54 replies to this topic

[dspace1]

First telescope was 4.5" tabletop dob.

 

Upgrading: after much research I was on my way to put a new Apertura 8in dobsonian in the cart to checkout, when a reliable connection sent me a club member's classified for a used AT125EDL, which reads:

 

"AT125EDL I bought this new from Astronomics 2 years ago. Lightly used. Includes everything stock …. Vixen bar, carrying handle, original shipping boxes. In VG shape. The optics are very nice. Focuser is nice and smooth. Has some cosmetic marks on objective lens cap. Also, a few cosmetic dings around focuser body. Because of this I have reduced the price. Also, included is a nice soft carrying case, which I bought separately. Asking $900." A new AT125EDL is price right now at $1,949.00 on Astonomics. 54% discount, with cosmetic dings. 

 

Now, with a ~2,500 budget (which includes a couple premium eyepieces), I had almost pulled the trigger on a new Astro Tech AT115EDT a few weeks ago, but landed on the dob for the traditional reasons, figuring why spend that much if I don't have to. My research says the great doublet in question has minimal-to-no noticeable CA visually, 95% comparable to that found in the triplet.

 

Granted, this person lives several states away and this would have to be delivered. There's no reasonable way for me to try the scope in person. BUT the middle man between me and them is very reliable, and many of you have read this person's long-time blog and watched their YouTube videos. Not that that ensures anything, but it does add some credibility imo.  

 

My priorities have been portability and versatility in what can be seen. Live in Bortle 6 skies with relatively easy access to Bortles 3-5. 

 

If you were me?

Edited by dspace1, 17 May 2025 - 06:14 PM.

[ShaulaB]

No mention of a mount and tripod. That would add another > $1000 to the mix.

[GolgafrinchanB]

The 8" dob still wins in my book. The frac is a great price for a great scope, but you still have to mount it and I think the dead is heavier but I'm not sure. There's a reason Ed Ting recommends an 8" dob at every budget level that can afford it (in addition to other stuff). It's easy, a bit but but not enormous, and a proper workhorse of a scope.

[Martinbruce]

Aperture usually wins but I would go with the AT125 EDL. I have a 8” SCT and a StellaMira 125ED and it is a toss up which I enjoy the most.  There are a lot of mounts that would work with the 125. The views are incredible. Good luck with this one. Actually, you can’t go wrong here. 

[lwbehney]

Depends upon what you want to look at. The refractor will serve you well in a Bortle 6 sky, especially if your local atmospheric seeing is mediocre, because the refractor will be less sensitive to atmospheric seeing effects compared to the Dob. The Dob aperture would win on globular star clusters and PN's. You will enjoy using an electric mount with your refractor, which is another plus for the EDL. Buy a used mount for your refractor and save. 

[Astro-Master]

I'd go with the AT 125 EDL it sounds like a great deal, you can always pick up a good used Dob. at a later date.  If you need a mount for the 125 EDL the Celestron AVX go to mount should work fine for visual observing'

[Jay_Reynolds_Freeman]

I suggest that aperture wins: It will be difficult for a 125 mm telescope of any design and quality to beat a decent 8-inch Dobson for any kind of astronomical observation, the sole common exception being for very wide-field views at low magnification. Furthermore, by the time you have gotten a decent mount for the AT 125 EDL it will be just about as bulky as an 8-inch f/6 Dobson, and probably more expensive, and note also that an 8-inch f/6 is likely easily car-portable in most vehicles.

 

For the record, I have owned and used both an 8-inch f/5 Dobson and a variety of high-end refractors with apertures from four to six inches, and if I myself had to choose just one telescope from just that lot it would be the eight-inch Dobson.

 

 

Clear sky.

[Ken Sturrock]

Eh. This forum has always been nicknamed the "Get a Dob Forum" for a reason. Quality refractors are nice. You'll enjoy it. As mentioned, you'll need a stable mount. If you still get the hankerin' for a big Dobsonian in the future, you can always do that too.

[SoCalPaul]

Although the AT125EDL is a very good bargain, I second what others have said above, that the 8" Dob is likely to provide more nights of enjoyable observing than the refractor.

