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5" Refractors

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#1 JimP

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Posted 19 August 2014 - 05:25 PM

There seems to be a real following of folks here who use 5" refractors (120-140mm). Why 5"?  Is it that a 6" costs so very much more for that one inch gain in aperture? If you use a 5" can you tell us why?



#2 SteveG

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Posted 19 August 2014 - 05:33 PM

Price point vs performance.

 

You just start to get really good planetary views at 120mm.

ED versions can be had for as little as $1000. The jump to a 6" ED means $4000.

They are manageable (mine rides on a GP).

The doublets cool quickly.

 

It is never enough though. I want a 6" ED real bad!


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#3 russell23

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Posted 19 August 2014 - 05:37 PM

5" is still small enough to be reasonable to mount but large enough to be interesting for both deep sky and lunar/planetary.   I find the 140mm f/5.7 is a perfect combination of aperture, portability, and widefield views.  

 

Dave



#4 moonnerd

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Posted 19 August 2014 - 07:13 PM

I have my 5" on a GM8 mount which I love, and which I can carry around the yard easily.  But to go to a 6" would require me to invest in a less portable mount.  So thats the deciding factor for me. 


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#5 Norm Meyer

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Posted 19 August 2014 - 07:19 PM

I have a 5" f12 D&G. I ordered the lens before I retired. I chose the 5"over the 6" mostly due to size/weight of the finisihed OTA.

The cost difference wasn't that great around $200 for the lens.

It is cumbersome to carry outside and set it up. I wouldn't be able to handle a 6". I have an observatory but already have a 7"Mak in that

and really don't want to change and put the 5" in there.Since I moved to my present location 20 years ago the sky is not nearly as dark as it was

so most of my observing is solar system objects and the Mak and the D&G work out fine.

 

Regards Norm



#6 stevew

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Posted 19 August 2014 - 08:21 PM

As reported before, a 5 inch is easier to mount than a 6 inch, and shows a considerable amount more planetary details than a 4 inch.

The 5 inch also gets you into sub arc second resolution.

 

Steve



#7 stevew

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Posted 19 August 2014 - 08:25 PM

There seems to be a real following of folks here who use 5" refractors (120-140mm). Why 5"?  Is it that a 6" costs so very much more for that one inch gain in aperture? If you use a 5" can you tell us why?

By the way, a 120mm is a 4.7 inch not a 5 inch.

Close but not quite 5 inches.



#8 DeanS

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Posted 19 August 2014 - 08:38 PM

That is why I got the TEC140, couldn't decide :)

 

Dean

 

Jim, you probably have had every refractor made at some point, including my TOA-150.  So what are your favorites in this size range?


Edited by DeanS, 19 August 2014 - 08:41 PM.

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#9 waso29

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Posted 19 August 2014 - 08:51 PM

The arrival of the more affordable chinese ed120 doublets and ed127 triplets definitely helped.

 

Hoping the economies of scale for the 6in ed/apo come soon!



#10 SteveC

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Posted 19 August 2014 - 10:18 PM

I decided to go with the TEC140 several years ago for many reasons - size, weight, aperture, reputation, sharpness/contrast, and bang for the buck. BillP has  a Lunt 152, which he raves about, and it seems to be the the new heir apparent for bang for the buck. I'd go for the upgraded Feathertouch focuser if you go the Lunt direction.

 

What can i say about the TEC140, aside from the fact that it has been a wonderful mix of many features for many years and I've enjoyed it thoroughly. 



#11 starcanoe

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Posted 19 August 2014 - 10:31 PM

Just getting into the refractor game myself.

 

But I'll note this. I have some Surplus Shed Jaegers lenses.

 

The four incher looks cute but respectable.

 

The five incher looks fair sized.

 

The six inch just looks (and feels) downright massive.

 

I'd probably get the vapors looking at an 8 inch lens set.



#12 Scott in NC

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Posted 19 August 2014 - 10:36 PM

:funny:



#13 tomjones

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Posted 19 August 2014 - 10:41 PM

Retired, poor, fixed income?  I love my Surplus Shed 5" f/9.4, it will take 280x on the planets, 300x is fuzzieness power.

 

Not too long, lite weight for us old weaklings at 12 lbs.  Yes you need a tall mount still if you don't want to be crawling in the grass,

 

but you can use your tripod legs extended all the way with a, short column.  And cheap at about $350 if you build it. 

 

A little over $100 more if you let some Chinese guy build it.  Astro-zap and Bressler have them new sometimes.



#14 samovu

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Posted 20 August 2014 - 12:35 AM

There seems to be a real following of folks here who use 5" refractors (120-140mm). Why 5"?  Is it that a 6" costs so very much more for that one inch gain in aperture? If you use a 5" can you tell us why?

 

Jim, are you looking to acquire a 5" or just wondering why some of us ended up getting one? I'd imagine that there are almost as many reasons as there are owners. 

