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Celestron 11" SCT Starter Eyepieces

eyepieces
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#1 Linwood

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Posted 13 July 2020 - 08:17 PM

Anyone care to provide a sanity check.  I've got a Celestron 11" EdgeHD on order, which comes with a 23mm eyepiece.  Let's assume it is decent quality; I have no idea. 

 

I have nothing now.  Seeing where I am will likely be average on a good night.  My main goal will likely be imaging, but I want to be able to visually observe when I do not want to work so hard.  no specific targets in mind. Show off to visitors (if we can ever have them again) whatever is up and bright enough.

 

My thinking is this: 

 

Get a lighted reticle just because I may need one at times for checking alignment (12.5 Agena tentatively). 

 

Get a wider view, maybe a Tele Vue Plossl 55mm

 

Get a higher powered, but not too high, thinking in the 13mm range.  Anything shorter seems unlikely to be usable.  I kind of got stopped here, as I read a lot of different opinions on something like the Ethos vs. Nagler and whether it's really worth it. 

 

Setting aside my dithering over the 13mm range, is this approach a good starting point to last me a while until I actually figure out what I need?   Am I wasting time at the short end in mediocre seeing at this focal length, i.e. is 23mm really enough for a while? 

 

 



#2 Jeffmar

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Posted 13 July 2020 - 09:19 PM

I can tell you which eyepieces I use most. I always star out with a 38mm 70 degree eyepiece I bought from Orion Telescopes years ago. The focal length is so long on my C11 that I need a wide eyepiece just to find things. The other eyepiece I use frequently is a 20mm Pentax. I think it is a 68 degree. It is a bit on the pricey side, but it is really good. I have found that I can use 20mm most of the time unless seeing is really poor. Until recently my other eyepiece I used often was my 10mm. It is the same type of eyepiece as my 20mm. I can only use the 10mm about half the time. Seeing is the limiter again. I recently got a 14mm to complete my Pentax set. I think the 14mm is more useful than the 10mm for my C11. It can be used more often. 

 

If I was just starting out I would keep the 23mm you already have and add a 14mm and a two inch 38-40+ mm eyepiece. The reticle eyepiece could be  a good idea. I have one, but I don’t seem to use it a lot.

 

If you can only afford one good additional eyepiece get a wide angle 40mm class eyepiece. I always use my 38mm, and sometimes it is the only one I use.

 

Good luck with your shopping, and I think you are really going to like your C11 edge scope. I love mine!


Edited by Jeffmar, 13 July 2020 - 09:22 PM.

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#3 sanbai

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Posted 13 July 2020 - 09:46 PM

I have a c8, so my experience is not exactly valid.
BTW, how is the seeing and the pollution in your area? Do you wear glasses while observing (astigmatism)?

A 55 Plössl may be too much of your sky has lot of light pollution. Otherwise, it's the way for large exit pupil, lower magnification and widest true field of view.

Another think to consider is the APM 30 UFF. It may be too close to your 23 mm, though, and not such a large field as the 55 mm. Of course, is you have the money the Nagler 31 and not too much astigmatism is a great eyepiece.

Remember that being f/10 your eyepieces won't be that challenged, so you can go for eyepieces cheaper than TeleVue ones with confidence.

I agree that after the 23 and given the focal length of such scope, something in the 15-13 mm will offer good amount of magnification. If you have great seeing in your area, and planets season just starting (let that cool down for a good while! Use reflectix!), something in the 9-8 mm will be very appreciated now. Later on you can go down to 5 mm but It's not that frequent that one can put so much power without clear degradation due to seeing.

If you don't need to do guiding for imaging, I would pass on the eyepiece with reticle at the moment. For alignment consider the Orion zoom 7-21 mm. It is receiving lot of praise right now and is cheap. It can be also useful for regular observation and complements the 23 quite well. You can experiment with it and realize which magnifications work best for you, before getting other eyepieces.

#4 sanbai

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Posted 13 July 2020 - 09:47 PM

Btw, do you already have a 2" diagonal?

#5 Linwood

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Posted 13 July 2020 - 09:55 PM

The scope comes with a 2" diagonal. 

 

I expect seeing here to be average at best.  There's a LOT of light pollution, though I do hope to head into the everglades occasionally where one can find really dark skies (also pythons, gators and mosquitoes, the latter perhaps the worst of the three).  Ignoring the light pollution though the air at times is quite clear, at least by eye (and some minor experience with a similar scope 20 years ago and 1000 miles away).  I got really nice steady images one morning when I work up and shot with a camera lens (400/2.8), much better than I expected.  

 

I do wear glasses, badly nearsighted and astigmatism, had not thought that through well, assumed I would use it with glasses on, but I guess the shorter focal length that might not work?

