Do eyepiece lengths affect telescope magnification?

[alias25]

eyepieces: SR4, H12, K20 in what order are they most powerful?
ive got a feeling it isn't a very good telescope..?
my parents brought it for me, i was thinking of getting one after checking qualities, reviews ..etc
but I am really exited its my first telescope!
do u think ill be able to see anything good with it?..im doing GCSE astronomy so I've got a fair idea about RA and declination..etc
i guess i may have to buy extra eyepieces

 

[russ_watters]

Magnification is focal length of the telescope divided by the focal length of the eyepiece (the number in the name is the focal length). So for that scope (found http://www.argos.co.uk/static/Product/partNumber/5803680/Trail/C$cip%3D29388.Photography%3EC$cip%3D29406.Binoculars+and+telescopes.htm", the magnifications are:

900/20=45
900/12=75
900/4=225 (in the link, there is a typo: an extra "2")

Take heed of the line in the description: "Optimum magnification 225x". Translation: Maximum useful magnification is 225x. Beyond that and you will see nothing but fuzzy blobs. And start low and work your way up.

 

[alias25]

so that's where they got it from..hmm
thanks! its too cloudy in uk most the time..what kind of images will i be able to see? like how detailed i tried searching for it on google images by mag 225 but i could find any.

 

[russ_watters]

You edited while I was posting (I do it too)...

ive got a feeling it isn't a very good telescope..?

Well, it's definitely a beginner scope, but as beginner scopes go, it's a lot better than average.

do u think ill be able to see anything good with it?..

Mostly planetary stuff - the moon (best during partial phases - not when it's full), moons and surface of Jupiter, rings of Saturn, etc. But also some star clusters and a few nebulae and galaxies (though they will mostly just be smudges without a camera). Get out now and look at Mars, because in a month it'll be moving away quickly and won't be close to see well for another 2 years.

im doing GCSE astronomy so I've got a fair idea about RA and declination..etc

That's good - with a little effort, an equatorial mount is a good thing and you'll be able to find a lot of objects and track them relatively easily. Tracking a planet manually at 200x magnification takes a little practice.

i guess i may have to buy extra eyepieces

No, what you have is fine for the telescope you have. In fact, the Barlow lens is mostly just for advertising purposes - it won't be worth anything for viewing. Once again: start out with low magnification. I can't stress that enough.

 

[russ_watters]

thanks! its too cloudy in uk most the time..what kind of images will i be able to see? like how detailed...

Attached is a photo of Saturn I took with a webcam on a telescope similar in size to yours. It's processed to improve the quality, but conditions at the time were pretty bad, so it's probably about equal to what you could see with your eyes on a good day(though somewhat brighter).

Just be ready to put some effort into this hobby - it really is one that the more you put in, the more you get out.

 

[alias25]

"Always cover the finderscope when using your telescope with the correct solar filter. ALthough small in aputure(i heard high aputure is better?) This instument has enough light gathering power to cause permanante and ireversable eye damage. The image projected by the finderscope is hot enough to burn skin or clothing."
i don't understand this statement fully does it mean i have to use solar filter all the time viewing anything? and what does it mean by cover the finderscope..i think this is the part where an LED comes from its what u use to align the telescope..does that mean after i used it to find an object i cover it? or does it mean something else by that. or is it only when looking at objects in day time?

im sorry i can't see what you attached where

 

[Garth]

Get out now and look at Mars, because in a month it'll be moving away quickly and won't be close to see well for another 2 years. .

That's a joke - the poor chap is in the UK!

I've been trying to see Mars all weekend but its nothing but 8/8 cloud and rain!

Nevertheless, alias, keep trying and you will do really well in your GCSE - do you want to follow it up later at university? Set yourself a target and go for it!

Garth

 

[alias25]

excuse me I am not a 'chap' ...sorry i can see ur attachment now russ
i want to do physics at university..actually I've already applied and i like astronomy but i don't want to rush into it at university level (im doing my A levels at the moment phys chem and maths plus astronomy GCSE)
thats a nice enough picture of saturn for me :)

 

[Garth]

excuse me I am not a 'chap'

Apologies!

Garth

 

[russ_watters]

i don't understand this statement fully does it mean i have to use solar filter all the time viewing anything?

No, it's only talking about during the daytime if you want to observe the sun.

and what does it mean by cover the finderscope..i think this is the part where an LED comes from its what u use to align the telescope..does that mean after i used it to find an object i cover it? or does it mean something else by that.

Heh - no, that just means that Celestron didn't edit your manual after removing the finderscope and putting on the red-dot finder. You don't have a finderscope, so it doesn't apply to you.

 

[alias25]

Thank you!
i got my eye on the Hubble now ( )

 

[alias25]

erm my eyes kinda ached (felt heavy like i was tired) after just looking through the telescope for a few mins is that normal?

 

[turbo]

erm my eyes kinda ached (felt heavy like i was tired) after just looking through the telescope for a few mins is that normal?

It's easy to strain your eyes when using an optical instrument. Try this: first, put your lowest-power ocular in the focusser, point the 'scope at a rich star field, relax and focus in and out until everything looks crisp and clear. Practice this until you can focus pretty much automatically.

