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Alpollo

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About Alpollo

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    Nebula

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    Canada
  1. Alpollo

    Cosmo Cafe

    That isn't too bad, I could live with that balance point. That looks like an awesome scope, are you still using it? I think my mirror only weighs about a pound, it should be here this week. Hey SkyBadger, are you still using your mirror grinding machine? Would you build that style again? Would you do anything differently? I am for sure going to build a turntable, I'm just undecided if I am going to animate the over arm or not.
  2. I don't know of one that has the proper dovetail, but if you can't find one you could try making one. With this adapter in the link, a 1/4"-20 tap and a old piece of dovetail and your all set. That is basically all they do for the "cold shoe" extensions, except they obviously use a different extrusion. If your dovetail is thin enough, maybe you could just drill a hole and put a nut on there. https://www.bhphotovideo.com/c/product/860269-REG/Revo_sa_cs_14m_Hot_Shoe_to_1_4.html
  3. Look at the Ampere Hours (aH)or Milli-ampere hours (mAh) that your battery is rated for. Figure out the charging rate of your charger, it will also be measured in mAh etc. 12v - 1mAh charger would take 10 hours to charge a 10mAh 12v battery. Other then that, it's a bit of guesswork as a weak 12v lead battery may read 12v with no load, but it's capacity is not yet restored. With a typical car battery charger, it's usually charged when the needle drops to a plateau for a while, however it will always accept a trickle charge so this isn't really definitive. Example when the battery is dead, it may draw 6 amps from the charger at first, then slowly drop and hover around 2 amps. At that point it is "charged" enough at least to be able to start the car, the alternator will eventually restore the capacity if it was in fact undercharged. This is generally speaking for solid lead acid type batteries, other types of rechargeable batteries require different techniques and precautions. These chargers may sense when the cell is full and shut off as to not overcharge. SLA batteries seem to be able to sit on a trickle charge for some time with no harm, but read your specific directions for your products to be sure.
  4. If I wanted a pier, I would design a mould from plywood and cast a concrete pier using some of the principles from that video I posted in the other thread. Like the base for a concrete bird bath. Saves the hassle of working with metal, it's cheap, kinda portable, it could even be used as a bird bath when the scope is not being used. If you don't want it any more, just could just break it up and bury it. When that fellow in the video made the point about oscillatory vibrations looking like bad seeing, that was when it kinda sunk in for me that it's not just a pole in the ground. It needs to be a dampening machine not an oscillating bell.
  5. Alpollo

    Cosmo Cafe

    EDIT: I forgot to say sorry to hear about your mount, that's tragic!
  6. There is a guy on youtube called "Astro Engineering" with some great videos that addresses the problem with "convetional" telescope piers. IMO these are excellent videos and just what you are after. Everybody should have a look. You might be surprised how bad your pier is. I know it turned me off of a lot of designs. Anti-vibration observatory piers Part 1 Anti-vibration observatory piers Part 2 Oscillatory vibration in telescope piers
  7. Indeed it may be a AP vs visual thing. I've tried to image at 750mm on my wooden deck, I literally had to hold my breath, not kidding, everything was making the scope move. Even when I image at 75mm (50mm on a crop sensor) with a tripod on grass, I have to walk extremely gently or it will ruin the sub. I start the exposure, then moonwalk about 15' to 20' away to my awaiting coffee. Even a 12lbs dog running within 8' of my tripod will disturb it at 50mm. This is why I say you should have your pier decoupled from the pad for maximum effectiveness. Mass aside, concrete is good at passing vibrations.
  8. Alpollo

    Cosmo Cafe

    I might do something like a folding OTA for a larger visual scope. This scope is more of an "on demand" type of thing, so even if I had a way to fold it robotically, I suspect it would still need collimating.
  9. The data on that website shows wide footings because most of the weight is downward with a brick house, no torque really to speak of. A wide footing distributes the vertical pressure reducing PSI on the soil, downwards. For any given amount of concrete, it will resist torque better if it is long and deep vs square. It just has to be wide enough. Decks around here are supported on ~10" - 12" round sonotubes and they don't sink with 1000s of pounds above, so that should be sufficient surface area for a telescope. A 12" x 48" deep hole or sonotube with a bit of rebar would only take about 1/10th of a meter of concrete and probably be just as effective in most cases as a big 1m block. Ultimately I guess it comes down to whether you are digging the hole and mixing the concrete by hand, or having machines do it.
  10. Just to add what others have said. Where I live, you have to put such things 48" down if you don't want them to be pushed about by the frost. It wouldn't take long to use up a meter if you expand this pier block to also become your observatory floor. That being said, 1 cubic meter might be overkill, especially if you neglect the pier. All the concrete in the world won't fix a vibrating pier, it might even make it worse. I don't know if there is a rule of thumb, but 10:1 seems to be a reasonable starting point. This would mean a 100lbs of scope and pier could use ~1000lbs of concrete. In that case I might think that 3915lbs is overkill perhaps underutilized. The way most piers are designed, they won't see any practical benefit from being bolted to 4000lbs vs 1000lbs they vibrate too much on their own. For those purchasing ready mixed concrete, the minimum is usually 1 cubic yard or meter, so perhaps that is why that volume is used often. Why not it's easy to do if the hole is there. IMO I would prefer to not have the pier block connected to the observatory floor. I would prefer to use a block 18"-24" wide and go deep. This helps to decouple your footsteps from the telescope. The floor should be a separate ~3" pad if you want one, separated from the pier block with an air gap. If you are visual only observer, these details wont matter as much.
  11. I like the idea of putting some wheels on it if you just observe from the yard. Your scope looks like it retracts to a fairly compact form. The biggest wheels you can fit will reduce the effort needed to cart it through the grass. If you like to travel, I would get a short, fast 6" Newtonian with coma corrector and rely on the eyepieces for extra reach rather then the native focal length. A third choice would be a nice refractor like the Orion ED80 etc, but I'll admit it doesn't have the aperture to please me and really isn't any more portable then a small Newt. Another option might be some sort of binoscope. Seems like they would give great views for a relativity compact size.
  12. Generally the charging rate is less then the discharge rate of devices, in that case the fuse won't be harmed by charging through it. Adding a second smaller fuse to just the charger is up to you, as the other fuse might be too large to protect your charger, generally speaking.
  13. Alpollo

