Galaxy/Nebula Eyepiece for 10" f4.7 Dob

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gpweis
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Joined: Fri Jan 20, 2023 3:58 pm
Real Name: Greg P Weisjahn

Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by gpweis »

Hi
I am relatively new to MAS and have been trying out telescopes through the loaner program. I think I have made a decision on a scope, a Celestron Starsense 10" Dob, 1200mm FL, f4.7. Now I started looking at eyepieces, even more overwhelming. The scopes lowest useful magnification is 36x, that puts me at about a 33mm eyepiece. I would like to get a 2" eyepiece as I have read this improves low power viewing. From what I have read if I go greater than 33mm the exit pupil size is greater than 7mm and my eye can not take advantage of that. Yes, I have downloaded the eyepiece calculator spreadsheet.
Question #1
Is the 36x lowest useful magnification an absolute barrier you should not cross?
Question #2
Going from a 33mm eyepiece to a 28mm eyepiece, magnification does not increase that much, is there a sweet spot where you get the most magnification and still get great deep space viewing?
Question #3
I understand TelVue eyepieces are the gold standard, but expensive. Does anyone have any comments about Omegon, Baader, and Explore Scientific eyepieces, value for what you get? Or other suggestions?
Question #4
Since this eyepiece is likely the one I would use the most, would biting the bullitt and getting a TelVue Panoptic 27mm work for my deep space viewing?
I live in a class 4/5 Bortle area.
Thanks for any suggestions you may have.

Greg
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SEmert
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by SEmert »

All answers herein are opinions, and as you know everyone has opinions and something else, and often both stink ;-)

Q1 - Nothing is absolute! Yes, too large of an exit pupil "wastes" light, but that hasn't really bothered me. Some others use 55mm eyepieces as wide-field "finder" eyepieces. My longest eyepiece is 24 or 25mm.

Q2 - My 24mm is my most often used eyepiece, with my 18mm second, then my 11mm. If you are picking just three eyepieces out of a series, select one from low mag, one medium mag, one fairly high mag. Also, if you are getting a 2x Barlow, remember that it can be used to double up the usage of any eyepiece, such as 24mm x 2 = 12mm, 18mm x 2 = 9mm, etc. so with the proper selection you can have six powers with three eyepieces. Remember, in general DSO's - at least the brighter ones - are happy at lower magnification. Very high mag is best for seeing detail on planetary objects.

Q3 - Yes, Televue's are the gold standard. The first time I saw M13 in an 11mm Ethos, I said we absolutely need one at CGO, and we got one right away. I love using Televue's of all types and focal lengths on the MAS club scopes. Having said that, personally I was too cheap to buy them. I elected for Explore Scientific 82mm AFOV eyepieces, and they have worked out well for me. I can't speak directly to Omegon and Baader, but they definitely have good reputations.

Q4 - I bet you would be very happy with that eyepiece.

But before you buy anything more than some Plossl's to get started (you can always use Plossl's, either in your primary scope or in a secondary scope, and when you are using your scope to show objects to the public and don't want to risk your good ones)... bring your scope to ELO or CGO and try out some of the club's Televue eyepieces in your scope before biting the bullet and getting your own. After all, that is part of the benefit of being a member of the MAS!
Steve Emert
MAS Membership Coordinator
12.5" f/4.7 Obsession Clone Homemade Truss Dob, sometimes equipped with Celestron StarSense Explorer app
Celestron C8 SCT OTA on AVX GEQ mount
Astro-Tech AT72 ED Refractor OTA usually on Orion HD Tripod
Celestron 5" SCT OTA usually on Synta AZ-4 Alt-Az Mount
Orion 150mm Mak OTA and Orion EQ-G computerized mount
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Dick Jacobson
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by Dick Jacobson »

I agree with everything Steve said and would add a few comments.

My most used eyepieces are ones with a Field Stop of around 40 millimeters or more. These give you the largest possible field of view in a 2" focuser. TeleVue shows the Field Stop in their specifications but most other brands do not. You can approximate the Field Stop by multiplying the apparent field by the focal length and dividing by 60.

