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Rusted

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Rusted last won the day on June 28 2021

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    http://fullerscopes.blogspot.dk/

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    ATM, imaging, solar, Solar system, photography, blogging, cycling, walking, birdwatching, digiscoping, audio, DIY, clocks.
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    Exiled to sunniest and darkest, rural Denmark!

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  1. It's not exactly your off-the-shelf item either. You'll probably have to find a dealer and ask for an original, replacement spare part. In aluminium! Failing that: Screwed sleeves or thread [size] adapters are widely used. Large male thread on exterior. Smaller female thread inside. Do an online search for M14 screwed sleeve. Assuming your part is actually M14. Presently unknown. You may have to modify an M14 part by drilling it out to size. Or having somebody do that for you in a lathe. Model engineer? Local tech college or school with a metal machine shop? The latter should have a thread pitch checking tool too. If you can find an M14 bolt or M14 threaded part you can hold your mashed up fitting against the thread to confirm the pitch is the same.
  2. Brass to brass, or aluminium to aluminium threads may want some lubrication. Sticking is called galling. Almost like local welding. Use tiny amounts of grease. NOT oil. You don't want anything runny migrating into the lens elements. I'd be checking the lock-ring[s] fit back on without the objective lens in place. Before attempting to insert the lens. ASK YOURSELF WHY YOU ARE RISKING THE PRECIOUS LENS! It would have to be filthy to have any effect on the view. Use a hand bulb blower first. Cleaning the visible surfaces with a lens cloth and approved cleaning fluid. Is far safer than a clumsy amateur trying to dismantle the lens from its cell. Removing the objective glass elements from the metal cell is fraught with serious risk! Most amateurs try to tip the lens[es] into and out of the cell. Which is just asking for trouble! The glass lenses will always want to tip and jam fast in its close fitting cell! The proper way to do it is to remove the metal objective cell from the telescope's main tube first. You then remove the lens locking rings[s] while working safely flat on the table. Not in mid air! Let's assume that you have removed the cell from the telescope main tube. You have already unscrewed the locking ring[s] and placed them safely aside. Now you pad a suitably sized, upright, drinking glass rim with a soft cloth. Clean hanky? Choose a drinking glass diameter which will pass easily though the lens cell. You then slowly lower the metal objective cell over the padded drinking glass. So that the objective remains supported on the padded drinking glass rim. Once clear, the cell is lowered to rest safely on the table around the bass of the glass. You then deal with the fragile and naked objective lens. Which, in a common doublet, usually consists of a flint and crown pair. One positive, biconvex lens and one negative concave lens. The back of the flint may be flat or slightly curved. The convex lens usually faces outwards. Though not always. The biconvex lens may even have two different curves! Where the curves between the lenses match they will usually have tiny, thin spacers. Some objective lens pairs may have a spacer ring between them. Make a note of which way around the lens sits in its cell. Check carefully for any pencil marks on the edges. Which, if present, will show their rotation, relative to each other. Or may be arrowed to point towards the sky. Your lens is now accessible for cleaning. I'd much prefer surgical gloves to anything else. This avoids fingerprinting the glass with skin oils. While usually providing a safe grip. Refitting the clean objective lens is done in reverse order. The drinking glass is standing inside the objective cell on the table. The lens is carefully placed on the rim of padded glass. The metal cell is then lifted very gently and straight upwards without tilting. Until the objective lenses sit safely within the metal cell. If the lens tips and sticks then very carefully lift the cell again. Squareness between the lens and cell is vital as they meet. Let's assume you have the lens safely in its cell but still unsecured by its ring[s]. Place the cell down on the table and remove the drinking glass to avoid accidents. You can now proceed to fit the locking ring[s.] With the cell and its lens safely resting flat on the table. You may not be able to remove the cell from the main tube. Check for locking screws around the edge of the cell. Unlikely, as most cells are screwed to the main tube with a fine thread. Try grippy rubber gloves to unscrew a tight cell. Don't use tools! Other than [rubber] strap wrenches. These are commonly used for removing vehicle oil filters by friction. You may need two. Facing opposite ways. One on the cell. The other on the main tube. Or, get a strong helper to grip the main tube while wearing grippy rubber gloves. While you try to unscrew the objective cell. Using both, gloved hands where there is enough room. Many cells will be very tight. Once loosened unscrew the cell very carefully. The risk of damage to the objective