Telescopic Accessories: Fill & Download for Free

Get an telescope catalog (When I list some I am not advertising I swear) and look at the technical specifications. If you don't know what a specification (spec) means look it up you obviously have internet to be on Quora. here are some catalogs:1) Telescopes, Telescope Accessories, Outdoor and Scientific Products by Celestron2) Classic Telescope3) Orion Telescopes: Request a Catalog

The Backyard Astronomer's GuideThe modern classic, completely updated.The newest edition of The Backyard Astronomer's Guide includes the latest data and answers the questions most often asked by home astronomers, from beginners to experienced stargazers. Terence Dickinson and Alan Dyer provide expert guidance on the right types of telescopes and other equipment; photographing the stars through a telescope; and star charts, software and other references. They cover daytime and twilight observing, planetary and deep-sky observing, and much more.With over 500 color photographs and illustrations, The Backyard Astronomer's Guide is one of the most valuable, beautiful and user-friendly astronomy books ever produced.New and updated for this edition:A 20-page full-color Atlas of the Milky Way provides location and context for hundreds of celestial objects mentioned throughout the book.A chapter on Astrophotography with Digital Cameras specifies what equipment works best and how to use it to collect a color gallery of celestial portraits.Telescopes for Recreational Astronomy features assessments of a wide range of new telescopes, from models for beginners to those for veteran astronomy enthusiasts, with special emphasis on computerized telescopes and how they work.Accessory Catalog spotlights the best of the accessories and flags the frivolous and irrelevant.Three practical appendices: Polar Aligning Your Telescope; Optics Cleaning and Collimation; Testing Your Telescope Optics.Any serious home astronomer must have this superb guide as an ongoing reference.

I see questions like this a lot. A lot of people think that computerized (what we call GoTo) functionality makes using a telescope easier and better. But, in fact, it’s more complicated than that. For the most part, however, and particularly for beginners, the truth is that a GoTo telescope is NOT always a great option.Let me give you an example. I have several telescopes. My primary telescope, which I use for astrophotography, is on a GoTo mount. About a year and a half a go I built a small roll-off roof observatory in my back yard so that I could keep the equipment set up all the time. Prior to that, if I wanted to use it, it would take me between 60 and 90 minutes to set up. Some of that was for the added photography equipment and time to align the telescope more precisely, but a lot was just typical setup. Here’s what I had to go through:1.) Haul everything to the back yard in several trips. The main components are the tripod, the mount head, and the OTA (the scope itself). I have a handful of plastic footlockers which contain my finder scope, power cable, extension cord, power cable, hand control, eyepieces, and lots of other widgets. All told, it was usually up to 8 or 9 trips from my garage to my back yard. The additional stuff for photography was only about 3 trips, so let’s say 5–6 for the scope and its necessary accessories. This all took around 10 minutes.2.) Set up the tripod and attach the mount head, then level and attach counterweights to the counterweight shaft on the mount head. For just observing, precision leveling isn’t critical. I could do this part in about 5 minutes. But sometimes leveling out those legs is a pain.3.) Unpack and attach the OTA. The OTA I was using at the time was an 8″ Schmidt-Cassegrain telescope. I also have a rear-attaching Crayford-style focuser. I unpack the OTA, set the dovetail connection in the saddle on the mount head, and tighten the screws to clamp it in place, then screw on the focuser. 5 or so more minutes.4.) Unpack and attach the finder scope and Telrad. I use a bigger finder than most people would - an 80mm refractor. I have to attach a set of tube cradle-rings then attach the finder. Admittedly, this takes longer than most people would - common finders have a simple attachment and take a minute. I’d take 5 or so. The Telrad is a non-magnifying finder. It only takes a few seconds to attach.5.) Run the extension cord and plug in the power cable. I always made sure to wrap a loop of the power cable around the tripod leg and make a knot. This way, if my foot snags the cord in the night, I don’t yank it out of the scope, definitely shutting it down and possibly damaging the connector. All told this takes about 5 minutes.6.) Attach the hand control and declination cable, Unpack the eyepieces and insert the eyepiece diagonal and an eyepiece. About 5 more minutes.7.) Power on the mount and let it start synchronizing the GPS. Meanwhile, balance the RA and Dec axes. Balance is important for this kind of mount. To do this, you unlock the clutch on the RA (usually you start with RA), and adjust the position of the counterweights so