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Perhaps a 120 is the sweet spot

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#1 Trevor N

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Posted 25 January 2021 - 04:09 PM

I've noticed that many here have several refractors and I'm lucky enough to own SW 120 and 150 models. I've always thought the 120 takes some beating and to be honest the detail I manage in images on good nights is very similar to the larger scope. I think seeing really is the key but the differences are very small. Given the lighter requirements for a mount and the ease of moving the scope around the 120 might just tip the balance. I'm convinced buying scopes is very much a law of diminishing returns. What do others think?

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  • Tycho-Clavius-c--x3-barlow.jpg
  • Plato-Alpine-valleyb--ED120-Jan-2021.jpg

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#2 Jim Waters

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Posted 25 January 2021 - 04:16 PM

I think these are great images for the 120.  Overall very nice imaging and processing.  Are these single images?



#3 drd715

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Posted 25 January 2021 - 04:18 PM

127 - 130 mm, 1000 - 1200 mm fl. At F-8 and above a doublet of best glass and supior larger focuser would be a cost effective scope.

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#4 drd715

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Posted 25 January 2021 - 04:20 PM

Or a F-6.5 triplet 140mm at twice the price.

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#5 Trevor N

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Posted 25 January 2021 - 06:09 PM

Thanks Jim. They were taken using an imaging source camera and processed in Registax 6. About 300 best frames of 1000 frame runs


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#6 John Huntley

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Posted 25 January 2021 - 08:14 PM

I have a SW ED120 and I've used a SW ED150. I also have a LZOS 130 F/9.2 triplet.

 

I agree that the SW ED120 is a very good scope in so many ways. Optically it competes with much more expensive scopes and it's size and weight make it portable and easy to mount well.

 

I don't feel a great urge to get another 150mm ED just now. Quite a lot more weight / length / mounting needs for relatively little gain, IMHO.

 

 

P1080684.JPG.6a9d556d67b34b2c82b50734348


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#7 teashea

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Posted 25 January 2021 - 09:52 PM

Those images are terrific.  Well done.


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#8 Echolight

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Posted 25 January 2021 - 10:26 PM

I have a SW ED120 and I've used a SW ED150. I also have a LZOS 130 F/9.2 triplet.

 

I agree that the SW ED120 is a very good scope in so many ways. Optically it competes with much more expensive scopes and it's size and weight make it portable and easy to mount well.

 

I don't feel a great urge to get another 150mm ED just now. Quite a lot more weight / length / mounting needs for relatively little gain, IMHO.

 

 

P1080684.JPG.6a9d556d67b34b2c82b50734348

Wow... It looks so small. If I had one of those I wouldn't even need an ED80.


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#9 Rollo

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Posted 26 January 2021 - 12:28 AM

I had a SW 120ED and liked it.   Nice all purpose scope and easy to set up.   But going to keep my Istar 152mm refractor for now,, or until my back gives out,, Lol.   lol.gif   I use my 102 F/11 refractor for grab & go.   I really like the correction and crisp views the F/11 gives.   


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#10 bulletdodger

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Posted 26 January 2021 - 08:43 AM

I would agree 120mm is about right, maybe to 130mm. These are not much heavier and generally get by on most mounts set up for a 4 inch. The 150 range will almost definitely need a heavier and more complex mount requiring more trips back and forth to be ready for action. There are some great simple mounts that can handle the weight such as the Twilight II.
As coincidence would have it, my first 120mm is on my way courtesy of Japan UPS and my friend Koji Matsumto.
The 120mm size is probably the largest grab n go with it's mount that can safely be moved from my Living Rm to outside with 2 German Shepherds constantly in my path.
Love the 80-90mm as well. That is my light grab n go. My heavy grab n go is My TV 102 on Vixen Porta II. Maybe the 120 will take over.
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#11 MrRoberts

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Posted 26 January 2021 - 08:51 AM

I have found my 120 to be a sweet spot. It and my C-8 are home kept. On the road, or G&G I reach for the 80 or C-6.