lens is very much higher if the metal cell can't be removed! In amateur hands the objective lenses tend to tip slightly as they enter the close-fitting cell. Which can cause a scallop of glass to be broken away from the lens surface! This usually occurs on the softer [rear] flint lens. Tears will soon follow such a disaster! Painting the scallop with black paint is considered safer than leaving it visible. A bare scallop might distort the light passing through the lens. A lens in its cell is expected to rattle VERY SLIGHTLY. This avoids squeezing the lens in very cold conditions. Which might distort the glass lenses by crushing. Glass has a much lower coefficient of expansion than metal. There are YT videos on telescope lens removal and cleaning but I haven't watched them! I use pointed, screw adjusting, dividers for undoing locking threads. Though professional tools are available. These resemble beam compasses.
  3. I believe the correct procedure is for "the model" to stare lovingly at The Precious. Staring at the camera makes me think of a kidnap victim holding up a Help Me! placard. Do all amateur astronomers have the same appearance? Except for the ladies of course. Then why do I suddenly feel like a clone! 🥸
  4. All that glisters.. The alleged prop would have a wilful desire to head nose up or tail up entirely at random. The geometry is terrifying! The absence of a humble cog only the last straw. In the battle for damages. When the heroin is summarily decapitated and then catapulted out of the nearest window by said prop. There used to be saying that authors should write only about what they know. To avoid hideous and hilarious mistakes transparent to all those in the know. Somehow the entertainment arts have forgotten this solemn lesson. Wilful ignorance is only the least of their sins. They had only to ask the local photography shop for expert advice. To avoid the zillionaire, bent on world domination. From performing with a cast-off from the props department. More reminiscent of the finest wares in the 10p jumble tub. At the local, backstreet, charity shop. 🙃
  5. Breathing on a lens is likely to deposit fat droplets full of bacteria, viruses and who knows what else. My fuzzy logic suggests that imbibing a spirit alcohol prior to spitting on the lens would be beneficial. The timing of said consumption, prior to the act of deposition, is crucial to the longevity of one's pride and joy. Too soon, and wayward behaviour including false confidence in one's mechanical dexterity are at serious risk. Too late, and the precious fluorite element may simply dissolve before your very eyes. Or appear to do so.
  6. You captured incredible detail in the major spot active region for a full disk! Light bridges everywhere! No need for close-ups when a few clicks expand the image in all its glory! Congratulations on truly exceptional images.
  7. That is pretty remarkable! You even managed to cram it full of spots this time!
  8. These rings show a difference in radius between two closely spaced lens elements. Provided they are central I'd ignore them, or admire them, according to personal taste. Even if they were off centre this might only be the result of your viewpoint relative to the optical axis. Newton's rings are used by optical workers to compare radii and to measure the flatness of plane surfaces under monochromatic light. Monochromatic light used to be easily available under every orange street lamp. Now less likely with updated tech and different spectra.
  9. You can easily tell that astronomy is a science: Unlike astrology. Which is a faith based religion. Every new probe or instrument reinvents our understanding. You could say that, if you live long enough, almost everything "up there" is further misunderstood. Teaching astronomy is best done virtually. By the time a book come out it is only of historical interest. It's lucky we no longer imprison the last generation for blasphemy when their theories prove inadequate. We were and always will be, working in the dark. 😉 Our constant progress is an insider joke within the broad subject matter. We should acknowledge this with a wry grin. Because every newly published paper ought to begin and end with a . That emoticon which best describes a visual astronomer whom is in on the joke. Whether they favour their right 😉 or their left eye. By next week the object of interest in our eyepiece, or camera, has already changed and has been changed by our constantly advancing wavefront of knowledge. 😉
  10. For lightweight OTAs the single weight on a kinked arm makes sense. Tripod clearance is only an issue pointing near the horizontal. The steeper the altitude pointing angle the more clearance is achieved. Some Manfrotto camera heads have a torsion spring. I found mine totally inadequate away from the horizontal. The so-called gimbal heads are vastly better with heavier loads. The OTA carrier can usually be fine adjusted vertically to be neutrally balanced in the vertical plane Ironically the gimbal head creates clearance problems with increasing altitude. I used my gimbal head for solar with my very heavy Lunt 60MT and 90mm spotting scope. The gimbal heads do not provide slow motions but have dropped considerably in price. FLO does not list gimbals heads but I recommend them where slow motions are not needed.
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