I used to have a newtonian 10 inch, have been contemplating a medium cassegrain, though it's not a priority, just a cool thing I would get if I can afford it.
My reflector was a metre long but a small cassegrain had the same power, so much more handy.
Cassegrain's start at $400 for 90mm, not quite sure what that equates to in magnification versus a 10 inch dobsonian but I think it's about the same.
Just getting to know the night sky provides a cool sense of orientation in the galaxy, and is something that really gives you a feeling of connection to timelessness.
When recording contrails, I also want to attach an additional camera (cell phone ?) to the exterior, to show the "live" "ground eye view".......along with the telescope close-up view (captured by a DSLR)
The problem with most up-close contrail videos, is they don't usually "back-out" (wide shot) to indicate the true length of the contrail.
The size of the objective lens/mirror, the surface area, determines how much light can be captured by the scope, magnification is a factor of the focal length of the telescope and the focal length of the eyepieces used, as is field of view. The bigger the objective lens/mirror, the dimmer the objects that can be seen. There's a big difference in surface area between 90mm and 130mm diameter objective. The quality of the optics is the biggest factor in image quality.
I have a 130mm Newtonian reflector on an equatorial mount and a 60mm refractor on a "goto" mount. Three of the most popular telescope designs for us amateurs are Newtonian reflector, Schmidt-Cassegrain and refractor. They all have advantages and disadvantages. One advantage Schmidt-Cassegrain scopes have is their compact size.
One thing to consider if you want to spot airplanes is the image in a Newtonian reflector is going to be upside down and there is no way to correct that. With refractors or S-C scopes, you can use an Erect Image Prism diagonal which goes in the eyepiece holder, the eyepieces then go into the diagonal, to correct the orientation. Imagine trying to track a fast moving object that's upside down, backwards and magnified.
Choice of mount is important, especially if you want to do both celestial and terrestrial viewing. An advantage of a dobsonian for plane spotting is the alt-azimuth mount, however the Newtonian reflector design means images are upside down with no way to correct that. An equatorial mount allows easy tracking of celestial objects but would be challenging for tracking airplanes. IMO, the ideal setup for both celestial viewing and plane spotting would be a Schmidt-Cassegrain (plus EIP diagonal) on an alt-azimuth mount and an "equatorial wedge" to make celestial objects easier to track.
Never been a fan of those electronic "goto" mounts, although my gf insisted on getting a goto for our first scope. I enjoy the challenge of finding stuff on my own.
Imagine trying to track a fast moving object that's upside down, backwards and magnified.........
..........
Never been a fan of those electronic "goto" mounts, although my gf insisted on getting a goto for our first scope. I enjoy the challenge of finding stuff on my own.
Thanks for the info.
Glad you have a GF that is interested.....that's awesome. Usually there is the "WAF" factor (wife acceptance factor) when buying man-toys.
Maybe I'll start hanging around the Cal Tech commissary more often....meet a cute nerdy gal.
Thanks for the info.
Glad you have a GF that is interested.....that's awesome. Usually there is the "WAF" factor (wife acceptance factor) when buying man-toys.
Maybe I'll start hanging around the Cal Tech commissary more often....meet a cute nerdy gal.
Yeah, I'm pretty fortunate. She's a botanist and we're both interested in science in general. You should see us on a hike, geeking out on identifying plants, birds, clouds, geological formations, animal scat and tracks. I don't even know how many field guides we have and the vast majority of our books are science related. Hope you find yourself a cute nerdy gal like I did.
When I hike.....I pay close attention to native and invasive plants.....I spot them out.
That's half the fun when hiking nature. I get amazed when finding something new or rare.....a plant, a bug, a critter.......
I guess I do "look up" as well.....hence my want for a telescope.......spotting native and invasive sky shapes.
There is something rather humbling, by a close look at things, that reveals a never-before understanding.
We can "hike nature" on a computer....but there's nothing like hiking raw nature.
One thing to consider if you want to spot airplanes is the image in a Newtonian reflector is going to be upside down and there is no way to correct that.
