Newbie need some advice on reflector telescope

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Mirkent05
Posts: 4
Joined: Wed Jul 05, 2017 7:42 pm

Newbie need some advice on reflector telescope

Post by Mirkent05 » Wed Jul 12, 2017 11:02 pm

Hi, I'm a newbie who just bought a reflector telescope, but din see any review of the telescope.
It's a 114mm x 900mm tasco galaxsee reflector 46-114500 with EQ mount.
By the specs given, it's almost near compare to celestron astromaster 114EQ.
My question is,
1) based on the aperture diameter and focal length given, I presume both scope observation power almost the same? The only restriction are from the eyepiece?
2) tasco eyepiece barrel diameter is 1.25". So izit interchangeable with other brand's EP for a better view?
3) my main purpose of buying this scope is to view nearby planets and also furthur stuff like the nebulae etc. My question is can this telescope do the job?

"Using a stock EP in a telescope is like racing a sport car with a stock engine." I saw this phrase somewhere else and that made me thinking of changing to eyepiece would improve the scope.

Hope you guys can help me out. [smilie=admire2.gif]

Hardwarezone
Posts: 268
Joined: Fri May 17, 2013 2:50 am
Favourite scope: maksutov

Re: Newbie need some advice on reflector telescope

Post by Hardwarezone » Thu Jul 13, 2017 2:02 pm

1) yes , both the tasco and celestron models you quoted are bird-jones reflector , google search the keyword.
They are identified when the focal length stated is much longer than the physical tube length of the newtonian reflector scope. Example 900mm focal length when the telescope is physically 500mm long.
It is due to spherical curvature main mirror and the additional lens at the bottom of the focuser where you put the eyepiece in.
In simple words , it is a limited scope. You should not spend too much money to upgrade it's accessories, the money is better to accumulate and get a better telescope.
Small cheap eyepieces $10 to $30 (ebay plastic aspheric $15) are fine though at this focal ratio.

2) The restriction of bird-jones design is the manufacturing cost allocated to the lens element built-in the focuser.
It cost much more money to produce a small lens that can correct for spherical aberration from the short focal ratio spherical curvature mirror.
To squeeze into the mass-market budget end , lots of sacrifices are made and problems left unsolved. These "problems" or aberrations cannot be easily solved by changing eyepieces.

There is very small difference in production cost (not final pricetag) between spherical and parabolic curvature mirrors at these small sizes as current generation of automatic polish machines can work with parabolic curvature at this size (said to be only 10 minute more machine time) , but consumers (urban living?) prefer a compact looking scope with big numbers in specifications.
The short tube length reduce vibration at a given magnification, allowing the manufacturer to pair it with a smaller mounting that cost less in materials.
Smaller cardboard box size is also cost savings in transportation and retail shelf space.
These are my speculation on why these design of scope are not phased out from production yet.

3) Yes 1.25" interchangeable , no need to follow same brand.

4) Yes, the image would be exciting and impressive for a newbie after getting the EQ mount aligned onto the target. Especially the Moon when it is half-full.
Familiarize with it during the daytime.




http://www.ebay.com.sg/itm/Newest-1-25- ... 1438.l2649

get the 10mm and 23mm , ignore the bad 4mm

Mirkent05
Posts: 4
Joined: Wed Jul 05, 2017 7:42 pm

Re: Newbie need some advice on reflector telescope

Post by Mirkent05 » Thu Jul 13, 2017 5:07 pm

Thx for the useful and detailed information!

Mirkent05
Posts: 4
Joined: Wed Jul 05, 2017 7:42 pm

Re: Newbie need some advice on reflector telescope

Post by Mirkent05 » Thu Jul 13, 2017 7:12 pm

Btw, I've come across a tutorial for using eq mount. So does this mean that I can point the telescope to anywhere as Long as the pivot point is aligned to the Polaris? And izit true that using stock eq mount in Sg (1.5degree N) is quite tricky and need some mods?

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