Solar Photography

Ray? · #1 27-07-2011, 03:42 PM

I've just started exploring astromony and associated photography, and with the nearest star not so far away, it's been the first easy target that I've attempted. After lots of searching through the net, I bought a solar filter to suit my basic camera/lens setup and with a clear day today, took this shot:

http://www.australianimage.com.au/im...neral/sun1.jpg

I shot RAW and did various adjustments in Lightroom to bring out some of the detail, but many articles that I've read, indicate that a Hydrogen alpha (Ha) filter gives you much better detail of the sun (solar prominences and whatever), but they certainly cost and arm and a leg.

I've been trying to find out whether there are cheaper alternatives to get somewhat similar results to the Ha filters and red filters appear to fit the bill (wavelegth wise), but I've not yet found one reference that gives any indication as to what to look for in such filters.

Has anyone tried something simple like this and achieved reasonable results?

Cheers

Ray

Merlin66 (Ken) · #2 27-07-2011, 04:09 PM

Unfortunately there's no cheap solution.
To observe the filaments/ proms etc you need an etalon type filter with a band width of less than 1A (0.01nm), a blocking filter, together with an energy rejection type filter - this all adds up to an expensive, but safe, set-up.
There is no combination of standard astro filters which can allow imaging etc in Ha.

Ray? · #3 27-07-2011, 04:19 PM

That's what I was worried about. The filters from Meade (Coronado), for example, seem hideously expensive.

Cheers

Ray

Merlin66 (Ken) · #4 27-07-2011, 04:24 PM

The Lunt35 or Coronado PST (40mm) are the usual entry points to Ha solar observing.
When you consider the optical accuracy required to provide the safe filtering of the light and provide detailed views of the Sun's surface and chromosphere, they are relatively cheap solutions.
A few years ago the basic Ha filter started around $5,000

now you can get the same performance for a few hundred dollars.

Osirisra (Ken) · #5 28-07-2011, 12:57 PM

I just bought the PST and it's a great scope for the price. Took my first shot with it and it not bad for a single frame newb shot.

http://www.iceinspace.com.au/forum/s...ad.php?t=78387

Now having the fever I want a solarmax II

Ray? · #6 28-07-2011, 01:49 PM

I've seen quite a few reports about the PST and SolarMax, and the results are awesome. The only thing that put me off was the fact that it was dedicated purely to solar photography and I wanted some flexibility.

That's why I wondered if there were some options with filters. All I'd actually need is a 35.5mm filter in a normal filter mount, but they don't seem to exist. That's why I thought that maybe one could cobble together a poor man's filter.

Cheers

Ray

Merlin66 (Ken) · #7 28-07-2011, 01:53 PM

The closest you come to that would be to add a SM40/ or SM60 etalon filter to the front of a refractor (ED80 etc) and use a blocking filter diagonal.
The price for the filters is about the same as a base PST/ LUNT.

Ray? · #8 28-07-2011, 02:47 PM

I checked some prices and all I can say at this stage is Ouch! I don't even know if they would work with what I have, as I'm using a 600mm solid cat lens with extenders.

Cheers

Ray

Poita (Peter) · #9 28-07-2011, 03:00 PM

There are some interesting hybrids around where people have taken a PST and attached it to the back of a larger scope with good results.

Paul Haese · #10 28-07-2011, 03:09 PM

I just want to make it clear that you need a blocking filter and an etalon filter with energy rejection filter at front. You can buy these as a complete set and put them on any refractor that will fit. You will also need an adpater plate to install the etalon on the front of the scope.

You cannot cobble something together. Buying just one part without the other will result in blindness or damage your imaging gear. I cannot stress this enough. This gear is expensive for a reason, because it is designed to save your eyes.

However as has already been said, this gear is now so much more affordable. When I bought my solarmax 60 0.5A scope it was 9K here and 6K from the States. I got it from the states. This unit is now worth around 2.5 grand. That is pretty cheap really.

Why not buy a PST and see how you like Ha? PST's are really affordable.

Most gear is really designed for refractors, so Cat orientated scopes are not suited for this type of imaging. Perhaps rethink having just the one scope, look at several if you want to do more imaging.

Ray? · #11 28-07-2011, 04:10 PM

I've actually got a polymer solar filter that attaches to the front of the lens, to block out the majority of the light, it's trying to narrow the wavelength that gets through that I thought could be done with applicable filter/s at the rear of the cat lens.

