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aser hisham

which telescope to choose?

67 posts in this topic

so what should i do should i wait for a while?

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25 minutes ago, aser hisham said:

so what should i do should i wait for a while?

Try locating a local astronomy club and go to their star parties.  Alternatively, locate a local astro enthusiast and observe with them for a while to discover what you like and don't like.  You said you have a friend with a C8 I believe.  Spend time with them to see if this is something you want to continue with.

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yes i do in fact spend some time with him and i go to an astronomy club frequently but i am worried that if i buy this telescope it wont perform well and i wouldl be stuck with it for long

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Then don't buy it. Go to your club and see what others are using and look through them if you can and make a more informed decision before parting with any money. The sky is going no where.

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Once you find a scope you like, investigate worldwide retailers who will ship to Egypt.  Find out what that will cost with shipping and tariffs.

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Aser,

Regarding the 152mm f/8 achromat on the EQ-4 mount there at the Voyager shop in Egypt, the EQ-4 will not support the 152mm f/8 adequately.  Incidentally, I watched the video of the inside of the Voyager shop, and quite frankly I didn't get too excited about the telescope kits being offered and showcased there.  The only way you're going to get a nice kit, and one to enjoy for years to come, is to order it from outside Egypt.

Teleskop Service in Germany is the premier international distributor of astronomical equipment, and they ship to Egypt...

http://www.teleskop-express.de/shop/index.php

If cost is a concern, then you can get the mount first.  When building a house, a home, one builds the foundation first, and the mount is the foundation of any telescope.  

Then you build the walls and roof; that is, you get the telescope later, and when you're able.

The following items are available from Teleskop Service...

The Sky-Watcher EQ-5 would support a wide variety of types and sizes of telescopes, and up to 8", possibly even 10" for some telescopes.  The EQ-5 is of metal, and should be able to withstand the trip and any rough handling...

http://www.teleskop-express.de/shop/product_info.php/info/p6693_Skywatcher-NEQ-5-Mount-with-stainless-steel-tripod---telescopes-to-10kg.html

After the mount arrives, you can assemble it and learn all about it.  The mount can even be upgraded to motorised go-to capability, in future.

When you're ready, you can then get the telescope.  For examples...

A GSO 8" f/5  Newtonian... http://www.teleskop-express.de/shop/product_info.php/info/p49_GSO-200-mm-f-5-Newtonian-Parabolic---2--Dual-Speed-Crayford.html

Or, if you want to get whole kit at once... http://www.teleskop-express.de/shop/product_info.php/info/p51_TS-Optics-GSO-8--F5-Newtonian-Telescope-on-Skywatcher-EQ5-mount.html

If you'd rather have an 8" Schmidt-Cassegrain... http://www.teleskop-express.de/shop/product_info.php/info/p1000_Celestron-C8-SC-XLT---203-2032-mm-Schmidt-Cassegrain--optischer-Tubus.html

Again, the whole kit if you'd like... http://www.teleskop-express.de/shop/product_info.php/info/p1002_Celestron-C8-auf-Skywatcher-NEQ5-parallaktische-Montierung.html

If you'd rather have a 6" f/8 achromatic refractor, the EQ-5 will support that, too, but only for visual use...

http://www.teleskop-express.de/shop/product_info.php/info/p7783_Bresser-4852120---152-mm-Refraktor--f-1200-mm--OTA.html

http://www.teleskop-express.de/shop/product_info.php/info/p1034_Skywatcher-Evostar-150-OTA---Refraktor-150-1200mm-opt--Tubus.html

If you'd prefer a somewhat smaller refractor... http://www.teleskop-express.de/shop/product_info.php/info/p3309_Skywatcher-Evostar-120---120-1000mm-Refraktor---optischer-Tubus.html

It, too, can be had as a whole kit... http://www.teleskop-express.de/shop/product_info.php/info/p3308_Skywatcher-Evostar-120-EQ5---120-1000mm-Refraktor-Teleskop.html

If, in fact, you do want a refractor, I'd get that combination, either whole; or one piece at a time, and the mount first.

At Teleskop Service, you have a WIDE selection and combinations from which to choose; now, that's a telescope shop.

If worst comes to worst, you can go ahead and get that 152mm f/8 on the the EQ-4 from Voyager, and then get the EQ-5 later.  You could always use the EQ-4 for a smaller telescope in future, and as a grab-and-go of sorts.

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i will check this distributor i hope that they can be imported to egypt and i think i will go with a cassegrain  which one would you recommend ?

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Posted (edited)

3 hours ago, aser hisham said:

i will check this distributor i hope that they can be imported to egypt and i think i will go with a cassegrain  which one would you recommend ?

The drop-down list for the shipping charges, and for every item they carry, includes "Egypt".

The Celestron C8 8" Schmidt-Cassegrain has a track record of quality optics, from sample to sample.  The 8" is also the "sweet spot" among the apertures of the design; not too small, and not too large.  The C6 6" can also serve as an amateur's only and sole telescope, but nothing smaller.  The C5 5" seems to be more suitable as an extra or secondary telescope to a main telescope.  Indeed, the C5 is offered as a daytime spotting scope in addition to its astronomical version.