Imagine trying to track a fast moving object that's upside down, backwards and magnified.
With the simplicity of a Dobsonian base though, it's quite doable. Despite the motion being awkward at first, you do get the hang of it and with practice it becomes second nature. Similar to what Stupid linked in the OP, I've had an Orion XT10i for eight or nine years now. Properly set up and adjusted, it's quite smooth. I've not yet tried my hand at airplane spotting but imagine it wouldn't be terribly different from tracking satellites or the ISS. I see veteran spotters posting excellent results with their Dobs and will have to give it a shot sometime.
Never been a fan of those electronic "goto" mounts, although my gf insisted on getting a goto for our first scope. I enjoy the challenge of finding stuff on my own.
Do they make simple automatic trackers that lock on an object but are not the full computerised go-to version?
Stuff in the sky tends to move quickly through the field of view, do you just track manually?
Is the stability of longer scopes an issue - more length would equal more potential vibration?
A SC can double (or triple?) the focal length (compared to it's actual length) through internal reflection, but yeah, it's the initial light gathering potential that is important.
And having less lenses means less potential distortion or artefacts.
Depending on optical quality and observing conditions, you can expect to get anywhere from 20x to 50x of useful magnification per inch of aperture. In other words, a 4-inch scope tops out at 200x under ideal conditions, but a 6-inch scope can work well as high as 300x under ideal conditions.
But that's the maximum; most of the time, you'll find that the best views are actually had at the telescope's lowest power. If the advertising on the box hypes super-high power, the manufacturer is trying to fool you.
Perhaps more importantly, big aperture also lets you see fainter objects. This is different from providing magnification. In fact, the problem with most astronomical objects is not that they're too small and need more magnifying, it's that that they're too faint and need more light — in other words, more aperture.
The Orion Intelliscope Dobs work that way, thanks to encoders you assemble in the base. After a brief calibration and two star alignment, you can use the object locator to direct you toward your chosen target. The locator displays arrows that guide you in moving the optical tube in the proper direction to view it through the eyepiece. It's a simple, handy solution that's powered by a 9V battery and includes a 14,000 object database. A video walk-through is available here.
With the simplicity of a Dobsonian base though, it's quite doable. Despite the motion being awkward at first, you do get the hang of it and with practice it becomes second nature. Similar to what Stupid linked in the OP, I've had an Orion XT10i for eight or nine years now. Properly set up and adjusted, it's quite smooth. I've not yet tried my hand at airplane spotting but imagine it wouldn't be terribly different from tracking satellites or the ISS. I see veteran spotters posting excellent results with their Dobs and will have to give it a shot sometime.
That's true, a Dob would be pretty easy to use once ya get the hang of tracking fast moving objects. Just thought it might be something to consider. I'd love to have a big ol' dob. I used to go stargazing and do some astrophotography in college with a friend who was an astronomy major and had built his own dob, it had a huge primary mirror, something like 14" or more in diameter and a few inches thick, real top shelf stuff. It weighed a lot but was smooth as silk on the mount. I had a really nice 35mm camera rig and a sweet zoom lens with a huge aperture that was pretty much a mini-refractor in it's own right, had like 4 or 5 lenses actually, filters. Now all that and more is available in a DSLR and just a couple of lenses. We worked out the location of the camera mount and counter weighting to make tracking as easy and smooth as possible. With a cross hairs eypiece adapter and remote shutter cable, long exposures were a breeze. It was fun, I'd keep track of exposure times and he'd focus on tracking, but we took turns too, but one person alone could do it with ease too.
The question about camera mounts, my newtonian came with a camera mount that can go on either of the 2 rings that hold the tube. There are mounts that can be purchased to put a camera on the eyepiece.
Vibration shouldn't be a problem in a solid well built telescope and mount of any size, the one my astronomer friend in college built was rock solid. The mount is the big factor. Cheaper, lighter mounts are going to have more vibration.
