Capabilities and Limitations

First, this is an entry-level telescope for hydrogen alpha viewing. It is the only model available for below £500 in the United Kingdom (or $500 in the United States) but, as such, has to be regarded as a serious breakthrough. Its optical quality seems sound enough, but a 40-mm objective (effectively reduced to about 30 mm by the telescope design) and 400-mm focal length mean that the resolution and maximum magnification are limited. Whilst I have managed "white light"

Figure 2.54. Canon Powershot SD450 mounted with the PST.
Figure 2.55. Canon Powershot SD450 used to snap prominences.
Figure 2.57. Afocal camera adaptor with Coronado CEMAX eyepiece.

Figure 2.58. PST and

RadioShack webcam capturing a PST image on screen.

Figure 2.58. PST and

RadioShack webcam capturing a PST image on screen.

solar observations under quite appalling conditions, I find that any sort of cloud can ruin the view.

However, during periods of clear (or almost clear) conditions, the PST can open up a world that was previously only open to professionals or amateurs with a large disposable income.

There is lot of talk about the cell structure of the Sun and faculae (brighter regions of the Sun). These are supposedly visible in "white light" using precision telescopes and high magnification (300x or more). As an experienced viewer of the Sun in "white light," I can honestly say that I have rarely seen these features and, on the rare occasions that I have, not particularly clearly. I have seen good umbral/penumbral shading of sunspots but not much more. In fact, medium aperture "white light" viewing shows sunspots better than the PST does.

Now, try a PST on low magnification or even look at the image before inserting an eyepiece. The cell structure is immediately apparent. Now it does not photograph that well using a domestic digital camera but that is hardly the point.

Next look at the faculae. These brighter regions are very clear and also surround sunspots but can also be seen on their own. Filaments also show well but do not show the detailed shapes visible in larger hydrogen alpha telescopes.

Now prominences themselves are the highlight of solar viewing. Superficially, they look like flames emanating from the edge of the solar disc. It is possible to see a solar disc under clear conditions with no prominences at all, but it does not happen very often. Most of the time, there is a small prominence somewhere and quite often there is an associated facula. On rare conditions, I

have seen prominences changing in real time, but it is more common to see them changing every 10 minutes or so. Sometimes they can be seen more clearly (and/or photographed better) if you crank up the magnification from 80x to 100x but not always, depending on conditions. The key is to try different ideas to see what works on the day, just like nighttime planetary viewing.

One of the nice features of the PST is its portability. As well as several car trips, it has accompanied me on business trips abroad, enabling me to follow my hobby while away from home.

The PST is not marketed as a photographic instrument and, indeed, does not support prime focus photography (without an adaptor), advocated by many astrophotography experts. However, it does support afocal photography (otherwise known as eyepiece projection) and an afocal adaptor is available (see Chapter 5 for details). Personally, I use a simple domestic digital camera for my photos and it is adequate for simple recording of the more prominent solar features. More sophisticated techniques are covered in Chapter 5.

Buying a solar telescope as we approach a solar minimum, on the surface, may not appear to have been such a wise thing. Yet there can be days, even weeks, where there is not a single sunspot visible in "white" light, but there is hardly a (clear) day when there is not any feature visible in a PST. If the solar disc looks bland, just wait a few minutes or so and something will come into view.

Using a PST and getting the best out of it requires totally different viewing habits to nighttime viewing. You do not need to spend hours staring at the solar image. If you like to relax in the garden on summer weekends, set up your PST and just take a look every few minutes or when you get up for a drink. I like to take it to work and look through it at lunchtime and even nonastronomers will stop to look through it. Astronomy in the daytime! Whatever next?

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