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OpticsBlog – Thoughts and reviews of binoculars, telescopes, scopes, sights, and much more - birdwatching, astronomy, target shooting - pretty much anything related to optics, nature, and life!Wednesday, August 31, 2011Telescopes for planetsI’ve blogged many times about what an excellent target the moon makes for telescopes and even binoculars when you find yourself stuck in an urban or suburban area and have to fight light pollution to do any astronomy at all. I’ve been reminded that I haven’t mentioned planets as much as probably should have, though, as equally suitable objects for urban observers. Planets are ideal objects to observe for urban bound astronomers, no doubt about it. For one, planets tend to be plenty bright, so they are little affected by light pollution - you may not be able to see faint stars from your urban location, but you will be able to spot planets in the night sky. For another, urban skies are typically better than rural skies for atmospheric stability (thanks to smog and so on) and atmospheric stability is essential for the high magnifications we usually use to see planets. To begin, when we talk about observing planets with a telescope and seeing detail, we are really only talking about the big three, namely Jupiter, Saturn and Mars, with Mars coming in a very distant third, detail-wise because of its small size. Other planets are either too small or too distant or, in the case of Venus, too covered by clouds to show detail. Telescopes for planets don’t need to be huge (Jupiter is almost painfully bright in my 12.5" Dobsonian telescope, for instance), but they do need to be large enough to produce good image quality at magnifications of 150x and more because that’s where you’ll be to get enough planetary image size to be interesting. I’ve done this on telescopes as small as 80 mm, but those were high grade 80 mm APO refractor telescopes, not typical 80 mm beginner telescopes. if you can afford it, 4 inch (102 mm) to 6 inch (150 mm) telescopes are much better choices for observing planets. When you hit 200x, though, the atmosphere becomes a limiting factor on what you can see, so going larger than this to handle higher magnifications may or may not pay for itself. Motorized mounts that keep the image in the telescope eyepiece are a huge plus for observing planets. Tracking at 200x, manually, is tricky even with a good manual telescope mount and all but impossible with a cheap telescope mount. Indeed, 200x is no place to be with a cheap, wobbly tripod and mount and that’s what you all too often get with beginner telescopes. If you have to make a choice between a large telescope on a poor mount and a small telescope on a good mount, go with the good mount. Trust me, one night of observing planets with a crummy mount will do more to convince you how important a good telescope mount is to success in astronomy than anything I can write. More on planets in future blogs. I promise. Tuesday, August 30, 2011Short focal length refractor telescopes One of the many advantages of astronomy binoculars compared to a typical telescope is the wider field of view in the binocular. This “big window” view offered by binoculars makes them ideal for observing the big stuff in the night sky, such as large open star clusters and huge nebulae. Typical telescopes just can’t down low enough in magnification to see these objects in their entirety, a classic example of not being able to see the forest for the trees. On the other hand, with the exception of a few specialty binoculars and zoom binoculars (always poor, optically), you are stuck with one and only one magnification with binoculars. That means you'll need to setup & use a telescope if you want a closer look or if you want to see smaller objects in the night sky. Wouldn’t it be nice if you could find an instrument that could provide both wide fields of view and the option of higher magnifications when you want to look at the small stuff? It's called a short focal length refractor and nothing is as versatile. These refractor telescopes typically have a focal length of 600 mm or less. My little 80 mm refractor, for instance, has a focal length of only 480 mm. With my Televue Nagler 22.0 mm eyepiece, I get 22x and a field of view that is comparable to a typical 20x80 astronomy binocular, such as the Celestron Skymaster 20x80. When I want much more magnification, though, I can add my Televue Radian 3.0 mm eyepiece and get a whopping 160x. Now that’s versatility! Short focal length refractors are also offer easy handling due to their short optical tubes. Is there a drawback to these short focal length refractors? Oh, yes, cost. To make a short focal length refractor to the same optical standards as long focal length refractors is very expensive. The best of this breed of refractors are typically made with special glass and usually have labels such as APO, ED and so on. Yes, you can still buy relatively