There is a reason for this: if you leave your 'scope just slightly out of focus, your eye is going to do its best to compensate and try bring the image into focus, and that is going to cause eye strain. Note that if you cannot bring objects into crisp focus because the optical elements of your telescope are not figured properly or are not aligned properly, you will continue to experience eye strain when using your scope.

To avoid eye strain (and other muscle strains and discomfort) you should relax and try keeping both eyes open as you observe. If there is too much ambient light, purchase or make an eye patch to cover your other eye. You may feel a bit silly, but you will definitely be able to observe more comfortably, and you will be able to see fainter objects with your observing eye. One last tip - when observing faint objects, do not look directly at them. Look a bit off to one side (this is called averted vision), so the image of the object will fall on more sensitive areas of your retina. Often, very faint objects will "pop" into view when you do this. The center of your eye's field of vision is very well-adapted to see detail and color, etc, but is less-well adapted to see very faint objects. Rule #1 relax and be comfortable. If you observe in a cramped hunched-over position, or stand off-balance, fiercely squinting with one eye tightly shut, you will be miserable and sore and you won't enjoy your telescope.

 

[Labguy]

I hate to be the fly in the ointment, but if you haven't bought this telescope yet, please don't. It is about the lowest quality money can buy and you'll be very dissapointed with any view through it.
I think you would be far better off just visiting any friends that might have telescopes and looking through their scope(s) for a long time until you have the time to find out what makes an acceptable scope and what is junk. The eyepieces listed with this scope are of designs that have the smallest field-of-view of about any eyepieces made since the 19th century (the 1800's). Also, the mirror is a "Spherical aluminised mirror", and at f/8 any reflector's mirror should be parabolic.
I suggest that you visit the web sites of large equipment suppliers and find their "How to buy a telescope" pages. Too much information to type here. Also, most astronomy magazines have an article about once per year on what to look for when buying a telescope. That 179.99 would buy a good binocular.
http://www.telescope.com/content/learningcenter/contentmain.jsp?iCategoryID=28&CCNavIDs=19,22,28 and
http://www.astronomics.com/main/definition.asp/catalog_name/Astronomics/category_name/Terms/Page/1 are just two of many.

 

[Chronos]

Turbo is your best friend when it comes to amateur astronomy. We sometimes disagree, but not on these issues.

 

[turbo]

I hate to be the fly in the ointment, but if you haven't bought this telescope yet, please don't. It is about the lowest quality money can buy and you'll be very dissapointed with any view through it.

I think her parents already bought her the 'scope, so that's done. Too bad, because for that price you can get a decent pair of binoculars and a nice set of charts. These should be the first tools every amateur buys. I would be willing to write a guide for beginning observers if someone here wants to make a sticky thread that others can contribute to. It's so depressing when people fall for the hype and spend money on sub-standard equipment. My parents did the same for me 45 years ago, and they could ill afford the expense. It would have been far better for me if they had bought me a nice pair of military-surplus 7x50 binoculars and a Peterson's field guide.

I've got a 15cm APO refractor (Astro-Physics), a 90 mm APO refractor (Vernonscope - the company that makes Questar oculars), both with 2" focussers, and a wide-field Celestron Comet-Catcher. Which instrument gets the most use? My 7x50 Nikon binoculars. And yes, I have Tirion charts, Uranometria, etc, but I still grab my Whitney star-finder and the Peterson guide pretty regularly.

 

[alias25]

wel i guess i could get them to return it and buy a pair of binoculars like u said or a different telescope...my parents said if its not a good scope then they won't mind changing it. (it was an late bday present)..but i think I am getting emotional attached to it(don't believe i just admitted that) even if its the worlds most pathetic telescope..but its mine. I think i should decide soon before it gets worse. soo would you people definatly suggest i change it?

 

[russ_watters]

I'm not so convinced you should change it. Binoculars are a good thing, but everyone needs a first telescope at some point. I'm 29, I'm an intermediate level amateur, and I don't regret my first telescope - and yours is significantly better than mine was. You can't see Saturn's rings or the Great Red Spot on Jupiter with a pair of binoculars, so if I hadn't gotten that crappy 60mm refractor, I don't know when I would have first seen them.

I'm a guy and I'm not afraid to admit that my first scope gave me the giggles when I first used it (as did my second scope, which is now a year old). Even though there were only 6 objects that I could really see with it (the Moon, Venus, Mars, Jupiter, Saturn, and the Sun), I still enjoyed using it. And there is something to be said for the ability to run outside at a moment's notice if you're sitting at home and decide you want to use it.

A pair of binoculars and a star chart is undoubtably the best path to becoming a serious amateur, but the pay-off to starting with that approach doesn't come until several years and a lot more money later. With a crappy scope, there is an instant payoff, just not a big payoff (viewed through the eyes of a serious amateur, it's not much of a payoff - but I guarantee you'll remember forever the first time you see Saturn's rings with it). I view my first telescope the same way I view my first car: it was a piece of crap, but I still loved it. And like you said: it was mine. And I still have that scope, btw, even though I haven't used it in 2 years.

edit: turbo-1 also advocates joining an astronomy club. I see his point, but my one experience with an astronomy club was at a Boy Scout camp when I was perhaps 14. Since there were a few people around, I only got 30 seconds at the eyepiece (it was Saturn and I still remember it well), but it was enough to say 'gee-wiz, I want one'. So go to an astronomy club meeting if that is feasible for you, but I suspect you'll end up where I was: still wanting your own telescope, no matter how crappy others say it is.

