Rusted

Just sharing what has been passed onto me. Liked your astro galleries.

Check Gong Ha to save time searching. I always look first for the practice. Then at Gong Ha to confirm what I may have missed. The images are updated frequently. It is not uncommon to find more proms than Gong shows. Some of the observatories seem to be better at showing subtle surface detail than proms. http://halpha.nso.edu/index.html

Same here on the seeing. Violent thermal agitation from early morn [7am] right through to lunch time. Both moon and sun results were a four letter word beginning with... p.. for poor. Is it the wind or the weather system stirring it up? Worst I've ever seen it.

A wonderfully even rendition. Never an easy task in my own very limited experience.

Amazing subtlety and finesse to your captured proms.

An excellent collection by the master!

Brass only gets into that state if it hardened by hammering. It can be softened again by heating and dunking in water. Which would harden some steels but not brass. Restoring such a damaged tube would probably require a matching mandrel and lots of experience. For a useful repair I'd seek a new main tube in yellow brass. If it can be found in the diameter just behind the cell. The original looks tapered. You'd need to take a wedge shaped slit out of the new [parallel] brass tube and solder the joint. Do check that the objective has survived the fall from the top of the lighthouse before spending any time or money. EDIT: DO NOT heat old brass indoors. It can be toxic and causes symptoms like collapsed lungs when I have done it in the past.

Nice images! I just saw the proms on Gong and thought I'd give it a try. Blue skies here for five minutes had me dashing across the yard. Now we have gales and heavy showers. I'm sitting here in the dome. Freezing my proms off at 46F! With the shutters closed but all set up. Hail is now crashing on the dome! Am I having fun yet?

An afternoon image showing a detached fringe [just visible] at lower right. The seeing conditions will not allow fine detail and high contrast. My efforts to bring out the detail are detracting from what I can see on the monitor. Basically a boiling mess with only occasional clarity.

Struggling with cloud, bad seeing and a milky sky again. Tried the tilt plate and changing the tilt of the internal D-ERF. I'm a martyr to off axis glare at the moment without obvious cause. Lots of scattered proms at 2 and 8 o'clock on the limb. Close-ups are with the WO 2x Barlow on the ZWO 120MC nose. CR150HD 150/8 [120/10] 90mm internal D-ERF. Stage 2 PST etalon and filters.

Ideally you want parallel pins rather than points for such mechanical work. Points may just lever themselves out of the holes if the ring is stiff. I use circlip pliers when the job suits. These come in several varieties. Straight and offset. Internal and external action. Sometimes I can get away with using long nose pliers or tapered, round jaw, wire forming pliers. An old and knackered pair of vernier calipers can sometimes work but don't ruin quality tools. If you could drill the jaws of an adjustable spanner for pins you would have a really solid, adjustable tool. Drilling hardened steel is [er-um] hard work. The hardness of an old adjustable spanner could be let down with lots of heat. Let it cool slowly. Or make your own tool with mild steel, drill a large hole and then halve it to fit around the projecting axle. Then drill smaller holes for the pins. Use a piece of paper, like a brass rubbing, to get the exact size you need. Power tools often have pin spanners for their grinding and sanding disks. You might be lucky if the pin spacing is just right. I often spend hours going through a shed full of tools. Usually when it's Sunday afternoon and I'm desperate to find something to fit a job. With all such tools you should be very careful about damaging the workpiece if the "pointy" tool slips. Lenses, in particular, don't like metal tools being scratched across their surface! Extreme care is required with these!

I [almost] hesitate to embarrass myself with this effort. But post and be damned! Milky overcast with teasers. The French would probably call it Malteasers. Non?

53° N is hardly Svalbard! Besides, you've got your hat!

It is long overdue giving you a knighthood Sir Peter!

Remarkable workmanship!

I have just added an Omegon 2" helical focuser to my H-a PST stack. Nice! 150/8 [120/10] internal 90mm D-ERF, PST, ZWO120MC 5% of 3000 @ 120fps. Seeing a bit "thermally" today. Occasional cloud. Breezy from NW.

If you build yourself an equatorial platform you can put the telescope on top. Then follow the sky for long enough to capture the moon and planets with a webcam type camera. You can find details of motor driven, equatorial platforms online. No great skill or expense required. Just a synchronous, gearbox motor for a drive. They used to have these little gearbox motors in washing machines. To run the wash programmes using microswitches and cams. A local washing machine repairer might have one of these motors. Or eBay is a good source if you don't have any locally.