The one thing I don't care for about living where I do in Oregon is the skies are cloudy pretty much all winter and a good portion of the fall and spring.
I'd love to have a big ol' dob. I used to go stargazing and do some astrophotography in college with a friend who was an astronomy major and had built his own dob, it had a huge primary mirror, something like 14" or more in diameter and a few inches thick, real top shelf stuff.
Just out of curiosity, do you have any observing preference when it comes to astronomical targets? Are you more interested in lunar/planetary viewing or deep sky objects? Or will airplane spotting be the main priority? How much of a concern is portability? These sorts of details might help narrow down your choices.
Just out of curiosity, do you have any observing preference when it comes to astronomical targets? Are you more interested in lunar/planetary viewing or deep sky objects? Or will airplane spotting be the main priority? How much of a concern is portability? These sorts of details might help narrow down your choices.
Honestly, binoculars are a great way to get started in observational amateur astronomy. These instruments are relatively inexpensive and are eminently portable and easy to use. A surprising number of celestial objects including many binary stars, open and globular star clusters, nebulae, and a number of galaxies can be detected with binoculars. Scanning through the heart of the Milky Way with binoculars from a very dark site is a truly fantastic experience.
I recommend purchasing a 10x50 (i.e., 10 power and 50mm aperture) binocular for astronomical use. A 10x50 binocular is usually not overly heavy for most people to hand-hold and provides a 5mm exit pupil that will be appropriate for most observers when age and observing site darkness are taken into account. Celestron, Nikon, Orion, and Pentax are good mid-price brands to consider. Something along the lines of the Orion Ultraview or the Celestron 10x50 Ultima would be a good choice. Look for a binocular with at least 14mm of eye relief if you must wear eyeglasses while observing.
Information on binoculars suitable for astronomical observing can be found at; http://www.astunit.com/faq/binocular.htm
As for a really good beginner telescope if you want to have a computerized mount with a database to help locate celestial objects than I would recommend the celestron nextstar 130SLT. You can grab it for right around 500 USD. Here's the cite, but you might find it cheaper if you do a little digging; http://www.celestron.com/astronomy/celestron-nexstar-130slt.html. If your just getting started though, I would recommend getting something even cheaper like a DYNASUN 70076, which I still have around because I got it for my 9yr old son. You can probably get it for less than a 100USD. Binoculars are a definite necessity, and honestly I find myself using them more often than my telescopes.
Since you are planning on using a telescope for both terrestrial and celestial viewing, there are a few important considerations that have to be made.
Telescopes which have a limited field of view (reflectors, cassegrains) and high magnification can present a challenge when attempting to use them to track objects moving across the sky. Conversely, they excel at planetary and celestial viewing/imaging. Although high magnification can often yield better detail, the limited field of view can make it difficult to keep the object you are viewing centered in the telescopes objective. Cassegrains are not ideal for observing moving targets as they do not have a fixed mirror design -- when the tube moves, the primary mirror wobbles. Newtonian reflectors have a fixed mirror, making them more suitable for such tasks but without a focal reducer, tend to have a narrow field of view.
A wider field of view can be obtained either by coupling a reflecting telescope with a focal reducer add-on, or by utilizing a different telescope design -- a refractor being a good choice.
One thing to note about branding -- telescopes which are branded as Orion, Celestron or Skywatcher are all manufacturered by the same company, Synta. I own a 120mm Skywatcher Black Diamond refracting telescope which has proven to be excellent for both terrestrial and celestial viewing and photography. It features a wide field of view and up to 240x magnification. It retails for around $2000 but Skywatcher also do refractors in the sub $1000 price range which are also excellent for the kind of viewing you are looking at doing and come in aperture sizes up to 150mm.
If you plan on capturing your viewing on camera, I recommend purchasing a telescope with a Crayford focuser -- regardless of what overall tube design you go with. Many telescopes are shipped with a 1:10 Crayford focuser which allows ultra-fine focusing, something which is usually missing from Cassegrains especially at the low-end.
