Mount advice..."ooh er"

[8kids]

I'm new to astronomy, but like all sensible men I jumped in with both feet and bought a 12" newtonian scope, (I should say my wife had auction fever and couldn't stop herself).

Obviously I hadn't really thought it through and now have a scope with no stand and no eyepieces, I can't run to a suitable eq mount so I'll use my cabinet making skills to make a dobsonian mount. Does anyone know of any good sites or designs that might suit my explorer 300pds. I'll think about eyepieces later unless you want to tackle that as well.

Many Thanks Gary.

[Ags]

Welcome to the forum. That is one nice scope you've got. I think it is a nice size for a dob. I can't help you out with designs though...

[Stu]

Hi Gary

Moonshane, who is on this forum made a dob base for his 16" newtonian which may help you out. Have a search for it, pretty sure he posted a thread with all the details of the build which would be very useful to you. If I find it I'll post a link here

Stu

[Stu]

http://stargazerslounge.com/showthread.php?p=1797095

This should be the one

Stu

[brantuk]

Yup - Moonshane's brilliant at the diy stuff for big dobs - drop him a pm if he doesn't see this thread

[Stu]

Welcome to the forum by the way Gary, was forgetting my manners

Stu

[Ags]

Regarding EPs I would go for a 25mm, 17mm, 13mm, 10mm and 6mm. The cheaper widefield EPs may not perform well in your scope which is quite fast at F5 (which needs better eyepieces). As it is an undriven dob perhpas you should look for EPs with a wider field of view - it makes tracking easier. The only EP I have that would work well in your scope is a Speer WALER 9mm, which gives an 82 degree field of view and is corrected down to F4.5. Costs around 150 new, but I got it for much less second hand.

[8kids]

Thanks for the welcome, I've been reading various threads on this site for a few days and many of my questions can be answered in them but it's always nice to get fresh advice. I'm sure I'll be posting more questions to you all. I was thinking of buying a few ep's to start with just to get my eye in so to speak, maybe a 30mm and 17mm just so I can learn my way around a bit easier, would that be sensible?

[Ags]

You need to consider the 'exit pupil' - the size of the bundles of light coming out of the eyepiece. The reason I suggested a 25mm was that the exit pupil would be 5mm - about the size of your dilated pupil (if you are younger can go a bit larger). With a 30mm EP the exit pupil would be 6mm, getting a bit big for some eyes. If the exit pupil is too large for your eye, the view gets dimmer.

Also, the contrast gets poorer as the exit pupil gets larger - you may find the views more pleasing with a blacker sky with the 17mm than the 25mm/30mm, especially if you have a fair bit of light pollution.

[8kids]

Thanks for the exit pupil info, I'm sure I'll fall into some of the newbie purchase mistakes but hopefully this forum will mean I won't fall into all of them.

Cheers Gary.