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DE22
2007-Mar-11, 05:47 PM
hey I Tried watching Skies with my telescope, its kinda cheap you could say, and it was the weakest telescope I found in the shop , the lens i got:
2.0mm
2.5mm
4mm
The big problem is they don't have any equiment for astronomy here in Dubai, I just HARDLY found these telescopes....:neutral:
If Anyone has idea were i could get some 5mm or 6mm lens, I would be happy for it,
Thanks,:)
DE22

redshifter
2007-Mar-11, 09:26 PM
Before we could make good recommendations for you, we need to know several things:

1) What type of scope do you have? Is it a reflector or a refractor? What is the focal length? Focal length will be given in mm. What is the aperature?

2) What type of observing will you be doing? Planetary? Deep sky objects such as galaxies, nebulas, etc.? Or a little bit of everything?

3) What size is your focuser? Will it accept 1.25" eyepeices? 2"? Or does it have one of those .965" focusers? The .965" focusers are usually found on the very low end 'department store' type of scopes, and eyepeieces for those are usually of very low quality. There are adapters for the .965" focusers that will allow use of 1.25" eyepeices however.

4) What is your budget?

To start with, it sounds like you need to see about ordering equipment online, if there's little astronomy equipment available where you live. Also, I'd look into getting a low power eyepiece, say 25mm.

I might suggest browsing this forum as well, there are a few threads dealing with suggested equipment upgrades.

DE22
2007-Mar-12, 03:46 PM
Sorry for not telling, Just forgot to give details, So sorry :doh: :



1) What type of scope do you have? Is it a reflector or a refractor? What is the focal length? Focal length will be given in mm. What is the aperature?


Mine is refractor...more speficly, maxvisiOn...
F20mm (1.25") AND 4mm (1.25')
I don't get what is the aperature...Sorry for this



2) What type of observing will you be doing? Planetary? Deep sky objects such as galaxies, nebulas, etc.? Or a little bit of everything?

You could say littie bit of everything...but mostly planety sometimes (cause some planets show very well here)


3) What size is your focuser? Will it accept 1.25" eyepeices? 2"? Or does it have one of those .965" focusers? The .965" focusers are usually found on the very low end 'department store' type of scopes, and eyepeieces for those are usually of very low quality. There are adapters for the .965" focusers that will allow use of 1.25" eyepeices however.

my focuser could handle 2 i think, Because my lens are 1.25"


4) What is your budget?

1000 Dirham=119 U.S. dollar
I still have even more in my wallet I guess
Thanks for helping Redshifter :)

aurora
2007-Mar-12, 09:11 PM
Sounds like you have two eypieces, a 20mm and a 4 mm. I suspect that you have a small refractor, and the 4mm eyepiece will be pretty hard to use as the lens you look through will be tiny with almost no eye relief and everything will be black since it will result in higher magnification than the aperture of your scope will support.

Aperture is the diameter of the lens on the front of your telescope -- the thing that gathers light. It should be stated somewhere, or you could measure it. It is probably a number like 60mm or 80mm or something like that.

Unfortunately, I do not know what vendors would ship to Dubai, so cannot recommend any specific places to order from.

But if what I said above is true, then you may want to get an eyepiece that has somewhat more power than your 20mm one, perhaps a 12mm, something like that.

More magnification will just make things bigger and dimmer and fuzzier, so for a given telescope on a give night looking at a given object, there is a limit to how much power (how small the mm on the eyepiece says) you can use effectively. At some point, more power just makes things worse. I suspect that is what has happened when you use the 4mm eyepiece.

yuzuha
2007-Mar-13, 01:15 AM
Near as I can tell, Maxvision is a brand of Kunning optical in China. Mostly they make giant binoculars, spotting scopes and little telescope/monoculars like these:
http://www.binocularschina.com/monocular.html
which aren't any good for astronomy.

They might be starting to make refractor telescopes.

DE22, can you find a web page with your telescope on it?

Aperture = diameter of the objective lens (the one that points at the sky) it is usually measured in inches or mm. Popular small refractor telescopes are 66mm 80mm and 100mm. Or it is the diameter of the mirror in a reflector/Newtonian or Maksutov telescope (popular sizes in those are 127mm 150mm, and 200mm).

We need to know that.

We also need to know the focal length. This should be printed somewhere on the telescope or in the papers that came with it. This is also measured in mm and should have "fl" before or after it. Should say something like "fl=560mm" or "1,800mm fl"

The "F" number is just a number that is often printed as "f/x" that you get by dividing the focal length by the aperture, so a refractor telescope with an 80mm diameter objective and a focal length of 560mm would have an "f" number of 560/80= of 7, which is usually printed as "f/7" Most telescopes range from f/5 to about f/15

To find out how much magnification you have, you divide the telescope's focal length by the focal length of the eyepiece (should be printed on the eyepiece), so a fl 560mm telescope with a fl 4mm eyepiece is 560/4 = 140x or 140 power, which would give a very small view of the sky and make it hard to find anything without a small guide telescope or finder to help you point it. Using a 20mm fl eyepiece will give 560/20 = 28x which should give bright wide low power views of the sky.

Things get too dim and fuzzy to see if you use more than 50x / inch of aperture, which is about 2x per mm, so a telescope with an 80mm aperture / objective lens should not be used with eyepieces that give more than about 2x*80 = 160x magnification. So, the shortest fl eyepiece that should be used with an 80mm fl 560mm telescope is 560mm/160x = 3.5mm. So, this telescope should not be used with eyepieces that have a fl smaller than 3.5mm or things will be too dim and fuzzy to see well.

