Another option to purchasing eyepieces is
what is called a Barlow. A Barlow is essentially a tube here with a lens at the end of the
barrel, and that magnifies the eyepiece that you're using in your telescope by a factor
of two or three, depending on the Barlow. Two or three being the most usable. If you're
wondering why you might use such a device, well typically your telescope will come with
at least one or two eyepieces of different focal lengths. This is a twelve millimeter
eyepiece here, and if you can see the lens we have to look through is not very generous
and it kind of be kind of difficult to find that sweet spot. So let's say this eyepiece
gives me 200 magnification in the telescope I want to use. This eyepiece right here with
a much more generous lens, gives me 100 magnification when I put it in my telescope. And as you
can see, greater surface area on the lens there makes it easier for me to look through
and easier to find that sweet spot. So in order for me to achieve the magnification
that this eyepiece has but still keep that generous relief, I'm going to insert the Barlow.
Here is a 2x Barlow. I'm going to put it inside the eyepiece here, or excuse me inside the
diagonal. I should take this lesson myself. And then the eyepiece goes into the diagonal.
Now I've doubled the magnification of my eyepiece. Now this 100 magnification gives me 200 magnification,
and it could be kind of a handy little tool to have. Again, I don't recommend more than
a 2x Barlow--200 magnification even is a little bit high, but in order to save the price of
another eyepiece, and to get a little bit more generous eye relief, a good Barlow will
run you about a hundred bucks and could be a good investment as well. Another fun accessory
for eyepieces is called a binoviewer. For planetary and lunar work, these will absolutely
spoil you. Well the idea is to get input to both sides of the brain by getting the light
to both eyes. When you have both eyes on the telescope here, 20 magnification, 50 magnification
really seems to fill out more and give you that 3D effect. So a binoviewer is a way to
essentially turn your big telescope into a binocular viewer. I've inserted the binoviewer
here. It does take two eyepieces this time of equivalent focal lengths. I insert them
into the binoviewer here, and just like a set of binoculars, as I approach the binoviewer,
I adjust the inner pupillary distance by starting with them wide, and then I'll just bring them
in until the two images merge, and I see one sight. For me, I really love using the binoviewers
on the moon, on Saturn, on Jupiter... it really makes those guys pop, a 3D effect. However
when you do get into deep sky objects, objects that are a little dimmer, a little harder
to see, the benefits of a two inch eyepiece will become apparent. Because as of now what
you're doing is taking an inch and a quarter of light--binoviewers are an inch and a quarter
barrel--and splitting that into two eyes. So the brighter objects look really well,
but if you're going to go for deep sky, for the dimmer objects, a two inch eyepiece lets
in more light and will give you a better image.