Refractor vs. Astrograph Reflector for DSOs

I guess “win” is a relative term. The refractor is plug and play with little worries about backfocus and collimation. The Carbonstar will not cover Full Frame with the Coma corrector if that’s a factor and it requires 55mm backfocus.

Aperture wins out in resolving finer details and collecting more photons, and the reflector will have less CA to deal with (although still some with the glass in the corrector). But, like Arun said, refractors are much easier to deal with with a portable setup.

I don’t know the edge correction of either optic, but especially if you’re looking at APSC, you’d have to compare raw images from each. I know with my 10” f4 Quattro with the well regarded Quattro coma corrector, I very much struggled to get a FWHM anywhere below the low 3”s. I was able to get similar or slightly better FWHM numbers from an Askar 140 APO despite the much smaller aperture, partly because it’s less prone to wind by a good bit and had nice optics. And my TOA-130 gets in the 2”s on a regular basis despite being yet smaller because of it’s incredible optics.

So all other things equal, yes, aperture “wins”. But all things are seldom equal.

I have three f4 newtonians (600-1000 mm), one RC 1360 mm and one apo 480 mm. For details of galaxies (except the giat M31) clearly wins a higher focal length of 800-1000 mm as mentioned already. My personal prefererence are newtonians, which however always have the collimation problem. If you buy one, you have to deal with collimation which needs special equipment such as a laser or an ocal system and experience. However, it pays out on a long term run.

CS Peter

I am currently using the CarbonStar 200 newt with CS flattener. It’s on a pier in a roll off roof observatory. Its definitely a refractor killer on a permanent setup. Collimation takes 10 minutes if needed. I would not hesitate taking it on a road trip, unless I had to fly, because the view is worth the climb.

“Unless you need rain. Clear Skies”! Heavenly Backyard astronomy.

I have gone down this path and have finally chosen to just use my refractors over my reflectors. In fact I just ditched my Epsilon 160ED in my remote observatory for an UltraCat 108. My long focal length setup is just a TOA-130 5.1 inch refractor.

Obviously people have had incredible results with the Epsilon and it is a fantastic instrument, but there are some intangibles that you don’t hear about at first, like the significant illumination drop towards the corners on a full frame sensor, and the very very difficult process of getting your stars in the corners to look remotely acceptable. Add to that the immense amount of diffraction spikes you have to deal with when imaging rich star regions in the milky way.

Personally I found that processing the data out of my refractors was a far more enjoyable experience than it was out of the Epsilon, even if they were substantially “slower”. All my setups are under B1 skies. I never spent 20 hours on a target with my TOA and thought at the end, “I just wish I used an f/3.3 Epsilon instead”. This included dark and reflection nebulae targets, and IFN.

While larger aperture reflectors in theory should be able to get better details, I think the vast majority of them are wasted under skies with subpar seeing conditions that don’t support that aperture and focal length. Eventually I would love to have a massive reflector under pristine skies, but for now refractors are doing fine.

Alex Nicholas · Nov 25, 2025, 12:31 AM

If your focus is Galaxies, 6” F/4 might be a little short, but then, not worse than a 3.6” f/6.7 refractor.

You have to factor in that the newtonian has more light gathering area (even accounting for the central obstruction), and at f/4, its almost twice as ‘fast’ at gathering light…

If you’re running a smaller sensor like the IMX585, IMX533 or IMX294, then a ~600mm focal length may be just fine for plenty of galaxies, but regardless of the desired target, a 6” F/4 is better than a 3.6” F/6.7.

Depending on your mount - the cost difference between the 150mm and the 200mm might be worth considering. 800mm will give you a lot more options regarding targets, and again, another massive step up in light gathering area.

Running those sensors at F6.7 would require an eye watering amount of time to get a good SNR. They really only make sense if you can get the focal ratio down to around F/3 and below. Even then, by that point there are so many optical errors that become magnified at those focal ratios that small pixels might be a wash anyways.

As for the stated goal of shooting galaxies, the OP might find 600mm lacking. The fun really begins around 1000mm, ± 200mm. By that point, refractors start to get expensive, assuming you want a decent focal ratio.

If you do switch to reflectors, be prepared for soft images for a bit while you get the collimation situation down. Reflectors can be pretty fun though; your knowledge of optical issues (and how to deal with them) will increase exponentially and your wallet will thank you. The only cost you have to pay is a bit of your sanity.

My view is pretty clear - what are your preferences? Is it easiness to operate, maintain and handle - then go for a refractor, is it speed and resolution - then go for a reflector.

Refractors usually in these days are easy to handle, no mirrors to be aligned and recalibrated, no mirrors which collect dust and spider webs, BFD is usually quite easy to achieve and balancing is also easier to do. But the main drawbacks are speed and resolution. Speed - onless you own a money printing machine, you are stuck with probably f/4.6 or similar as maximum speed for any refractor unless you want to sell your home. Most refractors are somewhere between f 5 and f7 - refractors, which are probably still affordable. That means you need to have more good and clear nights for imaging than with a fast reflector.

Reflectors can be a sensitive to travel, a bit more effort is needed to maintain them in a fine state of optical performance, the need recalibration - probably once a year or so and they need more effort to balance them properly ( especially Newtons). But their main advantage is speed and resolution. Reflectors can be very poweful regarding light collection - f/2.2 as example for the RASA series or f/2.8 for Sharpstar, not to talk about the speed monsters from ASA or other manufacturers - the new H-2 as example with f/2.95. This means half or even ¼ of the integration time compared to a fast refractor combined with a much higher resolution.
But they (most of them are “open”) need cleaning at least once a year and they need to looked after more than a refractor.