I'm pretty much taking first steps at the moment, so I'm trying to do what I can with what I have and trying to my moderate Gear Acquisition Syndrome (GAS) until I know what really interests me.

I'm already getting dirty looks because of the limited stuff that I've bought so far.

Cheers

Ray

Paul Haese · #12 28-07-2011, 04:18 PM

How much gear you can or cannot afford is up to your budget and no one is going to can you for that. If they do, they are not terribly nice people.

The reality with solar photography is that there is white light photography which can be very rewarding (take a search for some of those in the solar system forum) and great results can be obtained; and then there is Ha or CaK imaging. With Ha you cannot skimp, you cannot add or subtract any filters and add them to something you have already. These are system orientated. The nearest you can get is what Thousand Oaks makes with a prominence filter and even then I think you need a blocking filter with it. Please don't try some of the home made stuff on the net until you are absolutely certain you know what you are doing.

Ray? · #13 28-07-2011, 04:36 PM

Thanks Paul

I'm not going to do anything silly, I have a great respect for my fading eyesight and the last thing I need is to make things worse. Also, I've been working with danagerous things for a long time, so have a very heathly respect for such things and a cautious and calculated approach to everything.

Cheers

Ray

Merlin66 (Ken) · #14 28-07-2011, 05:16 PM

I've been using solar Ha filters for the past five-six years and have done many mods involving the PST etalon/BF.
Solar observing can be safer than driving a car.....providing the right equipment is used in the right way.
As Paul say's there's no cheap way of getting in solar Ha......

Poita (Peter) · #15 28-07-2011, 05:41 PM

Hey Merlin, I have been a long admirer of your PST modifications, it is a way to get into solar without it having to break the bank.

Merlin66 (Ken) · #16 28-07-2011, 05:52 PM

Thanks for that!

I think to-date we've done more than 50 successful mods....and hopefully more to come.
I have a detailed write-up available on PST mods (6.5Mb) just drop me a PM.

asimov (John) · #17 28-07-2011, 05:56 PM

I've only just kind of broken into this field of imaging, but I'm just going to stick to white light images for now. As noted, it's not cheap to get into in a big way. I did see the mentioned refractor kit available for less than 1K which I think is reasonable.

Paul Haese · #18 28-07-2011, 08:21 PM

Quote:

Originally Posted by asimov

I did see the mentioned refractor kit available for less than 1K which I think is reasonable.

Just for the record and I know you know this already John, but others might not know, if you get a single etalon this is good for prominence detail. For greater surface detail you need a double stacked etalon (there are other systems but these cost a lot more). As a minimum surface is best from 0.5 Angstroms to 0.2 Angstroms. Coronado and Lunt make models up to 0.5A. Lunt I think is really the better system with the etalons not having a central obstruction. They also make 100mm double stack models and for the really adventurous they make a 200mm unit also. Both manufacturers make scope with either single or double stacking.

The more expensive systems are made by Daystar and Solarscope.

The more money you can spend the better the views. However, good views can be improved upon. Buying a single system with a view to double stacking later is a good way of getting into the Ha viewing and imaging scene. Like John has said a 1k version is available.

Ray? · #19 29-07-2011, 02:01 PM

Ok, I've been researching Ha filters to see what's available and there are ones from Baader, Astrodon, Lumicon that aren't badly priced. However, there seems to be conflicting information as to where these filters could/should be used.

One retailer of Lumicon filters states that the Lumicon Ha filter is only for night sky use and should not be used for solar photography. Is this just a precautionary statement, or are these the correct type of filter to use, but clearly with a general sun blocking filter?

Cheers

Ray

Paul Haese · #20 29-07-2011, 02:35 PM

Filters you need to look out for are solar Ha filters Ray. The other Ha filters are only for imaging or night time viewing. Never use those filters and look at the Sun.

Here is a list of Solar Ha filter held by OPT.

http://www.optcorp.com/ProductList.aspx?uid=471-305

This is Thousand Oaks site, that makes a range of filters.

http://www.thousandoaksoptical.com/

For Solar Ha

http://www.thousandoaksoptical.com/halpha.html

Keep in mind that even the Ha system sold by thousand oaks is a complete system. To you need and ERF, adapter, blocking filter etc.

Lumicon do not make Ha systems for solar viewing.

Let us know if you need any more help.