Just brought a telescope need some help please.

[bigblakey87]

Hello, Yesterday I picked up a Tasco 302012 for £20 with a stand. Having never used a telescope before I spent ages understanding my mount and how to setup all of my axis correctly I also cleaned the mirror which had loads of fibreglass on it . So now my biggest problem is my lenses. It came with a 2x Barlow lens however there is no lens in the Barlow lens so this is useless. Secondly in the Barlow lens is a 20mm eyepiece which gives me 45x magnification. I can't understand what diameter eyepieces I should be looking for. In the manual these are my specs which I need your help to understand please.

Objective Diameter: 114mm (4-1/2") Please help me understand what the hell this means?

The rest of the specs I can understand. I can't work out if I need 2" eyepieces or 1.25" I have measured various points across the eyepiece area to try and get an idea of the eyepieces I need to buy.

Thank you in advance.

[happy-kat]

Hi

Measure the tube (not lens) end of your 20mm what is that ?

114mm is the size of the mirror or lens.

Is it an open tube with mirror at the bottom or a solid tube with a lens on the top end?

Edit just looked up the part number it is a reflector with a focal length of 900mm.

[Dom1961]

I think objective diameter is your aperture, so the size of the primary mirror. Measure the diameter of the supplied 20mm or the Barlow, it will be 1.25" or 2" or 0.925"

[Dom1961]

Whoops sorry happy Kat, your post didn't show up when I was typing

[bigblakey87]

OK. I have removed all the eyepieces and measured the hole looking at my own reflection. It appears to be 1.25. So should I order 1.25 eyepieces? I would like to get a kit with Barlow lenses can you point me in the right direction for a reasonably priced kit please. My scope says it is capable of 450x magnification but realistically what can I expect to see. Will I be able to see galaxies and good images of other planets? Are there any essentials you can suggest I get for my telescope? One more thing. Is my telescope good for the price and is it entry level or intermediate?

Thanks for your help

[dweller25]

Hello and welcome to SGL, you have a nice entry level scope that for £20 was a bargain.

It has a 114mm mirror so it's maximum realistic magnification is x220, but x150 to x200 will be better.

Here are some Youtube vids...

Eyepieces - I think your scope has a 900mm focal length so.....

Deepsky : 20mm giving x45

Luna       :12mm giving x75

Planets   : 5mm giving x180

Hope that helps

[bigblakey87]

Thanks for the information. Would something like this be ok? http://www.ebay.co.uk/itm/One-High-Quality-1-25-PLOSSL-Lens-for-TELESCOPE-Choose-from-10-Brand-New-/181107525282?pt=LH_DefaultDomain_3&hash=item2a2ad986a2#shpCntId

[SpaceWalker]

OK. I have removed all the eyepieces and measured the hole looking at my own reflection. It appears to be 1.25. So should I order 1.25 eyepieces? I would like to get a kit with Barlow lenses can you point me in the right direction for a reasonably priced kit please. My scope says it is capable of 450x magnification but realistically what can I expect to see. Will I be able to see galaxies and good images of other planets? Are there any essentials you can suggest I get for my telescope? One more thing. Is my telescope good for the price and is it entry level or intermediate?

Thanks for your help

It's entry level scope. Customer reviews on Excelsis say that it's a good one, but everything depends on the quality of your primary mirror. I hope you cleaned it with especial care  following instructions e.g. like

. If the primary mirror is good I guess your max should be around 140-160x.

It looks like it's a ~ f/8 scope so you may need 3 eyepiece minimum and a 2x Barlow. You said *reasonably priced* so I assume they should be Plossls. For example

32mm Plossl  will give max TFOV possible, 28x magnification, 4mm exit pupil

16mm Plossl,  56x magnification, 2mm exit pupil

12mm Plossl, 75x magnification, 1.5mm exit pupil

8mm (16mm/2x), 112x magnification, 1mm exit pupil

6mm (12mm/2x), 150mm magnification, 0.75mm exit pupil

You also may want to use your 20mm stock eyepiece, but I doubt it would be any good.

Thanks for the information. Would something like this be ok? http://www.ebay.co.uk/itm/One-High-Quality-1-25-PLOSSL-Lens-for-TELESCOPE-Choose-from-10-Brand-New-/181107525282?pt=LH_DefaultDomain_3&hash=item2a2ad986a2#shpCntId

I don't think so, they are unbranded plossls probably of a low quality. They labelled as *fully-coated*. It's OK for planets, but DSOs required higher light transmission so you'll need *Fully multicoated* like this GSO Plossl or at least *multi-coated* like this Meade Plossl. As an option, instead of the 16mm and 12mm Plossls you can get a zoom eyepiece like this.