Some Advice Please

morry · #1 20-05-2011, 06:46 PM

Hi All,

I must say this site is a wonderful resource for no idea newbies like me. I've been through the threads and after all the recommendations and advice, I decided on an 8" dob, which I picked up a few days ago.

Now I must say I am a total novice when it comes to astronomy and telescopes, so I've started on the long journey and went out looking for Saturn which I found.

I saw it very briefly with a 9mm eyepiece, however when I went to change eyepieces down to the 6mm, I couldn't find it again.

I put the 9mm on again and still couldn't find it.

The thing I am really struggling with is keeping the planet in view, do you guys have any tips etc on how best to do this? Also, is there anything I can add to the telescope to help me keep things in view a bit better?

Thanks guys.

Morry.

supernova1965 (Warren) · #2 20-05-2011, 07:00 PM

Welcome to IIS what do you have on your scope some kind of finder scope I imagine if you have you need to align this finder with the scope. Align the scope on a distant object in the day like a power pole or light pole then adjust the finder until you have the pole in the center of the finder. I recomend getting a TALRAD for ease of lining up on visable objects you align it the same way as for a finder scope. This probably doesn't need to be said but when using the scope in the day be careful that you are aware where the sun is because you will damage your eye's and your scope's eyepieces

ballaratdragons (Ken) · #3 20-05-2011, 07:34 PM

Hi Morry.

Geez, even after years of practice I find it hard to locate a planet with a 9mm EP in a Dob.

Start with a bigger EP like a 15mm or 20mm. A 25mm would be even better. Then centre the planet (or other object) in that EP, then quickly swap over to the 9mm.

Also, you will need exceptional seeing to get a good view with a 6mm EP.

What you will learn as you go along is that the more you magnify an object the faster it will zoom through the EP view, and a slight move of the scope is an enormous move in the view

supernova1965 (Warren) · #4 20-05-2011, 07:44 PM

I am glad you answered Ken I forgot that bit of advise

morry · #5 21-05-2011, 08:02 AM

Thanks guys, I'll be sure to grab a telrad.

What about with moving the scope when looking through the eyepiece, any tips on how to move it accurately to keep things in view?

supernova1965 (Warren) · #6 21-05-2011, 08:09 AM

Quote:

Originally Posted by morry

Thanks guys, I'll be sure to grab a telrad.

What about with moving the scope when looking through the eyepiece, any tips on how to move it accurately to keep things in view?

I try something like a nudge or if you have a handle that you can reach while looking through the EP to follow the planet remember that everything is revearsed up is down and left is right

Barrykgerdes · #7 21-05-2011, 09:08 AM

Hi Morry

Don't despair about trouble finding objects in you dobsonian. It takes a bit of practice to use higher manification in a manually steered telescope.

The first thing to do has already been mentioned as to aligning your view finder to your eyepiece and the advantages of a Telerad type finder.

The next thing to do is to check out your eyepieces so that they are parfocal. That is use spacers if necessary so that quick changes do no need a refocus.

Now find your object in your lowest magnification eyepiece. Most likely a 26mm eyepiece. Watch the direction it drifts as you view it and practice the direction you need to follow to keep it in view. Noting the drift direction place your object in the position that will give the longest drift path and then quickly change to your 9mm eyepiece. It will drift across your view a lot faster. Keep it centered while fine focusing and practice following it at the now much faster drift rate.

If you only have a cheap 6mm eyepiece I think you should not bother with it as the view while being slightly larger will not be any clearer.

If you lose the object put your 26mm object in and start again from there as locating objects in a small FOV will be very difficult unless you know the sky well.

Barry

morry · #8 21-05-2011, 10:58 AM

Thanks for the advice guys, I guess like anything new it just takes alot of practice and patience.

Fox · #9 21-05-2011, 05:26 PM

Hi Morry, and welcome! As others have posted, sounds like a simple case of over-powering your scope, so start with much lower powers and get accustomed with how to keep things centred. BTW, whats the aperture and focal length of your dob? Fox

Stu Ward · #10 21-05-2011, 07:19 PM

If you switch to a higher mag eyepiece, I always find it useful to slightly defocus the object ( when they are bright like planets) before you change to the higher power.
This will make it appear like a large bright reflection of your primary mirror.
This can then be easily centered in your higher mag eyepiece and then focussed down upon.

Hope this helps

Stu

morry · #11 23-05-2011, 10:32 AM

Quote:

Originally Posted by Fox

Hi Morry, and welcome! As others have posted, sounds like a simple case of over-powering your scope, so start with much lower powers and get accustomed with how to keep things centred. BTW, whats the aperture and focal length of your dob? Fox

200 x 1200

Brian W (Brian) · #12 23-05-2011, 11:43 AM

Moving a dob is not difficult and everyone has their favourite technique.

I like to put two fingers (the ones a person uses to make a V for victory sign) over the top rim and put my thumb against the outside of the tube. This allows for good control in my 8" dob.

As has already been noted the higher the mag the quicker things move through your field of view. Only solution is a bigger scope with lower mag.... aperture fever strikes .

Brian