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mal-j

New refractor or not

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Hi all,

I'm thinking about getting a refractor mostly for planets as I have an f4 12" reflector which is obviously more for DSO's.

Should I consider using a 3x or 4x barlow instead on the f4 or would I be better served with the frac?

I do have an 8" sct but I would like to see some more detail than that gives. I'd also like to put a frac onto the reflector as they will be permanently housed in an observatory.

I'm thinking of maybe a 4 or 5 inch achromat above f10 but can't be longer than 1200 mm I think.

Any comments welcome.

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when you say your current scope is more for DSOs than planets, I disagree. I have a 12" f4 OOUK dob too and it's superb for planets visually at least.

what are you currently not happy with? I'd expect that whilst also pretty able, a, say, 100mm f10 frac would be disappointing in comparison sompared to both your larger scopes. that's my opinion anyway based on experience of newts anyway (and brief experience of fracs).

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I agree with Shane. I'm a fan of refractors but I can't see a 4" or 5" achromat improving on the planetary views that either of your other scopes give. Under decent conditions the smaller refractor would lag well behind them in fact.

Your reflector and SCT should be quite capable of delivering very nice planetary views at 200x - 300x, conditions allowing. You might want to consider a shorter length eyepiece than your current 10mm or a really good quality barlow or Powermate.

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Hi Moonshane,

Well I assumed that f4 would be for DSO's. I haven't actually used the scope yet as I got it a couple of months ago and am awaiting the observatory to be put up.

So would you advise using barlows to get the f/ratio up? It would save me spending out if I didn't need a frac. Also any comments about imaging planets using this setup?

From reading other's comments it would seem that fracs give a better contrast and are generally best for planets but I guess everyone has their preferences. I just want to get the best views that I can with whatever will give me that within a reasonable budget.

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Thank you John, looks like I need some experience behind me in using this scope. I have been looking at possibly getting a decent barlow and like you say a shorter eyepiece.

Do you have any advice on which eyepieces would be appropriate i.e. which makes?

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this might help you consider options. http://stargazerslounge.com/topic/188794-eyepiece-groups/ I find that this collection gives me everything I'll ever need. you don't need to spend big bucks either for planetary, especially if you have a tracking mount. it's not essential but I recommend a coma corrector for f4. I am no imager so will leave that to others.

in my 12" f4, the most used on Jupiter recently have been (with paracorr) my 10mm Radian (134x), 9mm Baader Genuine ortho (149x), 8mm Radian (167x) and 7mm BGO (191x). Occasionally I can use my nagler zoom (223x-446x). I find a Baader Neodymium filter helps bring out contrast but honestly, the OOUK mirrors are so good that contrast is not an issue. I think you will be a little surprised how good they are on planets, even at f4. a 12" f4 dob is for me the 'goldilocks' scope.

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My 12" Orion Optics dob is F/5.3 so less demanding on eyepieces than the F/4 versions and it does not need a coma corrector. Shanes advice is very pertinent though as he has the same scope as you do. 

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I vote for you getting a refractor....the telescope of a jedi knight, not as clumsy or random as a reflector; an elegant telescope for a more civilized age.

:)

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Thank you Shane and all.

I take on board all you say and will probably invest in a range of eyepieces etc.

I already have a 2" 20mm ES and a Pentax 10mm XW as quality eyepieces, also a 8-24mm zoom.

As expected there are those in the reflector camp and those in the refractor camp. I have looked through a refractor and they do give nice views though I think I'll try first with the reflector and see how it goes. I've previously only had the 8" SCT so I'm in neither camp yet. :smiley:

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Thank you Shane and all.

I take on board all you say and will probably invest in a range of eyepieces etc.

I already have a 2" 20mm ES and a Pentax 10mm XW as quality eyepieces, also a 8-24mm zoom.

As expected there are those in the reflector camp and those in the refractor camp. I have looked through a refractor and they do give nice views though I think I'll try first with the reflector and see how it goes. I've previously only had the 8" SCT so I'm in neither camp yet. :smiley:

I have 3 refractors (4", 4.7" and 6") and 1 reflector (12") so I'm in both camps  :grin:

Seriously though, you might be pleasantly surprised at the views that your 12" Orion Optics gives of planets. The optics are generally very good in them :smiley:  

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John, thank you for your encouragement. Will look forward to using it and getting some more eyepieces, maybe secondhand on astrobuysell. :laugh:

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Your dobsonian will of course be far more susceptible to poor seeing than a refractor and will produce acceptable views on far fewer occasions. The other major down fall is at the magnification required for decent serious planetary observation makes dobstonians annoying to track, they're a little clunky to use to say the least, useable perhaps, certainly not idea.

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Your dobsonian will of course be far more susceptible to poor seeing than a refractor and will produce acceptable views on far fewer occasions. The other major down fall is at the magnification required for decent serious planetary observation makes dobstonians annoying to track, they're a little clunky to use to say the least, useable perhaps, certainly not idea.

I have the same scope that you do (the ED120) but thats not how I've found things to be honest with you.

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I recently sold a 10 inch Orion Opitics dodsonian or the reasons given above. On globular clusters mind it was the cats whiskers, horses for courses. NO waiting around for an hour before you get observing either with a refractor, particularly good quality achros. 

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I have the same scope that you do (the ED120) but thats not how I've found things to be honest with you.

I think moral is that it different things float different folks boats.

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I think moral is that it different things float different folks boats.

Thats true. I'm a huge refractor fan though, please don't get me wrong on that. I've owned more of them than any other type of scope and currently have 3 that I'm extremely fond of but I can't claim that any of them would out perform good quality 12" newtonian optics on the moon and planets. 

Most of my astronomy observing has been with refractors though and they do often punch above their aperture, just not that much above it, in my experience !

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John is quite correct.  Refractors do punch above their weight on stars and planets, but they don't defy the laws of physics.  I suggest giving your 12inch a good chance on the planets, it will give you some great views.  Whilst true seeing will sometimes limit it's sharpness and resolution, when it's reasonable it will simply blow away any 120mm refractor.  You'll also love the colours in the 12 inch, particularly on Jupiter, Saturn and Mars.  Enjoy it for a while and see how you get on.

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Thanks everyone.

Paul, I will wait and see how my 12" performs and I might still be curious enough to try a refractor later on.

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Thanks everyone.

Paul, I will wait and see how my 12" performs and I might still be curious enough to try a refractor later on.

Glad you're giving it a go, you might be pleasantly surprised with the performance :). You don't necessarily need a barlow, you could just use a shorter FL eyepiece ;).

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Thanks everyone.

Paul, I will wait and see how my 12" performs and I might still be curious enough to try a refractor later on.

Hi paul,

I think that you have made the right decision, inch for inch Apos wil outperform a Newtonian by quite a margin but 12" of aperture is just too much of a  light bucket with high resolution as a bonus.

Regards,

A.G

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