no, i am confused now..
sounds to me that if you have a 25mm eyepiece in and you can only just fit mars in your field of view that it is way out of focus. in that eyepiece mars shouldnt be very big at all.
ok... been thinking... i know what wrong but putting it in words is a different matter.
1. find mars in your finderscope
2. with the 25mm eyepiece in place lok for it in the eyepiece
3. center it in the eyepiece (you will notice it is not in the center of your finder now)
4. there are adjustment screw on your finder scope to move it around, use this to re-center mars in the finder. then your telescope and finder are aligned.
5. with mars in the center of your field of view in the 25mm eyepiece, turn the focuser either way till you get the smallest posible image of mars. this is when it is in focus.
if you change eyepieces then you will have to refocus. once again you are looking to make what you see thru the eyepiece as small as posible to achieve focus (see step 5)