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#12 25585

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Posted 26 January 2021 - 01:01 PM

I have 2 120mm refractors, an Equinox ED120 and TSA-120 triplet. Both are good un so many ways. They are heavier than 100mm scopes, and an Az Eq5 is shaky, but any larger or sturdier mount is fine, an AZ100 to be bought soon.

 

For carrying and mounting, no problem. Lifting, OK. Viewing is very pleasing. The TSA is better at high mags as I wanted. But my Equinox to 200x is very good. Trying to split Sirius is a good test, Vega, Rigel, Altair fine. Mars & Jupiter were good with my Equinox, & generally warmer G to C stars.

 

I use the TSA with its ED1.5x extender, giving me a F11 apo 120mm triplet. Flat field, and no CA, wonderful lunar detail!    


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#13 JeremySh

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Posted 26 January 2021 - 02:06 PM

I have 2 120mm refractors, an Equinox ED120 and TSA-120 triplet. Both are good un so many ways. They are heavier than 100mm scopes, and an Az Eq5 is shaky, but any larger or sturdier mount is fine, an AZ100 to be bought soon.

 

For carrying and mounting, no problem. Lifting, OK. Viewing is very pleasing. The TSA is better at high mags as I wanted. But my Equinox to 200x is very good. Trying to split Sirius is a good test, Vega, Rigel, Altair fine. Mars & Jupiter were good with my Equinox, & generally warmer G to C stars.

 

I use the TSA with its ED1.5x extender, giving me a F11 apo 120mm triplet. Flat field, and no CA, wonderful lunar detail!    

Have you split Sirius with your TSA 120?



#14 Stopforths

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Posted 26 January 2021 - 06:19 PM

Sirius is easy to split with a fine 100mm chromat Brother Kev owns its f14 and was made by the master Gary Nankivell decades ago.    There's colour in the image as you would expect but a wonderful clean split.  Mind you Sirius is virtually overhead here in NZ.

 

Interestingly Gary did the optics in one of the first corrected Dall Kirkhams in the world (possible the first?) the 1 Metre at Mount John Observatory.


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#15 John Huntley

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Posted 26 January 2021 - 06:26 PM

Sirius is easy to split with a fine 100mm chromat Brother Kev owns its f14 and was made by the master Gary Nankivell decades ago.    There's colour in the image as you would expect but a wonderful clean split.  Mind you Sirius is virtually overhead here in NZ.

 

Interestingly Gary did the optics in one of the first corrected Dall Kirkhams in the world (possible the first?) the 1 Metre at Mount John Observatory.

Where @25585, @JeremySH and myself are in the UK Sirius is really rather low at best. For me, I catch it in a gap between two nearby houses. Far from ideal.

 

Despite this, I split it regularly with my 12 inch dobsonian, occasionally with my 130mm F/9.2 triplet refractor but have yet to do so (convincingly) with my ED120 or Takahashi FC100-DL refractors. That is my challenge for this winter ! smile.gif


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#16 25585

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Posted 27 January 2021 - 02:53 AM

Have you split Sirius with your TSA 120?

Not noticed yet sadly, though maybe the scope did but I was too dazzled to see the Pup. 


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#17 25585

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Posted 27 January 2021 - 02:57 AM

Where @25585, @JeremySH and myself are in the UK Sirius is really rather low at best. For me, I catch it in a gap between two nearby houses. Far from ideal.

 

Despite this, I split it regularly with my 12 inch dobsonian, occasionally with my 130mm F/9.2 triplet refractor but have yet to do so (convincingly) with my ED120 or Takahashi FC100-DL refractors. That is my challenge for this winter ! smile.gif

Mine too. I need to go out of suburbia for long period viewing.


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#18 JeremySh

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Posted 27 January 2021 - 06:11 AM

Sirius is easy to split with a fine 100mm chromat Brother Kev owns its f14 and was made by the master Gary Nankivell decades ago.    There's colour in the image as you would expect but a wonderful clean split.  Mind you Sirius is virtually overhead here in NZ.

 

Interestingly Gary did the optics in one of the first corrected Dall Kirkhams in the world (possible the first?) the 1 Metre at Mount John Observatory.

