Jump to content

Banner.jpg.b83b14cd4142fe10848741bb2a14c66b.jpg

Observing the Sun - Solar Filters

MrCat

Recommended Posts

MrCat

MrCat

Posted
Posted

Hey folks,

I'm now quite keen to check out the sun having just seen the moon at high magnification I think the sun would surely be amazing!

I found that solar filters are pretty pricey, is there anything else I'd need apart from a filter and a solar finder?

Is this indeed what I'd be needing? -  http://www.365astronomy.com/Baader-ASTF120-AstroSolar-Telescope-Filter-120mm.html

Cheers

Link to comment
Share on other sites
  • Replies 35
  • Created
  • Last Reply
Floater

Floater

Posted
Posted

That is, indeed, the type of filter you might want. (But why you don't you buy from FLO?)

However, it's important that you know what you're going to see. These filters will allow you to view the sun in white light. You will see sunspots and some granulation. I don't know the scope you will be using this with but you linked to a 120mm filter so if that is the one for your scope you will have a decent aperture to work with.

Just hope you are aware of the difference between white light and Ha (hydrogen alpha) light. Ha allows you to view the prominences and filaments which you will not see in white light.

But I encourage you to follow up on being 'quite keen to check out the sun'. I don't think you'll regret doing so.

Link to comment
Share on other sites
Paul73

Paul73

Posted
Posted

I made a filter with the film listed above. Great value for money.

The sun spots are oddly beguiling.

Spending £70 on a film filter is a bit of a waste. That is over half a Hearchel Wedge which gives better views.....

Don't worry about the finder to start with. Just look at the shadows on the scope and use a low power to find the sun. Then up the mag once centred.

Paul

Link to comment
Share on other sites
Floater

Floater

Posted
Posted

Ah, MrCat! A different ball game.

For that you would be best with a dedicated solar scope - PST (personal solar telescope) or similar. I strongly advise you to do some research (Google, for example) on what the options are.

Words you could use in your search include: Hydrogen alpha telescope, Daystar Quark filter (neither of which are inexpensive), Astrozap filter (probably the most economical option), Herschel wedge and even Calcium line filters (rather esoteric and prolly best left to the imagers). Again, I suggest it's important that you do some reading up before spending anything at all ...

For the record, I'm hooked on Ha.

Link to comment
Share on other sites
MrCat

MrCat

Posted
  • Author
Posted

Hmmm well I just tried to look up h-alpha filters with little success, they seem hard to find and bloomin expensive! ...If I'm looking at the right thing, it seemed to be eyepieces that came up, so I guess you would use them in conjunction with the filter film above?

Link to comment
Share on other sites
MrCat

MrCat

Posted
  • Author
Posted

Don't even think about Ha. It will empty every penny from your bank (and more)!!!!!!

It does look pretty though.

Paul

A brief hunt online and it turns out you're absolutely right haha, ouch it's shocking!

Link to comment
Share on other sites
Alan64

Alan64

Posted
Posted

I have a white-light RG-Film solar filter for my 102mm refractor...

post-47381-0-71767600-1446266317.jpg

I can see the solar disk and sunspots.  Others like to see the surface-granulation and flares in addition, and that requires an H-Alpha kit.

Link to comment
Share on other sites
MrCat

MrCat

Posted
  • Author
Posted

Cheers, I may try some of the filter stuff on my scope, seems crazy not to :) Tho H-alpha does look amazing.

I've found about £700 to be the cheapest for a PST! Ouch, no chance, unless I can find one at the dump for £30 :D

Link to comment
Share on other sites
Stu

Stu

Posted
Posted

Cheers, I may try some of the filter stuff on my scope, seems crazy not to :) Tho H-alpha does look amazing.

I've found about £700 to be the cheapest for a PST! Ouch, no chance, unless I can find one at the dump for £30 :D

Don't under estimate the enjoyment you can get from white light observing. In addition to sunspots/active regions you can see granulation and faculae on the surface. These are possible with the film, easier with a wedge which you could probably pick up used for perhaps £120 ish?

