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should I buy this?

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#26 eric_zeiner

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Posted 09 January 2023 - 03:09 PM

I'm not a big fan of reflectors but I think a decent 6" Dob would do the trick.  Especially if it has a parabolic mirror.  Orion has them, OPT has them, Highpoint has them and so forth.  Also, most dobs come with a fairly good accessory kit.  Zhumells come to mind.


Edited by eric_zeiner, 09 January 2023 - 03:19 PM.


#27 eric_zeiner

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Posted 09 January 2023 - 03:20 PM

I just looked on the Orion website and they have a 6" dob for $549.  This scope has the potential to keep you busy for quite some time.


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#28 Echolight

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Posted 09 January 2023 - 08:56 PM

If the physcial length optical tube of a suspect reflector is roughly half of the stated focal length it is one of the pseudo-bird jones scopes.  It is not a good scope.  stay away.

 

AWB one sky is highly recommended.

If it has a focuser sticking out the side, that is.



#29 Protheus

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Posted 10 January 2023 - 03:18 AM

Circular..Spherical

No no, rectangular objectives are the next leap forward in optical performance.

 

Chris


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#30 JohnnyBGood

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Posted 10 January 2023 - 08:32 AM

The Celestron and Meade 127mm reflectors are difficult scopes to start with because their design makes them hard to get the mirrors aligned properly so that you have sharp views. Several experienced users have had success with these scopes but I'd recommend you look elsewhere for something to start out with.

I love all the people recommending $500+ scopes to you. Perhaps they're offering to pay the difference?

Anyway, if you keep looking you're likely to find a long tube 114mm scope out there for the same price or less. There are short tube versions with the same optical design as the 127, so be sure to pick one that has a tube that is about three feet long, not one that's only 18 inches long.

There is very little difference in optical performance between a 114mm scope and a 127mm or 130mm scope. Side by side I could not honestly tell much difference between the old Bushnell 114 I bought for $30 on a whim and my "nicer" Meade 130. Except the 114 was sharper at high power.

The downsides to buying most used 114mm scopes is that they likely come with low quality eyepieces. If that's the case you can get better ones for reasonable prices-- an inexpensive set of generic aspheric 23mm, 10mm, and 4mm eyepieces can be bought in eBay for about $35 and they'll work fine for you to start out with.

Don't fret about an equatorial mount. They're not *that* hard to learn to use, and if you get stuck people on here can give you pointers. Worst case scenario you can set it to 90 degrees latitude and use it exactly like an "alt-az" (up-down-left-right) scope.

You'll also need to pick up or make a collimation cap or something similar to help line up the mirrors, but that's not hard to do with a long tube 114.

Of course, you can probably also find a 70mm or 80mm refractor for a reasonable price as well which would be easier to use but dimmer objects won't show up as well and you won't be able to "zoom in" quite as much on the moon and planets. It's a tradeoff. I personally love 70mm scopes for their portability but others want something more powerful.
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#31 rob1986

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Posted 10 January 2023 - 08:42 AM

At f8, its hard to get colimation wrong. When I tried to fix mine for more classical colimation, I never seemed to make a difference. The images stayed razor sharp up to 200x. And this will no experience and nothing but eyes. (Hah! Dad never asked me to help collimate his 8" f4.5 with eyes only, but maybe thats why some feel newts are softer.)

Its not for nothing that collimation aides followed faster scopes.

Edited by rob1986, 10 January 2023 - 08:45 AM.


#32 rhetfield

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Posted 10 January 2023 - 10:20 AM

There is very little difference in optical performance between a 114mm scope and a 127mm or 130mm scope. 

They will all be different optically.

 

Some of the more popular 114mm scopes are F4 (sometimes even listed as F3.9).  Those scopes are designed to be wide field specialists and they can be hard to collimate and focus at high magnification and will play havoc with inexpensive eyepieces.

 

In turn, nearly all of the 130mm reflectors are F5.  They do better at high magnification than the 114mm/F4 scopes, but lose a bit of field of view.  They are a bit more forgiving on collimation, focus, and eyepieces.

 

Back to the 114mm scopes - they are also made in F8.  These do better on higher magnification and are more forgiving all around, but have very narrow field of view.

 

In the end, the 130mm scope is a general purpose scope while the various 114mm newts are specialized for different types of targets.



#33 vtornado

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Posted 10 January 2023 - 11:32 AM

If it has a focuser sticking out the side, that is.

I am speaking roughly, and typically the space taken by the mirror cell and the couple of inches that the diagonal is inside the tube account for the height of the focuser stack and the radius of the optical tube.

 

For example my true 130 f/5 newt has a tube length of 585mm vs. 650mm focal length.

 

These Bird Jones. scope such as the celestron power seek 127 lists the focal length

at 1000mm and the optical tube length at 508mm.


Edited by vtornado, 10 January 2023 - 11:33 AM.


#34 Dave Mitsky

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Posted 11 January 2023 - 11:35 PM

The 135mm Orion SkyScanner BL135mm Dob is currently on sale.  It has a spherical primary mirror but with a 5.3" aperture at f/8.1 spherical aberration will be at an acceptable level.

 

https://www.startrek...-find-its-place



#35 Dave Mitsky

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Posted 11 January 2023 - 11:40 PM

I just looked on the Orion website and they have a 6" dob for $549.  This scope has the potential to keep you busy for quite some time.

This telescope is also currently on sale.  The Orion SkyQuest XT6 is back and now has a 2" focuser.

 

https://www.telescop...pe/p/102004.uts



#36 epee

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Posted 12 January 2023 - 03:47 PM

This telescope is also currently on sale.  The Orion SkyQuest XT6 is back and now has a 2" focuser.

 

https://www.telescop...pe/p/102004.uts

Surprisingly good price as well.



#37 Nick Dangerr

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Posted 12 January 2023 - 04:27 PM

Here is Ed Ting's review of the Celestron Powerseeker 127EQ:

 

https://www.youtube....h?v=IXfR7YTF5a4

 

Telescopic Watch review:

 

https://telescopicwa...lescope-review/

After looking over the above reviews, you will likely conclude that this is not the scope for you. The second part of your question is "what are the alternatives?" Ed Ting to the rescue there, as well!

 

https://www.youtube....-g2eWj0Fs&t=11s




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