 

If you are relatively new to the hobby, I would think you want the most versatile scope you can get, and one that will show you the most objects with the most detail.

 

Don't get me wrong, I enjoy the contrasty, sharp views I get from my refractors (you can see them in my sig line below). But I find them to be an acquired taste.

 

During my first few years in the hobby, I graduated up to a 13" Dob. I still remember my excitement, delight and joy when I first saw the spiral arms of M51.

 

Sure, there is a sense of accomplishment at detecting a dim galaxy in my FS128, but most are at best a dim blob.

 

If I want to see any details- shape, size, dust lanes, spiral arms- aperture wins.

 

Aperture also wins on planetary details, if the optics are decent and well-collimated. My C11 way outperformed my FS128 on Jupiter earlier this year. Granted, that's more aperture than the 8" Dob under consideration, but it too is almost certain to outperform the AT on planets.

 

Clear skies,

Paul

[siriusandthepup]

That's a great deal on the AT125EDL. Can you travel to pick it up?

 

Shipping is expensive.

 

If you can go get it, then - Good!

 

Can't travel to pick up? Then get the 8" Dob. That wins the ease of use/transport contest anyway and can beat the 5" most of the time.

 

[Tony Flanders]

For me it would be a no-brainer. Refractors are cute in their way, but they have many annoying features, including terrible ergonomics and proclivity to dew. Refractors are prima donnas; they demand that you conform to them. Dobs, by contrast, are nice, comfortable, friendly, easy-to-use telescopes. And as an added bonus, they're relatively cheap.

From a strictly optical standpoint, a 5-inch APO has a few minor benefits compared to an 8-inch Dob, the most important by far being the ultrawide, well-corrected true field of view. And on nights of mediocre seeing, a 5-inch APO may give a slightly less bad view of the planets than a 8-inch Dob. But in all other ways the Dob is far superior; it can show much fainter objects, and in significantly greater detail. Try browsing the Virgo Cluster and you'd see exactly what I mean.

 

But for me it's the ergonomics that's the biggest deal. Refractors have long tubes with eyepieces at the bottom. That means they require big, heavy mounts, especially in longer focal lengths. The first principle of stability is keep everything as close as possible to the ground, and refractors violate it from the get-go. When you double a tripod's height you need to at least quadruple its weight to achieve comparable stability.

 

Worse, refractors maximize the problem of varying eyepiece height. With a refractor, your head is over the eyepiece when the eyepiece is highest -- namely when pointing to the horizon. And your head is below the eyepiece when the eyepiece is lowest -- when the scope points to the zenith. So your end up groveling on the ground when viewing the zenith and standing on tip-toes to view the horizon. With a standard 8-inch f/6 Dob, you can view in comfort all the way from horizon to zenith just adjusting the seat on your adjustable-height chair a foot or so up and down. That's because with a Dob your head is above the eyepiece when the eyepiece is at its lowest and below the eyepiece when the eyepiece is highest.

 

Also, solid-tube Dobs are very nearly impervious to dew, which is a very big deal in my part of the world.

Edited by Tony Flanders, 18 May 2025 - 06:48 AM.

[WillR]

First telescope was 4.5" tabletop dob.

 

Upgrading: after much research I was on my way to put a new Apertura 8in dobsonian in the cart to checkout, when a reliable connection sent me a club member's classified for a used AT125EDL, which reads:

 

"AT125EDL I bought this new from Astronomics 2 years ago. Lightly used. Includes everything stock …. Vixen bar, carrying handle, original shipping boxes. In VG shape. The optics are very nice. Focuser is nice and smooth. Has some cosmetic marks on objective lens cap. Also, a few cosmetic dings around focuser body. Because of this I have reduced the price. Also, included is a nice soft carrying case, which I bought separately. Asking $900." A new AT125EDL is price right now at $1,949.00 on Astonomics. 54% discount, with cosmetic dings. 

 

Now, with a ~2,500 budget (which includes a couple premium eyepieces), I had almost pulled the trigger on a new Astro Tech AT115EDT a few weeks ago, but landed on the dob for the traditional reasons, figuring why spend that much if I don't have to. My research says the great doublet in question has minimal-to-no noticeable CA visually, 95% comparable to that found in the triplet.