A used PST can be picked up for maybe £350 or £400 and is a great intro to Ha observing

Link to comment
Share on other sites
John

John

Posted
Posted

Don't under estimate the enjoyment you can get from white light observing. In addition to sunspots/active regions you can see granulation and faculae on the surface. These are possible with the film, easier with a wedge which you could probably pick up used for perhaps £120 ish?

A used PST can be picked up for maybe £350 or £400 and is a great intro to Ha observing

I don't think a wedge can be used with a newtonian though ?. MrCat has a 76mm f/9.2 newt I think.

I think a full aperture Baader film type filter is probably the best solution here. Either a commercially made one or a DIY one although with the latter it's important that the WHOLE front aperture is covered by either the filter or it's holder. You don't want any sunlight peeking though !

Also remember to cap your finder scope if it's an optical one - thats enough to do some damage too if the sun shines through it.

Link to comment
Share on other sites
Stu

Stu

Posted
Posted

I don't think a wedge can be used with a newtonian though ?. MrCat has a 76mm f/9.2 newt I think.

I think a full aperture Baader film type filter is probably the best solution here. Either a commercially made one or a DIY one although with the latter it's important that the WHOLE front aperture is covered by either the filter or it's holder. You don't want any sunlight peeking though !

Also remember to cap your finder scope if it's an optical one - thats enough to do some damage too if the sun shines through it.

Totally correct John, apologies MrCat I assumed you had a refractor.

Full aperture filter at the front using Baader Solar film is the best option in this case.

Thanks for picking this up John

Link to comment
Share on other sites
Adrian Condon

Adrian Condon

Posted
Posted

Hi MrCat,

Firstly, do you have a first name?

Secondly, John is correct, both Baader and Lunt recommend the Herschel Wedge for use with Refractor telescopes only.

Baader recommend that their wedge is only used on refractors in the range 90 to 110mm, Lunt say upto 150mm.

The Lunt wedge is a 1.25" as opposed to Baader 2" mark II wedge.

Before proceeding there is a warning, looking at the Sun can seriously damage your eyes... blindness is the reward for ignoring this advice!!

If you intend to use the Baader film filter, it is essential before putting it on the front of the scope to check it for pinholes. So read carefully the instructions that come with the film. It should not be stretched tight, as this does not give as good a view as it when it is a bit crinkly, YES the opposite of what you would think!!!

Stuart is correct about the finder scope.... I put gaffer tape on the caps of the finder scope.

If you have a Telrad, it should be removed, they have a reputation for melting especially in direct sunlight...

When I use the Baader film on my Swarovski ATS/80 scope I use a Televue Solo finder.

I have a Baader Herschel Wedge, Photo version, its the same as the visual version except it comes with 3 extra ND filters.

The Baader Herschel wedge uses ceramics to disperse the heat, it has a ND 3.0 plus a Continuum Filter installed at the factory, however you can change the filters to the other filters. Baader recommend that the added filters must be over 3.0 ND. All the filters must be installed in the light path AFTER the light has passed through the Herschel Wedge. Any filter in the light path before the Herschel Wedge will crack with the heat.

The casing of the Baader Wedge does not get very warm, plus the Sun is visible in a ceramic plate to the rear of the Wedge.

So the Televue Solo finder is not required.

I do not know how the Lunt Herschel wedge works, I think it has fixed filters one 3.0ND and a Continuum Filter

Finally, when I pause viewing for a few minutes I put a towel over the scope to keep it cool, if the pause is going to be longer, I point the scope away from the Sun.

Keep Safe!

Cheers

Adrian

Link to comment
Share on other sites
Drop Of Sun

Drop Of Sun

Posted
Posted

Baader recommend that their wedge is only used on refractors in the range 90 to 110mm,

I've not seen an upper aperture limit stated on the Baader before. If you are using a big, fast frac then could be the rear heat trap will get hot. Mine is nowhere near hot with an F7 120mm scope.