 

[turbo]

wel i guess i could get them to return it and buy a pair of binoculars like u said or a different telescope...my parents said if its not a good scope then they won't mind changing it.

If they can exchange the telescope and buy you a decent pair of binoculars and a good basic observing guide like Norton's Star Atlas, you will be doing yourself a favor. Add a Whitney Star-finder for a few dollars and you're already to learn your way around the sky. The Star-Finder will tell you which constellations will be visible from your location at any time of night, and then you can go to Norton's and see what interesting objects will be visible. Planning your observing sessions is fun, and it's really rewarding to learn where things are and see what is visible in your binoculars. Planning is also something that you can do anytime (especially handy when the weather turns lousy). In the meantime, you can save up money and with your parents' help, get yourself an inexpensive telescope with pretty good optics (like a Dobsonian) on your next birthday. Remember that one great strength of binoculars is that you can keep them near the back door, and when there's a break in the clouds, you can get out and observe for a few minutes - it's hard to be that spontaneous with a telescope. This is why my 7x50 binoculars get WAY more use than my telescopes.

Most young people have irises that can open wider than those of older folks, so the large exit-pupil of 7x50 binoculars is a good match for youngsters. Larger binoculars are available, but they are heavier, and are harder to hold steady for long periods. Higher-powered binoculars are available (10x50s are common), but in my experience, the 7-power models are more comfortable to use, and easier to hold steady. They also show you a wider field of view, and unlike a telescope, you get to use BOTH eyes, so the views are great. You don't realize how much information your brain gathers from integrating the signals from both eyes, until you are forced to observe with just one.

A tip about money and quality. You can get great quality binoculars (and not spend too much) when you look for binoculars made by a great company that sells expensive ones, then choose the most basic no-frills model from their line. (I bought a pair of very basic Porro-prism 7x50s made by Nikon on sale for less than $100 and they are superb.) You can also take them on hikes, use them for birdwatching, etc, so they are valuable for lots of things besides astronomy. Good luck, alias25.

 

[alias25]

thanks everyone..

 

[alias25]

what would an object of magnitude 3.5 look like through this telescope would it even be visible? what's the dimmest object i would be able to see (what mag?)

 

[turbo]

what would an object of magnitude 3.5 look like through this telescope would it even be visible? what's the dimmest object i would be able to see (what mag?)

If you live in an area with dark skies, you should be able to see objects down to mag 6 with your naked eye (3.5 is really bright) and perhaps to about mag 13 with your telescope. Here is a calculator that can help you figure out what to expect. Be aware that you can see small faint objects like stars more easily than extended faint objects of the same magnitude. Contrast is a big player, here.

http://www.go.ednet.ns.ca/~larry/astro/maglimit.html

 

[russ_watters]

Also be aware that just because you can see an object, such as a galaxy, doesn't mean it is going to look like the pictures in a book. While the center of a bright galaxy might be at mag 3.5, you won't be able to see the spiral arms, for example.

 

[L4Snoopy]

best choice

Heya, I'm also just thinking of buying a telescope- and had the celestron powerseeker 675 in mind- however i am a complete novice. if that telescope isn't really up to standard what telescope would you suggest that is better and still around £200?

I would like to be able to see as much as possible!

 

[russ_watters]

In bang-for buck light-gathering, it is tough to beat a Dobsonian: http://www.telescope.com/shopping/p...RODUCT&iMainCat=4&iSubCat=9&iProductID=238462

Read the whole thread, though - I liked my equatorial mounted beginner scope and that Powerseeker is considerably better than what I had.

 

[russ_watters]

Funny, a Google for that telescope bings up this thread on top.

 

[Patridor]

i have the telescope and i think it is a rather good one the magnifation through it is no 200 odd it is infact 825x mag and i can see the orion nebula , the craters of the moon , and Jupiter , uranus , saturn and the zeta ruticula so it is a good one

 

[Drakkith]

i have the telescope and i think it is a rather good one the magnifation through it is no 200 odd it is infact 825x mag and i can see the orion nebula , the craters of the moon , and Jupiter , uranus , saturn and the zeta ruticula so it is a good one

The magnification of a telescope is misleading. Useable magnification is based on the size of the aperture, aka the size of the opening in the front that the light comes through. Bigger apertures have more useable magnifications, however it is very rare that you would ever need to use the max. Atmospheric conditions and the apparent size of many deep space objects usually keep you down to 100-200x or less. Higher ones are for viewing planets and the moon and such, lower ones are to view large extended objects such as the orion nebula or the Andromeda Galaxy.

Changing the eyepiece is what changes the zoom. The "longer" the eyepiece, the lower the magnification. So if you have a 25mm eyepiece, it will have less zoom than a 15mm eyepiece.