affordable short focal length refractors if you are willing to sacrifice some optical performance, but if you want sharp, clear and crisp all the way across the field of view, you will have to pay. Nevertheless, inch for inch of telescope size, there is no finer view in the telescope world than that provided by highly corrected short focal length refractors (and inch for inch, nothing more expensive, either). Monday, August 29, 2011Good spotting scopeI’m an optics addict and I’ll be the first to admit it. I drool over good image quality, regardless of whether I get it from fine binoculars, spotting scopes, telescopes or digital cameras. Show me the view that only great optics can provide and I tend to lose self control when it comes to the checkbook. In my opinion, the view you get from a premium spotting scope is the one that will most likely cause you to abandon your good sense. Yes, the image difference between fine birding binoculars and average quality binoculars is noticeable and so is the difference between good telescope optics and so-so telescope optics, but it pales in comparison to the difference between great spotting scope optics and cheap spotting scope optics. I’ve witnessed this plenty of times on birdwatching outings where several birders are carrying various brands of a birding spotting scope mounted on tripods and everyone compares their spotting scope to the next one in line. I can’t even begin to list all the “Whoa” comments I’ve heard when some birders get a chance to see what really good (and, unfortunately, very expensive) spotting scopes can do. So, consider this a warning if you love good optics and have never had a chance to see what a premium spotting scope can do. Once you do, there is a very good chance that your budget is going to take a hit. Astronomy challengeI often wonder why so many of us astronomers can’t resist a challenge. Why is it that we seem to go out of our way to put some lesser known, and certainly not too visually impressive, objects in the telescope eyepiece when there are so many impressive objects that are much easier to find? Is it because we like to challenge our observing skills or is it because we like to push our telescopes to the limit to see what they can do? I think I speak for many of my astronomy brothers and sisters when I say it is both. There is something quite satisfying about finally spotting a faint, tiny planetary nebula or galaxy after many tries, even though typical non-astronomy folks would probably remark, “You went to all that trouble just to see that little nothing of a smudge?” Yes, we would, because the thrill of the hunt is a big part of what keeps us old timers coming back to the telescope, year after year. That, plus the fact that there is so much to see. I suspect I could setup & use a telescope for another forty plus years and still not see it all. May it ever be so. Friday, August 26, 2011August nights with the telescopeIt may seem a little out of place to be thinking Blue Snowball in late August, but August is actually a good time to look at the Blue Snowball. I’m talking, of course, about the Blue Snowball nebula in the constellation Andromeda, which is now high enough in the sky to provide a good view for those who want to explore its astronomical treasures with astronomy binoculars or telescopes. To see the Blue Snowball, you will need a telescope. This planetary nebula is plenty bright enough to be seen in even average sized binoculars, but it is simply too small to appear as anything but a star without the magnification you get with a telescope. The good news is that even a small telescope will show reveal a small round disk with just a tinge of blue color under good conditions. For instance, in my 80 mm refractor telescope at about 90x, you definitely know you have something other than a star, but the image in the telescope eyepiece is quite small. The nebula is definitely there, but, once I have located it, I push the magnification up a bit more. In my 12.5” Dobsonian telescope, the Blue Snowball really struts its stuff. With my Televue Nagler 17.0mm eyepiece behind a Televue Big Barlow for 187x in that scope, you really appreciate the name, Blue Snowball. It is worth pulling out the big telescope for this one object, alone. Of course, since you’ve already gone to the trouble to setup & use a telescope, might as well check out some of the other great sights in the Andromeda neighborhood. Love these August nights with the telescope! Thursday, August 25, 2011Spotting scope zoom eyepiecesZoom eyepieces on spotting scopes are not all created equal. In fact, it’s not even close. Just as there is nothing as optically bad as a cheap zoom eyepiece found on inexpensive spotting scopes, there is nothing quite so optically delightful as some of the zoom eyepieces found on premium spotting scopes. So, okay, why not take that zoom eyepiece on my inexpensive spotting scope and replace it with a good zoom eyepiece? The problem is that you