Make sense? If you can tell us these numbers and what types of things you want to look at, we could maybe suggest some eyepieces for you.

DE22
2007-Mar-13, 08:16 PM
Near as I can tell, Maxvision is a brand of Kunning optical in China. Mostly they make giant binoculars, spotting scopes and little telescope/monoculars like these:
http://www.binocularschina.com/monocular.html
which aren't any good for astronomy.

hmm, I see, So Chines telescopes and other binoculars are good for using or not?


DE22, can you find a web page with your telescope on it?

Sorry didn't found one, but something nice :)
I just scanned the manual so you could know the telescope,



Aperture = diameter of the objective lens (the one that points at the sky) it is usually measured in inches or mm. Popular small refractor telescopes are 66mm 80mm and 100mm. Or it is the diameter of the mirror in a reflector/Newtonian or Maksutov telescope (popular sizes in those are 127mm 150mm, and 200mm).

I think its 1 inch,am not too sure about it but I measured it with my fingers :think:



Things get too dim and fuzzy to see if you use more than 50x / inch of aperture, which is about 2x per mm, so a telescope with an 80mm aperture / objective lens should not be used with eyepieces that give more than about 2x*80 = 160x magnification. So, the shortest fl eyepiece that should be used with an 80mm fl 560mm telescope is 560mm/160x = 3.5mm. So, this telescope should not be used with eyepieces that have a fl smaller than 3.5mm or things will be too dim and fuzzy to see well.

This is right, when I try the 4mm, its bad view, and I kinda hardly see Venus well


Make sense? If you can tell us these numbers and what types of things you want to look at, we could maybe suggest some eyepieces for you.

is the information enough?
If not , I will photo the telescope...
But I got to go now, See you later!

yuzuha
2007-Mar-14, 02:19 AM
Some Chinese scopes are good, some aren't so good (many of the big brand names have scopes made in China... same factories, different names). The ones that I said weren't good for astronomy were the little tiny hand-held "golf" scopes (they are better for watching sports events). Big binoculars are good for astronomy 7x50 and 10x50 are the ones used the most, though they make huge expensive ones like 20x100 that are too big to hold (need a tripod for them).

Yes, that is very helpful. Does your scope look like this: http://www.star21c.co.kr/mall.php?cat=002001001&query=view&no=8
or this: http://www.astromart.co.kr/mart/item.php?it_id=2095
(the pages are in Korean.

It looks like they are putting the focal length and the objective diameter into the model number, so if you have the dt700x60az you have a 700mm fl, 60mm objective f/11.6 scope
the dt800x60az would be 800mm fl, 60mm, f/13.3 if you have the dt900x60az it would be 900mm fl, 60mm, f/15, and if you have the dt700x70az, it is a 700mm fl, 70mm diameter, f/10 telescope.

I do not know which of the 4 telescopes you have so the maxiumum power you should use on the 3 60mm telescopes is 120x and the maxium power on the 70mm telescope would be 140x

for the 700mm fl telescopes a 5.8mm eyepiece would give you 120 power... the closest eyepiece they make would be 6mm (about 117x) and if you have the 70mm objective model, you can use a 5mm eyepiece for 140 power.
If you have the 800mm fl scope a 6.6mm eyepiece will give you 120x, so a 7mm eyepiece would be good (114x). And, if you have the 900mm fl scope then don't use anything smaller than a 7.5mm eyepiece (this one would be best for looking at planets since an f/15 scope will show more contrast between light and dark but is harder to aim since the angle it sees is smaller. A short f/5 scope is good for looking at big objects like nebula and galaxies at low powers, an f/10 is in the middle and can do a little bit of both)

Eyepieces like these http://www.optcorp.com/ProductList.aspx?uid=30-718-512-513 would work and do not cost too much (they are orthoscopic and while they have a narrow field of view, are good for viewing things like planets).

There are also a lot of Plossl eyepieces that are low cost http://www.optcorp.com/ProductList.aspx?uid=30-718-54-55
(probably made in China and come with many names) They will have a wider field of view so are good for looking at larger things like nebula, but you have to get your eye closer to the shorter ones which may be uncomfortable (an eye relief of 10mm is okay if you don't wear glasses).

Shipping charges might be expensive though.... Since you are in Dubai, you might check with these people http://www.dubaiastronomy.com/ to see if they know of a good place to buy eyepieces in the UAE (or maybe a mail order place that is closer so shipping costs will be lower)

If you want to buy several eyepieces, it is good to multiply by 1.4. So, if your telescope will work with a 6mm eyepiece, 6*1.4=8.4, they don't make an 8.4 so you could pick an 8mm or 9mm, an 11mm or 13mm and a 15 or 17mm etc. (maybe the shorter ones in orthoscopic and the longer ones in plossl) to give you magnifications between your 6mm and 10mm.

Hope that helps.

DE22
2007-Mar-14, 05:30 PM
Thanks so much yuzuha, I think I will fit in that fourm, Thank you so much agian,
Topic may be closed, No help is needed.
:)

yuzuha
2007-Mar-15, 03:00 AM
Good! Hope they know a good place to buy eyepieces near you. Let us know how things work out.