Solar Viewing & Filters

[groberts]

Few queries on solar viewing:

Scope: I currently own a SW 150PL and a WO 81GT ED APO, what are the pros and cons / preferences of using either of these scopes for solar viewing? I am thinking the 'open' construction of the Newtonian might help with heat dissipation? Given a proper filter is fitted, can damage still be done to any of the equipment? 

Filter: Subject to thoughts on the first question, which filters are recommended? 

General: I am assuming that it's just best to remove the finder scope but are there any other guidelines / safety issues for solar observing? I presume once you have a good filter fitted photos can be taken - preferences for CCD / Webcam vs DSLR?

As always, thanks

[JB80]

I use the 150PL almost daily for solar stuff and I use a home made filter out of Baader astro solar film which is readily available from most astro shops. I would heartedly recommend buying a sheet of that for which ever scope you use. I just cover up my finder with an end cap or you could always cover it with a little piece of the solar film but it's not really necessary.

The 150PL will give you excellent white light views visually and if conditions are good photographically too. http://www.astrobin.com/users/JB80/ Every white light shot in my gallery has been taken with the 150PL. Some are real good and others are affected by the heat given the OTA is big and black the air currents in the tube really do swirl around as things heat up. Then again I am in Spain dealing with hotter weather.

I use a dslr for my full disc shots, it fits perfectly on screen and a ccd for the close ups but that's a new toy so haven't got a lot done with it so far.

As far as safety always check your filter to make sure there are no holes or scratches and if you have to remove it from the scope make sure you have slewed away from the Sun first.

I'm sure a good argument can be made for the APO too but with no experience of one I can't really say.
 

[groberts]

Thanks JB80, encouraging.  Nice photos but why the difference in colour of say white and yellow / cream - if the said filter inherently produces a white view aren't all photos going to be white?

Any other comments on the OP elsewhere?

[groberts]

PS I have seen elsewhere that prominences will not be seen using a Baader Astro Filter, is there any other way they can be seen that doesn't break the bank?

[JB80]

The yellow is just me adding in false colour to the finished image in photoshop afterwards. It's just for something a bit different and if I have a better pic I tend to do both a grey and yellow image. I could make it green if I like but yellow/orange is the colour people associate with the Sun so that is what I go for.

[NGC 1502]

PS I have seen elsewhere that prominences will not be seen using a Baader Astro Filter, is there any other way they can be seen that doesn't break the bank?

The Baader filter does a great job with sunspots, but sadly, to see solar prominences does require a dedicated hydrogen alpha ( Ha ) telescope, the least expensive being the Coronado PST or the Lunt 35 Ha.

You can purchase ready made Baader filters for a wide range of scopes, or an A4 sheet and use with a DIY holder to fit securely over the front end of your scope. Make sure you get the ND 5 Baader for visual use, the ND 3.8 is for imaging only.

Link for ready made and DIY Baader filters - 

http://www.firstlightoptics.com/solar-filters.html

HTH, Ed.

[Stu]

The other option you could try is a Herschel Wedge on your refractor, I would expect you would get great views and images with this.

The smaller aperture and tube would be less susceptible to cooling currents, and will also cut through the seeing a little better on hot days.

I use one regularly with an 85mm scope and the detail is stunning. It is not as cheap an option as the Baader film (which you could also use on your refractor), but I believe the results are better.

http://www.firstlightoptics.com/lunt-solar-white-light-systems/lunt-white-light-herschelsolar-wedge.html

You need a polarizing or continuum filter for the eyepiece in addition to the ND3.0 which is fitted to wedge. These can't be used in newts or compound scopes (maks etc), just refractors.

Just another option to consider.

Cheers,

Stu

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