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Viewing Jupiter


Guest pvcprinting
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Guest pvcprinting

Using a Skyliner 200p Dob scope, what is the best eyepiece to use to view it


 


Options are


 


10mm


20mm


25mm


 


I assume using a x2 Barlow with one of the above is a no brainer?


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Guest pvcprinting

so a 10mm is higher than a 25mm?


 


I thought of it as a field of vision thing...


 


10mm would be like looking through a hole in a sheet of paper made my a pin


 


20mm would be a hole in a sheet of paper made with a dart


 


25mm would be looking through a hole in a sheet of paper made by a knitting needle


 


 


of course as a novice, i guess i might just have this all wrong


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The focal length of the eyepiece effects magnification, FOV depends on the make/model I think.


 


The shorter the focal length of the eyepiece, then the higher magnification you get. Magnification is given by focal length of telescope divided by focal length of the eyepiece, so a larger focal length will give less magnification (a larger area of the sky visible).


 


You need higher magnifications for planets to bring out the detail :)


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Thanks for that....

 

So a 10mm eyepiece with a x2 Barlow is the best i can get using a Dob 200p?

 

Yes it's the highest magnification, however it may be too high if the seeing isn't very good, as if you over-magnify something it will start to become blurry and you will lose detail. 

 

For the 200p I think the best views you will get of the planets will be with the 10mm on its own, unless the seeing is good. However try the barlow yourself, you might be able to see what I mean by 'over magnifying' a bit better than me explaining it!

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Best (clearest) views of Jupiter I get through my 200P are with a televue 2x powermate and 13mm televue ethos which is effectively 6.5mm with good seeing and then I can resolve good detail visually.

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A 6mm eyepiece in your dob Pete will give 200x magnification. Seeing has to be pretty clear to go much above that. Felix 13mm Ethos eyepiece in the 2x Powermate (sort of barlow) gave him 184x mag. A 4mm eyepiece would give you 300x - probably too much on 99% of UK dark nights - but still do'able on rare occasions.


 


Magnification does contribute to the size of the fov (as per your pin/dart/knitting needle). However the size of the eyepiece barrel (2" or 1.25") also contributes, as well as the design, configuration, and number of lenses in the eyepiece. Some eyepieces are made as wide field eyepieces and others designed specifically for narrower fields.


 


A typical planetary eyepiece may have a 50degs fov using a single lens, whereas a 2" wide field eyepiece can have 100degs or 110degs fov and incorporate 7 lenses for the ultimate in wide field correction. Of course there's a huge variation in price too. Hope that helps :)


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