Astronomical imaging usually requires a mount of german equatorial design which is capable of tracking the night sky as the Earth moves, to ensure that longer exposures do not exhibit star "drift". If you intend to take images of the night sky, the choice of mount is important and the quality of the results you can expect is proportional to how much you spend on a mount.
A Dobsonian is a great telescope for astronomical purposes, but you do need to learn how to navigate the sky. You should be able to identify the constellations and perform star hops, which are easiest to learn with binoculars. For plane watching I'm not sure how easy or hard that will be; that's not something I've really done with a Dob. I've found it to be quite manageable with my LX200 Schmidt-Cassegrain, but as mentioned above you do have to deal with mirror flop. It's not an insurmountable problem though, if you focus the telescope such that the final focusing direction applies tension to the mirror you can usually get away with it and not have to worry too much about mirror flop. At least that's the case with my 8", I can't speak much to larger apertures. If you do decide later to go with a more advanced motorized scope, you might give this software a try: http://www.optictracker.com/Home.html
My classic LX200 isn't compatible with it unfortunately, but there is a free demo version and it seems like it might be handy for tracking aircraft. I do a lot of satellite and space station tracking myself with software designed specifically for satellites. It's quite tricky but with practice it can be done.
Thanks for all the replies.
I am looking to capture images as jpg or prefer
...tiff....and also live video capture.
I'm not seeking the ultimate resolution but I'm seeking the best resolution at around the sub- $1000 price range.
.......plus the ability to track at a 30k foot airliner from a telescope mount. The mount movement should be as smooth as possible.
I may be asking too much for a sub-$1k device.
I would rarely use the scope for deep celestial viewing, as I live at low altitude in a So. California city.......but it would be nice if indeed the opportunity occured....to bring the scope to a more remote location, for celestial events.
Thanks for all the replies.
I am looking to capture images as jpg or prefer
...tiff....and also live video capture.
I'm not seeking the ultimate resolution but I'm seeking the best resolution at around the sub- $1000 price range.
.......plus the ability to track at a 30k foot airliner from a telescope mount. The mount movement should be as smooth as possible.
I may be asking too much for a sub-$1k device.
If you are trying to work within a $1000 budget, the Dobsonian as MikeC suggested guarantees maximum aperture size for your dollar and unlike other tube designs, does not require the purchase of a mount since it's part of the Dobsonian design. The downside to the Dobsonian -- at least the cheaper models which do not include GoTo function (the ability to control the slewing action with a hand controller) -- is that they can be awkward to maneouver when trying to follow a moving target. You should, however, be able to hook up an SLR camera with the appropriate attachment (they are readily available from a number of vendors) and take quick exposures of airplanes without any hassles. If you fancy a bit of planetary imaging they are proven to be good in that area also.
With a $1k budget, the Dobsonian is probably your best choice but if you are serious about needing smooth tracking then I would consider looking into investing in something which has motorized slewing/GoTo action.
If you do decide to go ahead with a Dobsonian, I would recommend one similar to what MikeC linked -- a closed design which is ready to use straight away and does not require assembly. Some models have the secondary mirror mounted on a scaffold which extends away from the base of the unit. Although this makes them more portable, they do have to be assembled each time you want to use it and to ensure that you have a clear image, the mirrors have to be collimated which can be a hassle.
What might be a good idea, if convenient, is to visit a local astronomy club if there is one in your area. That way, you can try out different scopes and get a better idea of which one is right for you. One last and important point -- when you do buy, shop around because prices vary wildly. Often you can save a few hundred dollars simply by ordering from someone not-so-local.
The "lazy susan" ball-bearing approach seems to swivel nicely, but there is likely too much "play" (looseness).....making the mount unstable and shakey.
Some sort of true Teflon might be in order. Plus a stand-off handle to guide the swivel at a lesser (and more accurate) degree of thrust.
(quick idea drawing)
The "go-to" function will not be useful to me when following moving jet travel.
Or the handle can be directly pointed at the axis.