When 100-degree field eyepieces first came out, I was skeptical that I would need more than 82 degrees, but the first time I looked through one I was hooked! It's like going from a "window in space" to a "domed porthole in space". But beware, they might cause balance problems since they are so heavy (not to mention expensive).

Most middle-aged or older people have maximum pupils of about 5 millimeters. One way to measure your pupil size is to take a set of drill bits into a dark room, and find the smallest drill bit that completely blocks the view when held close to your eye.

If you can afford it, it's good to have enough eyepieces so you can select one that nicely frames whatever you're looking at, with 2 or 3 times the width of the object.
30-inch homemade Newtonian with periscope
20-inch homemade equatorial Newtonian with periscope
14-inch homemade equatorial Newtonian
10-inch Newtonian that folds flat
6-inch Russian Maksutov-Newtonian on Vixen equatorial mount
Too many small scopes and binoculars to mention
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Deane Clark
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by Deane Clark »

On low power eyepieces, don’t let the “wasted” exit pupil worry you too much. It’s good to have something that gives you a large field for finding objects, and some objects need as low a power as you can get to fit in the view - think M31, M44, M45. You can go overboard of course. If the exit pupil is too big, you will start to see the shadow of your secondary mirror. Trying out some club eyepieces at a star party is a good idea.
Deane Clark
Eagle Lake Observatory Committee
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FF2Rydia
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by FF2Rydia »

Steve, regarding your answer for Q2, what's the best for splitting doubles?
Kris Hultner
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merle
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by merle »

FF2Rydia wrote: Mon Jan 23, 2023 7:47 pm Steve, regarding your answer for Q2, what's the best for splitting doubles?
A good refractor... :-)
Clear skies,
Merle Hiltner
MAS Eagle Lake Observatory Facility Director
Onan Observatory • Sylvia A. Casby Observatory • HotSpot Classroom
merle.hiltner@gmail.com
FF2Rydia
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by FF2Rydia »

merle wrote: Tue Jan 24, 2023 3:14 pm
FF2Rydia wrote: Mon Jan 23, 2023 7:47 pm Steve, regarding your answer for Q2, what's the best for splitting doubles?
A good refractor... :-)
Obviously, but you still need to know what power eyepiece to use.
Kris Hultner
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Deane Clark
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by Deane Clark »

FF2Rydia wrote: Tue Jan 24, 2023 6:28 pm
merle wrote: Tue Jan 24, 2023 3:14 pm
FF2Rydia wrote: Mon Jan 23, 2023 7:47 pm Steve, regarding your answer for Q2, what's the best for splitting doubles?
A good refractor... :-)
Obviously, but you still need to know what power eyepiece to use.
Not to be flippant, but the one that splits it cleanly without making it look like mush. In other words, it depends on the telescope, the object and the conditions. The nice thing about splitting doubles is you can use any eyepiece that’s decently sharp in the center of the field. Even cheap eyepieces usually get that part right. Field of view isn’t much of a concern, but you probably want something that gives you medium to high powers in your scope - say 150-300x to get those super close ones like the double double or Izar. If I had to make one recommendation, it would be the Nagler 3-6mm zoom.
Deane Clark
Eagle Lake Observatory Committee
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I can quit any time I want. I just don't want to.
www.aponon.org
gpweis
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Real Name: Greg P Weisjahn

Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by gpweis »

I would like to thank everyone for their advice, it is all very helpful.
I have also download Stellarium to help with choosing different eyepiece focal lengths with different scopes.
Does anyone have any good /bad experiences with buying used eye pieces on Astromart?
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Deane Clark
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by Deane Clark »

I haven’t bought anything on Astromart in years, but the few times I did, everything went fine. Check the seller’s feedback and talk to them on the phone. It also helps to be familiar with what you’re buying of course, so you can ask the right questions.
Deane Clark
Eagle Lake Observatory Committee
------------------------
I can quit any time I want. I just don't want to.
www.aponon.org
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merle
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by merle »

