Peter Drew

I use this style for large domes, it has a number of advantages. I built a 26 foot dome by converting a silo, this had to have a parallel aperture cut through it. My advice? forget it! 🙂

I think it is a Vixen Polaris mount, the forerunner of the Super Polaris mount. Be careful of the polarity of the power input, most Vixen controllers are negative. 🙂

Looked like a lunar crater on the Sun today. 🙂

Try contacting Tenerife Astronomy Society <Tenerife astronomy society @TenerifeAstro> They should be able to give latest advice and may even be able to arrange a trip. Message Simon Rowland. 🙂

If you bring it along to me at the Astronomy Centre I can do it while you wait and show you how to do it yourself next time its needed. 🙂

I thought the Faststar system had a location feature which ensured the correct alignment each time it was removed and replaced. This just leads to recollimation of the secondary which is straightforward in method. If you have "Bobs knobs" you can operate them easily whilst looking into the front of the OTA, get every reflection looking concentric which will be near enough before refining it on a star. If all else fails, I could do it for you, I was a SCT vendor jn my earlier life. 🙂

Correct. 🙂

Very happy with my 8se, it's on the top of the weight limit for the mount but operates well if you treat it gently. Not suitable for DSO imaging but good solar system results are possible. 😀

Yes, in principle once you have a PST and a suitable donor telescope, all you need extra is an ERF. A full aperture front fitting ERF is best but very expensive, a smaller internally fitted ERF provides a very similar performance and is much cheaper and better shielded from damage and contaminants. A 2" fit Baader 35nm filter is an ideal ERF for a 4"Tal/PST mod. The only other extra you need is adequate metalwork facilities and the experience to use them. If you decide to go down this route I will always be pleased to advise if necessary. 🙂

I've had dozens of PST's apart and every one has had a tilted prism, either someone is assembling them incorrectly or, as I'm convinced, they are purposely tilted to avoid unwanted reflections. The prisms are pentaprisms, a property of which is constant deviation so a small amount of tilt does not affect the optical performance. This also results in the image orientation being retained as astronomical with NSEW reversed despite the 90 degree attitude of the eyepiece. 🙂

I'm not sure about the attenuation of a KG3 filter, you won't want to make the image too dim, on the other hand your description of the current performance suggests it might be too bright and this is what is swamping your surface detail. The 5mm blocking filter usually provides enough field to cover the full disk plus enough for average size prominences, the "sweet spot", the area on full Ha band, is smaller than the low power field and an object needs to be centred for best effect. PST's have a manufacturers acceptance tolerance of between 1A and 0.7A which can affect the resolution and contrast of surface details, the lower number is the best. Tuning of the etalon by rotating the tuning ring is another important consideration when judging performance. 🙂

@markse68. I've just read through your other thread, you have a 4" Tal refractor and a poorly PST?, the time is ripe for converting them into a Ha mod. Apart from a bit of mechanical work and the purchase of a Baader 2" 35nm filter you have the makings of a 100mm Ha solar telescope with the performance of a Lunt 100 and look at the difference in price!. I've made a couple and they work really well.

The main purpose of the coating was the same as that of an ERF, to reduce the thermal loading on the etalon and blocking filter. Failure or more likely reduction in efficiency should not present a danger situation, just sub par performance. Unfortunately you can't replace anything easily on the early PST's, later ones have an internal filter that can. If you are concerned about IR leakage you can screw an IR cut filter into the eyepiece. 🙂

It's a very disturbed extra focal image, this condition can produce all sorts of artefacts. Were there any anomalies at best focus? 🙂

The change in final focal plane in a Cassegrain system is approximately the distance changed between the primary and secondary times the amplification factor squared so the final focal plane changes rapidly in a non linear fashion. Based on this, it should not be necessary to alter the secondary spacing towards the primary much to provide an accessible focal plane position. The optical dimensions suggest that the original purpose involved some form of photography, possibly infra-red which might reduce its benefits for normal photographic/visual purposes. Adjusting the inter-mirror distance would certainly be the best way forward. 🙂

I found that my hacksaw solved all of these problems including air transport. 🙂

Yes, as already noted, keep the objective capped when not in use, youngsters have an irresistible urge to touch glass. Also take decent but not your best eyepieces, they are prone to fingerprints and "lashings" of mascara. Trust me, I'm an outreach veteran. 🙂

Brilliant, this excellent image confirms my suspicion, reported on another thread,, that this was indeed a filaprom. 🙂

Watched it today at half hour intervals as it seemed to be lifting off slowly. Somewhat fainter this afternoon by 6pm but still large and very complex. I noted earlier that one end of the prom appeared to be tethered to a point inboard of the limb as their was a short filament at that position, even if it was just coincidental it certainly produced a 3D effect with the other end of the prom having continued over the visible edge.

Huge prominence on the Sun today, well worth a look if you can. 🙂

An interest in both night time and day time astronomy is best served with two telescopes. You already have a potentially excellent 10" for the former and just need a refractor around 4" aperture for solar. Most telescopes are struggling to perform at their best with the planets currently being so low. 🙂

I visually observe the Sun in Ha with a 6" refractor with a minimum of 150x magnification. I sometimes think I can see real time changes in the shape of active proms and specially plasma globules as they change brightness, these appearances are often reported by others. However, an object on the Sun's surface travelling at the speed of light would still take several seconds to travers the disc so visual real time movement is probably an illusion. It's similar to watching the movement of the minute hand of an average clock, you can almost see it move but lose concentration or look away for a moment and it has moved. 🙂

The "Todmorden" pier is the easiest and cheapest to make but they are a DIY item, you won't be posting one! 😀

🤣

A dome base, typically circular, ideally should be around the same height as the telescope positioned horizontally. The dome has to rotate so the feature that it rides on is bolted to top of the base, the dome then has to have one of various methods to prevent it from blowing off in high winds. As far as attaching the base to the patio, cement or a sealant if the base is a bolted down design, is usually sufficient. 🙂