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Eyepiece for viewing planets & deep space

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#1 blade009

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Posted 11 January 2019 - 09:09 AM

  I own a Mead 10" LX200 GPS Im looking for a eyepiece for viewing planets, From what I can figure out on my own is a eyepiece of 8mm x 50 or a 11 mm x 50 seems to be my best option, Can anyone tell me if thats my best option with this scope, I already own a 1 1/4 13mm x 68 ,2-in 35mm panoptic & a ETH210 21mm Ethos 2-in. 



#2 sg6

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Posted 11 January 2019 - 09:55 AM

10" = 250mm more or less, and as it is an SCT that is 2500mm focal length, again more or less.

8mm eyepiece is therefore 312x.

11mm eyepiece is 227x

(8mm and 11mm make me think of TV plossl's???)

 

11mm should work a good number of nights, the 8mm only when conditions are in your favour.

And the planets will remain low for the next few years.

 

Planets are "unfriendly" to eyepieces, you will find that you need a selection, and fairly close increments. I would have said 8mm, 10mm, 12mm to cover the range of conditions. The ones you have identified of 8mm and 11mm are good.

 

Assuming 8+11 are the TV's it means alternatives and really unsure. Maybe the Vixen line of SLV's but no 8mm in those, 10mm and 12mm however.

 

The classic planetary eyepiece seems to be an Ortho. TV plossls are of a similar design - 4 elements - and TV plossls I expect match the performance, immaterial of claims.

 

Suppose Delites are going a bit too high up the cost scale, but they are good and they are in 2mm steps: 5mm, 7mm, 9mm, 11mm, 13mm, 15mm.

The 9mm and 11mm seem fair then flip a coin for 7mm or 13mm. Or stick at 9mm and 11mm.

 

Looking at it the only problem I have with your initial idea of 8mm and 11mm is simply the 3mm gap in focal length between them. However I think you will want to fill that gap eventually. That is what I found on my Paradigms, they go 5mm to 8mm and I had to buy a 6mm to fill in.



#3 Stellar1

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Posted 11 January 2019 - 09:58 AM

Your scope has a focal length of 2500mm, to determine the magnification of any eyepiece you want to divide the focal length of the scope by the focal length of the eyepiece.

 

lets say your 8mm and 11mm for example.. (i'm not sure what you refer to by x50) 

 

2500mm divided by 8MM = 312x magnification

2500mm divided by 11mm=227x magnification

 

Having said that, the MAX amount of useful magnification you can squeeze out of any scope, with good optics and, under perfect seeing conditions is generally accepted to be 50x magnification per inch of aperture. This means that under perfect conditions your scope is capable of 500x while maintaining good image quality, these conditions rarely present themselves. Usually the more realistic scenario (considering seeing conditions and how it varies night to night) is about 25-35x per inch you may find will be the average range you'll use. 

 

On to your question now, you have both 8 and 11mm eyepieces, considering what was mentioned above regarding average magnification you'll be able to use considering seeing conditions, roughly 25-35x per inch, your 8 and 11 fall almost square within that sweet spot. On nights of great seeing you will be able to squeeze more detail out of Saturn and Jupiter for example, so you may want that one eyepiece that you'll use on that great night (they don't happen often) maybe 6mm which will give you just above 400x but this eyepiece will spend a lot of time keeping warm in your eyepiece box considering how perfect seeing conditions are few and far apart.

 

I hope this helps, i am sure others will chime in that use your scope and have first hand experience with eyepieces they favour under average seeing conditions.


Edited by Stellar1, 11 January 2019 - 10:01 AM.


#4 PETER DREW

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Posted 11 January 2019 - 10:07 AM

I find with mid to large SCT's that a decent zoom eyepiece like a Baader Hyperion covers most planetary needs. It's ideal to be able to easily zoom the image to suitable maganification for the object or the seeing conditions.


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#5 blade009

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Posted 11 January 2019 - 10:44 AM

Your scope has a focal length of 2500mm, to determine the magnification of any eyepiece you want to divide the focal length of the scope by the focal length of the eyepiece.

 

lets say your 8mm and 11mm for example.. (i'm not sure what you refer to by x50) 

 

2500mm divided by 8MM = 312x magnification

2500mm divided by 11mm=227x magnification

 

Having said that, the MAX amount of useful magnification you can squeeze out of any scope, with good optics and, under perfect seeing conditions is generally accepted to be 50x magnification per inch of aperture. This means that under perfect conditions your scope is capable of 500x while maintaining good image quality, these conditions rarely present themselves. Usually the more realistic scenario (considering seeing conditions and how it varies night to night) is about 25-35x per inch you may find will be the average range you'll use. 

 

On to your question now, you have both 8 and 11mm eyepieces, considering what was mentioned above regarding average magnification you'll be able to use considering seeing conditions, roughly 25-35x per inch, your 8 and 11 fall almost square within that sweet spot. On nights of great seeing you will be able to squeeze more detail out of Saturn and Jupiter for example, so you may want that one eyepiece that you'll use on that great night (they don't happen often) maybe 6mm which will give you just above 400x but this eyepiece will spend a lot of time keeping warm in your eyepiece box considering how perfect seeing conditions are few and far apart.

 

I hope this helps, i am sure others will chime in that use your scope and have first hand experience with eyepieces they favour under average seeing conditions.

 

The X50 is the field of view of the eyepiece & the 8 & 11 Are the eyepieces i was looking to bye, sounds like the 11 is a better option and they are the plossl eyepieces i was looking to bye. but will look at any brand eyepiece that would give me a real good view with the scope i have, I knew i should have gone bigger when i bought the scope LOL




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