 

Granted, this person lives several states away and this would have to be delivered. There's no reasonable way for me to try the scope in person. BUT the middle man between me and them is very reliable, and many of you have read this person's long-time blog and watched their YouTube videos. Not that that ensures anything, but it does add some credibility imo.  

 

My priorities have been portability and versatility in what can be seen. Live in Bortle 6 skies with relatively easy access to Bortles 3-5. 

 

If you were me?

Be aware that the refractor is not really going to go much deeper than the 4.5” you now have, despite what the refractor people may say.  Sharper, yes. More pleasing, sure. But the 8” dob, or better yet, a 10” dob will go much deeper.

 

And as was pointed out, does this come with a mount and tripod? It doesn’t sound like it, and it doesn’t sound like you have one. This will double the price.

[dmgriff]

First telescope was 4.5" tabletop dob.

 

Upgrading: after much research I was on my way to put a new Apertura 8in dobsonian in the cart to checkout, when a reliable connection sent me a club member's classified for a used AT125EDL, which reads:

 

"AT125EDL I bought this new from Astronomics 2 years ago. Lightly used. Includes everything stock …. Vixen bar, carrying handle, original shipping boxes. In VG shape. The optics are very nice. Focuser is nice and smooth. Has some cosmetic marks on objective lens cap. Also, a few cosmetic dings around focuser body. Because of this I have reduced the price. Also, included is a nice soft carrying case, which I bought separately. Asking $900." A new AT125EDL is price right now at $1,949.00 on Astonomics. 54% discount, with cosmetic dings. 

 

Now, with a ~2,500 budget (which includes a couple premium eyepieces), I had almost pulled the trigger on a new Astro Tech AT115EDT a few weeks ago, but landed on the dob for the traditional reasons, figuring why spend that much if I don't have to. My research says the great doublet in question has minimal-to-no noticeable CA visually, 95% comparable to that found in the triplet.

 

Granted, this person lives several states away and this would have to be delivered. There's no reasonable way for me to try the scope in person. BUT the middle man between me and them is very reliable, and many of you have read this person's long-time blog and watched their YouTube videos. Not that that ensures anything, but it does add some credibility imo.  

 

My priorities have been portability and versatility in what can be seen. Live in Bortle 6 skies with relatively easy access to Bortles 3-5. 

 

If you were me?

With a budgt of ~2500usd

 

The 125EDT is 900usd. A  Stellarvue M002c alt/az mount with column is 520usd, a surveyors tripod is ~100usd. Total 1520usd

 

A ES FirstLight 8in dob is 500usd at Woodland Hills, 600usd elsewhere

Package includes 2.5in Hexafoc rack and pinion, Telrad type finder (No red dot), 2 finder shoes.

https://telescopes.n...RgaAux1EALw_wcB

 

You could buy both

Edited by dmgriff, 18 May 2025 - 10:02 AM.

[Jon Isaacs]

From a strictly optical standpoint, a 5-inch APO has a few minor benefits compared to an 8-inch Dob, the most important by far being the ultrawide, well-corrected true field of view.

 

 

Tony:  

 

This 125mm F/7.8 has a 975 mm focal length.  That means the widest possible field of view is 2.7 degrees.  The widest possible field of view with an 8 inch F/6 Dob with it's 1200mm focal length is 2.2 degree... Not so different.

 

I saw the AT-125 EDL when it was first posted.  I considered it, it was quite a deal and I have a mount, diagonal and eyepieces so I wouldn't need to spend anything more to get it up and running.  But I have had two Orion 120mm F/7.5 ED/apos in the past several years, great scopes but they were in no-mans land.  Not as handy as a 4 inch apo while being significantly less capable than my trusty 10 inch Dob.  

 

I looked in the Classifieds for this scope but the ad seems to be gone so I think someone bought it.  Maybe the Original Poster, maybe someone else.  