that the mount is neutrally balanced. An out of balance mount is hard on the motors and can actually damage the gears. Once the RA is balanced, you balance the Dec, which can be more difficult because it often requires shifting the position of the OTA in the dovetail saddle. All told this normally took 5 mins but could be longer.A couple notes here: first, not all scopes have GPS. For those that do, you don’t have to worry about inputting your lat/long coordinates, nor the time - just confirm. If you don’t have GPS, you’ll need to do that, which probably adds 5 or so minutes.Also, my mount has a special balancing routine in the hand control. This takes more time to use, but is more accurate. It probably takes me closer to 10 minutes, sometimes more, to balance, but I’m getting a better balance, which improves the GoTo accuracy.8.) Assuming it’s dark enough, polar align. This can take several minutes. For an equatorial mount such as mine to provide accurate tracking and GoTo performance, the right-ascension (RA) shaft must be aligned to the celestial pole, in my case the northern celestial pole (which is near, but not exactly on, the star Polaris). This requires looking through a little scope that’s mounted in the shaft and making minor adjustments to the mount’s altitude and azimuth controls (which are only used for this alignment process). If I’m just viewing visually, this doesn’t have to be too precise (even aligning right on Polaris can be good enough for a night of just viewing). For photography, I need to be very precise and often spend another 20–30 minutes doing a drift alignment procedure which refines the alignment considerably. But for plain visual, let’s call this 5 minutes (which is fast).9.) Align the finder and Telrad to the OTA. To do this, I typically would point the scope at a distant streetlight or radio tower (a cell tower a few miles away with a red light on top works great for me). Then I look through the finder scope and adjust it’s alignment so it’s centered on the same light. Lastly, I do the same with the Telrad. All told, this is about 5 more minutes.10.) Star-align the scope. Inside the computer in the hand control is a model of the sky above me. When I power it up and give it proper GPS coordinates and and accurate time, it knows, relative to where I am, where everything in the sky above me SHOULD be. But minor errors in polar alignment, GPS coordinates, and time and date entry can throw it off a little. Every GoTo scope I know starts out with a star-alignment process. Typically you start the telescope in a known position (usually with the RA axis set so the counterweights are pointing at the ground and the scope is directly on top and the Dec axis set to due north, 90º. On the hand control, then, you select a star (almost always by name) from a list and the telescope moves to the position it THINKS the star should be in. You then look through the scope and make any minor adjustments, if needed (which they will be), to center the star in the field of view and then acknowledge this on the control pad. Most scopes require 2 or more such stars, and the more you add, the more accurate your GoTo performance will be. This usually takes another 5 or so minutes.Once this is complete, in theory at least, you’re ready to observe.Adding this all up, it’s about 55 minutes or so - about an hour from start to able to observe (and at least another 30 minutes for setting up camera equipment).Now, some of this could be shaved down, depending on the equipment. But if you were to get something like, say the Celestron Advanced VX with the C8 OTA, you’re looking at a good 30 - 60 minutes from start to viewing.I also have a 10″ Dob. Let’s look at setup for that:1.) Haul it out to the yard. I keep mine on a furniture dolly, so it’s easy to roll out of the garage. It has two main components: base and OTA. Throw in one container for finder, Telrad, and eyepieces, so it’s 3 trips to the back yard from the garage. 5 mins or less.2.) Place OTA on base. A few seconds.3.) Attach finder and Telrad. 1 minute.4.) Add eyepiece. A few seconds.5.) Align the finder and Telrad with the main scope: 5 mins (or less).Done.Add that all up? about 10 minutes, or less. That’s ALL it takes to set up a Dob.I should add that checking and adjusting collimation is a good idea here. Technically, that’s true with the SCT too, but SCTs hold collimation much better than the Newtonian OTAs of Dobsonians telescopes. Collimation is the proper alignment of the optical components of the telescope. An experienced user can do it in just a few moments. If you take care of your telescope, you should only need to make some minor adjustments. Many users have laser collimators to aid them. With my laser collimator, I can get it fairly close to proper alignment in about 5 minutes or less. If I want good collimation (which improves the view), I can take a few additional minutes to refine the collimation on a star. This can take a little bit longer, but, again, experience is the key. Still, even with good collimation, it should take less time to set up.So, the clear winner here ease of setup is