Just another doubt in relation to a previoulsy asked question

[aksingha]

Hello all members, I recently posted a question on how good the celestron travelscope 70mm will be as i am about to purchase but then accidently i came across the celestron powerseeker 70 az with Focal length of 700mm,f:ratio of 10 and magnification of 35x and 175x with 20mm and 4mm eyepiece and also comes with 3x barlow. So now i am really unable to decide between the travelscope 70mm and powerseeker 70mm scope.Does anyone own those scopes.Please help me out for the last time. Thank you

[rwilkey]

Hi aksingha, both specifications on various websites makes claims beyond the scopes' capabilities so beware. For example, a 70mm objective (the lens at the front) has a maximum useable magnification of 140x, so the claim of the Powerseeker of 175x is completely beyond the scopes' capability, so the inclusion of a 4mm eyepiece is a non-starter, it cannot be used with this scope, neither can the 3x Barlow, which cannot be used most of the time, though it is possible to use it with the 20mm ep giving you 105x. The limiting stellar magnitude (of stars able to be seen) of 11.7 is also a very steep claim.

I think the Travelscope gives you slightly better options plus it also includes two eyepieces you can actually use with the telescope (20mm and a 10mm) giving you 45x and 90x. Again the limiting stellar magnitude is a bit on the steep side at 11.7. As far as I can see one of the differences between these scopes is the focal ratio, the Travelscope has a f/ratio of 12.86, and the Powerseeker an f/ratio of 10. Both these limit you to Moon and planets as main astronomical targets. As regards DSO's (deep sky objects), you will be very limited unless you start to consider a larger aperture of 90mm or above and a lower focal ratio.

When looking at adverts for starter scopes, always ignore high magnification claims, they are often beyond the capability of the scope. Quality of image is more important than magnification in astronomy.

Good luck with your choice!

[aksingha]

Thank you rwilkey for the opinion.SO the travel scope is still superior than the powerseeker.Are there any scope available within $230 which would turn out better than travelscope 70mm or should i invest in eyepiece for the travelscope.thank you

[cantab]

As far as I can see one of the differences between these scopes is the focal ratio, the Travelscope has a f/ratio of 12.86, and the Powerseeker an f/ratio of 10.

The Travelscope 70 I looked at is f/5.71 .

Basically the Powerseeker's a more traditional long-tube refractor. This keeps the chromatic aberration (false colour) down for better high magnification views, but means the tube is longer and it won't give binocular-style widefield views. The Travelscope's a short tube refractor so more compact and good for widefield but not so good for high magnification.

[rwilkey]

Hi Cantab, I see that one now, at Harrison Telescopes, yes, that focal ratio would be much better for deep sky. Not sure what I was looking at before. That is much better.

Thank you rwilkey for the opinion.SO the travel scope is still superior than the powerseeker.Are there any scope available within $230 which would turn out better than travelscope 70mm or should i invest in eyepiece for the travelscope.thank you

Yes, I think the Travelscope will serve you better than the Powerseeker, though I don't know what else to recommend at your budget - it always pays to spend a bit more and for me refractor telescopes start to sing at 90mm or above. As regards an eyepiece for the telescope, I would try out the ones that come with the telescope first and see how you get on and what your preferences might be.

[E621Keith]

Thank you rwilkey for the opinion.SO the travel scope is still superior than the powerseeker.Are there any scope available within $230 which would turn out better than travelscope 70mm or should i invest in eyepiece for the travelscope.thank you

I see you use $ instead of £. Do you live in the US?

For your budget, I'll go for an Orion Starblast 4.5 over either Celestron 70mm refractos. The Starblast mini dob has received many good review over the years, and you still have money left over for a few plossl eyepieces.

http://www.telescope.com/Telescopes/Dobsonian-Telescopes/Classic-Dobsonians/Orion-StarBlast-45-Astro-Reflector-Telescope/pc/1/c/12/sc/13/p/102010.uts?refineByCategoryId=13

[ronin]

Considering the budget is in $ I assume the US.

Why not a 90mm from telescopes.com.

There are 3 on their site.

A Meade Terrastar 90mm for $170

A Celestron Astromaster 90 for $215 (Az mount)

The Astromaster 90 on an EQ mount for $230

Even have a Meade ETX-80 goto for $225.