Rusted

You're not taking this seriously enough! At my age every millisecond counts!

Hi Mauro Not exactly sure what you are asking for: I have used a cheap "Skywatcher" 12V DC gearbox motor on both my FT focusers. 2.5" and 3.5" Driven by a 12V DC supply and controlled [on screen] by a HitecAstro box. Belt drive to the fast focus knob. Allows the belt to slip when you need to refocus over a long distance. Adjustable in steps or continuous. Fast or slow. The motor comes with brackets for mounting. Your task is to attach the motor bracket to the focuser of choice. I made a black, clamping plate for the area just behind the focusing knob. My material for the clamping plate was was a black plastic, kitchen cutting board.

Superb animation!

Flares can appear very quickly and be gone again. I tend to catch them due to my rapid capture technique when imaging. Lots of short videos. While live processing the last capture. No doubt there is some velocity involved with flares but it is mostly line of sight. My gut feeling would be internal reflections for rapid prom movements beyond the limb. I do so little visual observing these days. Unless you count watching a huge H-alpha sun in B&W on a 27" HD monitor. No doubt there is a name or acronym for that these days. AMSR? Augmented Monochrome Solar Reality?

Same problem over here. Thin high cloud and white sky around the sun. I was fooled yesterday into spending hours in the obs in a desperate attempt to capture AR3068. Even the last dregs before the trees were shaky and indistinct on the monitor. Just focusing became a guessing game.

Perhaps the problem of high velocity should be examined from an alternative viewpoint? Was there any recorded prominence activity at the time of the observation? The sun is under fairly constant scrutiny. All it needs is the UT of the observation. UTC + 1 for British Time. If we can assume that "Elp" is viewing from Britain.

Soft and shaky seeing conditions made focusing more like guesswork. Last capture before the sun hid behind the trees.

Exactly! Except they are very much cheaper "abroad." About £18 in Denmark. 25x25cm base x 50cm high. Thanks for responding.

Do not forget the cosmetic issues. You hope to supply a very demanding market. The slightest flaw in the mounting and instruments on it, will result in a return to dealer. Most factory scrapped items in such a market are probably due to cosmetic issues. Ugly, exposed welding, battered [s/h] and and ground surfaces will not have a ready market! Welding multiple tubes together will be likely lead to thermal distortion. The simple, finned tube "rocket" piers are nicely stiff but seem expensive for what they are. [IMHO] Will you advertise yours as being far worse but much cheaper? How will you protect your complex tubing from rust? Over all surfaces? How will the proud [but penny pinching owner] keep your design clean and attractive? What will it look like in a smart garden after a few months/years? Which common birds will want to nest in it? I've had blue tits nesting in the base of my MkIV.

What he said!

A friendly scrap yard owner is your source here. Tell him you are looking for aluminium tube. You could be very surprised what turns up. I have recently bought [as new] 50x200mm and 100x200mm aluminium, box section tube for peanuts in 2m lengths. 😊

Your tubes are far too close together to gain anything from beam stiffness. Each tube acts as a simple tube. No gain from multiples of tubes. Separate them and you begin to see the greatly increased stiffness. No extra weight! Now clad them with thin, pop riveted plates of aluminium. Stiffness goes up almost exponentially. Stressed skin triangulation. [AIRCRAFT!] Space them at the bottom and taper them towards the top AND plate them. Hey presto! Now you are using simple geometry to your maximum advantage.

The Norton "Featherbed" motorcycle frame used beam stiffness by widely separating the tube members. [Search!] The two tubes replaced a single down tube which was commonplace until then. Flexible! A tripod spreads the feet wide into a pyramid. Yet it is often pitifully weak because of using thin tubes. Or, the tops of the tubes are poorly connected to the top plate. The Berleback tripod is a well designed geometrical exercise. [Search!] The portable piers use a series of very clever geometry measures to remain stiff yet light: [Search!] Widely spaced hinge points at the top plate and wide, tapered legs for example. Do an image search for portable pier and use your three scaffolding tubes as spaced uprights. Then find a way to use short lengths of scaffolding pole for your legs. Tube diameter or rigid spacing is everything where stiffness is important. Anybody who has used a crane to load and unload tubing will confirm this. Even a tightly bound bundle of thin, horizontal tubes will bend like grass when lifted in the middle. A large diameter tube will show no visible bending. [Search!] If you cannot afford a large diameter tube then you must space your thin ones. Then triangulate them. So that the smaller diameter tubes do no bend under load. Think about unsupported aerial/antenna masts. A classic example of triangulation. As are high voltage pylons. [Search!] You could make a super stiff and strong pier using scaffolding poles. All it takes is to fully understand your subject and do a lot of image searching for examples. Beam stiffness, triangulation, stressed skin effect and pyramidal are all good [initial] search terms.

In my narrow universe, your design is inherently weak in the middle. It suffers from poor stiffness due its greatly reduced beam dimensions. It is the exact opposite of a Serrurier truss. A triangulated, parallel pier has maximum beam dimensions. A tapered pier with triangulation is stiffest. The large base provides automatic triangulation with a smaller top plate. Triangulation is most easily achieved by plating over the upright tubes. I used a simple, four sided pyramidal pier 4m/ 14' / high. Timber 10x10cm/4"x4 " uprights with ply cladding. Legs splayed to just fit within the 3m/ 10' circle of the observatory.

Are you confused over the definition of refractor V reflector? There are [usually] no mirrors in a refractor. Which has a large lens at the front. A reflector has a larger mirror at the bottom of the tube. Plus a smaller, second mirror at the top. To divert the light into the eyepiece.

Hi, Precast concrete footings are readily available in many countries. The usual source is builder's merchants and DIY superstore chains. However, I can't seems to find them in a UK online search. Has anybody seen these on their travels? Thanks

Unless you aim high you will never reach a distant target.

Congratulations! We are all martyrs to the wibbly-wobbly.

Nice images! I couldn't get them all in one frame.

Nicely captured!

Thanks for your encouragement.

The seeing wasn't too bad today. Fairly sharp and fairly steady. 6-7/10?

Superb set!

Congratulations on capturing the drama so beautifully Steve!

Thanks Pete. I just wish the seeing was better.