# Planning to buy a first telescope?

by turbo
Tags: planning, telescope
P: 245
 Quote by Chronos The 25mm plossl will be ok. It is unfortunate the OWL is unavailable, its a great EP for the money. You can still cruise ebay for a used wide field EP.
I found this eyepiece, along with these filters. I'll probably just buy these two separately and save myself the head-ache of trying to rely upon other people buying what I don't need.
 Sci Advisor PF Gold P: 9,090 14mm is a bit short for a wide field. You really want something in the 20+ range.
 P: 14 Hey guys! I am interested in buying another telescope and was wondering if any of you had any advice about either of the two i'm split between. It seems to simply come down to a quality? vs aperture argument. The first scope is a Zhumell Z12 with a 12 inch aperture seen here... http://www.telescopes.com/telescopes...rtelescope.cfm or a smaller but from what I have read online (hence the apprehension) a more quality scope in the Meade Light Bridge 10 inch dob shown here... http://www.telescopes.com/telescopes...iandeluxe2.cfm Any and all advice on which would be the better choice as a 2nd telescope would be greatly appreciated. Cheers! -Jack
 Sci Advisor HW Helper PF Gold P: 3,725 That telescope would be very similar to what you already have. What bump in quality do you seek? If you are mainly concerned with the optical quality, I would consider replacing the diagonal with this one. If the focuser isn't up to snuff.... replace it too! Maybe have the main mirror refigured and recoated eventually?
PF Gold
P: 2,170
 Quote by chemisttree That telescope would be very similar to what you already have. What bump in quality do you seek? If you are mainly concerned with the optical quality, I would consider replacing the diagonal with this one. If the focuser isn't up to snuff.... replace it too! Maybe have the main mirror refigured and recoated eventually?
not really

the scope he bought some time ago was a 90mm (f10) refractor
I had to go searching through this thread to discover for myself lol

 Quote by CowedbyWisdom Hey ya'll. I just ordered up this telescope and am waiting for it to come in the mail now. http://www.telescope.com/Telescopes/...335/p/9024.uts What do you guys think? Any good? I thought 90mm was pretty big for a refractor. What do you think i'll be able to see best with this?

Both these 2 scopes being decided between will make awesome "light buckets" :)
10 - 12 inch at ~ f5 or so will be quite fast optics compared to the refractor and
nebulae etc will appear so much brighter

CowedbyWisdom .... I can assume by your trend in choices of scopes that you are not really interested in goto ability or motorised tracking for astrophotography use ?

either of these 2 dobo's will make great viewing of the skies .... see if you can find some independant/unbiased reviews of both of them .... ie. not reviews that may be posted on the sales page sites

I own a 10inch f5 dobo, solid not truss tube, if you got the truss tube one, you would need the shroud to wrap around it to keep ambient light out
I also own a Celestron C9.25, 9.25inch f10,
each has its uses the f5 is a light bucket, but lower magnification
fast optics like f5's can suffer from a little spherical and chromatic aboration but this is normally only visible around the outter edges of the field of view and under higher magnifications. They are great for wider field objects, globular and open clusters, diffuse nebulae etc

The f10 scope offers much higher useable magnification and get great for small bright objects
planetary nebulae, galaxies, planets etc

Both those scopes say max useable mag of ~ 500x. I suspect that would be really pushing it and a bit of sales hype, In practice I would suggest that ~ 200 - 300x would be closer to the truth before the aborations spoken of earlier become quite obvious
Thats from personal experience with several fast scopes over the years

Dave
HW Helper
PF Gold
P: 3,725
Quote by davenn
the scope he bought some time ago was a 90mm (f10) refractor
I had to go searching through this thread to discover for myself lol
 Hey ya'll. I just ordered up this telescope and am waiting for it to come in the mail now. http://www.telescope.com/Telescopes/...335/p/9024.uts What do you guys think? Any good? I thought 90mm was pretty big for a refractor. What do you think i'll be able to see best with this?
DOH! I even chimed in on that one!
 PF Gold P: 10,767 Dave, other than the obvious effect the focal length has on magnification and eyepiece choice, why would the faster scope give brighter views? Or is that all you meant?
PF Gold
P: 2,170
 Quote by Drakkith Dave, other than the obvious effect the focal length has on magnification and eyepiece choice, why would the faster scope give brighter views? Or is that all you meant?
for the same reason a low f stop gives more light through a camera lens

f2 more light ( brighter image) than f5, than f10 than f22 etc

this is a function of the mirror, lens itself

this really becomes a benefit when doing astro photography cuz for a f5 you dont need to do the same much longer exposure time that you would need to do with a f10

Dave
PF Gold
P: 10,767
 Quote by davenn for the same reason a low f stop gives more light through a camera lens f2 more light ( brighter image) than f5, than f10 than f22 etc this is a function of the mirror, lens itself this really becomes a benefit when doing astro photography cuz for a f5 you dont need to do the same much longer exposure time that you would need to do with a f10 Dave
For AP sure, but for visual use, if the magnification through the eyepiece is the same between two scopes, nothing is different, correct?
PF Gold
P: 2,170
 Quote by Drakkith For AP sure, but for visual use, if the magnification through the eyepiece is the same between two scopes, nothing is different, correct?
personal experience tells me that I can see a difference, say M42, the Orion Nebula

maybe will have to have both scopes outside together again one nite
just to confirm or deny my long held beliefs haha

