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Old 16-11-2020, 08:59 AM
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Eyepiece suggestions f/5 newt

Just picked up an 8 inch GSO f/5 ota from Glend. I have been used to using f/6 to f/12 scopes. The idea of spending 100s of dollars for a well corrected 24mm or there abouts eyepiece for widest true field of view, stops me dead in my tracks. Could i just use my two inch ed barlow and pretend i am looking through a C8 again, or get the GSO coma corrector? I have an 84 degree Widescan 3 20mm 1.25 inch eyepiece and a 30mm 80 degree two inch which came from Andrews years ago. Believe it or not, the best view so far for low power was my 32mm plossl.
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Old 16-11-2020, 10:14 AM
glend (Glen)
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Doug, there are many very fine EPs on the market, and personal choice maybe different for each of us. At one time i had a nice collection of Televue Naglers, but found that more often i reached for my GSO Superviews first. I have used, and still keep, three of the GSO Superview eye pieces. They are, the 2" 30mm five element Superview; the 1 1/4" 20mm five element Superview; and the 1 1/4" 15mm four element Superview. These are the best value EPs in my opinion, and a great match for that scope imho.
There is also a 1 1/4" 40mm Superview camera projection eye piece, where the top unscrews to a T2 thread, and the mid body lock screw is used to adjust the barrel.

If you want a good coma corrector, the Baader MPCC Mark III is hard to beat:

https://www.bintel.com.au/product/ba...v=322b26af01d5

Again, just my personal opinions.

Last edited by glend; 16-11-2020 at 12:32 PM.
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Old 16-11-2020, 11:45 AM
astro744
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Adding a 2x Barlow effectively cuts the true field in half defeating the purpose of a wide field eyepiece. Adding a coma corrector especially one with zero aplification factor wont do anything for eyepieces that are not corrected to f5 or better.

A coma corrector is used to reduce the effects of primary mirror coma; it does nothing for the eyepiece. A Tele Vue Paracorr has a slight 1.15x amplifying factor which flattens the field ever so slightly for eyepieces that may exhibit field curvature in certain focal length telescopes and telescope types. The biggest advantage of the Paracorr is that it has a tuneable top which is important for visual use so that you can tweak the distance from eyepiece field stop and Paracorr for optimal correction. The Baader model appears to be more suited for photographic work but as I have not used a Baader I cannot comment further.

In any case the biggest difference you will see in any telescope especially in a relatively short Newtonian is with an eyepiece corrected down to f4. Once you look through one you will then see only primary mirror coma which at 1000mm focal length in your telescope will be quite small and most likely not objectionable. Most people say f5 is about where you start to require a coma corrector but I believe it is more of a personal preference. I can see and appreciate the difference one makes in an f6.4 telescope (1640mm focal length) although most of the time I'll view without one. I can also view quite happily without a Paracorr at f4.5 (1829mm focal length) since the Tele Vue eyepieces I use have none of the abberations present in some of the lesser corrected eyepieces I have. I mainly switch to the Paracorr if I want my Newt to come close to matching the pin point stars the TV-101 gives me across the entire field.

I do not recommend a coma corrector before getting better corrected eyepieces and therefore recommend you put the money you would spend on a coma corrector toward a highly corrected eyepiece as you will notice the difference. A not so well corrected eyepiece will show eyepiece coma and astigmatism with or without a coma corrector. Note not all eyepieces have top be highly corrected to work in your 'scope as you may find a combination that works nicely for you. However highly corrected (tested to say f4) eyepieces do work in any telescope you are ever likely to own.
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Old 16-11-2020, 01:31 PM
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Ok then gentlemen. Which eyepieces around the 24mm 25mm 60 to 68 degree AFOV do you recommend? Starting with the least expensive. I am visual only observer, so absolute photographic not required. Also on a tight budget. How would a 25mm Starguider do?
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Old 16-11-2020, 04:54 PM
croweater (Richard)
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Hi Doug, I have been using the saxon hd cielo eyepieces (60 degree) in my f5 and f6 newts and am very pleased with them. So far I have 4.5,6.5 and 12mm and intend getting the 25mm next. They are the exact same as the celestron xl lx line (well known and good reviews). At around $130 posted from Astropetes very good value. I find them very comfortable to use. Views very good. I used to have a couple of premium naglers but could not justify to myself having so expensive eyepieces sitting around not getting used enough. These work very well for price.
Cheers, Richard
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Old 16-11-2020, 10:56 PM
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Thanks Richard. I belive by the time you get to the 25mm models of this kind of eyepiece, there is no barlow element in the design helping to reduce adorations in the outer field. From what i read on Cloudynights the Celestron x- cell 25 is better than the Starguiders. I will look into your recommendation, but await your hopefull soon to testof the Cielo 25.
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Old 16-11-2020, 11:15 PM
croweater (Richard)
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Quote:
Originally Posted by doug mc View Post
Thanks Richard. I belive by the time you get to the 25mm models of this kind of eyepiece, there is no barlow element in the design helping to reduce adorations in the outer field. From what i read on Cloudynights the Celestron x- cell 25 is better than the Starguiders. I will look into your recommendation, but await your hopefull soon to testof the Cielo 25.
No worries Doug. Not sure how soon will be getting the 25mm. Just hit a roo the other day and wrote off my wife's car. Was insured and already got another car but had to come up with $600 excess and a couple grand extra to upgrade. Might set me back a few weeks.
Cheers, Richard
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Old 19-11-2020, 05:12 AM
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Quote:
Originally Posted by doug mc View Post
Ok then gentlemen. Which eyepieces around the 24mm 25mm 60 to 68 degree AFOV do you recommend? Starting with the least expensive. I am visual only observer, so absolute photographic not required. Also on a tight budget. How would a 25mm Starguider do?
24mm Explore Scientific 68
24mm TeleVue Panoptic 68
24mm APM Ultra Flat Field 65
25mm Celestron X-Cel LX 60
25mm Astrotech Paradigm 60 (aka BST Starguider ED)
If you're on a tight budget The Paradigm is fine.
If you want a relatively inexpensive eyepiece with better optics, the APM.
The APM is also sold under the Meade, Orion, and Altair labels.
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Old 19-11-2020, 06:41 AM
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Thank you Don. Just what i was looking for. A straight list.
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Old 21-11-2020, 05:03 PM
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Went and ordered the 25mm X-Cell LX. Will let you know how it goes.
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