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Is a 127mm refractor enough for DSOs?

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#1 Diomedes

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Posted 07 April 2020 - 07:19 AM

Hello, I’m not expecting the same views as with a  8” dob but I’m curious to learn what to expect. The AR127mm is about as much weight as my twilight AZ mount can handle so I can’t really go any higher. 


Edited by Diomedes, 07 April 2020 - 07:20 AM.

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#2 emilslomi

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Posted 07 April 2020 - 07:34 AM

Almost anything can be enough for DSOs. It completely depends on your expectations. I enjoy my 100 a lot for DSOs. The 140 shows more, but not that much more. I used my 50 and 80 for DSOs too, but since I have used the larger scopes, the smaller ones are not that appealing any more. The 50 is actually more or less retired, and the 80 is mainly for grab and go.

 

Sometimes I think a 125/127 would be the optimum.

 

Emil


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#3 russell23

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Posted 07 April 2020 - 07:39 AM

I only have 102mm and 120mm APO's and use them all the time for deep sky. There is always a larger aperture to show you more. I don't worry about that and just enjoy what I am using.
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#4 Diomedes

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Posted 07 April 2020 - 07:41 AM

I had a similar experience. My 70mm was amazing until I got my 102 and now the 70mm is retired.  I have a 8” dob but it’s a hassle to setup and I really like refractors.  With my 102 I got a very decent view of M35 but objects like the poor man’s double cluster were way to dim. I’m in a Bortle 9  so I have a ton of light pollution.


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#5 25585

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Posted 07 April 2020 - 08:05 AM

Depends on what you want to find & see - what types, how many & how much detail. 

 

Open clusters are great. Bright nebulae & globulars are too. Galaxies apart from M31 less so.

 

It also depends on your skies, not just locally, but globally year round. .


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#6 Jond105

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Posted 07 April 2020 - 08:06 AM

Depends. You have a 102. In my experience my old 120Ed you could tell was going deeper than my old 100ED, but in my sky it didn’t mean I gained more targets, but I did gain a few fainter stars in Pleiades or other open clusters. 


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#7 Destrehan Dave

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Posted 07 April 2020 - 08:14 AM

Hmmm.

It’s all about location, location and location.

I’ve owned a 127, 100, and 2 80mm refractors.

From my light polluted backyard, the 120 and 127 allowed me to detect and enjoy a few of the brighter DSO, but the 100 and 80s struggled even with M4.

All are wonderful on open clusters, but I’d highly recommend you inverst in a C8 or DOB if you are purchasing a scope to view DSOs.

YMMV, especially if you are in a much darker location than I’m in.

DD
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#8 SeaBee1

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Posted 07 April 2020 - 08:21 AM

In my opinion, LP is a refractor killer... in order to get enough aperture to make any difference at all, the cost goes up exponentially, and not just for the OTA... you will need to get a beefy/expensive mount to sling the beast around with any satisfaction. My wallet cringes every time I think about a larger refractor...

 

BUT... all that being said, a 120mm - 130mm refractor is a formidable instrument in light pollution and is considered by many as a sweet spot for refractors... if you pick the right targets and temper your expectations. I did upgrade from a Celestron 102mm to a SW120ED and I use my SW120 primarily for splitting doubles, moon viewing, planets, bright open clusters (the Pleiades is absolutely stunning in this scope using my ES 30mm 80°...). My Bortle number is like Bortle 40 or something... Galaxy, nebulae, dim clusters of any type... ain't gonna happen, not even with my 10 inch reflector.

 

Target selection... expectations... that will determine if a larger refractor is worth it... it was for me as I had already solved the target/expectation equation...

 

Good hunting!

 

CB


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#9 MrRoberts

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Posted 07 April 2020 - 08:31 AM

I have a C-8/E and both the Esprit 80 and 120. I find all 3 of these wonderful for different reasons. I am for the most part a visual person. I currently keep the C-8/E and 80 in S-AZ and the 120 here at home base in NE-IL  As a previous owner of a custom 15" dob I will say it won't see as much as your 10" dob (but not much less) of course, but you will be surprised at how well it see's.

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#10 ddegroot

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Posted 07 April 2020 - 08:36 AM

You probably know by now that these questions are impossible to answer because the answer is bound to be so subjective. Everything depends on what you mean by enough (for many of us, nothing is ever enough), what you mean by "DSOs" (different telescopes do better at different objects), what you mean by "a refractor" (there's a world of difference between an FS 128 and a Celestron Omni) the conditions where you live (how's average seeing, differences in temp, etc.), and more. 

With all that said: a five-inch refractor is a wonderful instrument that can rival the performance of higher aperture telescopes of other design on a wide selection of objects. It can keep most people happy for a very long time. 