don’t get that option on inexpensive spotting scopes, because (a) manufacturers don’t offer optional eyepieces on spotting scopes much under $600 or so and (b) even if they did, you’d still be stuck with what the manufacturer offered because spotting scope eyepieces are not interchangeable between one brand to the next or even between different spotting scope models in the same brand, in some cases. Nope, even if you could afford the fabulous Swarovski 25-50xWW zoom eyepiece, it won’t fit in that budget spotting scope. If you want to use that eyepiece, you’ll need to use it in one of those great Swarovski spotting scopes. In other words, unless you are willing to spend a goodly amount on a spotting scope, you are stuck with the zoom eyepiece that comes with the spotting scope. There are exceptions in spotting scopes that allow the use of telescope eyepieces, but these represent a small minority of spotting scopes on the market and, in the world of telescope eyepieces, zooms are relatively uncommon. All in all, the quality and performance of the zoom eyepiece on a spotting scope is the first thing that gets my attention. It is the deal breaker one way or the other when I choose to buy a a birding spotting scope. Wednesday, August 24, 2011Telescope maintenanceAre you the type that is rough on equipment or the type that doesn’t want to be bothered with a lot of routine maintenance? If so, you need to factor this in when it comes time to choose the right telescope. Absolutely, some types of telescopes require more in the way of care and feeding than other telescopes. Telescope maintenance is not difficult, but some types require more maintenance than others. Refractor telescopes are probably the most rugged and maintenance free. All it takes is a little cleaning of the objective lens (front lens) with a lens cloth and only when the lens becomes dirty enough to affect performance. Less is more when it comes to touching a telescope lens or mirror – every time you touch a lens or mirror you risk a scratch. Schmidt-Cassegrains, Maks and even Schmidt-Newtonians with their corrector lenses that serve to protect the internal optics from exposure to the open air are not too far behind refractors in the maintenance department and, like refractors, make great choices in the smaller sizes as grab and go telescopes. And that brings us to reflector telescopes. Yes, reflector telescopes are the poster child of telescope maintenance, but they are easily the most practical telescope for a beginner on a budget since they remain the cheapest telescope design per inch of size and size is the most important factor in telescope performance. For many of us, then, the reflector telescope is our ticket into the big telescope game. So what is the issue of maintenance with reflector telescopes? Is it as bad as many beginners are made to believe? Absolutely, not. The most common issue maintenance issue with reflector telescopes is collimation – alignment – of the mirrors. If you want your reflector telescope to perform at its potential best, you need to learn how to collimate your telescope. However, collimation is one of those things that looks intimidating when you read about it, but when it comes to the actual doing, it is no big deal, especially now that we have laser collimators. I collimate every time I use my reflector and I only have to do that because I must wheel my reflector over some rough ground to get where I want to observe. That shakes up the mirrors a bit. If you can baby your reflector, you will need to collimate it much less frequently and, besides, collimation typically takes only a minute or two unless your mirrors are badly out of whack. The other issue with reflector telescopes is that open tube, which exposes the mirrors to the elements, especially dew. Dew, when using reflectors, is, frankly, a pain in the you know where. The good news is that you can easily attach dew heaters to the mirrors to fight this and they do the trick, quite nicely. You will also need to remove the mirrors every once in a great while to clean them, but, again, just a matter of experience and no big deal. All in all, I think it is a huge mistake to let the maintenance issue of reflector telescopes bother you, but if you are the type that doesn’t want to touch your telescope beyond changing a telescope eyepiece and focusing, one of the other telescope designs is a better choice for you. Tuesday, August 23, 2011Telescope magnification A lot of beginners in astronomy, not to mention folks who have never done astronomy, mistakenly believe that astronomy with telescopes is all about magnification and a lot of it. Nothing could be further from the truth; in fact, even with very large telescopes, magnifications used tend to be on the low side. High magnification does have its uses, to be sure, but on my 12.5” Dobsonian telescope, I only rarely use more than 150x for the things I most like to see – deep-sky objects (star clusters, nebulae and galaxies) and 