    Cosmo Cafe

    Yes it is just a little guy. I have come across the Skybadger mount quite a few times, nice work. I look forward to seeing how it works out with the RA motor. Originally this was going to be based around a 12" primary, but the physical size pretty much required a full size observatory. I would like a full size Obsy one day, but it's not feasible at this time. Hence I thought I could fill the void with a little remote robotic observatory that only stands 4'-5' high.
  14. Here is the telescope project I am currently working on. The big picture is to have a 900mm Newtonian on a Bailey split ring equatorial mount. The rig will be used in a backyard mini remote observatory and also be portable. I may put it on a small trailer I have, I'll have see how "portable" it is first. I might be able to just put it in the back of my SUV if it's not too heavy, then just mount light duty wheels on it for carting it around the yard. Most of the time it will reside in the backyard, under cover of a mini remote observatory, well that would be nice anyways. At the very least it will have a small enclosure to protected from the elements and to keep it ready for imaging. I won't go into details on how I am going to control everything, because I don't know yet. I do have a generally layout for the scope cobbled together. It is a Serrurier truss ~900mm f/6 150mm. I'm going to try to keep the trusses symmetrical front to back, but the COG may change depending on how things weigh up. When my mirror blank gets here I will be able to start building my mirror cell. I've already got that part more or less figured out. I'll fine tune the drawing based off of actual measurements, right now I've just drawn a 6" nominal blank. It is a moving mirror frame with roller edge support like what Lockwood and JPastro use on their big mirrors. I've just made mine under-hung to line the COG of the mirror over the collimation points. I am going to grind the primary and fashion a secondary elliptical mirror from Zerodur flats. It has a 1.2" /1.92° diagonal 100% illuminated area which will cover a cropped DSLR sensor using a 2" secondary. The central obstruction is 33%. I'm flip-fopping on the focuser right now. Ideally it's going to be stepper driven kind of flat Crayford dovetail sled thing. The nice thing about this concept is I don't need a T-ring or anything, perhaps just a field stop baffle, the camera would be mounted by the 1/4"-20 connection on the camera. This plan might be temporarily diverted in favour of a simple manual helix focuser. My DSLR is a Sony, so I can't go crazy just yet until I know how to get the Sony working with autofocus, remote imaging etc, if it's even possible. It's looking like I'll have to get a new camera down the road at some point and build the custom sled then. This means I will probably make the front half of the OTA removable to accommodate an upgrade, which is less then ideal but perhaps the pragmatic thing to do. The helix and T-ring would make attaching a collimation cap possible, I wasn't sure how I was going to collimate the DSLR on a sled using live view, though I'm think something could be sorted out when I go that route. The focal ratio was chosen as a balance of field of view, tracking abilities, ease of mirror fabrication and dependencies on correcting optics. I was originally considering f/4 or f/5, but this requires a higher degree of skill and effort to make the mirror and makes the mirror tied to a comma corrector. I would prefer to have all reflecting optics only. I don't want my fancy pants mirror to be dependant on a refracting lens, that would be blasphemy. lol. I'll save the coma corrector purchase for a big fast visual scope one day, my mirror is small and not visual so why battle coma. Also with f/6 I'm hoping is going to have a decent field curvature plane vs a faster mirror for my DSLR sensor. It will be made from 17.5mm/~3/4" Baltic Birch plywood. The OTA below is ~900mm/36" long and 305mm/12" in diameter. Baffling will be added and fine tuned later on. I'm really only concerned with 100% FIF but in reality it's very close to the 75% illuminated diameter in this configuration, so will just go the the 75% baffle diameters that Newt for the web gives me. It is a fun project.
  15. I will put some coffee on and check out some videos, thanks.
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