some advice please

darnun · #1 24-09-2009, 12:39 AM

Hi all.
Can any one in iceinspace land give me some advice please.

I currently own a Skywatcher 8" or 200mm by 1200mm Dobsonian. Mounted on a HEQ5PRO go to.
My problem is it fits into my car no worries, but I cannot have back seat
passengers, especially if I'm staying over night somewhere dark.
So, I am thinking of selling the dobsonian and buying a Maksutov-Cassegrain
only because it is half the length.
My question is, what size would be best a 127mm, a 150mm or a 180mm?
I hope to keep the same if not better viewing power as the 8" Dob,
using a plossl 25mm lens and perhaps a 2x barlow.

PCH (Paul) · #2 24-09-2009, 12:54 AM

Hi Darnun,

for the same (or better) viewing power (brightness), you will need the same (or larger) diameter scope. It's the diameter of the tube (ota) that determines the amount of light that can be gathered - or viewing power as you call it.

The Mak Cas will have a slightly longer focal length, (typically 1900mm or longer versus the 1200mm for your present scope) which means you'll be able to get a fair bit more magnigification out of it just by using the same eyepiece that you already have.

Hope this helps

mswhin63 (Malcolm) · #3 24-09-2009, 12:58 AM

8" Apeture will give you the light collection in any scope, so to get same or better you will need to get the same or better apeture.

The next is to consider focal length, The scope you are looking for usually have a longer focal length to a DOB although not all the time so magnifacation will be a bit more.

Since starting I found magnifacation is not the key as there are some really good views in wide field. Planets though would be better viewed in higher magnifacation.

Goo luck with your search or like me get a staion wagon

mswhin63 (Malcolm) · #4 24-09-2009, 12:59 AM

Pipped me at the post Paul.

darnun · #5 24-09-2009, 01:03 AM

Yes,that really does help me PCH(Paul).
So, it basically means a 200MM Mak-Cass could be the way to go.
Especially since I already have the mounting rings to suit.

Clarry (Clayton) · #6 24-09-2009, 01:27 AM

Or you could just buy a luggage pod for the roof of your car, if you have racks. I take my 8" dob with me on holidays like that. Useful for other things too.

astro744 · #7 24-09-2009, 07:53 AM

Do you want or need tracking ability when you go out? If not why not consider the Meade 8" Lightbridge deluxe. Very compact indeed.

Another option is an 8" SCT OTA to fit your HEQ5PRO. Currently does the mount ride in the back seat too or only the 8" Newt? If both then I'd go with to compact Meade 8" Lightbridge.

PCH (Paul) · #8 24-09-2009, 09:57 AM

Quote:

Originally Posted by Clarry

Or you could just buy a luggage pod for the roof of your car, if you have racks. I take my 8" dob with me on holidays like that. Useful for other things too.

I have quite a nice little trailer that, although not fully enclosed, can be towed behind the car quite safely. I find the wife and kids fit on that quite nicely. They have complained when the weather gets a bit rough, or the road is a bit bouncy, but you just have to accept that you can't please all the people all the time. Some people will never be happy

Clarry (Clayton) · #9 24-09-2009, 04:36 PM

Quote:

Originally Posted by PCH

I have quite a nice little trailer that, although not fully enclosed, can be towed behind the car quite safely. I find the wife and kids fit on that quite nicely. They have complained when the weather gets a bit rough, or the road is a bit bouncy, but you just have to accept that you can't please all the people all the time. Some people will never be happy

Sometimes no matter how hard you try, there's no pleasing them.

DavidU (Dave) · #10 24-09-2009, 04:39 PM

Quote:

Originally Posted by PCH

I have quite a nice little trailer that, although not fully enclosed, can be towed behind the car quite safely. I find the wife and kids fit on that quite nicely. They have complained when the weather gets a bit rough, or the road is a bit bouncy, but you just have to accept that you can't please all the people all the time. Some people will never be happy

Same problem here, wife complains it mucks up her hair.

PCH (Paul) · #11 24-09-2009, 04:50 PM

A policeman stopped me once and said "did I realise I'd lost my trailer a couple of miles back?" I said "thank god for that, I thought I'd gone deaf !"

rogerg (Roger) · #12 24-09-2009, 05:35 PM

Quote:

Originally Posted by PCH

A policeman stopped me once and said "did I realise I'd lost my trailer a couple of miles back?" I said "thank god for that, I thought I'd gone deaf !"

That and the last few posts convert very nicely in to a joke

Just tried it out on my cousin who's getting married on Sunday.

PCH (Paul) · #13 24-09-2009, 05:44 PM

We aim to please Roger

Please be sure to pass on my commiserations