100x or even less is common. That’s not a lot of magnification, considering my Dobsonian telescope has optics that can easily handle 300x when conditions are right, though seeing conditions seldom allow me to use that much magnification, effectively. In other words, I tend to be conservative with magnification. Given a choice, I’ll take a telescope eyepiece that provides low magnification over a telescope eyepiece that provides high magnification, any day. Why? Keep the magnification down and the telescope is easier to use, both when it comes time to locate objects and when it comes time to track objects. Besides, most of the things we astronomers like to see are large enough. The problem is that they are often too faint to easily see. You solve that problem with telescope size, not magnification. Telescope size, in terms of the mirror size in reflector telescopes and lens size in refractor telescopes is the secret to locating and seeing faint, difficult objects, not magnification. If it was just a matter of magnification, we wouldn’t go to the expense and trouble to setup & use a telescope that is often at the limit of what we can physically carry and move. If a little is good, a lot is better is NOT something that applies to magnification in a telescope. Keep that magnification down. Monday, August 22, 2011Deer in the binoculars and the yard
We feed wildlife on our property, mostly birds, but if you feed birds, you also end up feeding squirrels and, if you have them, also chipmunks. The squirrels and chipmunks do a fairly thorough job of cleaning up under the bird feeders and, of course, the little rodents will be more than happy to climb right up into your feeders and help themselves unless you do some serious squirrel-proofing of your feeders, which we do, of course. Still, we enjoy watching the furry stuff right along with the feathered stuff in the binoculars and spotting scopes and, of course, all make good targets for digiscoping. We also throw seed corn on our lawn. This serves to distract the squirrels and chipmunks away from the bird feeders, thereby reducing problems, but the corn also attracts deer. Deer are fun to watch, of course, and they make super subjects for digital cameras. Deer can also cause problems, though and some concern about feeding deer is certainly justified, especially if you have gardens. In our area, as in so many areas of the country, these days, if you want to any type of gardening, you must protect your garden with deer proof fencing. Period. That's why I stopped putting out corn on the lawn, this summer. It didn't work. Deer visit our yard every day, with or without us feeding them corn and help themselves to whatever isn't protected by a fence. This didn’t really surprise me. After all, the deer live here and the neighborhood yards are part of their range. We’re feeding them whether I throw corn out on the lawn or not. They are lovely neighbors, though. Friday, August 19, 2011Why I use binoculars, spotting scopes, telescopes I’m sure that anyone who reads my blogs or visits our OP forum and reads my posts (Jne_K) on binoculars, spotting scopes, telescopes or digital cameras, or reads the many how to articles I have written for OP, must assume that I am a techno geek or something. Okay, yes, I have a very detail oriented side to my personality and it has served me well over the years in various professions such as science teacher, writer, musician and so on, but the truth is, I am very much more of a so-called touchy-feely, aesthetic kind of person than a technical person. I use my technical side as a tool to excel at what I love to do, but it is my aesthetic side that motivates me and keeps me going. My birdwatching is one example. If I was just a hardcore birder interested only in keeping lists of the birds I have seen, I would take one look at a bird, add it to my list and move on to the next bird. That is so not me. For example, I have seen probably a million Cardinals in my birding binoculars over the years, but no matter – if I spot a Cardinal, I will always put in the binoculars and ooh and aah and smile. It makes me instantly happy to see something that beautiful. No doubt about it, I could see another million Cardinals and never see enough Cardinals. Same for the things I typically see in the telescope eyepiece. I have seen the Ring Nebula, M57, in the telescope probably about as often as I have seen Cardinals in binoculars, but every time I see this famous planetary nebula, my heart rate goes up and I am instantly hypnotized by its beauty. Problem for someone like me is that there is so much beauty and wonder in Nature to see and life is just so darn short. It’s been one hell of a ride, though. Thursday, August 18, 2011Moon tablesThe moon is in its waning phases this week, so time to start checking moonrise and moonset tables for best times to setup & use a telescope or my astronomy binoculars. Knowing what the moon is doing is critical for success in astronomy