 

Opening a CN thread on a potential purchase, particularly when it is dynamite deal, it very risky..  By the time you decide, it is likely to be gone.  It is better to contact someone you trust and ask them. 

 

Jon

Edited by Jon Isaacs, 18 May 2025 - 10:00 AM.

[arg0s]

My priorities have been portability and versatility in what can be seen. Live in Bortle 6 skies with relatively easy access to Bortles 3-5. 

 

If you were me?

 

I really hate to be the guy to make your dichotomy a trichotomy, but a solid tube Dob/Frac don't even hold a candle to a Cassegrain in the portability department in the apertures we're talking about. I know, I know, not an option you brought up, but I was surprised to hear you say portability was a priority at the end of a post regarding a 8" F/8 F/6 Dob vs a 5" F/8 Frac, and just want to make sure you know they're an option.

Edited by arg0s, 18 May 2025 - 05:41 PM.

[rjacks]

A 5 inch refractor is a lot bigger, bulkier, and heavier in person than it appears in a photo. It needs a high-quality heavy-duty mount, or vibration will be an issue. A 5 inch refractor is by no means grab and go. If it were me, I'd go with the 8 inch dob and spend some of the savings on a pifinder for navigation.  

[grace]

Be aware that the refractor is not really going to go much deeper than the 4.5” you now have, despite what the refractor people may say. Sharper, yes. More pleasing, sure.

+1, I don’t see 4.5” to 5” as an upgrade really, especially if it’s supposed to be your main scope…

[vintageair]

I'm a newbie too so I'll speak from my perspective of limited experience. I was in the same boat a little over a month ago except I did click that mouse button and had an Apertura AD10 delivered. First of all I'll say that going for the 10 inch has it's pros and cons, it is pretty big and I do wonder if getting an 8 inch might have been a better choice but that's just advice for others now as I'm committed and there's no turning back.

 

Anyway, from the replies I've read I think the biggest issue is going to be the mount. Even with the ultra low center of gravity of my Dobsonian I can see how any tiny disturbance translates into a wild gyration through the eyepiece and this can be caused by even a moderate breeze. With a Dob while sitting in an observer's chair you can actually hug the tube and hold it steady with your entire body and it's quite comfortable. That's the other thing I have learned, comfort while viewing is an important aspect of this new hobby.

[vtornado]

I like refractors in the winter because of their rapid cool down.  (I live in the upper midwest)    I had a 120mm ED refractor and it was a beautiful scope, but ...  a lowly synta 8 inch dob was better at just about every target.  The 120 was a $1000 scope used, and required a fairly beefy mount.  (I used a sky tee with a 2 inch tripod).  The tripod/mount to hold it requires a second trip, so it is just as much trouble to set up as the dob.   So the refractor got sold due to price/performance.     Most of the time I can set the dob out to cool in the winter.  Sometimes because of a busy day I can't.  Cool down issues with the dob can be mitigated if you can store it outside.  I can't.

Edited by vtornado, 19 May 2025 - 10:42 AM.

[WillR]

I really hate to be the guy to make your dichotomy a trichotomy, but a solid tube Dob/Frac don't even hold a candle to a Cassegrain in the portability department in the apertures we're talking about. I know, I know, not an option you brought up, but I was surprised to hear you say portability was a priority at the end of a post regarding a 8" F/8 Dob vs a 5" F/8 Frac, and just want to make sure you know they're an option.

I don’t know if an 8” SC is that much more portable than an 8” dob. It still travels in two parts? I say this not having owned one.

 

And the SC  will have a longer cool down time? A consideration when traveling to a dark site.

[Jay_Reynolds_Freeman]

I don’t know if an 8” SC is that much more portable than an 8” dob. It still travels in two parts? I say this not having owned one.

Truth is in the details here: With a mounting that folds up fairly compactly (telescoping legs, et cetera) an 8-inch Schmidt-Cassegrain will be a bit more portable than an 8-inch f/6 Dobson that uses a solid tube, mostly because the pieces of the Schmidt-Cassegrain will all be a bit smaller than the long tube of the Dobson. The Schmidt-Cassegrain will take more time to set up and take down, however -- which may be a portability consideration for some -- and will cost more than the Dobson.

