 1/20 for the wedge and 1/1000 for the ND3. An ND5 front filter is 1/100,000 so the wedge and its filter is some 5x more then a Baader solar film filter on the front.

 

Another good item is a continium filter that passes through at the 540nm range so green in appearance but the sunspots are supposidly more detailed. Never found I use enough magnification for "big" sunspots and there is at present precious little on tne sun anyway. Slight hiccup of a continium filter is the cost, they are not inexpensive for what is a green filter.

 

You may want to get a UV/IR cut filter in there. Sort of extra protection and if doing outreach nice to be able to say one is installed.

 

From memory I do not think you will necessarily need a "finder". Sure the Baader projects the image of the sun on to a rear screen with a cross on it. You manouvre the sun image on to the cross and the sun should be central in the scope/wedge setup.

 

Just remember it is still only a "white light" image, not the detailed Ha or CaK.


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#4 Avgvstvs

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Posted 03 March 2021 - 03:21 AM

The old prism is a great way to do white light solar observing.

Image quality is much better than full aperture solar filters.

And a great way to see if solar is for you before you invests 1000's on that perfect solar scope

I had a 2" Lunt wedge which was great, most come with ND filters ready to go



#5 philmor56

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Posted 03 March 2021 - 06:49 AM

Hello Cners,

I am not new to the hobby, but will be new to Solar observing and would like opinions on using a Baader 2" safety cool Hercshel  prism diagonal. Besides using this diagonal is there anything else that I need to know?  I will be using this either with a AT102ED or a Altair 102ED F/11. 

 

THANK YOU AND KEEP LOOKING UP Jethro

Here's a recent thread that may be of use.

 

https://www.cloudyni...erschal-wedges/

 

Cheers


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#6 Jethro7

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Posted 03 March 2021 - 08:52 AM

The only crucial point is that you use either a neutral density, a rotatable polariser or a solar continuum filter after the prism. I find the solar continuum filter (540nm) gives the most detailed view but the image is bright yellow-green.

 

Herschel wedges can be used with refractors only. I use mine with a TOA150.

 

I have used my Tak 1.6x extender before the prism without difficulty. This is probably not recommended but I locate it well inside focus (roughly 8") so the illumination is not too extreme. I have had no issues.

 

You may want to get yourself a solar finder. I find the Televue Sol-Searcher works quite well. You can also try the ScopeStuff offering - I have an older version which I secure using a bit of bungee cord.

 

The old prism is a great way to do white light solar observing.

Image quality is much better than full aperture solar filters.

And a great way to see if solar is for you before you invests 1000's on that perfect solar scope

I had a 2" Lunt wedge which was great, most come with ND filters ready to go

 

Here's a recent thread that may be of use.

 

https://www.cloudyni...erschal-wedges/

 

Cheers

Hello thank you noise jammer, SG6, Avgvstvs and philmor56,

The Baader wedge comes with a solar continuum filter, I have all of the other filters on hand.

I appreciate the tips and the knowledge that the Baader wedge is a good way to go for white light observation. 

 

When I get home from work I will read up on the threads.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro



#7 starbug

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Posted 03 March 2021 - 09:41 AM

The Baader wedge comes with ND3.0 and Solar Continuum installed. In the Photographic version lighter ND filters (ND 0.6 / 0.9 / 1.8) also included in the package.

Have it (photographic set), like it.


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#8 noisejammer

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Posted 03 March 2021 - 10:19 AM

My experience is that the permanently installed ND3 filter is not enough for comfortable visual observing although it has dimmed the Sun's light by roughly 70% compared with naked eye observation (assuming a 6" refractor and a 2 mm constricted pupil.)

 

Before migrating to the 540nm filter, I tried a ND2 and rotatable polariser. I find the polariser most comfortable but the continuum filter offers the most surface detail.

 

It's unlikely to matter in our lifetimes but I was able to observe the cyan blue (nitrogen) ring around Venus during first contact of the 2012 transit. This would have been missed if a narrow band filter was in use. (I missed it in 2004 for both contacts because I was using a Thousand Oaks objective filter.)


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