with binoculars or telescopes, no matter what type of observing you do. Where do you get this information for your area? I get mine from the weather forecast from the Weather Underground which supplies moonrise and moonset times. If you are using a telescope to observe the moon, this will be a good week. Yes, a partially lit moon is much better for observing than a full moon with its detail robbing glare and lack of shadows. For sure, my small refractor telescope will see some action for the next ten days before the moon is new. Standard procedure here is to follow the terminator – the boundary between the lit and unlit portion of the moon – as it moves across the moon each night. This produces a new and quite different view of the moon every night in the telescope eyepiece. If you do not want the moon in the sky, as when you are trying to observe the faint stuff, you definitely need to check the moon tables. I prefer to pull out the big telescopes and go to work at least a half hour after moonset for my location, rather than trying to squeeze in some observing before the moon comes up. That way I don't have to worry about a rising moon cutting short my time at the telescope eyepiece just when the viewing is getting good. By the time we reach new moon on the 29th, I can log in a lot of hours with my Dobsonian telescope. All this assumes, of course, that I get some clear nights in the next two weeks. Wednesday, August 17, 2011Laser collimator for telescopesTelescopes are, in essence, simple to operate; you aim the telescope at the object you want to see, select the appropriate magnification by choosing the correct telescope eyepiece, focus and observe. Simple, right? Not quite. The secret of getting along with a telescope is in the tuning. It’s the little things that make all the difference. A telescope that is not tuned, correctly, will be difficult to impossible to use to its potential and will be a pain in the butt to use. If you are going to the trouble to setup & use a telescope, you might as well take the extra steps to do it right. On my large reflector telescopes, for instance, I currently collimate the mirrors prior to every use. Why? I have to wheel the telescope over some rough terrain to get to my observing site in the backyard and all that jostling puts the mirrors slightly out of alignment by the time I get there. I paid some big bucks to get the mirrors in this telescope and the optics they provide and I’ll be darned if I’m going to settle for less simply because I am too lazy to take the extra step of adjusting the mirrors, correctly. The good news is that a laser collimator for telescopes makes adjusting the mirrors on reflecting telescopes quick and easy and they are so much more accurate than the old tools we had to use before lasers. Oh, yeah, a laser collimator is one of the best telescope accessories you can buy if you own a reflector telescope. Monday, August 15, 2011Astronomy does not have to be an expensive hobbyAstronomy does not have to be an expensive hobby. Let me repeat that. Astronomy does not have to be an expensive hobby. You can spend as much or as little as you want when buying astronomy binoculars, telescopes or telescope accessories. There is something within reach of nearly any budget. I bought my first telescope, for instance, when I was the proverbial poor, starving college student. On the other hand, astronomy can absolutely be an expensive hobby if you let it. No question about it and I am guilty, as charged. I’ve spent as much on a single telescope eyepiece, for instance, as some folks have on an entire telescope, if that tells you anything. Heck, I’ve spent more on a finder scope for a telescope as some folks have on a complete telescope. Now, then, I am content to spend the money on something I so dearly love, but I get a bit concerned that our amateur astronomy community sometimes scares away potential newcomers with all out high priced gear. We need to supply constant reminders that it doesn’t take a lot of expensive equipment to begin in astronomy. For the most part, I think our astronomy media does a good job in this regard, despite all the talk and advertising hype about high end equipment that tends to dominate the conversations. Still, we all need to do our part and remind folks. Again, astronomy does not have to be expensive. My first so-called astronomy binoculars were nothing more than a common, cheap 10x40 binoculars I bought at a department store for $30. I bought my first telescope in the same place and paid a whopping $60. Yes, I could have made better choices had someone been there to guide me and I certainly could have made more expensive choices, but it was enough - enough to start a love of astronomy that has yet to cool after forty plus years of observing the night sky. Spotting scope view Perhaps it’s because I spent most of my years on the prairie, but shut me off from a view that allows me to see some distance and I get very uncomfortable. I