observing moon with dobsonian

[ryyyiu]

Hello, i'm really new in astronomy, i have bought lastely dobsonian 12"(GSO). It came with superview 30mm and plossl 9mm lens. Actually i have bad weather, but i want at least to observe moon with best view experience, what can you recommend? Any informations, etc.. , please .

[Langy]

Hi and welcome to SGL. I'm new too and know nothing of your scope. However you have two EP and the best way will be for you to stick in the 30mm and view the moon when we finally get better conditions, then flip to the 9mm.

I'm sure your first viewings will be amazing like almost every other person on their first time.

Jupiter is clearly visible to the naked eye and will be an easy find with your scope. As of today it is just east of the moon.

Download the free software Stellarium to make the most of your planning and viewing time.

[John]

Hello and welcome to the forum 

I also have a 12" dobsonian and use a range of eyepieces to observe the Moon. The 9mm will be more useful in seeing detail than the 30mm is it gives much more magnification. Your scope can go further than that though so you would also find 7mm and 6mm eyepieces useful. The plossl type eyepieces are inexpensive and quite good quality but there are many other choices of eyepiece too.

This report might help, if you have not already read it:

http://stargazerslounge.com/topic/43171-eyepieces-the-very-least-you-need/

[ryyyiu]

Hey, thanks for answers, i have used two times stelarium, it is very good program .

Hm, what about eyepieces, i thought about barlow 2x for rnav spotting with this dobsonian, what you think about this?

And does it make any difference using polarised moon filter , and standard one(the green cheap one) ?

[todd8137]

Any filter is better than the cheap green ones

Pat

[John]

I don't find I need any filter when observing the moon even with my 12" scope.

A 2x barlow lens with your 9mm eyepiece would give you 333x magnification which might be useful on the moon on the very best nights but could often be too much. A 6mm eyepiece might be a better way to add to your eyepiece collection.

[todd8137]

I don't find I need any filter when observing the moon even with my 12" scope.

A 2x barlow lens with your 9mm eyepiece would give you 333x magnification which might be useful on the moon on the very best nights but could often be too much. A 6mm eyepiece might be a better way to add to your eyepiece collection.

Even when it's a waning gibbous ?

Pat

[John]

Even when it's a waning gibbous ?

Pat

Yes. I'm usually observing at 200x or more so I'm seeing a portion of the disk and I find my eye adjusts quite quickly to the brightness. 

Of course I don't go looking for faint DSO's right after observing the moon but with the moon in the sky those are best left until a moonless night anyway 

[DRT]

I don't find I need any filter when observing the moon even with my 12" scope.

A 2x barlow lens with your 9mm eyepiece would give you 333x magnification which might be useful on the moon on the very best nights but could often be too much. A 6mm eyepiece might be a better way to add to your eyepiece collection.

I was viewing (a tiny little bit of) the moon at 700x tonight- Baader Zoom @ 8mm on a 2x Barlow with my CPC 1100 - it was very clear but very bright and I had to use a filter. I had a look for an American flag but couldn't find one

[John]

I was viewing (a tiny little bit of) the moon at 700x tonight- Baader Zoom @ 8mm on a 2x Barlow with my CPC 1100 - it was very clear but very bright and I had to use a filter. I had a look for an American flag but couldn't find one

You say you "had" to use a filter. Why ?

At 700x the image is really not going to be that bright, even with an 11" scope. 

Perhaps my eyes are different from yours ? 

[DRT]

You say you "had" to use a filter. Why ?

At 700x the image is really not going to be that bright, even with an 11" scope. 

Perhaps my eyes are different from yours ? 

I find I always have to use a filter on the moon unless there is some high-level cloud to replace the filter. If I don't I end up with strained eyes and find it difficult to focus. It reminds me of when my son used to think it was funny to shine his new LED torch in my eyes when I wasn't expecting it

[John]

Well I guess it proves we are all different 

[DRT]

Well I guess it proves we are all different 

Exactly. I'm putting it down to me being 48 with the eyes of an 18 year old.

What's your excuse?

[umadog]

Exactly. I'm putting it down to me being 48 with the eyes of an 18 year old.

