Ep for moon and saturn?

[Cosmicnaut913]

Hi i just got a vixen rs130sf with a vixen nlv 9mm ep, what should be my next size if im gonna be observing the moon,saturn and other planets?

[Capricorn]

As best I can tell a scope specified as vixen rs130sf doesn't exist. Any details on it like focal length etc?

For Jupiter and Saturn try 120x magnification.

Saturn is smaller and further away then Jupiter so you could get away with 80x. I have been down to 30x and still seen detail.

The moon is big so you do not need much for the whole lot in one view, however if you intend to start picking out specific parts then magnification comes in to it. Again 80-120x should be good.

For Jupiter and Saturn I believe that you need a sharp image more then straight magnification.

[nightfisher]

sounds like its the 130mm newt with 650mm focal length

[Cosmicnaut913]

Im sorry i had the specs wrong. Its a r130sf vixen newtonian 130mm w 650 focal lenth, light gathering 345x. The scope sits on a porta II altazimuth mount.

[newman]

There's more to choosing eyepieces than just knowing the focal length of your telescope. For example, whether or not you wear glasses (and need/want to wear them when observing) will determine just how much eye relief you want. Do you prefer wider fields or will a narrow field be good as long as the image is sharp and contrasty? Wider fields are in theory not as necessary on higher magnifications, but I find them very useful on undriven mounts - takes longer for the target to get out of view. But for that particular trick you want a wide field that is sharp to the edge - there's little point in it if your target turns into a blurry smudge when not in the center of view.

Last but not least, your budget will be a big determining factor as well. In general, if you don't care about wide AFOV and don't mind tight eye relief, orthoscopics deliver excellent views. Baader Genuine Ortho's have a great reputation, for example. I'd recommend against wide fields if you're on a tighter budget, there's little point to a wide field if the image is only usable in the center, and the ones that are sharp to the edge of the wide field are generally not cheap.

[Cosmicnaut913]

Ty for the info. I guess eps are really personal preference, trial and error

[Capricorn]

To see Saturn it will need about 100x, even then the image may be a bit small. 100x means a 6.5mm eyepiece.

A 5mm eyepiece would give 130x on yours, a better magnification for Saturn, but getting into the realm where scope and eyepiece have to be compatible.

The moon is 1/2 degree in size, so to get it all in one view means say a 1 degree actual field of view. In a plossl this means a magnification of 50x, that is a 13mm eyepiece, a 15mm is probably easier to get hold of.

The eyepiece for Saturn, 5mm, would allow you to pick out a bit of the moon. Tycho for example.

Which eyepieces, well TMB planetary's are an option, the clones are a bit less and come in more focal lengths.

BST Explorers are good and come in a 5mm eyepiece and 12mm option.

Plossls are another but the 5mm plossl may not perform in your scope and the eye relief of a 5mm plossl means it could act more like a contact lens.

Have both TMB's and BST and the BST are the beter but I have the TMB's in focal lengths less then 5mm which the BST's do not come in. You may eventually have to consider the same if you want greater then 130x, or use a barlow.

Overall a 5mm, 12mm and eventually the 25mm BST's should make a nice set of 3.

If you had/use a decent barlow then 25mm, 18mm, 8mm BST. Which with a 2x barlow give additionally 12.5mm, 9mm, 4mm effectively.