 

I started with a 4" and then wanted something larger but not too large so I got a 5". And then I had to have a 6" and haven't decided whether to keep the 5" or not. The 6" requires a heavier mount than does the 5 but both take about the same amount of time to drag out and set up. 

 

Also, since I almost exclusively buy used, when it decide to sell I will not lose much if anything. Sort of like free rent if you will. Of course, if I trip gong down some stairs and the OTA hits the ground before (or after) I do, there goes the investment. 



#15 aa6ww

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Posted 20 August 2014 - 02:24 AM

You probably have to own a 4" a 5" and a 6" to know which one works best over all with you because you always want more, till you have what you think you want, then realize its more than you really should have bought.

You'll know your refractor is really too big overall, when you start thinking about owning a second smaller lighter one and the larger one starts spending more time in doors than out.

...Ralph
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#16 RTLR 12

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Posted 20 August 2014 - 04:41 AM

I really like my 5" scope. It was the next step up from my 4" scopes that I really enjoy using. I can manage the weight easily. I can use it on my smaller lighter CG-5 mounts, and the 5" was at the limit of how much money I wanted to spend on a scope. A 6" is way to expensive for me. Requires the use of a larger mount, which means I probably won't be using it as much as I would be using the 5"er and a 6" it is just a lot more scope for this 65 year old to muscle around. Light, portable and affordable. That's what a 5" scope is.

 

Stan



#17 t.r.

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Posted 20 August 2014 - 06:41 AM

5" Refractors?....Simple, the "Goldilocks" refractor...not too big, not too small, not too expensive, not too cheap, not too much resolution, not too little resolution...They are juuuust right! ;)


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#18 Illinois

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Posted 20 August 2014 - 07:19 AM

I Used 80 then 100 and now 127. I love my 5 inch refractor however I would like to get 6 inch f8 ED but cost lot of money so I am happy with my 5 inch plus two great eyepieces for great view! ES 24 82 degree for 40X and ES 5.5 100 degree for 174X. If I need little more power to look at Mars and details in Saturn's rings then I use ES 8.8 82 degree with 2X barlow for about 217X.

 

Of course I always want larger refractor but for now 5 inch is just right for everything..... that's what t.r. said!



#19 beanerds

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Posted 20 August 2014 - 08:24 AM

iStar make awesome 5inch lens's.

Here is mine. I have this 5 inch frak as well a 'Chromocor;d' Synta 150mm f8 that performs excellent'ly but as said here a true 5 incher like my true 127mm iStar f8 achromat is very close in performance , yes a 5 inch refractor really hits the spot in my books .
Google iStar , see whats available .

Brian. .

Just getting into the refractor game myself.
 
But I'll note this. I have some Surplus Shed Jaegers lenses.
 
The four incher looks cute but respectable.
 
The five incher looks fair sized.
 
The six inch just looks (and feels) downright massive.
 
I'd probably get the vapors looking at an 8 inch lens set.

Attached Files


Edited by beanerds, 20 August 2014 - 08:29 AM.


#20 JimP

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Posted 20 August 2014 - 09:18 AM

Thanks guys I really appreciate your thoughts. Just fyi I chose 120-140 because the Tak TSA 120 I owned was awesome and for me performed more like a 5" than a 4" scope. Just me. Those with a 140 might want their scope in the 6" category...

 

After almost 49 years of observing (first scope in September 1965) I have ended up with big  big refractors mounted in observatories which are wonderful but I am looking for something smaller, a refractor, either an ED or preferably an  apo for visual observations only that is easy to set up and take down. I am now semi-retired and I cannot just buy anything I want. While I might prefer a 6" I would have to be Very careful about the weight. Many years ago I owned an AP 155 with 2.7" focuser and the weight was good. I sold it and later got another, this time with the 4" focuser and I did not like the increase in weight. I am not certain what those scopes weighed but I am thinking 23-25 pounds or so. I would have to check on those weights before I went out for example and bought an Esprit 150 which weights 32 pounds. Yes, at 63 and having had disc surgery, I am a wimp when it comes to lifting. As I recall a TOA 150 weights a ton. I have bought and sold many telescopes over the years. My favorite 5" scope was an AP 130 F/8 EDT. 

For me, in my life right now, a 6" apo (I think an AP 155 goes for $11-12K these days) is either too heavy or too expensive or both. My experience has been that a 5" is a big step up from a 4" and a 5" might be what I am looking for. Visual observations only, with an emphasis on doubles, and after that  lunar and planetary. Lightweight and affordable..



#21 Jon_Doh

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Posted 20 August 2014 - 09:22 AM

Six inch refractors tend to be big and require big, heavy mounts like the Equatorial variety.  I had one and loved the views, but really wasn't into laying on my back at times to view objects near zenith.  The 120 APO I now have is much smaller and lighter and easier to handle.  Plus it mounts on an AZ mount which keeps me off the ground   :) (which given my damaged joints - knees, shoulder- from playing football is a big plus)


Edited by Jon_Doh, 20 August 2014 - 09:23 AM.