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#11 MalVeauX

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Posted 07 April 2020 - 08:38 AM

Heya,

 

You can certainly see lots of things from a 127mm aperture under a dark sky. But, it's still a 127mm aperture. It will not do what a 8" or 10" or 12" or 14" or 16" aperture will do, in the same conditions. No magic behind being a refractor, aperture is aperture with respect to seeing DSO. But under a dark sky there are thousands of things to see with a mere 80mm aperture. So a 127mm aperture will go significantly deeper under that dark sky and again have thousands of subjects to go after. You will not see the arms of a spiral galaxy like you will in a 12" but you will at least see its fuzzy core and be able to say you found it and saw it and can check it off the list, for example at least.

 

Very best,


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#12 clearwaterdave

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Posted 07 April 2020 - 08:42 AM

I have pretty good skies and I can see a fair difference between a 102 and a 127.,not sure how it will go with higher lp.,

  But if you like refractors more and have a mount that will hold it.,Good luck.,be careful keeping them in the same room.,lol.,

 

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#13 junomike

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Posted 07 April 2020 - 08:43 AM

IMO one doesn't' choose an  OTA for DSO's, they choose the DSO's for a given OTA.

In other words a 5" Refractor is fine as long as you choose the ideal objects to view through it.

 

IMO a 5" F5 or F6 would be better as it will show more FOV, thus more available DSO's and be lighter and have less leverage (strain) on the mount as well.


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#14 Jason B

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Posted 07 April 2020 - 09:11 AM

I use my AT111 for deep sky observing all the time.  I just pick objects I know I can see, sometimes challenging myself to see stuff at the edge of my scope's limits more for "i did it" than trying to see any detail,etc. I do have larger scopes at my disposal but find myself returning to the 111 more than any of my scopes.


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#15 MarkGregory

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Posted 07 April 2020 - 09:33 AM

I use my AT111 for deep sky observing all the time.  I just pick objects I know I can see, sometimes challenging myself to see stuff at the edge of my scope's limits more for "i did it" than trying to see any detail,etc. I do have larger scopes at my disposal but find myself returning to the 111 more than any of my scopes.

CLOL. I also own an AT111. Love it, But I really only used it for the Moon.


Edited by MarkGregory, 07 April 2020 - 01:43 PM.


#16 bobhen

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Posted 07 April 2020 - 09:51 AM

A telescope like the AR-127 is optimized for different classes of deep sky objects than a larger telescope with greater light-gathering but a narrower field of view.

 

Generally…

 

Large clusters, large nebula, large dark nebula, multiple deep sky object in the same field etc. are what you want to concentrate on with a wide field refractor, and they are best used under a very dark sky.

 

Smaller objects like galaxies, globular clusters, planetary nebula and the like are best observed with larger scopes.

 

If you observe under heavy light pollution, the only answer is to add some technology like an astro-video camera or a night vision Image Intensifier. You will still see things without adding a camera or intensifier but depending on your conditions, the views will be compromised  accordingly.

 

Bob



#17 mikeDnight

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Posted 07 April 2020 - 10:24 AM

Hello, I’m not expecting the same views as with a  8” dob but I’m curious to learn what to expect. The AR127mm is about as much weight as my twilight AZ mount can handle so I can’t really go any higher. 

The first thing to understand is that the deeper you want to go, the greater the aperture you'll need. Having said that, a 127mm refractor can deliver impressive, contrasty, well defined and "bright" views of many of the better known DSO's. Just to give you confidence in the ability of a 127mm scope, I've attached three sketches made using a 100mm refractor. The trick lies in blocking out distracting local light sources by using a blackout blanket or your head and eyepiece, and really studying the object before moving on to the next. The attached sketches were made from the suburbs of a town in the north west of England.

 

646146244_2017-07-1819_16_53.jpg.f8ca41786a61849a88e814bb8df5c71b.jpg

1952923925_2017-07-1709_13_23.jpg.1b4937fa0f94c33a295227b0c22d5b77.jpg IMG_20160205_175527.JPG.8141fecf4ac4948e3e44ea9d7fe36d7a.JPG


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#18 Jon Isaacs

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Posted 07 April 2020 - 10:27 AM

I use refractors from a 50 mm F/4 To a 120 mm F/7.5 for viewing DSOs. They all have their place. They're best under dark skies alongside a large reflector. Companions.

 

According to ES, the AR-127 weighs 15.6 lbs, that doesn't seem right but anyway, my point is that a 5 inch refractor on a decent mount is about as much hassle/effort to setup as an 8 inch Dob but don't have the horsepower. 

