One thing I haven't seen mentioned yet is that there is also a quality difference between refractors. These come as achromatic (less expensive and better suited to low power viewing due to chromatic aberration) & apochromatic (much more expensive and much more favoured for photo). You cannot expect to get the image quality as David from an achromatic refractor. Achromatic refractors have a major weakness in focusing the entire spectrum. The only achromatic refractors that begin to control this are very long focal ratio instruments, like Matt's 6" monster. A 6" f/5 achromat is not a patch on a 6" f/12 achromat at high magnification. But a 6" f7 apo is a match, and there is some call for a superior image in the apo, but a bee's dick in it.
In a reflector, today's mass produced one's are much better in quality than was available 30years ago. And on average, these are also very good in figure. To the point that Newtonians today CAN now be pushed to their optical theoretical limits. A very good quality mirror today will begin to rival a similar aperture apo refractor, yes with a difference in contrast, but not enough to say the reflector is inferior in quality, and certainly can out perform an SCT.
What has been mentioned often is there is no all purpose scope. I too have several scopes, 4 Newtonians, one SCT and a refractor. Each is unique and sevre different applications. My refractor is a 4" f/5 achro that I use only for expansive wide field viewing. My SCT I use exclusively for the Moon and planets. My Newts, all dob mounted though two can be eq mounted, are my general purpose/deep sky instruments. My 12" also compacts down to the size of a small suit case. My 17.5" is smaller than a mass produced 'collapsible' 8" scope when stowed. So you see, the application of scopes varies as does their physical design.
Now, a refractor being superior to a reflector for photo? From what I can see in the various photo forums here that it more depends on the operator than any single scope design. Don't forget that there is an amateur astronomer in Broken Hill employed by NASA to verify features spotted by the Cassin probe of Saturn, and vise-versa, and I believe he uses a 12" Newtonian.
Someone mentioned light gathering power. While a 12" might have 4 times that of a 6", it's only half the story, in more ways than one. What matters is what you can actually do with all that extra light, and it's less than the number might suggest.
It takes 4 times more light to show an image twice as big, at the same brightness. A factor of 2, not 4. The 120ED vs Lightbridge simulation, although not exactly 2 times bigger, shows that nicely.
Similarly, resolving power (whether based Dawes or Rayleigh) is proportionate to the lens or mirror diameter. The diameter is the denominator in the equations. According to them, a 12" will resolve twice "as finely" as 6". A factor of 2, not 4.
The answer to me is surprisingly simple. A 12" is, at most twice as good as a 6", not 4 times as the "light gathering power" thingy may suggest, provided both scopes of comparable quality. A 6" achro vs. a 12" Zambuto equipped whatever will give a vastly different outcome. Similarly, if the 6" was a high grade APO, and the 12" anything less than a top-notch newt, I would not be surprised if that margin became desperately thin.
Similarly, if the 6" was a high grade APO, and the 12" anything less than a top-notch newt, I would not be surprised if that margin became desperately thin.
Yes, but as others have said, it's the "bang per buck" that separates them for most amateur astronomers on a budget. How much will the high grade 6" Apo set you back? And how much would you pay for a "less than top-notch" 12" Newt?
Yes, but as others have said, it's the "bang per buck" that separates them for most amateur astronomers on a budget. How much will the high grade 6" Apo set you back? And how much would you pay for a "less than top-notch" 12" Newt?
Obviously. Same could be said about top quality newt vs. mass produced archro. And what's "bang per buck" anyway? Aperture per dollar? Quadrupled light gathering power? Give me a break.
I think the most "bang per buck" is the ability to be awed by the night sky without any additional equipment. Lose it, and no aperture, however big it may be, is ever going to be enough.
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I think the most "bang per buck" is the ability to be awed by the night sky without any additional equipment. Lose it, and no aperture, however big it may be, is ever going to be enough.
Couldn't agree more, I stopped at Spire View lookout at Coonabarabran at 1am yesterday morning, turned off the lights got out of the Merc and stood in absolute awe of what was a beautiful, clear sky. Although I had the FSQ & T-Rex as well as binoculars with me they were not necessary and would have been a distraction. All the aperture I needed was two 58 year old pupils.