#22 Paul G

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Posted 20 August 2014 - 09:36 AM

Thanks guys I really appreciate your thoughts. Just fyi I chose 120-140 because the Tak TSA 120 I owned was awesome and for me performed more like a 5" than a 4" scope. Just me. Those with a 140 might want their scope in the 6" category...

 

After almost 49 years of observing (first scope in September 1965) I have ended up with big  big refractors mounted in observatories which are wonderful but I am looking for something smaller, a refractor, either an ED or preferably an  apo for visual observations only that is easy to set up and take down. I am now semi-retired and I cannot just buy anything I want. While I might prefer a 6" I would have to be Very careful about the weight. Many years ago I owned an AP 155 with 2.7" focuser and the weight was good. I sold it and later got another, this time with the 4" focuser and I did not like the increase in weight. I am not certain what those scopes weighed but I am thinking 23-25 pounds or so. I would have to check on those weights before I went out for example and bought an Esprit 150 which weights 32 pounds. Yes, at 63 and having had disc surgery, I am a wimp when it comes to lifting. As I recall a TOA 150 weights a ton. I have bought and sold many telescopes over the years. My favorite 5" scope was an AP 130 F/8 EDT. 

For me, in my life right now, a 6" apo (I think an AP 155 goes for $11-12K these days) is either too heavy or too expensive or both. My experience has been that a 5" is a big step up from a 4" and a 5" might be what I am looking for. Visual observations only, with an emphasis on doubles, and after that  lunar and planetary. Lightweight and affordable..

 

The AP 155 EDFS weighs 23 pounds, a little less than a TOA 130. The 4" focuser bumps the 155 up to 27 pounds.



#23 Jared

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Posted 20 August 2014 - 09:38 AM

Over the years I have had a 60mm refractor, four different 80mm refractors, a 102mm, a 127mm, a pair of 130mm's, and a 152mm.  All were either ED doublets or triplets, so focal ratios varied between f/6 and f/9--nothing really long.  I have now settled on a 130mm as the "perfect" size.  It's really just the compromise of portability vs. quality of view.  The views--especially the planetary views--are noticeably better in a 5" than in a 4", but my scope can still be carried on a fairly small mount.  

 

I had a lovely 6" scope for a couple years, and there is no question it showed more than the 5".  But the cooling time was significantly longer--often over an hour--before the views became good, and there was enough extra equipment required, including counter weights and pier extensions, that I would often leave it behind.  When I found myself wondering whether the weather was good enough to justify bringing out the beast, I decided the scope was just too large and "downgraded" to a 5".

 

One other factor to consider is price/performance.  Beyond 140mm's the cost per inch of aperture for a good quality refractor really starts to grow.  Heck, you could argue that 120mm is really where things start to get a bit silly, let alone 130mm or 140mm.

 

By the way, I still have an 80mm and a 60mm that each get occasional use.  There are times when even the 130 is too much.

 

- Jared



#24 Scott99

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Posted 20 August 2014 - 10:30 AM

I use an early 90's AP Star 12ED and love it, 120-130mm is a great size range.  Very small and portable, enough aperture to do some damage.   Recently I set up the Star 12 under some dark skies and roamed the Virgo galaxy cluster with a 16mm wide-field.  The FOV was full of galaxies, big ones with lots of detail visible, many smaller ones of different shapes and sizes.

 

I've had a 6-inch refractor for many years, but my own arthritis is often too bad to lift it & use it.  I started using an 80mm refractor for a 2nd scope, then I owned a series of 4-inch apos, then a Traveler, finally I migrated to the Star 12 ED.  At only 11-12 pounds it's just as easy to transport as a 4-inch.  I've thought of upgrading further to an AP130 or TEC140, but then the scope and mount would be bigger & heavier, might as well use the 6-inch.

 

Totally agree about the 4-inch focusers, I migrated from an old AP 6-inch F8, with the irrigation tubing and lightweight imported focuser, to the AP160, the weight difference was dramatic.  I think the old 6-inch was only around 20 pounds, I think the 160 is 28.  I suppose an older 155 f/7 or TEC's 160FL f/7 would be more practical for me, but the AP160 is such a unique scope I don't want to let it go.

 

TSA120 would be a great 2nd scope, great lens and nice mid-range f/ratio, you won't need to barlow up.


Edited by Scott99, 20 August 2014 - 10:33 AM.

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#25 aa6ww

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Posted 20 August 2014 - 12:55 PM

Dont forget the Lunt 152ED. Its a beautiful big refractor and light weight also!

 

...Ralph

 

 

There seems to be a real following of folks here who use 5" refractors (120-140mm). Why 5"?  Is it that a 6" costs so very much more for that one inch gain in aperture? If you use a 5" can you tell us why?








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