the Dob. I should note, however, that I’m referring to solid-tube Dobs here. If you have a trus Dob, which are made to disassemble for transport or storage, the setup time is closer to that of an SCT (though I know a guy with a huge 36″ trus Dob that can be up in running in less than an hour including hauling it out of the trailer required to transport it).Now, for performance.For visual astronomy, the most important consideration tends to be the telescope’s aperture - the diameter of the primary mirror or objective lens of the scope. This dictates how much light the telescope collects, and that’s what an astronomical telescope is for - gathering light. Magnification, while it can be useful, is a secondary concern, and one we have some control over. But you cannot adjust aperture (well, you can reduce it, but you can’t increase it without buying a bigger scope). Obviously, 12 inches is larger than 8. The important thing here is not the diameter, but the area of the aperture. In the case of an 8″ (203mm) mirror, you have about 32,500 square millimeters (mm^2) of light gathering area. In the case of a 12″ (305mm) mirror, you have almost 73,000 mm^2. Thus, a 12″ mirror has about 2.25 times as much light gathering area as an 8″ Telescope. That’s a pretty big difference and will dramatically affect what you can see with the telescope. Furthermore, a larger aperture provides more detail resolution when trying to view the moon and Planets. Most 12″ Dobs have focal ratios around f/4.5 to f/5, so the one area the 8″ SCT actually might perform better is in contrast. But in nearly every other category, the 12″ beats it out significantly.As I said at the beginning, GoTo isn’t always a great option. First of all, it can be a little misleading. I see advertisements for scopes all the time which say things like “able to find over 40,000 objects!” This sounds impressive. 40,000 objects is a pretty good database. However, just what ARE those objects?110 of those will be Messier objects. 8 Will be planets. Then there’s the Sun, Moon, Pluto, and possibly a few asteroids. Add to this the NGC and IC Catalogs, which total about 13,000 objects or so. Let’s round this all up to 13,500 objects. Depending on the database, the rest are most likely going to be stars (frequently doubles and variables and a proton of the SAO catalog). But how many of them can your scope actually see? You can probably see all 110 Messier objects in an 8″ SCT (depending on your location and light pollution). You can see all 8 planets, the sun (if you have a solar filter) and the moon. You MIGHT just barely see Pluto. From a pretty dark location on an amazingly clear night, I saw Pluto in a friend’s 8″ SCT… it was VERY faint and took a while to see through averted vision). You can see a good number of NGC objects. But most likely you will not be able to see all 40,000 objects in your catalog. You can use the hand control to point you at them all, but just own’t see a lot of them.And this then comes to my last major point: the observing experience.When you use a Dob and have to star-hop to find an object, the experience is enhanced. You become much more tuned to the sky above. By having to take the time to find patterns and use them to move to your target object, you end up taking in a lot more of the sky than you realize. You often see things you never expected to see - serendipity is part of the fun of star hopping - and actually have a more connected experience to your telescope. It becomes more an extension of your eye AND your mind.A GoTo scope removes a lot of this from the experience. You tap a few buttons and the scope moves to the new target, and you look through the eyepiece. You don’t end up seeing the sky around your target, not much, just the field of view containing the object. You focus in on just the object itself and miss out on the richness of the sky in general.Worse still, a lot of GoTo users don’t even take the time to really observe. They peek. They bring up an object, take a look for a minute or two, say wow, and go on to the next object. If you star hop to find an object, you are more invested in the object you found, and tend to spend more time really soaking it in. This, of course, isn’t universally true, but it’s very common in my experience (I’ve been guilty of it myself).Among the many serious amateur astronomers I know, the bulk of them use Dobs. Actually, the two most experienced observers in my club, an older retired couple, have matching his and hers 12″ Dobs.Before buying anything, however, I have one recommendation: join a club. There’s probably one near you, and joining them offers several benefits. In the US, membership usually runs $50 or less per year, and most clubs have people that enjoy helping new members learn more about telescopes and using them. Most clubs have regular star parties, and at such events you’ll get a chance to see a variety of telescopes in action and talk to their owners about their pros and cons. You might even find someone selling a telescope to fund their next purchase (I’ve bought most of my equipment this way).Good luck and clear skies!