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have just brought...what difference?


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today i just got myself a 6mm pllosl (whatever!) eyepiece and a moon filter by celestron to go on my celestron 102 slt.what differences can i expect compared to the standard 9mm?

also what is a barlow apart from a bigger eyepiece for magnification? can i get one to use with my 6mm and will it actually make a difference or am i going the wrong way completely? i want to view the moon as close as possible without much distortion. :moon:

ben

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he has edited the link. BUT im sorry people i really need to go back to school as i really dont understand anything on that website(yes im a newbie) can that not be explaned easier? if ive got a 6mm eyepiece do i need to get a barlow lense and if i do will it still be ok to view the moon which is what i want to do the closer the better?

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The Plossl is a good all round eyepiece design and is very popular as it has good eye-relief (you don't have to scrunch your eye right next to the eyepiece to see anything) and also has a fairly wide field of view so spread out objects can be seen more easily.

Having 9mm and 6mm eyepieces are fine but with a barlow you may find that you are asking too much of your scope and sky to give a clear & stable image.

I would get a low power eyepiece between 25mm & 32mm which will give you a 12.5 -16mm eyepiece with the Barlow.

This will give you Low, medium and high magnifications.

Cheers

ian

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Your 6mm Plossl will give you 110x magnification through your 102 SLT telescope. Your 9mm gives you 73x. A x2 barlow lens, as it's name implies, basically doubles the maginification that each eyepiece gives so your 6mm would then give you 220x which, as has been said, is probably too much power to use often with that scope and with the sky conditions we get. With your 9mm eyepiece though the 2x barlow gives 146x which might be a more useful high power for use on double stars or the moon and planets on a really clear night.

If you dont already have one, an eyepiece which gives less maginifcation might actually be more useful to you (as Lunator says) - a 25mm mm would be a useful one and would give you a magnification of 26x and nice wide views - good for star clusters, nebulae, galaxies and the like.

To find the magification that an eyepiece gives divide the focal length in mm of your scope (660mm in the case of your 102SLT) by the eyepiece focal length (ie: 6mm, 9mm, 25mm etc).

Hope that helps a bit.

John

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Not sure if this trick works for ALL barlows but I read somewhere that with some shorty barlows you can unscrew the end of the barlow and screw it into the end of the eyepiece to get x1.5 of the mag you'd normally get from the eyepiece. That'd give x165 out of your 6mm which should provide you with a very nice view of Saturn. Pretty sure that's what I read but I will leave it to the resident experts here to confirm or not.

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ok so just using my 6mm is good enough for my scope on its own but if i want more get a barlow and buy a better than standard 25mm eyepiece.do you have to use the diagonal or can you just put the eyepiece in the end as it does fit? surely the diagonal looses some of the manification or does it amplify slightly? has anyone heard of what steelrat says about screwing the eyepiece into the barlow?

thanks for all responses

ben

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... do you have to use the diagonal or can you just put the eyepiece in the end as it does fit? surely the diagonal looses some of the manification or does it amplify slightly?

You don't need the diagonal (assuming your focuser will rack out far enough to bring the image into focus). In fact, optically, it is better not to use the diagonal. But, without the diagonal it can be difficult/uncomfortable to view objects overhead. The diagonal will not alter the magnification.

has anyone heard of what steelrat says about screwing the eyepiece into the barlow?

Yes, as Steelrat says, the lens assembly on some barlows can be removed and screwed into the eyepiece filter thread.

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