need to be able to see a long way to feel at home. I’ve spent too may years scanning distant horizons with both binoculars and spotting scopes to change, now. It’s in my blood. Gotta have that spotting scope view. Trust me, I had reservations about retiring in the north woods, for this very reason.. Originally, my husband and I were planning to pull up stakes and move out west into the Great Wide Open, but when we found our current place in northern Wisconsin, we just fell in love. When they say woods, up here, though, they really mean woods One of the things that sold me on our current home was a narrow clearing through the forest that provides a distant view across the lake. I have my spotting scope permanently setup near my deck window and have it aimed across the lake. When I’m feeling a bit closed in by the surrounding forest, one look through the spotting scope eyepiece at the distant shoreline across the lake gets me some much needed relief. When I am feeling especially claustrophobic, I grab the spotting scope and tripod and head down to the dock where I can scan a much wider area. Thank heavens trees don’t grow out of lakes. :) Friday, August 12, 2011Small telescopes do have their advantagesI added a good 10x50 finder scope to my 12.5” Dobsonian telescope this last week to aid me in locating some rather obscure and difficult to locate objects in the night sky. It took some tricky counterbalancing on the bottom of the telescope to handle the added weight of the finder scope and its bracket at the top of the telescope near the telescope eyepiece, but all is well and I can’t wait for the next dark, moonless night to really put things to the test. Moonless is not what we have this week, though, since the moon was full over the weekend. That means the big telescope will have to wait its turn to shine and get in line behind my small refractor telescope which I have now assigned to moon duty. Yes, I could use the 12.5” for viewing the moon, but the view is so bright through such a large telescope when the moon is at its brightest as to be actually painful. Besides, my small refractor telescope, being an APO refractor, delivers terrific images of the moon and for darn sure, it is easier to move around the yard than my 12.5”. In fact, if the moon is in the right position, overhead, I can setup & use a telescope like my small refractor on the deck right off my kitchen. Small telescopes do have their advantages. Thursday, August 11, 2011Bird photography techniques
Over the years I’ve done a lot of bird photography, starting with film cameras and telephoto camera lenses, back in the 70s. I then attached film SLRs to spotting scopes and used the spotting scope as a telephoto lens in the 80s and 90s. About ten years, ago, I switched to digiscoping with spotting scopes and small digital point and shoot cameras behind the spotting scope eyepiece. In other words, if there is a way to take bird photographs, I’ve probably used it at one time or another. So which bird photography technique and equipment setup is best? The media you intend to use to view your results is everything and I do mean everything. If you are going for the gold and trying to publish or plan to enlarge and print your results to hang on a wall with the intent to sell, you’ll need the very best and the most expensive super telephoto lenses and professional DSLR in order to compete, simply because that’s what everyone else in the business is using. Dedicated camera lenses with enough focal length for bird photography produce the very best in image quality, but they don’t come cheap. You could buy a pretty good used car for the asking price on some of these lenses. Most of us, though, are not going into business and only rarely do we even print our results. That means we will be viewing our pics on a computer screen and likely sharing via email or posting on the internet. No need for incredible resolution, here, since the resolution of the viewing screen is the limiting factor and the resolution on computer screens, even HD screens is low compared to what is available in cameras. Once on the screen, I have been unable to discern much of a difference between old pics taken with 4 MP cameras (see pic, above) and my more current 12 MP digital cameras. In fact, you can make a case for keeping that resolution down a bit, since it is much more convenient to email and also post smaller files of less resolution than those huge 12 MP files. As for a field technique for bird photos that will only be viewed, digitally, you just can’t beat digiscoping for practicality, ease of use and convenience. Pic quality won’t match up with a ten thousand dollar telephoto lens, but your friends probably won’t know the difference, anyway. Wednesday, August 10, 2011Small telescopes, first telescopesLucky, indeed, is the astronomer that can afford to have more than one telescope, but owning more than one telescope is a fairly common occurrence. Fact is, most astronomers tend to