 

Clear sky ...
 

[Herodotus]

8" DOB...... my choice

[arg0s]

Whoops, the AD8 is actually F/6, not F/8. I don't know how I misremembered that.

 

I don’t know if an 8” SC is that much more portable than an 8” dob. It still travels in two parts? I say this not having owned one.

 

And the SC  will have a longer cool down time? A consideration when traveling to a dark site.

Portability as in "it physically fits in a vehicle", the AD8 can do that fine, it easily fits the width of my sedan. Portability as in "I can fly with it", I think people have flown with 8" SC's, though I would never do that with either. Portability as in ease of handling or lugging, yes, I think Cassegrain's have a considerable edge.

Comparing the AD8 to the something like the Nexstar 8, that's a 50lb vs 30lb setup, and you could even call that 50lbs vs 35lbs to save room for a better mount than the Nexstar, but all the same, 15lbs is nothing to scoff at. An SCT is less than half the length of an AD8, which makes stairs, walking around corners, having a free hand to open doors, using less space in your vehicle, etc, all substantially easier. I suppose it would be easier to move around with it already mounted, but I wouldn't take it for granted that you could or would want to.

 

Of course, Dobs that are trussable are a whole different animal, and they can win the portability/weight edge back at the cost of other truss related downsides.

 

Cooldown is always a concern at 8 inches, but yes, a Schmidt cooldown would be longer. Some people swear by Reflectix, but I've never used it. I'd be a bad person to ask about that specifically, as going to a dark site when its cold enough to have serious cooldown problems sounds dreadful; my winter observations are in my backyard where I have all the time I need for cooldown. If that's something you want to do, or if you live somewhere super humid, you might be served better by a classical instead of a Schmidt if you want a Cassegrain.

Edited by arg0s, 18 May 2025 - 06:59 PM.

[Oldfracguy]

First of all, welcome to Cloudy Night  .

 

I've had a couple of these AT125EDL scopes, and they will outperform an off-the-shelf AD8 on everything except star clusters and faint DSO targets.  That extra aperture will bring in more stars, especially on globular clusters.  It will also outperform the AT125EDL on faint galaxies and other DSO targets such as planetary nebulae as well as some spread-out nebulae like the Veil and North American.  Here is a picture of an AT125EDL on a mount that 1) has the payload capacity to handle a 17.5 lb. OTA outfitted with a diagonal, finder scope and eyepiece; and 2) can get it high enough off the ground so you can sit in a chair to observe with the scope aimed high up near the Zenith:

 

 

 

I like to say that AT125EDL just gets out of 3rd Gear at 300x magnification.  The scope excels at views of the planets, the lunar surface and double stars.  In these categories it will outperform an AD8.  Using a good Prism Diagonal, you will see no trace of color fringing (CA, or Chromatic Aberration), even on Sirius at 300x.  The AT125EDL is no slouch on DSO targets, either.  I've had great views of Omega Centauri when it gets about 10° above the Southern Horizon from one of the dark sky sits I visit a few times a year, as well as many other open clusters and globulars that get drowned out in my light-polluted backyard. 

Edited by Oldfracguy, 18 May 2025 - 09:33 PM.

[maniack]

Comparing the AD8 to the something like the Nexstar 8, that's a 50lb vs 30lb setup, and you could even call that 50lbs vs 35lbs to save room for a better mount than the Nexstar, but all the same, 15lbs is nothing to scoff at. An SCT is less than half the length of an AD8, which makes stairs, walking around corners, having a free hand to open doors, using less space in your vehicle, etc, all substantially easier. I suppose it would be easier to move around with it already mounted, but I wouldn't take it for granted that you could or would want to.

Even the Evolution 8 is just over 40lbs, and gets you tracking and GoTo within that weight. Now the AD8 will give you wider field of view and probably slightly better on-axis performance, but the SCT is pretty much the king of portability.

 

I do find it strange to be discussing a 5" apo refractor in a beginners' forum. This is not really a beginner's telescope, as the nearly 3 ft length requires a pretty substantial mount for comfortable viewing.