The longer the handle away from the axis (distance), the more precise the movement. (may offset the balance though)
Thanks for all the replies.
I am looking to capture images as jpg or prefer
...tiff....and also live video capture.
I'm not seeking the ultimate resolution but I'm seeking the best resolution at around the sub- $1000 price range.
.......plus the ability to track at a 30k foot airliner from a telescope mount. The mount movement should be as smooth as possible.
I may be asking too much for a sub-$1k device.
I would rarely use the scope for deep celestial viewing, as I live at low altitude in a So. California city.......but it would be nice if indeed the opportunity occured....to bring the scope to a more remote location, for celestial events.
The whole package I outlined above can be had just over $1000, but it will allow for computerized tracking of any plane. You just slew to it with a joystick looking at your computer in one window for the guide camera, then toggle the automated tracking and start recording with both cameras. If you wanted to reduce the cost you could go for the 4se model instead but I wouldn't recommend going below 6" for aperture.
Thanks Astro.......very interesting !!
Yes I have a mid-range ($) Nikon DSLR (current model, DX format)
I always wondered what type of system NASA used for video-tracking of their rockets, after takeoff. The technology eluded me, but I had a hunch it was there.
A computer based "visual lock".
Surveillance videos also can have this feature....but glad to see it in the telescope possibility realm, for home viewers/astronomers.
(off topic)....Hollywood film/video camera operators often have a professional sonar based focusing system like many cheaper digital cameras, only better, and made specifically for film production. I assume sonar has a limited range in this instance.....and is only for "focusing".
It was I think $200 or so. I'm new to this field, and I really wanted to check out the sky at night so I ordered it a while back, I'm waiting for warm weather / clear skies to break it out. Anyone else use one of these before? Was it worth the money I paid or should I have got a pricier scope?
I have this model of Celestron:
It was I think $200 or so. I'm new to this field, and I really wanted to check out the sky at night so I ordered it a while back, I'm waiting for warm weather / clear skies to break it out. Anyone else use one of these before? Was it worth the money I paid or should I have got a pricier scope?
Well, to be honest, I would have saved my money. It's a long focal length small aperture refractor on a tripod that is really intended for a camera. I fear that pointing it accurately and keeping it pointed at objects will be quite difficult; the long focal length will produce high magnifications which are undesirable in this case. The tripod doesn't look like it's steady enough for high magnification views. Scopes like this are often sold on promises of "high magnification," but the dirty secret is that any telescope can use any magnification, it's just a matter of changing the eyepiece or adding a barlow lens. Not every magnification is useful, however. The limit of useful magnification is determined by the size of the aperture, beyond the useful limit the view just gets blurrier since no more optical resolution is available. On a more practical level, with cheap telescopes like this higher magnifications frequently result in frustration as objects quickly leave the field of view as earth rotates and the shaky tripod does not settle down fast enough when you move the telescope to try to keep up.
I recently won a similar telescope in a photo contest. It's a Celestron with the same camera tripod, but the optical tube has a larger aperture (114 mm). It also has half the focal length, so the magnification for a given eyepiece will be half of what your telescope produces. That's what you want in a small scope on a "highly portable" tripod shall we say. Less magnification means vibrations are less distracting, objects are easier to find and stay in the eyepiece longer, and the higher aperture and smaller focal ratio mean that objects look brighter in the eyepiece. Overall it's just much more forgiving and the experience is usually more enjoyable.
I haven't tried out the prize scope yet, but I'm intending to give it as a Christmas gift to my daughter. If she takes to it I can always upgrade the mount to something more sturdy. I'm also a bit surprised you paid 200 for that telescope. I can find it online for $150. Even mine only retails for $180. http://www.celestron.com/astronomy/cometron-114az-telescope.html
Honestly if you can I would try to return it or exchange it for the above. Sorry.
Thanks. To be honest, I just got it mainly to try to take pictures of the moon. If I understand correctly it should at least be able to do that decently, right?
