Peter Drew

Hello Bill, welcome to SGL. I have an apartment in Tenerife with a few telescopes. I visited regularly before the pandemic and look forward to another visit when possible. 🙂

Probably one made by the little known Don Jobson. 🙂

Difficult to see another source of a 10" F2 mirror suitable for any telescope at that price. 🙂

!0" reflector at 20" focus means it's operating at F2. My guess is that someone had a 10" SCT with a broken corrector and has used the primary to make a very fast Dob mounted Newtonian. If so, the results should be "interesting". I think the included Moon shot sums it up. 🙂

I'm sure he can HANDLE it Jeremy. 🙂

Not worth it to me. I have the highly regarded Vixen 102mm FL, reckoned to be comparable with a Tak optically, (objectives made by the same company, Canon). Apart from very occasional white light solar it's one of my least used telescopes, a Tak, for me, would not be worth the outlay. 🤔

Good read!. I think it highlights that relatively small increments of aperture result in small increments in detail. The greatest differences are usually the observer, the conditions and the accessories in use. 🙂

The poor image description seems indicative of insufficient thermal equalibrium, specially the multiple image issue. 🤔

I believe they can be used for radio astronomy, we had on in the process of converting it for the purpose but were donated a professional bona fide 3.8M complete radio telescope in need of refurbishment. This has recently been mostly completed and we expect "first sound" to be available shortly. Images of the system are on our website. 🙂

Possibly a typo, should read NAFF. ? 🙂

Yes, that would work. I've done a similar thing with a 20" Dobsonian using the encoders from an Orion Intelliscope. 🙂

I too, would recommend the Baader visual standard solar film. The Thousand Oaks material is thicker, the thinness of the Baader film is what gives it it's unique optical properties and it will give a superior view. In its favour, the Thousand Oaks film will produce an orange coloured Sun. Anyone doubting the strength of the Baader film should take an offcut and try and break it by pulling it apart. All film filters are of course can be cut by a sharp object, so be careful. 🙂

I'm sure Swoop1 is correct. Well spotted, I'm an amateur astronomer and haven't seen one yet so you are one up on me! 🙂

No comparison really, two different instruments with different strengths. I think a 3" or thereabouts refractor would complement your current binoculars and Dobsonian better than an extra binocular.

It depends on what is currently available to be seen in "white light". Given the opportunity, you should be able to see sunspots, faculae which look like slightly lighter granular patches usually towards the limb. Genuine solar granulation can be seen during excellent seeing although 10" aperture, assuming a full aperture filter, might just be overkill due to daytime seeing conditions. 🙂

I'm mainly a solar observer these "days" so can't currently comment on light pollution. However, I do believe the air quality and hence the transparency has improved. I have a 5 finger test for solar air quality. It is based on how many fingers on an outstretched hand are needed to occult the Sun's disc plus the surrounding scatter. Recently there have been many 1 finger days. 🙂

Poor Helen, perhaps better known for her dropping the Olympic torch. 🙂

Sounds rather odd. If you can focus with just the eyepieces you should be able to focus with the Barlow. Usually, a Barlow will bring the focus point out which seems to be the opposite of your problem. 🤔

The star diagonal will give you an erect image but laterally reversed. My experience with erecting prisms is that those with 90 degree angle seem to work best. 🙂

I've worked on a couple of AP 6" "Super Planetary" refractors. I shortened the one owned by the late Douglas Arnold so that he could use binoviewers on it and folded one for another owner so that it would fit into his small observatory. The only AP refractor I've actually looked through was an early version 92mm Stowaway, someone, can't remember who, loaned me one for a day at Kelling. I have to say that terrestrially it was amazing, regardless of magnification it still gave a perfect image. Sadly it was cloudy at night and I didn't get the chance to use it at night. Would I wait years for one? NO. 🙂

There is a caveat with this otherwise sound advice. I's true that working on Ha is a monochromatic wavelength so no need for an apochromatic class telescope. However, chromatic aberration isn't the only limitation of inexpensive refractors, spherical aberration and so-so figuring also conspire to provide less than perfect images. So if contemplating an achromat, make sure it's a good one. 🙂

On paper, the StellaMira 85 would be a good choice as the fr 6.6 coupled with the Quark's 4.2x Barlow gives the optimum overall focal ratio for the Quark system. 🙂

I use the same method, a 1mm stainless steel strip running on stainless steel rollers that are themselves in bearings. The free movement is controlled by an adjustable PTFE pad. 🙂

Narrowing the band width does reduce the brightness which is one of the reasons why imagers prefer the system as the enhanced surface details can be brightened by exposure and processing. Visually, double stacking dimness can be offset by placing an opaque covering over your head. If the PST is preowned it will be worth checking the ITF, the filter just before the blocking filter as theses deteriorate over time and also reduce the brightness of the image. Finally, using a Ha telescope and more so a double stacked version is quite a steep learning curve with many nuances to deal with. The usual advice is to tune the single stack to provide the best view and then to tune the double stack unit until the brightness is best. Further refinement can be made by "clocking", rotating the double stack unit relative to the rest of the telescope. 🙂

Whatever you do to try and release it, don't subject it to mechanical shock. This could detach the etalon plates which are only kept together by molecular bonding. 😱