Thanks Dave. I'm suffering from asymmetric glare in the image at the moment. I have a tilt plate but it seems to do nothing at all visible up to its [say] 5mm max. So I'm trying to eliminate the glare by trial and error elsewhere. I'm temped to run adjusting rods to the internal Baader 90mm D-ERF to try tilting that. Or make a door and manually shove it about. Poor summer seeing isn't helping. Early morning seeing just won't stretch to a full day.

Nope! It was inches of sag. 2m long x 35 cm Ø circles carrying eight 16mm dowels.

The problem with any beam begins when you rotate it on its axis. Beams do not function well when the loads are across the minimum dimension. An equatorially mounted beam OTA will soon find the weak dimension. My twin profile beam was 4"x4" but hopelessly weak in torsion. I could have put my whole weight on the centre of the beam when "upright." Not having a laser handy I used a light but stiff crossbar. This easily indicated the OTA's own twist as I moved it around on the GEM. Square beams are not as stiff in torsion as round ones. The absolute worst OTA I ever made was with eight, parallel 16mm dowels arranged around eight plywood rings. It could not even support its own weight without sagging several inches at either end. I hope your new OTA works simply as a result of increasing its dimensions. Previously it had a very similar profile to a rainwater gutter. Which must be the absolute worst possible profile for resisting torsion.

You mean to say there are other planets above the clouds? I always thought it was an old myth. To go with "tridents" and things. How I wish I had an aeroplane, like you lot, so I could see them too. I'll have to look at FLightOptics website about booking a ticket.

It is not usual to have to clean between the glass elements of an objective. So leave it assembled and clean only the front [and back] if necessary! Blower first and then only drape a lens tissue in gentle, radial movements. Never rub hard! No matter how disgusting you have let the precious lens become. There is a considerable risk to any lens removal and replacement from its cell. The problem is the lens getting out of square and jamming fast in its cell. So just tipping the lens out of its cell is the worst possible thing to do! This error is likely to lead to a scallop of glass being cracked away from the lens surface. Usually from the softer and weaker flint. There is a simple method to lens removal and replacement which helps to keep the lens square to its cell. It involves a suitably sized short, drinking glass with a piece of cloth or several tissues placed on the rim to protect the lens. The short glass having already been placed on a firm table at which you are sitting comfortably. Swab please, Nurse? Now send her out of the room. You don't want any distractions! First you unscrew the retaining ring and place it safely aside on the table. Then you lower the cell with its objective over the drinking glass while keeping the cell horizontal. So that the lens is left behind, lying on top of the protected glass. With the cell now resting safely down on the table around the glass. Now carefully check the lens for edge marks or arrows. There should be pencil lines across both elements. The lens must be reassembled so that the marks match their original position and orientation. To do otherwise may result in serious optical problems or damage. Photograph the lens maker's marks if you can. Or make a drawing and keep it safe from marauding kids or negligent wives!! Send them on holiday first! Or take a day off work while they are at finishing school. This will help to ensure the lenses are re-assembled in the correct order and orientation. Reversing the procedure involves placing the lens sky face down onto the protected drinking glass. With the objective cell already lying on the table, the same way up as before, around the glass. You then LIFT the cell slowly and carefully around the lens until it rests safely inside the cell. Lower the cell again at the slightest sign of jamming and be more careful with your levelling of the cell. Once insertion is achieved, the cell and its objective are laid down on the table. Ready for for the retaining ring to be replaced. DO NOT PUT IT BACK DOWN ON TOP OF THE GLASS! NEVER TIGHTEN THE RETAINING RING TOO TIGHTLY! There should always be the slightest rattle in an assembled objective Unless, of course, a compression ring is part of the design. Remember where the ring went! Front or back? In between? Any spacer rings? YOU MADE NOTES or took photographs, or both didn't you? The sky face of the lens will always be facing downwards before re-assembly. Those of nervous disposition may like to start with the supporting glass half full of whiskey. [Or a spirit of your own choosing.] Which may ONLY be consumed afterwards as a reward for success! Or ONLY afterwards to drown your sorrows for abject failure. Probably leading to a nasty flake being gashed from the surface... of the priceless, historical and utterly irreplaceable, 24" Zeiss, Triplet, APO objective.

Chriske> You really are seriously multi-talented!

Convex facing the sky.

Stop glaring at me!