D
 Sci Advisor PF Gold P: 2,170 I think part of the thing is... even at the same magnification, the f5 system is going to give a wider FOV which even on its own is letting more light through D
PF Gold
P: 10,767
 Quote by davenn I think part of the thing is... even at the same magnification, the f5 system is going to give a wider FOV which even on its own is letting more light through D
That doesn't make sense to me man. At the same magnification the object should appear exactly the same brightness in both scopes. The difference in FOV would only be because of the eyepiece design. And I'm not sure what additional light you are referring to. An F/4 newt and an F/8 newt with equal objectives have exactly the same light gathering ability. You just need to use different eyepieces to get the same magnification on each one.
P: 14
 Quote by davenn not really the scope he bought some time ago was a 90mm (f10) refractor I had to go searching through this thread to discover for myself lol Both these 2 scopes being decided between will make awesome "light buckets" :) 10 - 12 inch at ~ f5 or so will be quite fast optics compared to the refractor and nebulae etc will appear so much brighter CowedbyWisdom .... I can assume by your trend in choices of scopes that you are not really interested in goto ability or motorised tracking for astrophotography use ? either of these 2 dobo's will make great viewing of the skies .... see if you can find some independant/unbiased reviews of both of them .... ie. not reviews that may be posted on the sales page sites I own a 10inch f5 dobo, solid not truss tube, if you got the truss tube one, you would need the shroud to wrap around it to keep ambient light out I also own a Celestron C9.25, 9.25inch f10, each has its uses the f5 is a light bucket, but lower magnification fast optics like f5's can suffer from a little spherical and chromatic aboration but this is normally only visible around the outter edges of the field of view and under higher magnifications. They are great for wider field objects, globular and open clusters, diffuse nebulae etc The f10 scope offers much higher useable magnification and get great for small bright objects planetary nebulae, galaxies, planets etc Both those scopes say max useable mag of ~ 500x. I suspect that would be really pushing it and a bit of sales hype, In practice I would suggest that ~ 200 - 300x would be closer to the truth before the aborations spoken of earlier become quite obvious Thats from personal experience with several fast scopes over the years Dave
Thanks for the response. To answer your question, I don't find the goto scopes necessary or fun. I like doing my own star finding and am not interested in astrophotography. Since I doubt there is anyway to upgrade my little refractor to make it up to snuff with a 10 or 12 inch dob (?) I felt might as well get a bigger scope. I'm also considering getting a Smith Cassegrain of some sort any suggestions are welcome. My budget is 700 dollars or less. I will be using the scope for looking at mainly the planets and galaxies.
 Sci Advisor PF Gold P: 2,170 You mite get a new 6" schmitt-cass for up to that price, maybe an 8" but I doubt it have a good look through scope sales sites, a non-goto 8" may well be affordable you should/mite be able to get a good respectable condition second hand one for ~$700 my 9.25" goto schmitt-cass was$3300 My 10" dobo was \$600 look, if you are not worried about astrophotography, just stick with a good decent sized dobo either of those 2 above would do you well for a few years, till "aperture fever" starts to bite hard ;) haha cheers Dave
 P: 27 I found these on amazon "Celestron UpClose Porro Series 10-30 x 50 Zoom Binoculars"...Are they good?
 P: 15 Wondering. How good are the National Geographic Telescopes? Specifically NATIONAL GEOGRAPHIC 114/900MM AZ. Say compared to the Bresser Galaxia 114/900.
PF Gold
P: 10,767
 Quote by BH Wiz I found these on amazon "Celestron UpClose Porro Series 10-30 x 50 Zoom Binoculars"...Are they good?
 Quote by Storm89 Wondering. How good are the National Geographic Telescopes? Specifically NATIONAL GEOGRAPHIC 114/900MM AZ. Say compared to the Bresser Galaxia 114/900.
A good rule of thumb is "the more you spend, the better they will be".
Obviously it's not always that simple, but generally it works out that way in my opinion. I'd look for similar products and see what the price range is for them. If yours is at the bottom of the bucket, it's probably not too good.
P: 15
 Quote by Drakkith A good rule of thumb is "the more you spend, the better they will be". Obviously it's not always that simple, but generally it works out that way in my opinion. I'd look for similar products and see what the price range is for them. If yours is at the bottom of the bucket, it's probably not too good.
Of course. That's the rule of thumb I've gone by on most occasions. From what I can see the two are somewhat similar, but the difference is in the stand, which I understand is quite important.

I'm actually asking cause my birthday is right around the corner and I've been meaning to put a telescope on my wish list and these are around the price I could probably sum up if most of my family gathered round. I doubt they will, but you can always live in the hope, can't you?

I can't find much else than Bresser Galaxia 114/900 or Bresser Pollux 150/1400 (but without a 3x Barlow) or Bresser Lyra 70/900 at that price range. The National Geographic one is a little cheaper, but the stand appears somewhat worse.

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