end up with more than one telescope if they stick with astronomy for any length of time. The typical scenario is to start with a small telescope, mostly for the sake of cost, and then work up to a larger telescope, at a later date, for the sake of performance. If you are careful to choose the right telescope as your first telescope, i.e. one of good quality, you will still find it to be quite useful, even after you have moved up to a larger telescope or even telescopes. Smaller telescopes are more portable telescopes and often easier to operate telescopes than larger telescopes. This all translates to more convenience and that convenience can make the difference when trying to decide if you have the ambition to get out and observe after a long, stressful day of work or caring for the kids. In fact, I know several astronomers who actually use their small telescope more often than their super duper large telescope for this very reason. Small telescopes, despite their smaller performance, are also a good match for some types of observing. You don’t need to setup & use a telescope that breaks your back to effectively observe the moon or even the planets. Small telescopes will even allow you to sample the different types of deep-sky objects – star clusters, nebulae and galaxies – though you’ll need the performance of a larger telescope to see these objects in good numbers. With the moon nearing full moon tonight and the forecast for clear skies, you can beat I won’t be rolling out my large Dobsonian telescope. Small refractor telescopes like mine are ideal for observing the moon. Tuesday, August 09, 2011Mars or even back to the moon?Ever since I started using astronomy binoculars and telescopes to view the wonders of the night sky, I have wondered if our species would continue to explore the universe with manned space flights. I say continue, because I first decided to setup & use a telescope shortly after man stepped foot on the moon in 1969. In fact, that event was a big reason I took up astronomy. Yes, I still wonder the same thing, today, all these years, later, but I am now convinced that I will never live to see man step foot on Mars or even make a return trip to the moon, for that matter. It’s not that we don’t have the technology or even the resources to do the job; it’s simply that we lack the will and the motivation as a people to undertake such ambitious scientific and technical projects, these days. I suspect we would not have even gone to the moon in ’69 had it not been for fear of the Russians beating us, there. That was probably not a realistic reason for going to the moon in the first place, but it did give us the push we needed, all the same. Sad to say, doing something for the sake of science and knowledge has never been enough of a reason for us as a people to undertake such large projects. Still, I will always wonder when I look through a telescope eyepiece what it would be like to explore the millions of worlds I see. Monday, August 08, 2011Upside down images in reflector telescopesIs that fact that reflector telescopes produce upside down images and telescopes that use diagonals, such as refractor telescopes, Schmidt-Cassegrian telescopes and Maksutov telescopes, produce reversed right to left images a big deal? Is one better than the other? Should I buy one of those telescope accessories that correct the image so the telescope is easier to use? These are valid beginner telescope questions. In general, my answer to the last question is no, for two reasons. One, image correcting prisms degrade the image and reduce the performance of your telescope and, two, learning to accommodate the way your telescope presents images is just a matter of experience. It becomes second nature over time. Will I have an easier time accommodating upside down images or reversed right to left images? I often switch back and forth between telescopes that provide both orientations and have no problem with either, though I suspect a beginner will be more comfortable with the upright, though reversed, images provided by telescopes that use diagonals. Still, reflectors telescopes provide so much performance for the dollar that I would never advise a beginner to avoid them. In fact, I prefer the upside down images provided by reflectors for some types of observing, notably when working the moon. I just turn my moon map upside down and I’m set. When the craters and features are reversed, though upright, as in my refractor, things are actually more confusing. Friday, August 05, 2011Where to setup & use a telescope in the yardIf you live in an urban or suburban location, sometimes you don’t have a lot of options of where to setup & use a telescope for astronomy, but there are ways to tweak what you do have for a location for better viewing. One of things I always do in a new back yard location is to grab the astronomy binoculars, first, rather than the telescopes, and do some wandering around the yard on a dark night. The