 

Can you elaborate on

 

 

Remember that being f/10 your eyepieces won't be that challenged, so you can go for eyepieces cheaper than TeleVue ones with confidence.

I kind of assumed with such a long focal length optical weakness would jump out and grab me? 



#6 dustyc

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Posted 13 July 2020 - 09:55 PM

Use the 23mm as an outreach eyepiece. 

After my C11 purchase I bought a 35mm, a 17mm, and a 12mm eyepiece. After some time a 5mm joined the ranks. 



#7 Linwood

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Posted 13 July 2020 - 09:56 PM

Use the 23mm as an outreach eyepiece. 

After my C11 purchase I bought a 35mm, a 17mm, and a 12mm eyepiece. After some time a 5mm joined the ranks. 

Meaning 55 is way too wide?  



#8 sanbai

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Posted 13 July 2020 - 10:56 PM

The scope comes with a 2" diagonal.

I expect seeing here to be average at best. There's a LOT of light pollution, though I do hope to head into the everglades occasionally where one can find really dark skies (also pythons, gators and mosquitoes, the latter perhaps the worst of the three). Ignoring the light pollution though the air at times is quite clear, at least by eye (and some minor experience with a similar scope 20 years ago and 1000 miles away). I got really nice steady images one morning when I work up and shot with a camera lens (400/2.8), much better than I expected.

I do wear glasses, badly nearsighted and astigmatism, had not thought that through well, assumed I would use it with glasses on, but I guess the shorter focal length that might not work?

Can you elaborate on

I kind of assumed with such a long focal length optical weakness would jump out and grab me?

The larger the f/#, the more forgiving is the scope with eyepieces. It's about the angle of incidence, not the magnification. The scope quality of construction is something else.

I remember how the mosquitoes suddenly appeared in the Everglades at the end of my visit last February. I had to hurry up, that was a full army!!

Myopia (and hypermetropia) are corrected by the focuser. Astigmatism is not, but depending on the resulting exit pupil (focal length eyepiece divided by "f/#”) you may see it or not. With 0.75 astigmatism I better put my glasses on when using my 55mm (in the C8), but I don't need them for my 31mm and below. See this plot to get an idea:

http://www.televue.c...=54&Tab=_Choose

Edited by sanbai, 13 July 2020 - 10:59 PM.


#9 Linwood

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Posted 14 July 2020 - 11:28 AM

Myopia (and hypermetropia) are corrected by the focuser. Astigmatism is not, but depending on the resulting exit pupil (focal length eyepiece divided by "f/#”) you may see it or not. With 0.75 astigmatism I better put my glasses on when using my 55mm (in the C8), but I don't need them for my 31mm and below. See this plot to get an idea:

http://www.televue.c...=54&Tab=_Choose

Thank you, I had no idea how that worked.  I'm at 1.25, so this gives me a good feel for it.  Looks like if I did get a 13mm lens, which is one that might be hard with glasses, I'll be under the visibility point.  The one that comes with it at 23mm may or may not.  Very nice info to have... I need to start a collection of helpful links! 



#10 Linwood

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Posted 14 July 2020 - 02:25 PM

So I dropped back to a 41mm Panoptic.  I probably should have saved money and bought something cheaper but it's hard to know when you go too cheap, and with all I'm spending to get the initial setup last thing I want is to end up thinking "would this look better if... ". 

 

I'm holding off on the short end until I get set up; I ordered a 9mm illuminated reticle so I can get a feel for high power (if likely poor quality) and how short I should go for an observing one. 

 

Thanks everyone.  Will post back if I learn anything when it all comes in.


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#11 dustyc

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Posted 14 July 2020 - 02:37 PM

Since the focal length of these scopes is so long I found myself buying more eyepieces in the lower power range. I have a 41mm Pan too. I think you'll like it. Much more FOV than the 55 Plossl. 



#12 dustyc

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Posted 14 July 2020 - 02:41 PM

Meaning 55 is way too wide?  

No. The 23mm has some weird (too me) brightening towards the edge of the field stop. 

Do a search on 23mm Luminos and EOFB (edge of field brightening) 

It does give you a taste of that 82mm wide field view (like Naglers).



#13 Linwood

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Posted 14 July 2020 - 02:47 PM

No. The 23mm has some weird (too me) brightening towards the edge of the field stop. 

Do a search on 23mm Luminos and EOFB (edge of field brightening) 

It does give you a taste of that 82mm wide field view (like Naglers).

Ah.  Well, I didn't expect a great eyepiece included with the OTA.  I should have been able to expect it, but I didn't.   

 

Thanks for the info.  




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