The Great Solar Eclipse of 2017 is closing in and you want to safely watch it. What to do? If you have a refractor you can do what I did and get yourself a Solar Wedge. If you are strapped for cash, get some solar film or a pre-made front white light filter, and if you are really strapped buy a pair of solar glasses.
White Light filters such as the Lunt Solar Wedge offers the ability to simply view the phenomena known as sun spots, all that is needed in addition to the Lunt Wedge is a refactor, say a 60mm up to 130mm. But before you run off an start looking at the Sun - DONT! Viewing the sun requires specialized equipment and I am not advocating you attempt or use anything mentioned in this article. If this is your first solar viewing experience find a trained Solar observer to assist you, nothing wrong with asking for some help as some of the terms and filters can be confusing. With that out of the way....
This article covers the Lunt White Light Solar Wedge - A mini Review: I will also refer to it as the Wedge, or Solar Wedge in the article.
So what is a Solar Wedge? In the most basic of layman's terms, it is a special diagonal which splits concentrated sunlight into two paths one sends 90% of the light and heat to a rear thermal area, this area absorbs the rejected light and may become hot with continued use. Lunt uses a RED aluminium plate located at the back of their wedge to dispense with the extra heat. The other 10% of the light is sent up through the diagonal passing through a Neutral Density 3 filter to further reduce the brightness making it easier to view the solar disk with the human eye. For some people even that is too bright if so, you would require adding another ND 1 or 2 filter or possibly a Variable polarizing filter on the eyepiece. I recommend if you are buying a solar wedge also buy another ND filter (ND 1.5) just in case your eye is sensitive to the degree of brightness passing through the wedge.
Expense: The Lunt White Light Solar Wedge currently cost around $288.00 if you can find one, Right now with all the hype of the Solar eclispe they could be scarce. The cost reflects the fact the Solar Wedge is a premium long term use item that you will probably keep for years. The cost is triple a more traditional quality front end solar filter film/glass arrangement. The benefit of the wedge is that you can use it with other refractors as it fits as a diagonal, up to a certain size refactor- see Lunt's literature on this, I recall 150mm. So, if you change refractor your wedge will probably still work just fine and therefore saving you the expense of buying a new front end filter, or trying to mod the one you had.
Ease of Use: Simple, you use it just like a star diagonal, Just plug it into the back of your refactor and use a standard eyepiece and make sure you attach the wedge BEFORE pointing the telescope to the Sun. Concentrated sunlight is dangerous! Lots of funny but serious ramifications can occur - like setting your pants on fire. Lunt offers both a 1.25 and a 2" version of the solar wedge. The 2" version comes with a step down adapter for those who want to use 1.25 eyepieces and cameras. I prefer the 2" version as the opening is larger and supports larger camera sensors. Either works equally fine for viewing.
Build: Like a tank. Everything is well crafted and solid, this wedge will last you a life time and is shipped in a nice metal carrying case. Lunt uses a red heat sink at the back with a caution about touching it after prolonged use, yes it does get hot, and is nicely machined and does the job of keeping the wedge cool.
Visuals: What can you expect to see? Looking through a dedicated Solar Wedge provides a much more detailed view of the solar spots and photosphere as opposed to the front film filter versions. You will see a white disk and if the sun has sun spot you will see them as well showing up a black dots of various sizes. Please be advise, you should seriously consider the polarizing filter, and is recommended by Lunt. The views aer pretty bright as default, and for comfortable views I recommend a polarizer filter or ND 1.5 in addition. The Polarizer can be adjusted to reduce light in varying degrees, making the experience more enjoyable as well as enhancing your views. No, a Solar Wedge will not provide Chromosphere or Prominence details, just a big white disk with black spots. If you want to take it up a notch buy a Continuum filter, and you can then see very fine details and enhanced sun spots
Imaging: This is where things go a bit sideways. Depending on your telescope, focuser and camera type, you may have difficulty with prime focus. Out of my three telescopes, I was only able to use my camera with one telescope. This is due to the way Lunt secures the eyepiece tube onto the wedge base, it is not removable because they have in place a Neutral Density filters cemented in line. So, you can not "screw" a camera direct to the wedge as most star diagonals allow, you have to use the adapter, which extend the focal plane further out.. In my case, I could not move my focuser far enough IN to get prime focus. This could be easily fixed if Lunt simply engineered the eyepiece attachment as two screw on sections. First section is the non-removable ND filters. Section right above is the removable section allowing the camera to be about an inch closer in, and for me would have solved my prime focus issues. But all in all with the right camera and telescope you can get some very nice images with this wedge. When you process the images you will see better details as opposed to visuals.
Pros: Easy to use, Great visuals, solid build, not overly expensive, will last a lifetime.
Cons: Not optimally designed for imaging, Prime focus difficult or impossible with some refractor combos - be advised.
Recommendations: For the price point I do recommend this wedge, especially if you are a visual observer. Consider this wedge as an option especially if you do mostly visual work, otherwise check around in forums for others using this with your telescope for their experience with prime focus set up. if you are only interested in watching the Solar Eclipse go with a front film filter.
I recommend the Solar Wedge to anyone who has a refractor and wants to experiment with Solar Observing.