If M31 through a 6inch newtonian and a 10 inch Dob, how big and clear the image will be?

That would depend on the atmospheric seeing conditions and the eyepiece that you use. You are obviously a beginner by asking this question, this way.





I would like to suggest that you join a local astronomy club or astronomical society BEFORE you spend your money on a scope. There are many different kinds of scopes and what is perfect for one person is not perfect for another. Everyone has their own set of eyeballs and no two are the same. If you join a club, you can attend a few of their star parties and try out members scopes to see what works best for YOU, before you buy a scope. The members can also help you when you get your scope and show you how to get the most out of your new scope as well as to help teach you where the treasures in the sky are located. Most clubs have loaner scopes and extensive libraries that you can gather more information from too. Most clubs will have monthly membership meetings with informative presentations given by members and by guest speakers. You can really learn a lot from these clubs and an added plus is all the great new friends you make there too. Go to this site to find a club in your area. http://www.astroleague.org/societies/lis鈥?/a>


This only has clubs that belong to the National Astronomy League, so there are many more which do not appear on this list. Continue searching google if you don't see one in your area here.





There are several different kinds of telescopes and all of them have some excellent features. Refractors and Reflectors, plus Schmidt-Cassegrain, APO refractors, Mac-Cass, and many more. There are also several mounts to chose from and the mounts are just as important, if not even more important, than the scope is. All of the different scopes and mounts have some features that some people like and do not like. No two eyeballs are the same and the perfect scope for one person might be completely wrong for another person.





There is no one scope that is ';better'; than another ---except for the junk scopes out there which are all just a waste of money. Never, ever buy from Walmart, Costco, Target, or any other discount store like that. Junk scopes are flooded into the market from those stores. You will be buying nothing but bad optics and plastic.





If you are new at this, then stay away from anything used from any site. If you don't know what you are buying and who you are buying from you will most likely be getting someone else's headache---with no warranty either. Some great deals on used equipment are out there, by people who know how to use and take care of scopes, but if you don't know what you are doing, you might be spending a lot of money on worthless junk. One improper cleaning can destroy a scope. Buyer Beware.





I recommend: http://oriontelescopes.com/





Orion is the very best for value and for customer service too. I have 3 of their scopes and I will only buy from them from now on. My first scope was a manual controlled scope and I am very glad that it was because it forced me to learn where things are in the night skies. Go-To type scopes can be frustrating to use. If you do not have them aligned exactly perfect, they do not find the targets. If you are a beginner, you will be frustrated unless you spring for a GPS Go-To. An object locator is just that---it will locate objects for you (must be aligned first) but an object locator is not a tracking motor. It will not keep the scope on the target.





The Orion site has some excellent diagrams and explanations of all types of scopes and mounts.





Things to consider are size--can the user lift and transport the scope to the viewing site easily? Does it fit in your car? If not, then it will gather dust in a closet. I recommend a carrying case too so it is protected in storage and transport. Can the viewer reach all the knobs and buttons? I have a long tube large manual refractor and it is very difficult for me to reach the knobs when I am pointed to Zenith. I am not a tall person.





Take your time in making your decision.





Some people will suggest that you purchase binoculars. Not a bad idea but don't buy anything less than 10x50 and you must have a tripod too or you will not be happy with your astronomical views because they will be too shaky from your movements. Even your pulse will make them shake. Personally, I prefer a scope to binos because if binoculars are not aligned properly at the factory, then you get double images and distortions that can't be fixed. Most of the cheaper binoculars are not properly aligned. That is not as important for terrestial viewing, but it is a killer for astronomical viewing. Binos can also be bumped out of alignment and become useless for astronomy.





When you buy, go Orion and you wont be disappointed. Don't try to learn everything all at once or you will be overwhelmed and discouraged. Patience is the key to Astronomy.





You will need a good star chart program too.


http://www.stellarium.org/


This is great freeware that you can download to show you where and when to look for objects in your skies. I wish you the very best. Enjoy!If M31 through a 6inch newtonian and a 10 inch Dob, how big and clear the image will be?
I have to say that M31 is usually very disappointing to me when viewed through a telescope, with one exception. Generally I prefer the view through 20 x 80 binoculars on a parallelogram mount. One reason for this is the size of M31 which is 3 degrees wide (that's 6 full moons wide). In general though I much prefer a 10 inch scope over a 6. The 10 collects more light, and all else being equal will show more detail.





Galaxies are called ';faint fuzzies'; because they are very faint and fuzzy. Generally you don't see all that much detail.





The one exception I mentioned earlier was one time at a very dark site and under unusually good conditions I viewed M31 through my 10 inch f/4.8 dob with a borrowed 31 Nagler eyepiece. That view was stunning. Even though it gave a 2.1 degree field of view, it showed M31's dust lane clearly as well as the satellite galaxies M32 and M110.








Edit, M 31 should be easy to find but not this time of year unless you want to wait up till 2 or 3 in the morning. You probably won't be able to see much from a city, you need a semi dark location. Under light pollution you need a larger scope.If M31 through a 6inch newtonian and a 10 inch Dob, how big and clear the image will be?
it's the wrong time of year. wait a couple of months.





you can see the main dust lane in a 10 inch under dark skies. in anything smaller you see a glowing oval with two glowing blobs (m32 and m110) in tow. i'm looking forward to seeing what my 18'; will make of m31. g1 here i come! :-)





if you're trying to make a purchasing decision, you're going about it all wrong. get off the computer, look through some telescopes, and see for yourself.
3 x 1 degrees according to source below. The moon is 2 degrees. You will see a little bit more structure out of the Dob, but it will mostly just look like a piece of dull blue cotton.