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loweka22

By loweka22
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mike2012

mike2012

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hi i just bought a saxon 1309 130mm mirror and 900 focal length i only have a 10mm and 25mm and a 2x barlow at the moment.Can any one help me on eyepieces for better magnification?.Will also get some filters soon.have had some good views of jupiter and its moons can i get anything more outta this scope thanks for the help.

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JamesM

JamesM

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Hi Mike and welcome to the forum. Any questions on kit are better placed in the 'Beginners Section or in one of the more specific equipment sections if you want more people to answer your question. Some people favour certain parts of the forum than others and so they may never visit this part to be able to answer your question.;)

Now I saw some marketing blurb on your scope which contained the statement "...maximum useful magnification x337. Well to be honest that statement is a load of theoretical rubbish, as the maximum 'practical' magnification that you can reasonably expect to use on any scope in this country is around x180 to x200 due to our atmosphere. There are very few nights in the year that will ever let you exceed that which makes them special when they happen. So given that the focal length is 900mm, we can divide this by the focal length of say a 5mm eyepiece to arrive at a figure of magnification of x180, a 6mm eyepiece will give you (900/6) x150 magnification. Now you have a x2 barlow which effectively halves the focal length of an eyepiece, and as you already have a 10mm eyepiece, the barlow will then provide you with the maximum (10mm/2) 5mm eyepiece that will give you the maximum useable magnification and will certainly be enough to show the banding on jupiter etc. Now there is an argument that says that using a dedicated 5mm eyepiece is preferred (as opposed to a barlowed one) because you are using less glass between the object and the eye. So given that you looking through 'supplied' eyepieces you have a choice, either to buy a better x2barlow lens (Tal inexpensive but good) or a dedicated 5mm eyepiece (Celestron & Meade are fairly inexpensive). Unfortunately, you haven't given a budget so I can't be more specific and I have no idea of the quality of the eyepieces that came with the scope as your scope is not a brand that I am familiar with. I would have a look on First Light Optics website to see what takes your fancy really - they will all be good enough for your needs. Hope that helps with the understanding.

Clear skies

James

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