Very envious of you guys in NZ. One of my best views of the night sky was from Mount Cook.


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#19 Paul Sweeney

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Posted 28 January 2021 - 01:29 PM

I have a 120mm Achro that I bought years ago. It is the perfect all-rounder. The only real issue is false color at high powers. I an thinking of upgrading to a 120ED. If I could only have one scope, this would be it.
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#20 Tyson M

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Posted 28 January 2021 - 02:48 PM

I have a SW ED120 and I've used a SW ED150. I also have a LZOS 130 F/9.2 triplet.

 

I agree that the SW ED120 is a very good scope in so many ways. Optically it competes with much more expensive scopes and it's size and weight make it portable and easy to mount well.

 

I don't feel a great urge to get another 150mm ED just now. Quite a lot more weight / length / mounting needs for relatively little gain, IMHO.

 

 

P1080684.JPG.6a9d556d67b34b2c82b50734348

Refractors are not known to scale up well lol.gif


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#21 Ihtegla Sar

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Posted 28 January 2021 - 03:12 PM

Those are some nice photos of the moon!  It's hard to define the "sweet spot" between portability and aperture since everyone's situation is different.  For me, I think the sweet spot is at 100mm given the optical quality of my FC100DF and FC100DL, how light and portable both of those scopes are and how fast they cool, which is important for quick trips outside when the clouds break.  I often have nights when only an hour or two (sometimes less) is suitable for viewing due to clouds, so having something that is quick to set up and cool down is crucial.

 

The 100mm FC Taks are significantly lighter than any 120mm so they can ride on a lighter mount.  I typically use a Meade LX70, which probably would support a 120mm refractor okay but might not be as rock solid stable as it is with my 100mm Taks. But  I have also used the FC quite successfully on my Twilight I which seems much too light  of a mount for a 120mm.  The 100mm FC Tak doublets also cool much faster than a 120mm, especially an air spaced triplet.

 

My next step up in aperture will skip 120mm and jump directly to the TEC140FL, which I have on order.  I picked the TEC140FL for its relative light weight (19 pounds) and for the quick cooling of an oil spaced lens cell.


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#22 jcj380

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Posted 28 January 2021 - 03:29 PM

I would agree 120mm is about right, maybe to 130mm. These are not much heavier and generally get by on most mounts set up for a 4 inch. The 150 range will almost definitely need a heavier and more complex mount requiring more trips back and forth to be ready for action.

The 120mm size is probably the largest grab n go with it's mount that can safely be moved from my Living Rm to outside with 2 German Shepherds constantly in my path.

Love the 80-90mm as well. That is my light grab n go. My heavy grab n go is My TV 102 on Vixen Porta II. Maybe the 120 will take over.

waytogo.gif   Agree with a lot of this.  My largest refractor is an ST120 and I doubt I would go larger.  The 120 is about 11-12 pounds and that puts it at the high end of what my current mounts can handle. A bigger scope would mean a bigger mount, more storage space needed, and so on.  I do make one trip for the mount and one for the OTA, just to minimize any chance of snagging on something or tripping.  

 

I wish I had a GSD to get in my way, but there are currently no pets in the house. 

 

I use my 80mm most frequently since it's so light and portable, but it does lack some oomph of the 120 in my bad LP skies.


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#23 litesong

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Posted 28 January 2021 - 04:49 PM

Mind you Sirius is virtually overhead here in NZ.

Yeah, yeah...& ya got Canopus, & Rigel Kentaurus, & Hagar, & Mimosa, & Acrux & Omega Centauri, & NGC 104, the Large & Small Magellanic Clouds, & NGC 55, 247, 253, & 300, & the entire southern Milky Way to yourself, & ya got the Great Attractor.....
Well....here’s what I’ve got to say about that....ya got a lot of stuff down there...ya do....so....there....take that...

....& ya did....

Edited by litesong, 29 January 2021 - 10:05 AM.


#24 Robindonne

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Posted 28 January 2021 - 11:11 PM

Im also curious if a 120 mm is the sweetspot of fracs. You must have a real refractor fetish to go bigger i guess. I assume my next >120mm choice will be a reflector.


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