GazofCorra

I was one of those novices who thought i would see close up, colorful images of everything like i see in the books.

Only to feel let down when i actually looked through my new telescope, but what has surprised me is i am still passionate and intrigued by space and all that is out there.

My most memorable evening was spent looking at Saturn and even though it was small (very small) i can say i have seen it and it's rings with my own eye's and as the OP states the longer you look the more you see, so don't spend just a few minutes starring at the new found object and then move on to something else, plan on a good hour or so and you will see a whole lot more than you did in the first few minutes i guarantee it.

BTW you don't have to keep your eye at the EP the whole time, you look for a few minutes at a time, take a swig of coffee, relax and marvel at the fact that what you and others see as a star with the naked eye is actually something a whole lot more when viewed through a telescope.

Great post and a must read for all new and old into astronomy.

Would someone please explain the name "plossl" to me? Is that a trade name or does it refer to something else?

There is a wide price range between lenses. Does the quality differ to the degree inferred by, what appears to be, the exorbitant prices?

The name Plossl refers to the design of the eyepiece and is named after G.S.Plossl who devised this design in 1860.

A true Plossl eyepiece is a four - element design consisting of two nearly identical pairs of lenses.

Many manufacturers now market five-to-seven-element Plossl variations carrying various trade names.

Compared with Orthoscopics the Plossl has a slightly wider field of view and works better on f/6 or faster scopes but has shorter eye relief.

HTH

Thank you Warthog for the explanation and a superb post that has helped a whole lot , as it guided me to choose the correct EP's for my dob (Skywatcher Skliner 200P F5.91 fl1200mm) as i was about to buy an EP that would have taken me to 240x and even though the scope can take it as you say best to be around 200x on a dobsonian, so i went for wFOV EP's so i do not have to nudge the scope around excessively and good eye relief too.

Cheers Gaz

DOBSONIANS

To get a 5mm exit pupil out of a 250mm mirror, you will need an eyepiece that gives you 50x. This means a 25mm eyepiece. To get a 7mm exit pupil out of the same mirror means a magnification of 36, and a 35mm eyepiece.

Hi guys and i have spent alot of time reading this post, but i cannot work out the formula above?

I got to the 250mm (size of mirror or aperture) / 5mm (or what exit pupil i require) = 50x (which means an EP which gives this mag will give a exit pupil of 5mm) it is the next bit that throws me, why does it mean a 25mm eyepiece, where is the formula?

I am sure i am missing something, doh!

To work out what an eyepiece can do for my own scope i take the focal length of the scope and divide it with the focal length of the EP = Magnitude, so (1250/25=50x) and from this i can then work out what the exit pupil will be, still assuming we have the 250mm (10") F5 scope, i then use the aperture or mirror size of the scope and divide it with the mag of the EP (250/50=5mm)