I have seen this from Baader:

"Any commercial refractor with an aperture ranging from 90 to 110mm (e.g. Celestron Omni-XLT series refractors, Skywatcher Evostar series etc) will already show all visible Solar phenomena accessible to the Astro amateur."

I read that as meaning that this kind of aperture is recommended to clearly see all the features the wedge is capable of showing, like granulation.

Some good safety advice from FLO:

IMPORTANT:

1. The Baader Herschel Wedge must only be used with Refractor telescopes with metal and glass construction, not plastic. Telescopes with apertures 70-120mm work particularly well. Larger apertures can cause the rear heat trap to become uncomfortably hot.

2. Not suitable for use with Petzval or other telescope designs with a rear lens element positioned close to the focuser drawtube.

3. Due to production standards, the 2“ nosepiece in front of the Baader Safety Herschel-Prism features a 2“ (M48) filter thread. However - never mount a 2"“ filter in front of the Baader Herschel Wedge! Any filter mounted into the full beam of Solar energy so near to the focus point will become extremely hot and damaged within seconds (see safety advice, page 3 in manual). Filters must only be mounted above the exiting side of the prism.

4. Solar observing is dangerous and can be hazardous to eyesight. Safety is everyone’s responsibility, please use the correct equipment and read the safety notes supplied with the products carefully.

http://www.firstlightoptics.com/solar-filters/baader-coolceramic-herschel-wedge-solar-diagonal.html

I love solar h-alpha and for me white light is brilliant too, the detail you can see in large sunspots in white light with about 100mm of aperture in good conditions is impressive! :laugh:

Link to comment
Share on other sites
D4N

D4N

Posted
Posted

If you can't afford an etalon to get the wonderful prominence views in Ha then you can improve your white light views with a Baader solar continuum filter, this will greatly increase the contrast in the granulation so long as you don't mind looking at a green sun. Failing that I have heard that some people use their OIII filter to similar effect. Of course you would still need to use a full aperture ND5.0 solar filter as well.

/Dan

Sent from my iPad using Tapatalk

Link to comment
Share on other sites
Adrian Condon

Adrian Condon

Posted
Posted

Hi,

Thanks for highlighting FLO cautions and advice.

Having a Baader Herschel Wedge mark II, the Baader quote you give is correct,

"Any commercial refractor with an aperture ranging from 90 to 110mm (e.g. Celestron Omni-XLT series refractors, Skywatcher Evostar series etc) will already show all visible Solar phenomena accessible to the Astro amateur."

I interpret this as the best safe working range. The larger the scope aperture the more light and therefore heat is captured.

I use my wedge with the Altair Wave 115mm APO refractor, I have never had a heat problem with it, it keeps remarkably cool.

I believe the ceramic plates are attached internally by 4 screws to the body, thereby transferring very little heat to the external surfaces.

Yes, there is a 2" filter thread on the front of the Wedge and Baader give say on pages 3 and 5 of the Instruction Sheets not to put any filter on those threads.

FLO has basically and quite rightly copied the advice from Baader, I was trying to make it even clearer!!

Baader also say that they have used the Wedge successfully at 6" and 8" apertures.

I must admit that it is a beautiful piece of kit and am happy to hear that you too appreciate it!

Sunning Days.....

Cheers

Adrian

Link to comment
Share on other sites
MrCat

MrCat

Posted
  • Author
Posted

So, just to clarify a bit about what you can/can't see with the different options, I wouldn't mind the sun in green :) but you can't see the likes of solar flares and activity round the edge?

I found this which looks pretty cool to me! :D 

https://www.google.co.uk/search?q=solar+telescope+filters&rlz=1C1MSIM_enGB646GB646&es_sm=122&source=lnms&tbm=isch&sa=X&ved=0CAgQ_AUoAmoVChMIjLyUpuXsyAIVxT4UCh3YCAo4&biw=1920&bih=955#imgdii=6pYd7FRfNHOWVM%3A%3B6pYd7FRfNHOWVM%3A%3BHH6bthOyC0ieMM%3A&imgrc=6pYd7FRfNHOWVM%3A

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.