If you don´t mind more work with and during imaging, then go for a RASA - their speed will surprise you. You can take a “final” image in one night for which you need two to three nights with a conventional reflector or four to eight nights with a refractor. But the RASA got major restrictions - unless you use a tiny system with integrated filter changer like the QHYminiCam8, you cannot use a normal mono camera with attached filter changer - you must change filters, one by one, manually. Or you can use an OSC camera with a multiband contrast filter like those from Askar - the Color Magic C or D series.

I use a 12” TrussRC with three options - f/8 at 2450mm fl, f/6.4 at 1950mm and f/5.4 at 1650mm, a RASA11 with f/2.2 at 600mm and a Hypergraph6 with f/2.8 at 420mm. A reflector I do have on my mind for the time when I cannot handle my current systems anymore (I am getting 77)… so to say, a retirement optics - easy to handle and simple to maintain :-)

One last remark - check carefully your options, look at the varios sytems before you go an buy one!

CS
Georg

I have to admit I am biased, but I gave up trying to use newts. I felts like I was messing with collimations all the time, and never felt confident that I had it right. And every time I hit a bump driving to site in the jeep, I worried I had to start over and redo collimations and calibrations.

No doubt the larger aperture gets more light, and not doubt that lb for lb you can get way more aperture for way less weight and money. I had a 6 inch refractor and the fear of dropping that while mounting/unmounting on a freezing cold night was a real thing.

I honestly feel like for me the 130mm refractor is the sweet spot, if I wanted more aperture after that, Id be going SCT or Astrograph,

My uneducated view on dealing with Coma was that it was a total pain, and if I have to drop 300$ on a good Coma Reducer, then the money I saved over a refractor just got offset.

(Yes I know refractors have CA, but if you get a good triplet, its almost un noticeable. )

My refractors generally dont have to deal with cool down wait times or mirror shift,

I feel like people much smarter than I still love Newts and Astrographs, so I might be missing something, or I am just extra lazy.

My opinion

Clayton Ostler:
I honestly feel like for me the 130mm refractor is the sweet spot, if I wanted more aperture after that, Id be going SCT or Astrograph,

I started astrophotography in 2010 and I’ve owned almost every type of telescope since. Here’s the blunt breakdown:

Refractors:
Convenient, quick, easy. Great for widefield. But they hit the ceiling fast unless your bank account is unlimited. Premium refractors get expensive very quickly for the aperture you get.

Reflectors / RC / Newt:
If you set them up properly, they deliver far cleaner light and far more performance per euro. Almost all of them benefit from a focuser upgrade that’s normal but once dialed in, the results speak for themselves.

My setup today:

• Widefield: refractor (speed + simplicity)

• Galaxy hunter: RC astrograph

My RC with all upgrades ended up around €4,000.
A €4,000 refractor simply cannot match an RC in optical performance or resolution. Not even close.

And for context:
Almost every professional observatory on Earth uses RC or RC-derived designs. There’s a reason for that they scale, they handle long focal lengths properly, and they’re built for real deep-sky work.

If you want convenience → refractor.
If you want long-term performance → reflector, especially RC

Read noise Astrophotography · Nov 27, 2025, 07:09 AM

I started astrophotography in 2010 and I’ve owned almost every type of telescope since. Here’s the blunt breakdown:

Refractors:
Convenient, quick, easy. Great for widefield. But they hit the ceiling fast unless your bank account is unlimited. Premium refractors get expensive very quickly for the aperture you get.

Reflectors / RC / Newt:
If you set them up properly, they deliver far cleaner light and far more performance per euro. Almost all of them benefit from a focuser upgrade that’s normal but once dialed in, the results speak for themselves.

My setup today:

• Widefield: refractor (speed + simplicity)

• Galaxy hunter: RC astrograph

My RC with all upgrades ended up around €4,000.
A €4,000 refractor simply cannot match an RC in optical performance or resolution. Not even close.

And for context:
Almost every professional observatory on Earth uses RC or RC-derived designs. There’s a reason for that they scale, they handle long focal lengths properly, and they’re built for real deep-sky work.

If you want convenience → refractor.
If you want long-term performance → reflector, especially RC

For galaxies, the resolution of the optical train is most important. RCs clearly can have higher focal length, resulting in higher enlargement, but this is not resolution. Most import for resolution is the aperture of the telescope, not so much the focal lenght . I have a f4 1000 mm newtonian (250 mm tubus opening) and a 1626 mm RC with 200 mm opening (f8). For my galaxy pictures, the newtonian clearly wins. In addition the correct collimation of a RC at least in my hands is a problem (for me). From the earth the resolution of telescopes with a larger opening than about 250 mm is strongly limited by the seeing influence of the athosphere. This is certainly better on moutains and lousy in my location in Northern Germany.

The argument that RC are used by NASA and all other professional astrophotgraphers is simply the easy construction of RCs for space conditions. Also the seeing is perfect in space with no athmospheric artifacts.

Again, I think from my experiences, a newtonian is better (for my) galaxy astrofotographies.

CS Peter