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#1 GA-12345


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Posted 11 December 2019 - 11:33 PM



My brother just purchased a CPC 1100 GPS. He is a beginner, and I know very little. I was looking to get a quality eyepiece, or another accessory, for him as a Christmas present. As I have spent the last little while looking I realize there is a lot of factors effecting the quality more than just the eyepiece, it must also match the scope itself.


Optical Design Schmidt Cassegrain
Aperture 280 mm / 11"
Focal Length 2800 mm
Focal Ratio f/10
Focuser Internal
Eyepiece Barrel Diameter 1.25"
Diagonal 90° Star
Finderscope Yes
Optical Tube Dimensions Length: 23" / 58.4 cm


He purchased a pack of eyepieces here.


Judging completely from pricing I would have to assume these are not high quality but I can't tell what makes the difference. Does anyone have any recommendations for an eyepiece he can use for planet/glob/nebulae viewing on a regular basis, perhaps a multi-range lense? Or any other accessory that would improve his ability to view?


Thank you

#2 Sky Muse

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Posted 12 December 2019 - 12:08 AM

At f/10, the Schmidt will not require corrective and costly eyepieces for sharp, pleasing views.  Wider-angle eyepieces, over the kit-Plossls, from 8mm to 24mm or so would be nice additions.


If at all possible, I would urge the return of that eyepiece kit.  Choosing eyepieces for a telescope can be akin to purchasing a pair of prescription-eyeglasses from an optical dispensary, depending on the needs of the individual.  Eyepieces are best purchased one or two at a time, and after careful research.

#3 havasman


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Posted 12 December 2019 - 12:08 AM

Hi and welcome to the forums!


Your brother's got a very very powerful telescope on his hands. waytogo.gif


So really any eyepiece will blow his socks off. I recommend that he take those out and look around for a couple of months and get some idea of what's out there to see. It's completely amazing.


Yeah, those eyepieces are minimally capable. But they're a lot more capable than he is just now. What he needs is a bit of experience and some concept of what his ongoing budget is likely to be for astro gear. Then come back and ask your good question again, adding some budget limits. You'll get hundreds of answers. Some will be good.


Look around at some retail websites. I highly recommend Astronomics and Agena Astro. See the ranges of eyepieces for some concept of what's out there. Very good eyepieces range from @ $60 a pop to @ $1000 each. That f10 scope can perform to its capability with high quality eyepieces that are less complex and therefore less expensive. That's a strength of the design.


The best accessory for any new scope is more time spent observing from under good dark skies.

#4 Jeffmar



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Posted 12 December 2019 - 02:28 AM

The eyepieces in the kit will work just fine for a while unless your brother needs longer eye relief for glasses or just for comfort. At 150 dollars, that eyepiece kit isn’t a big investment. you don’t have to spend 500 dollars, each, on high end Televue eyepieces to get great views from a telescope like a C11. If you are looking for eyepieces that can give a noticeable improvement they might cost 70 to 300 dollars each. They will usually have a wider field of view, better lens coatings, and sharper to the edge optics. I like any eyepiece with 17mm of eye relief or more, and 60 to 70 degrees of apparent field width. There are at four or five brands I can think of that have those specs. 


I started out with about 2 cheap plossls and a Barlow lens. I slowly replaced them with Pentax, Televue (not the 500 dollar models), and Baader eyepieces. Orion has some good 70 degree, wide field, 2 inch eyepieces that are pretty good and pretty cheap. I have the 32mm and 38mm versions of those Orion eyepieces and I use them all the time. Your brother will need a 2 inch wide diagonal for the eyepieces I just mentioned. 


Variable eyepieces I have looked through have narrow fields of view. Even basic plossl eyepieces will give you wider views. You also might get more distortion from zoom eyepieces. Some people really like them in spite of any shortcomings just because it keeps thinks simple when you are out in the dark.

#5 Astro-Master



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Posted 12 December 2019 - 02:39 AM

I would suggest getting him the large Astro-Physics 2" back with the 3.5" flange that replaces the stock flange and opens the back to 2 full inches.  It just screws right on in a few seconds.


It has a massive compression ring to hold the heavy 2" eyepieces he will need for low power wide field with that long 2800mm focal length.  Its not even expensive, I paid around $40 for mine 20 years ago.

#6 sg6



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Posted 12 December 2019 - 05:44 AM

The kits are generally not great and at the focal lengths of 6mm, 8mm, 13mm, 17mm, and 32mm I would say the 13, 17 and 32 will be used the most.


The CPC is nice but a big beastie. We have one and takes 2 to move it safely, 3 people are better.

With the focal length of it a lot of targets will be simply too big to be seen in one go.


At 2800mm a 32 plossl gives 87.5x magnification and a view of 0.6 degrees - that means a lot of objects just will not fit = M42 Orion Nebula, M45 Pleiades and just don't think of M31 Andromeda galaxy. Even a full moon will just squeeze in. And just squeezing in is not I find actually pleasant.


Eyepieces: Really wide is probably the way to go and Wide is the ES 24mm 68 degree. Max of 117x (fractionally under)and a field of 0.58 - odd the plossl comes out as more, makes me wonder if the kit is claiming numbers that do not match the eyepiece?


The scope is not I suggest the best start. It is somewhat specialised and not a general look at most things scope. The narrow field could make alignment difficult although the one here has GPS and once level it is simply center the stars suggested and it all works fine. Mind you it does tend to not suggest some very obvious stars and ones it asks for can be somewhat unknown.


Really the way to go is to fit it out for 2" eyepieces. Trouble it the refiting costs and the eyepieces then also cost. And 2" eyepieces are big, as in B I G!


For a present of a good eyepiece the ES 24mm 68 degree eyepiece is really the option (still puzzled by the field), for 2 get the 16mm or 20mm also. However just one seems sensible at this time. See how brother gets on with the CPC first. Also the 16mm or 20mm makes one an option for the next present.


One of you had better learn about the scope, it is a bit extreme in quite a few aspects. Just answered in a post about 60mm ED refractors, oddly one of those may have been better then a CPC1100 as a first scope.

Edited by sg6, 12 December 2019 - 05:58 AM.

#7 MikeBOKC


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Posted 12 December 2019 - 07:07 PM

The best gift for a new CPC owner might be an adjustable observing chair. Drop by a music store and get a drummer's throne with he hydraulic up-down adjustment. Makes for some comfortable viewing, especially of targets higher in the sky.

#8 whizbang


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Posted 12 December 2019 - 08:06 PM

The 1100 has a heck of a lot of magnification and a very, very narrow field of view.  It will do best with wide field two inch eyepieces.


For general purpose observing, 68, 70 or 82 degree two inch eyepieces in the 32 to 40mm range are the way to go.  Unfortunately, these require a two inch diagonal and possibly a two inch visual scope.  And you probably don't want to cheap out on these...  The price to good optics is eye catching to say the least.


The most bang for you buck for a dandy eyepiece is the Explore Scientific 68 degree 24mm.

#9 PNW


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Posted 19 December 2019 - 05:59 PM

That's one fine telescope to start with. The eyepieces are adequate and will evolve over time. Might I suggest a Dew-Not heater strip and controller box might be a more meaningful Christmas gift.

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