What's your excuse?

Likely the same as mine: light-adaptation and the moon having low absolute brightness.

[Blazar]

The full moon can be a tad bright....was messing around last year with a DSLR on the refractor, and managed to take a snap of my neighbours TV ariel, with the moon behind it....quite bright really....and my neighbour needs to remove the cobwebs of his ariel of course :-) Most of the time though I don't need a filter....last night was out with it, and was at x5, and no issues at all...

[swamp thing]

Size of scope makes no difference to the surface brightness of the moon. It's no brighter through my 20" Dob than my 4.5" Newt. It's just a lot bigger in any given eyepiece.

[ryyyiu]

Hm ok, so 6mm would be best to observe moon for 12 inch Dobsonian?

I bought green moon filter, it was cheap, about 8$, i also bought this cover for sun filter http://puu.sh/6QKQt.jpg (about 18$) + baader foil nd5.0. Should i give back this filter and cover? 

Also if this will be good eyepiece http://agenaastro.com/gso-6mm-plossl-eyepiece.html ?

@John so i gues you was observing moon with 7,5 mm eyepiece to get 200x , right?

[ryyyiu]

Hm which barlow will be better, this: http://astronomia.co.uk/index.php/accessories/barlow-lenses/vixen-barlow-lens-deluxe-2x-1-25-31-7mm.html (i can buy it for 65$ used) or this http://agenaastro.com/gso-2-2x-ed-barlow-lens.html (can buy new for 90$)

[John]

Hm ok, so 6mm would be best to observe moon for 12 inch Dobsonian?

I bought green moon filter, it was cheap, about 8$, i also bought this cover for sun filter http://puu.sh/6QKQt.jpg (about 18$) + baader foil nd5.0. Should i give back this filter and cover? 

Also if this will be good eyepiece http://agenaastro.com/gso-6mm-plossl-eyepiece.html ?

@John so i gues you was observing moon with 7,5 mm eyepiece to get 200x , right?

You really need a range of high power eyepieces so you can select something that best suits the object being observed and the viewing conditions at the time.

With my 12" dob (which is an F/5.3 by the way) my high powers are mostly delivered with 8mm (199x), 6mm (265x) and 5mm (318x) eyepieces. I do have eyepieces that go higher than that but they are less often used with the 12".

[John]

Likely the same as mine: light-adaptation and the moon having low absolute brightness.

Yes, thats it 

[Moox]

I was viewing the moon last night (first decent go at it since getting my 200p dob) and found that even with a slight bit of high cloud that it was a tad too bright for my eyes and a bit of filter wouldn't have gone amiss. Maybe i've got very sensitive eyes?

[ryyyiu]

What you think about buying vixen barlow 1,25 2x ?

[Beulah]

John, can I jump in here and say you have Telfon eyes?

I need a filter to see the moon!!

[John]

John, can I jump in here and say you have Telfon eyes?

I need a filter to see the moon!!

They are just ordinary as far as I know. When I observe the lunar surface it's generally at 200x or more so I'm seeing a limited section of the lunar terrain. Sure it takes my eye a minute or two to adjust but I never feel "blinded" or "dazzled" at all. 

I find the same with Jupiter - a minute or two to adjust and then I can start to tease out the more subtle belts, barges, festoons etc.

I have tried filtering the above a few times over the years I've been in the hobby but I just feel that the filters get in the way plus usually present the subject with a tint of some sort which, again, I'm not too keen on. I keep trying this as well having recently acquired a set of 2" colour filters to use but, so far, they are not adding anything to my observations.

This topic comes up very regularly on the forum and I know from previous threads that I'm not the only observer that does not use a filter when observing the moon, so I'm not that weird ! 

I have the 12" dob cooling outside right now actually so I'm off out to risk life an limb observing sunlight reflecting off the lunar regolith

[Beulah]

Looks like I'll be popping out soon with my 16" dob & lunar filter...I'm the one's that's weird...

That'll be after I've taken the last batch o' cakes out of the oven.  A woman's work is never done..........

Scrap that, as I took out the last tray out the clouds have come over.