These 'fractor vs 'flector discussions will persist with good motives and reasons for both types. Eventually it all comes to horses for courses. I still maintain that the ideal astro quiver has 3 arrows, a 60mm F5.9 Fluorite refractor, a 100-150mm ED Apochromat refractor and a good quality 10" F4.8 - F6.0 reflector.
That's a beautiful image of Saturn just the type of image I am looking for, fingers crossed. I am thinking maybe I should have purchased a refractor. lol
That's a beautiful image of Saturn just the type of image I am looking for, fingers crossed. I am thinking maybe I should have purchased a refractor. lol
No, you are saying the next scope to add to your collection will be a refractor, just like the rest of us
Starlight,
My Ebay account is cluttered in the same way as your yard is, only the account is cluttered with scope-stuff not scopes. This discussion has made clear the importance in having access to more than one type of scope. It very interesting that a couple of the images in this thread were made using. The same scope but by different astronomers at different times, that is very cool!
Cheers
All I can add is that at one point I had both a refractor (60mm) and an 8" Dob (which I still have!)...One night I did a Jupiter comparison: I used a 60mm planetary EP in both and found that Jupiter was sharper in the Refractor but much larger in the Dob: obviously there is a whopping big aperture difference here, but it was interesting. The Dob image was vastly more impressive but slightly (and mean, slightly) more fuzzy. I also viewed Jupiter in my mates 11.5 inch SCT and then with my 8" Dob and the difference there was miniscule! I think the mirror in my Dob may be a good one....my 2 cents worth!
I am a newbie as far as astronomy is concerned. I have read widely about scopes and the strengths and weakness of refractors v reflectors arising from this reading it seems that a 130mm refractor is roughly the equivalent of a 12" reflector in terms of image quality. Is this a correct interpretation of the rough/relative comparison between the image quality of refractors v reflectors. Or is it a result of my miss reading the relativised comparison between the two types?
Again from what I have read, I would much prefer to lug a 6" refractor around, rather than a 12" reflector.
Funny thing, I've had both a 12 inch reflector ( bintel ) and a 132mm APO refractor ( Williams FLT 132) given the refractor costs 5x the reflector, it's probably a no brainier for a beginner.
Image quality is a fine topic but it's also a theoretical one influenced by atmospheric conditions etc, there are only so many nights where high magnification is possible, same goes for astrophotography, hence why the professional scopes are high on mountains in uninhabited areas.
It would be nice to decide what was the perfect scope before you bought so that you would only ever buy one and that would do. BUT despite all the experience on the forum, the folks here continue to buy scope after scope in search of the ideal one. Truth is it really depends on what you want to do, and as a beginner how could you really know.
I've done visual and in all honesty staring at colored dots really doesn't grab me, globs do look nice, but details in galaxies is a slight smear here and there.....( not for me)
planetary imaging, done that, and after a while Jupiter looks just like it did last night and the night before, occasionally the dedicated will find a comet strike or a slight atmospheric variation.
Imaging, gaudy colors, detail, lots of objects to shoot at varying lengths, for now that does it for me.
Research and scientific study, surprisingly there is work for amatuers to do, rotations of asteroids etc, but you need to be somewhat dedicated.
So back to the original premise, as a beginner, if you want to do visual go grab a 12 inch dob, photography grab a small refractor (ed80 ) then once you've got miles on the clock, decisions will become clearer. Image quality essentially costs money, the more you spend the better you get. Yes I've got a $6000 refractor, but in all honesty I can't say it's any better to look through than the $900 reflector. But for astrophotography it's chalk and cheese, but not nescesarily for the reasons one would first expect.
Like buying a car, do you want a formula 1, a rally car, an offroad SUV, or a passenger transport, so many choices all will drive on a road, some are better at some things than others, as a first car buy a reasonably priced everyday car, drive around for a while, find out what works for you then buy it..... Then buy some thing else.... And something else again.... That's how it works in astronomy anyway
Yikes Clive That has to be one of the best posts I have read on the what should I get question….so true. It takes time, measured in years for me, to work it out.
. The 120ED vs Lightbridge simulation, although not exactly 2 times bigger, shows that nicely. 
That has to be one of the best posts I have read on the what should I get question….so true. It takes time, measured in years for me, to work it out. 