binoculars allow you to do some astronomy as you scout, so you are not wasting precious observing time. First thing I check is the locations of lights – yard lights and street lights – and then try to place a tree or building between me and the lights to reduce interference. A difference of a foot or two can be critical, here. Next, check the sky glow in all directions. In most urban areas, it will be most concentrated in one quadrant of the sky. That will be the least desirable quadrant to see in the telescope eyepiece, so setup the telescope with other quadrants in mind. Of course, you don’t always get a say in the matter, but if I had to choose the most desirable quadrants of the sky to see for the sake of backyard astronomy, I would pick the south and the east – south because that’s the direction of the galactic center and that area holds the biggest treasure trove of objects and east, because that’s the area of sky that darkens, first, after the sun goes down in the evening. That gets you out observing at an earlier time, which is nice if you need to get to bed at a decent hour. Yes, backyard astronomy is often a matter of damage control, but even in a small backyard, you need to carefully select a location to get the most out of your telescopes. Thursday, August 04, 2011Tripods for spotting scopesTripods are a necessary evil in the world of spotting scopes. Like most spotting scope users, I learned this the hard way. In my early days, I did everything I could to avoid using a tripod with my spotting scope, but, to no avail. Handholding at even 20x was out of the question for birdwatching, so I next devised a gunstock mount. That was a definite improvement at 20x, but it proved to be less than adequate as magnification went up. At about 30x on the spotting scope, I was right back where I started by handholding as far as holding the spotting scope steady enough to be useful. I finally broke down and bought a tripod, but, of course, I made the mistake of buying a cheap tripod. Even so, it was a vast improvement. For the first time, I could use my birding spotting scope the way it was meant to be used and, for awhile, I was happy. Happy, that is, until I tried using the tripod and spotting scope in any kind of breeze or when I tried to actually use the spotting scope at 60x. I vowed to someday get a good tripod. That cheap tripod made the decision for me, anyway, by falling apart after only a few months use. Although I was on a limited budget, I saved my pennies, skipped lunches and waited until I could buy a good Bogen tripod and have never needed another tripod for my spotting scopes, since. It may be trite to say that a spotting scope is only as good as the tripod, but it is true, all the same. Tuesday, August 02, 2011Finder scopesI get on these observing missions with my telescopes, now and then, and, being the hard worker I am, I tend to push myself a bit. Lately, I’ve been spending most nights at the telescope chasing down some of the lesser known planetary nebulae. Check any magnitude 7 or 8 star chart and you’ll find plenty of these, but, believe me, it is a lot easier to find obscure planetary nebulae on a star chart than in the telescope eyepiece. The problem with most of these lesser known planetary nebulae is that they are small, much smaller than the larger and easier to see celebrity status planetary nebulae such as M57 or M27. In fact, most of these obscure targets are so small as to appear star-like at low magnifications. That means you’ll need to crank up magnifications to 150x or 200x to make them standout from surrounding stars, but with higher magnification, comes narrow, tiny fields of view. That means that when it comes time to point the telescope, close doesn’t count. Your navigating skills must be excellent if you use a telescope without a computer, as I do, and even, then, it often takes many attempts to get that little planetary centered in the telescope eyepiece, especially when that little planetary is located far from any bright guide star. Believe me, 200x is no place for casual scanning or crossing your fingers and hoping to get lucky when you are trying to locate a specific object. For this work, I prefer to use a good magnifying optical finder scope. There are times when seeing a bit more of a star field, as provided with a good magnifying 8x50 finder scope such as the Stellarvue 8x50, can be a real plus when working with a star chart. Non-magnifying red dot finder scopes are great for getting you in the neighborhood and are all you will ever need for bright objects or even faint objects located close to bright stars, but for those objects located out in the middle of nowhere, so to speak, far from any bright star, that extra precision you get with a good magnifying finder scope can be a real plus. That’s why I have both a red dot finder scope (a Telrad) and a magnifying finder scope (10x50) mounted on my Dobsonian reflector. |
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