 

Jon


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#19 janapier

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Posted 07 April 2020 - 10:29 AM

Well, I own an excellent US-made C8 /w StarBright, and I find it to perform about equally as well as my pretty good 6" Skywatcher Esprit ED Apo. Therefore, a 127 mm frac is bound to perform substantially worse than a 8" Dob on any object, assuming their optical quality is not too different. 



#20 LDW47

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Posted 07 April 2020 - 11:08 AM

Hmmm.

It’s all about location, location and location.

I’ve owned a 127, 100, and 2 80mm refractors.

From my light polluted backyard, the 120 and 127 allowed me to detect and enjoy a few of the brighter DSO, but the 100 and 80s struggled even with M4.

All are wonderful on open clusters, but I’d highly recommend you inverst in a C8 or DOB if you are purchasing a scope to view DSOs.

YMMV, especially if you are in a much darker location than I’m in.

DD

Read post 4 !  Clear Skizes !


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#21 Diomedes

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Posted 07 April 2020 - 11:34 AM

thank you all for sharing your thoughts!

I'm new to the hobby so I'm observing the Messier objects first. My favorite type of objects are open clusters like M45. The views in my 8" dob are great, it just comes down to preference. Over the last few months, I learned that I don't like the collimation process, and I find it several times easier to drag around the AZ mount and refractor over moving the dob. That being said I still plan on using my dobsonian to complement the refractor. My question was a bit vague. I asked if a 127mm would be enough, what I meant was what can I expect to see out of 127mm, and reading your responses have given me a good idea of what to expect, thank you !!


Edited by Diomedes, 07 April 2020 - 11:37 AM.


#22 Jond105

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Posted 07 April 2020 - 11:45 AM

thank you all for sharing your thoughts!

I'm new to the hobby so I'm observing the Messier objects first. My favorite type of objects are open clusters like M45. The views in my 8" dob are great, it just comes down to preference. Over the last few months, I learned that I don't like the collimation process, and I find it several times easier to drag around the AZ mount and refractor over moving the dob. That being said I still plan on using my dobsonian to complement the refractor. My question was a bit vague. I asked if a 127mm would be enough, what I meant was what can I expect to see out of 127mm, and reading your responses have given me a good idea of what to expect, thank you !!

You have the same skies as me. I live in a Bortles 9 zone here in metro Detroit myself. I’ve had the dobs and refractors. The dobs give you a shot of seeing something. The refractors are nice and easy to use.  We will never see what most here can at their dark sites, but it’s still fun. I think a 127mm you’ll enjoy over a 102mm, if you’ve got the mount. 



#23 Diomedes

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Posted 07 April 2020 - 11:49 AM

Yeah, at first I thought I would not be able to do any astronomy from Home but it's doable. Is better when I get to drive to darker areas but due to life that's not a every week kinda thing. I have the following mount https://explorescien...wilight-1-mount which can hold up to 18pounds. The AR127mm is about 15.6 which is close to the limit but should still work I think. 

 

 

You have the same skies as me. I live in a Bortles 9 zone here in metro Detroit myself. I’ve had the dobs and refractors. The dobs give you a shot of seeing something. The refractors are nice and easy to use.  We will never see what most here can at their dark sites, but it’s still fun. I think a 127mm you’ll enjoy over a 102mm, if you’ve got the mount. 



#24 Jason B

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Posted 07 April 2020 - 11:50 AM

CLOL. I also own an AT111. Love it, But I really only used it for the Moon. If it’s not too much bother, can you tell me some of the DSO’s you view with your AT111? Thanks, Mark

I really like planetary nebula and clusters (globs and open). Some planetaries are challenges for the little 111 but I enjoy the challenge and really like my scope. I have been going through the Astro-League books for globular clusters and planetary nebula.  Very few have been invisible so far but a few have been challenges to say the least. Nice thing about my observatory set up is that I have much larger scopes if need be but the 111 is still the most used (both visually and photographically).

 

It provides great views of the planets too.


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#25 Jond105

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Posted 07 April 2020 - 11:58 AM

Yeah, at first I thought I would not be able to do any astronomy from Home but it's doable. Is better when I get to drive to darker areas but due to life that's not a every week kinda thing. I have the following mount https://explorescien...wilight-1-mount which can hold up to 18pounds. The AR127mm is about 15.6 which is close to the limit but should still work I think. 

I wouldn’t do it myself, but I guess it doesn’t hurt to try. Once you add your eyepieces you’re adding a few more ounces. It’s got the big dew shield and more of a momentum arm. Over 800mm focal length on that mount. May be ok at super low power only. Still may be rough. Just my 2 cents. 




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