You'll probably be satisfied if what you were intending was to take images afocally (hand holding a cell phone or other small camera above the eyepiece), but it'll probably still be quite difficult to do properly. I don't want to sound like an astrophotography snob though, I've been doing lunar astrophotography for about 14 years now so I tend to keep pretty high standards for myself when it comes to taking lunar images. As a beginner I'm sure it'll provide plenty of enjoyment, but if you keep at it and upgrade to better equipment later you'll reminisce about how frustrating it was and how much your results have improved.
I thought it might be best to send you a PM about this, since I don't particularly feel like getting into a public debate .....snip
The telescope he's suggesting is a disappointment waiting to happen and I'd like to take a moment to explain why that is.
1. Schmidt-Cassegrain telescopes suffer from something called Mirror Flop. When the tube moves, the primary mirror (located at the lower end of the tube) wobbles like mad. It also wobbles whilst you're adjusting the focuser, which is as annoying as hell when you're trying to focus on a small object -- it makes it nearly impossible to determine whether you are in focus or not and once you wait until the mirror stops wobbling, the target has moved and you're back to square one.
2. It has a focal ratio of f/10 -- this means that it's a "slow" telescope, meaning the light has a long way to travel after it enters the scope before it reaches your camera. The result? Low contrast and grainy/fuzzy images at high shutter speeds. This tube is best for looking at extremely bright objects which are not moving or are moving relatively little (the moon, or planets). The focuser on this tube is also really "coarse". Chances are, if you're chasing a plane... by the time you get into focus, the plane will be long gone.
3. The mount can't have another tube added to it later on. If you decide you want to try something else, you'd be forced to buy the whole kit all over again.
If you don't find the Dob appealing, your best bet for what you want to do specifically (whilst maintaining the ability to upgrade at a later stage) is to try and get a motorized mount (but NOT a Celestron -- these are made from old parts that Synta are trying to get rid of since they bought Celetron and took over manufacturing) and either a Newtonian reflector (fixed mirror, no wobble!) or a refractor (80-100mm is a good size to start with). You will still be able to track targets with this design without the hassles I mentioned above.
I apologize for posting a private PM, but it is in the interest of relaying all available info, to whomever it will be of value.
While I appreciate the criticisms, I have used a very similar system (f/10 Schmidt Cassegrain) for tracking ISS successfully for years. I dare say it's much more demanding than tracking planes. Mirror flop is something to keep in mind, but by turning the focuser counter-clockwise as your last focusing motion you will get less mirror flop. The automated tracking will also allow you to adjust the focus while tracking is occurring. No, the mount isn't designed to accept other tubes, but that is why I was reticent to recommend this particular system; it's purpose built as I've laid it out for tracking aircraft, rather than being ideal for astronomy in general at that price range.
*To show that this can work, here's what this setup does with a 4se nexstar, the smaller version of the telescope I mentioned:
I have a celestron astromaster 76eq. I live in Minneapolis, Minnesota and I was wondering where I could go to get the mirrors recalibrated for a cheap price. When I got it new 4 years ago, you could see the rings on Saturn and really sharp details, but now I can barley see the moon.
I have a celestron astromaster 76eq. I live in Minneapolis, Minnesota and I was wondering where I could go to get the mirrors recalibrated for a cheap price. When I got it new 4 years ago, you could see the rings on Saturn and really sharp details, but now I can barley see the moon.
It was I think $200 or so. I'm new to this field, and I really wanted to check out the sky at night so I ordered it a while back, I'm waiting for warm weather / clear skies to break it out. Anyone else use one of these before? Was it worth the money I paid or should I have got a pricier scope?
Ha hey I got an even cheaper version of this type and yes its as astro said not the best but i got some good enuff looks at the earths shadow on mr moon last nite now Q whats that great Scrabble word for when sun planets or moons line up with each other
Ha hey I got an even cheaper version of this type and yes its as astro said not the best but i got some good enuff looks at the earths shadow on mr moon last nite now Q whats that great Scrabble word for when sun planets or moons line up with each other
