diagonal?

[tingting44]

hey guys, me again, just wondering if there is a diagonal alternative for my scope as i think my scope does not take diagonals? would like something tho to help out with them awkward viewing angles

[astrofox]

Why do you say your scope doesn't take a diagonal?

[tingting44]

been told by several people

[astrofox]

What make is it?

[tingting44]

its all in my aviator to the left mate

[astrofox]

Right I understand. Newts don't have a lot of back focus so maybe a diagonal would take you past focus. If so ever thought of rotating the tube in its rings to bring the eyepiece round? I think Astrobaby wrote up about using a second set of rings as a guide to help rotation and keep the tube from slipping. Also I have seen propriaty slipping rings for a newt but they were pricey. Hope this helps

[DirkSteele]

Typically you would not use a diagonal with a Newtonian telescope such as your Sky-Watcher Explorer-130P. I assume it is in a Alt Az configuration so the eyepiece should never end up in a awkward position.

Why do you think you need a diagonal?

Clear skies,

[tingting44]

thanks astro fox will have a look,

hey dirk, not sure if its in alt az config bud? how would i tell, just sometimes when im looking it feels awkward, just wanted to know if there was something i could get is all

[DirkSteele]

hey dirk, not sure if its in alt az config bud? how would i tell, just sometimes when im looking it feels awkward, just wanted to know if there was something i could get is all

Easy check. Do you need to polar align your scope when you first set up? Looking at pictures of your scope my view is that you don't and it is in Alt Az configuration. As such as the telescope tracks an object using both axis of movement, rather than just one as it would if it were an equatorial mount. The benefit of the mount in Alt Az, is the eyepiece orientation should not change as the scope points to different parts of the sky. You may well be able to move the scope within its mounting ring to position the eyepiece in a more comfortable place for you.

As for using a diagonal, I have never seen anyone use one on a Newtonian. The reason you may have been told that your scope cannot use one, is all scopes with fixed primary elements (the primary mirror in a Newtonian, or the front lens in a refractor) have an unchanging focal plane. With the introduction of additonal elements like a diagonal, you will move the eyepiece beyond the focal plane and be unable to bring the scope to focus. This is due to a lack of "back focus," i.e. the focuser cannot move in to the scope far enough to bring the additional elements in so the eyepiece can focus. If you were determined to use one, you could introduce a barlow lens to the set up, as this will expand the converging light cone that your scope is producing and increase the distance the focal plane is outside the the telescope.

[Cornelius Varley]

hey guys, me again, just wondering if there is a diagonal alternative for my scope as i think my scope does not take diagonals? would like something tho to help out with them awkward viewing angles

You were told right. A Newtonian telescope like yours has insufficient back focus travel to accommodate a diagonal in the light path, Also, because your mount is an alt-az the eyepiece should always be at a comfortable angle for viewing.

Peter

[E621Keith]

Newtonian usually do not need a diagonal because the tube can be rotated to a position where you can look down into the focuser. Refractor and CAT always look up and it gets uncomfortable after a while, so they need a diagonal to turn the view by 90deg so you can look down into the tube

[tingting44]

i get ya!!! thank you guys all for helping me clear this up!! yes my scope would be an alt one then, thank you kindly think i might try lowering the scope tripod as its really high at the mo, then if its low i can try and sit down to view which would be better i think, thanks again

[E621Keith]

If you are unsure how to use your scope, I suggest you should take it to a local astronomical society. Southampton AS has a club meeting next Thrusday (26th). You should send them an e-mail if you are interested.

[tingting44]

thanks keith, i just need to get a power source 1st and i will cant wait to get out further then my garden lol i will email them now tho, thank you