Best eyepiece info

[Chaza]

Just now, John said:

I don't know any scopes with an 80mm focal length. 800mm perhaps ?

Sorry yes 800mm

[John]

Ok - to get the magnification that a certain eyepiece gives, you divide the focal length of the scope by the focal length of the eyepiece. For the eyepieces you have the results are:

25mm = 32x

12.5mm = 64x

4mm = 200x

The barlow lenses have the effect of multiplying the magnification given by an eyepiece by a factor which is expressed on the barlow lens eg: 2x, 3x etc.

So, use the 2x barlow lens with the 25mm eyepiece and you get 64x (the same as the 12.5mm eyepiece used on it's own). With the 3x barlow though you get 96x. With the 12.5mm eyepiece the 2x barlow gives 128x magnification and the 3x barlow 192x. Using either barlow lens with the 4mm eyepiece will give much too much magnification to be any use = 400x or 600x

To use Saturn as an example, you would generally observe that with higher magnifications so I would suggest the 2x barlow used with the 12.5mm eyepiece could be useful. Starting off with lower magnifications does make sense though because it makes targets easier to find and you can gradually build up the magnification to see what gives the sharpest image. The seeing conditions (the atmospheric conditions) play a large part in determining whether high magnifications are going to be useful which is another reason for starting low and building up.

 

[domstar]

@Chaza    To echo what @JOC said above, start with your lowest magnification eyepiece- in your case 25mm and when you have it in the middle, change to a higher magnification and refocus. I had big problems at the beginning getting objects in the field of view and keeping them there. With lower magnification you see more sky so this is easier and once you have an object in your eyepiece you can swap it for a higher mag one. 

[JOC]

@Chaza as the others have agreed you start with the lowest magnification you have because a lot of targets are easier to find at lower magnification, you then gradually sneak up the magnfiication a bit at a time until things don't improve any further.  At each stage make sure the object is bang in the centre of the previous view and be very gentle as you change EP's as each higher magnification shows an increasingly smaller bit of sky and you can easily miss the target as you go up especially if you try to do so in too larger jumps.  Also the object, as also mentioned, will spend less time in view at higher magnifications and therefore can be easier to get a good look at before you have to move/nudge the scope at a lower magnification.  

It took me a while the realise that magnfication is NOT the be all and end all of astronomy, for various optical reasons at high magnfication objects are not as bright, are often not as sharp and spend less time in view.  The planets are a case in point, esp. Jupiter - Yes, I can view it in a top quality 5mm Pentax EP and get higher magnification, however, the quality is {mild expletive} and the view is far more satisifying in a 8mm BST EP or even the little 10mm Plossl the telescope came with.   I also find that I can't be bothered messing around with Barlows - you have three decent magnification intervals in the EP's that you already have and you might find that after the first couple of times you consign the Barlows to the back of the cupboard and never use them again - that's what I did.  I even bought a Barlow thinking that they sounded wonderful things and now rarely touch it apart from to attach my DSLR camera to my setup as it has a handy thread on it.  Apparently they can be handy if you want a higher magnifcation off of an Eyepiece with good eye relief (you don't need to get your eye so close to it so the viewing is more comfortable esp. for specs wearers) as the Barlow maintains the Eye-relief, but I am un-impressed with them otherwise.

 

[Forester17]

I vote for BST! fine eyepieces, and will get you into using that scope for very little cost.