However, I, myself, am not too keen on an 8" Schmidt's 2032mm focal-length, as that is a bit too long for me, and I happen to prefer moderate-to high powers in my observations; no rhyme nor reason, eh?  For example, an 8" f/6 Dobsonian has a focal-length of only 1200mm, which allows for an improved shot at wide-field low-power observations, as well as high-powered views at the other extreme.  But prospective buyers look past the unusually long focal-length of the C8 when given the chance to possess an 8" aperture in such a short, compact optical-tube.  Still, the C8 is very popular among amateurs, and perhaps the best-selling Schmidt of all time. 

What about the mount; the foundation?  :D

Edited by Alan64
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There could be importation tax as well you'll need to check if there are other import costs on top of just shipping costs, these can be the buyers responsibility.

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@Alan64  Is it possible to use something like 50mm EP with a C8 to get low power for nebulae? a 50mm eyepiece would give 40.6x and 5mm exit pupil. I guess most of the EPs would be in 2" size.. but something tells me there is something else missing.

For the first time (my first thoughts on the subject of cassegrains) I understand why some people say they are really good for planetary observation, 25mm will give 81x!!

Edited by N3ptune

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2 hours ago, N3ptune said:

@Alan64  Is it possible to use something like 50mm EP with a C8 to get low power for nebulae? a 50mm eyepiece would give 40.6x and 5mm exit pupil. I guess most of the EPs would be in 2" size.. but something tells me there is something else missing.

For the first time (my first thoughts on the subject of cassegrains) I understand why some people say they are really good for planetary observation, 25mm will give 81x!!

With an 8" Schmidt, sure, you can use a 2" 50mm(41x) or even a 2" 60mm(34x) ocular.  But there's one caveat: the hole in the center of the primary mirror is not 2" wide...

58fab87742c24_8Schmidtprimary.jpg.db63fc502eed38fdd6d668707c6a18cb.jpg

It's about 1.5" rather, or 38mm.  Therefore, there would a narrowing of the field-of-view as a result, but you would have the low magnification nonetheless.

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@Alan64 Okk the opening is 38mm, I did not know that.

Normally to get the TFOV I do: TFOV = AFOV of eyepiece / magnification given by eyepiece

Telescope C8: 200mm x 2032mm / F10.16 with for example a 50mm EP and 82d AFOV

2032/50 = 40.64x then 82d/40.64 = 2.01 TFOV but with a full 51mm view of the secondary mirror (like on a Newtonian) How can I know how much TFOV is lost because the hole in the primary of the cassegrain is only 38mm? just to get an rough idea.

Edited by N3ptune

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52 minutes ago, aser hisham said:

if they get into egypt  which is unfortunately a low percentage

Hi aser hisham, I think this is probably your problem.  I guess what we in Europe, and North America don't have any comprehension of is how difficult it can be to get objects through customs in some countries let alone something as suspicious looking as a telescope.  It is def. possible for you to spend a considerable sum of cash and still not allowed to import the final package into Egypt.  What we take for granted is unfortunately a big issue for people in the middle and far east.

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13 hours ago, aser hisham said:

if they get into egypt  which is unfortunately a low percentage , i think i will go with these , any thoughts ?

http://www.teleskop-express.de/shop/product_info.php/info/p1002_Celestron-C8-auf-Skywatcher-NEQ5-parallaktische-Montierung.html

 

That would be good as a start, if that's the telescope you want.  The EQ-5 mount can be upgraded to motorised go-to capability in future.

The type of telescope that would probably give the least amount of trouble at customs would be a Newtonian, and once it's explained that it's a design that cannot generally be used for land targets, for surveillance, like refractors and catadioptrics(Schmidt and Maksutov) can, and are.

You might want to test the customs "waters" by ordering just the mount first.  If that comes through okay, then take a chance with the telescope.

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23 hours ago, N3ptune said:

@Alan64 Okk the opening is 38mm, I did not know that.

Normally to get the TFOV I do: TFOV = AFOV of eyepiece / magnification given by eyepiece

Telescope C8: 200mm x 2032mm / F10.16 with for example a 50mm EP and 82d AFOV

2032/50 = 40.64x then 82d/40.64 = 2.01 TFOV but with a full 51mm view of the secondary mirror (like on a Newtonian) How can I know how much TFOV is lost because the hole in the primary of the cassegrain is only 38mm? just to get an rough idea.

This 50mm... https://www.harrisontelescopes.co.uk/acatalog/Revelation_50mm_Widefield_Eyepiece_2_.html

...has a 60° AFOV.  I use this... http://www.csgnetwork.com/telefov.html

There may be better calculators out there, but that one works for me.

58fc632c51a2b_8f10Newt50mmSchmidt50mm-40mm.jpg.d1b828188d5503e9a198915c90443ae0.jpg

In red, a 1.25" 40mm 43° ocular with a 200mm f/10 Schmidt

In blue, a 2" 50mm 60° with a 200mm f/10 Newtonian

Those two are accurate.

And as near as I could calculate, in yellow, a 2" 50mm 60° with a 200mm f/10 Schmidt.

But don't hold me to that last one.

Incidentally, that afocal shot was taken with a 1.25" 30mm 50° with a 100mm f/4 Newtonian.  

Rather spacious, eh what?

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