FF2Rydia wrote: Mon Jan 23, 2023 7:47 pm Steve, regarding your answer for Q2, what's the best for splitting doubles?
Regarding the double stars, I saw this on Cloudy Nights forum:

https://www.cloudynights.com/topic/5159 ... uble-star/
or
https://www.cloudynights.com/topic/6158 ... ble-stars/
or
https://www.cloudynights.com/topic/8116 ... ble-stars/

Maximizing the exit pupil aside, like many of us, just start low and increase until you get a clear split, which of course would vary depending on the angular separation. I'll echo Deane's recommendation of medium to high powers and the Nagler 3-6mm zoom.

Merle
Clear skies,
Merle Hiltner
MAS Eagle Lake Observatory Facility Director
Onan Observatory • Sylvia A. Casby Observatory • HotSpot Classroom
merle.hiltner@gmail.com
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DahnGee
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by DahnGee »

gpweis wrote: Wed Jan 25, 2023 4:56 pm Does anyone have any good /bad experiences with buying used eye pieces on Astromart?
I've never paid for AstroMart, but I've bought a dozen items off the CloudyNights classifieds and have never had an issue. Like Deane said, check feedback (and leave feedback if you buy something)and communicate with the seller. Use PayPal so you have a resolution path if there is an issue (although I've never used it so I have no experience on how that goes...)

As for eyepieces, I have a 27 Panoptic I use in a 15" f/4.5 and really like it (bought it used off CloudyNights). I'd be willing to let you borrow it at a star party once the weather turns nice.
Don Gazdik
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SEmert
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Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by SEmert »

DahnGee wrote: Thu Jan 26, 2023 2:20 pm
gpweis wrote: Wed Jan 25, 2023 4:56 pm Does anyone have any good /bad experiences with buying used eye pieces on Astromart?
I've never paid for AstroMart, but I've bought a dozen items off the CloudyNights classifieds and have never had an issue. Like Deane said, check feedback (and leave feedback if you buy something)and communicate with the seller. Use PayPal so you have a resolution path if there is an issue (although I've never used it so I have no experience on how that goes...)

As for eyepieces, I have a 27 Panoptic I use in a 15" f/4.5 and really like it (bought it used off CloudyNights). I'd be willing to let you borrow it at a star party once the weather turns nice.
Yeah, it's too bad you have to subscribe to Astromart to trade on it. I have off-and-on a few times throughout the years (I think I'm still current right now) and have bought a few things there with no problem.

Back to the question of splitting doubles, I agree with the other replies: the right scope, the right amount of magnification before the image goes to mush, *and* good collimation. At one Florida star party I looked at the Trapezium in M42 through a 12" Teeters truss Dob. All six stars were sharp pinpoints, even the two smaller stars that are harder to see. Went back to the 16" truss Dob I had at the time and could only make out four fuzzier stars. Re-checked collimation and tried again. Still four stars. I'm happy to say that when I have good collimation on my own 12.5" truss Dob, it rivals that Teeters scope.
Steve Emert
MAS Membership Coordinator
12.5" f/4.7 Obsession Clone Homemade Truss Dob, sometimes equipped with Celestron StarSense Explorer app
Celestron C8 SCT OTA on AVX GEQ mount
Astro-Tech AT72 ED Refractor OTA usually on Orion HD Tripod
Celestron 5" SCT OTA usually on Synta AZ-4 Alt-Az Mount
Orion 150mm Mak OTA and Orion EQ-G computerized mount
gpweis
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Real Name: Greg P Weisjahn

Re: Galaxy/Nebula Eyepiece for 10" f4.7 Dob

Post by gpweis »

I did not realize cloudy nights had classified ads.
Thanks for the tip.
I also found there someone posted a eyepiece buyers guide spread sheet, listing most eyepieces specs and prices, very useful.
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