Perkil8r Posted March 9, 2012 Share Posted March 9, 2012 This hobby is addictive, that is for sure. With that in mind i keep looking at various scopes thinking hmmmmm... I wouldn't mind adding to my scope to grow a family of scopes. Thing is, there are so many out there. I understand how they all work, that's not the issue, but the prices vary so much I have to wonder if to a degree, price is linked to the images you will see with them. Which leads me to ask: If you were to have a Newtonian, a Maksutov-cassegrain and a Refractor of the same apature and of similar quality, which would be the better for observing: a, Planets b, The Moon c, DSO's and in what way? Next, if not the same apature, what apature would you want to replicate the results gained with an 8" Newtonian? Link to comment Share on other sites More sharing options...
Rusty Strings Posted March 9, 2012 Share Posted March 9, 2012 (edited) Aperture isn't the only important attribute, the focal length will all determine how effective it will be with the different types of object. We'll assume an aperture of 8". Short focal lengths or "fast" scopes produce wider fields and brighter views, just the thing for DSO's, so an F5 -F6 newtonian will be best suited to this. Long focal lengths are a feature of refractors and Maksutov-cassegrain, it produces a narrower field of view which is not as bright and generally yields greater contrast which works great on the moon and planets where the objects is very bright. The longer focal length also means higher magnifications from the same eyepieces. The size of the scope becomes an issue with longer focal length. Maks have a folded optical design using mirrors and as a result are very compact. Newts are also reasonably portable at 8". An 8" refactor would not be classed a portable scope as a focal length of F10 - F15 would result in a tube 80" to 120" or 10 feet!!! The best all round scope is a difficult beast to achieve without compromises but many folks around here, myself included, have gone for the 8" newtonian and are very satisfied with the results. Edited March 9, 2012 by Rusty Strings Link to comment Share on other sites More sharing options...
Perkil8r Posted March 9, 2012 Author Share Posted March 9, 2012 I too have an 8" Newtonian and am very happy with it (although a few more inches would never hurt) I'm just interested in expanding to more than one scope, and have seen so many that I can't decide. Link to comment Share on other sites More sharing options...
Guest Tweedledum Posted March 14, 2012 Share Posted March 14, 2012 For me the versatility of the SCT just cannot be beaten. I have had an 8" Newt, 102mm mak, and have sold my 10" SCT and 127mm frac in order to make way for a 12"sct and a largish apperture apo. Maks are planet killers, great contrasty views from a small package. My short tube frac 120mm is my grab and go, bullet proof!. I am drawn back to the sct simply great for what I want which is observing. Put on high mag for planets and lowish power and widefield of view ep for fuzzies. The 8" scts are highly portable, any bigger caution is required, my 10" weighed in at 75lb so you needed to be careful mounting it! So I think you have raised the burning question, thats why when you get to my age you have several scopes! And when the mrs asks why more scopes than eyes reply why more bits of jewellery than fingers!!. Cheers Link to comment Share on other sites More sharing options...
Brantuk Posted March 14, 2012 Share Posted March 14, 2012 Pretty much the same for me - my kit covers pretty much all bases that I want to explore observing - and various types of imaging - when I get the time to do it. However if I had to sell all but one - it's the Sct that I'd keep as a great all rounder Link to comment Share on other sites More sharing options...
Perkil8r Posted March 15, 2012 Author Share Posted March 15, 2012 So to sumarise, Newt is better for DSO's due to being faster, Refractors and Musks are better suited for Planets due to being better contrast due to longer F/L. In which case I might narrow my search for a next scope to a refractor since they seem to be a bit cheaper per apature. SHould be able to get better views of planets. Is this about right? Link to comment Share on other sites More sharing options...
cgolder Posted March 15, 2012 Share Posted March 15, 2012 (edited) Hello, Not sure where this info is coming from but for dso assuming the same magnification focal lenght makes no difference.... Use a 10mm in a 2000mm f10 scope it will be the same image as a 5mm in a 1000mm f5 scope. both will have 200 mag and the same field of view and the image brightness the same. However, the f10 in cheap eyepieces will have a nicer image due to the eyepice correction being less demanding in this scope. Also depending on the eyepiece design a 10mm is generally nice tp use than a 5mm. A well collimated reflector will generally show more on planets and dso but.. you would need yo get around the defraction spikes on the viens (i hate these) and the loss of resolution from secondary. Normally the additional light gathering makes up for this Edited March 15, 2012 by cgolder Link to comment Share on other sites More sharing options...
cgolder Posted March 15, 2012 Share Posted March 15, 2012 A poorly corrected refractor (achromat) will show false colour which gets worse the faster the focal ratio. This makes cheap refractors undesireable for solar system viewing and astrophotograhy. A well corrected ed refractor is expensive and get more expensive the larger they get so reducing what you see by light gathering ability. A maksutov is a slow scope in a folded design and are good for anything providing you can fit it in the fov. All scope designs have the same fov limitations at the same focal lenght, a 1500mm mak has the same max fov as a 1500mm frac but a 1500mm frac is 1.5m long so a lot less common. Link to comment Share on other sites More sharing options...
cgolder Posted March 15, 2012 Share Posted March 15, 2012 (edited) Maksutovs are generally better for planet sharpness over an sct due to better collimation, better overall image correction and smaller obstruction. But a maksutov is limited in size due to the thickness of the front corrector. It geta thicker the larger the scope, so more expensive and heavy. A sct can grow larger as its corrector is thin. A mak is a planet killer because, it has a better price/size ratio than an ed refractor and a sharper, less obstructed view than an sct or reflector. Disadvantage to this is cool down times due to the thick corrector Edited March 15, 2012 by cgolder Link to comment Share on other sites More sharing options...
cgolder Posted March 15, 2012 Share Posted March 15, 2012 I have two stop now as typing on a phone is a pain lol, Btw I worked out I have owned... 5 maks 3 scts 11 fracs 4 reflectors 1 mak newt :-) Link to comment Share on other sites More sharing options...
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