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Orion 120 at f5

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15 replies to this topic

#1 pdenning

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Posted 01 December 2019 - 09:04 PM

I'm sure it's been mentioned here before. I just got the 120 at I'm using as my primary imagining scope and as I have already read the focuser is at best substandard. I'm looking for suggestions on a good upgrade preferably 200 or less.
thanks for any input
Patrick

#2 Astro-Master

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Posted 01 December 2019 - 09:47 PM

The Orion 120 F/5 Achromat is not suited for imagining, too much CA.  Buying a new focuser for it would be like putting lipstick on a pig.  Save your money, buy a nice APO and a good mount, then you can spend even more money for all the rest of the equipment you'll need.  


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#3 BFaucett

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Posted 01 December 2019 - 10:25 PM

I'm sure it's been mentioned here before. I just got the 120 at I'm using as my primary imagining scope and as I have already read the focuser is at best substandard. I'm looking for suggestions on a good upgrade preferably 200 or less.
thanks for any input
Patrick

 

GSO focusers:

https://agenaastro.c...ractor-gso.html

 

GSO Focuser Compatibility:

https://agenaastro.c...patibility.html

The Orion ST120 uses either the GSO96 (96.6 mm) or the GSO112 (112.5 mm) focusers.

 

How to Attach a Finder to your Crayford Focuser:

https://agenaastro.c...rd-focuser.html

 

Cheers!  Bob F. smile.gif


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#4 nirvanix

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Posted 02 December 2019 - 05:18 PM

Looking at the reviews and image gallery on Orion's website, it appears that lots of people are having success using the 120 ST for imaging. It could definitely use a focuser upgrade. I put a GSO 2-speed from Agena Astro on my Orion 100 f/6. Turns out the lens was sharper than my two apos so it was well worth doing.


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#5 LDW47

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Posted 02 December 2019 - 05:56 PM

GSO focusers:

https://agenaastro.c...ractor-gso.html

 

GSO Focuser Compatibility:

https://agenaastro.c...patibility.html

The Orion ST120 uses either the GSO96 (96.6 mm) or the GSO112 (112.5 mm) focusers.

 

How to Attach a Finder to your Crayford Focuser:

https://agenaastro.c...rd-focuser.html

 

Cheers!  Bob F. smile.gif

Theres nothing more to say, its all right here, I have 2 of then they replace the original in about 20 min. ! One single and one two speed.


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#6 Kisslija

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Posted 22 January 2020 - 07:45 PM

Did you guys have any back focus issues with the GSO focuser on the 120ST? Also, do you use a Baader Clicklock with them? If so, what size?



#7 aa6ww

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Posted 23 January 2020 - 01:55 AM

You would want the Linear bearing GSO focuser so it could handle the weight of any large camera or eyepieces you may use with it, effortlessly.

 

https://agenaastro.c...cuser-96mm.html

 

 

https://agenaastro.c...user-112mm.html

 

 

...Ralph



#8 MalVeauX

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Posted 23 January 2020 - 07:12 AM

Heya,

 

The GSO dual speed focusers are pretty decent and less expensive. They're not superb like a Moonlite/FeatherTouch. But they're better than the stock stuff.

 

I put one on my 120mm F5 and it's a great improvement on a great scope. Be aware that there's some tolerance error between the latest 120/5's and the latest GSO focuser flange. It's less than 1mm tolerance difference but it could matter. This has been reported a few times in other threads by users. I had to shave the inside of my OTA tube just a bit to get enough room to get the focuser in without it getting jammed up. It fit. But apparently there is a tolerance error that didn't used to be there (quality control?).

 

I got the linear bearing version. It handles big payloads.

 

I have FeatherTouch on another scope and they're luxury. I would put them on all my scopes. But.... cost. So, my beater scopes like this 120/5 gets the GSO.

 

48529916441_f581c75e82_c.jpg

 

48530070152_5651874d3e_c.jpg

 

48609364278_fc59dc7421_c.jpg

 

Handles my Quark + Binoviewers no problem.

 

48606945678_c632537687_c.jpg

 

Very best,


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#9 Kisslija

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Posted 23 January 2020 - 09:25 AM

You would want the Linear bearing GSO focuser so it could handle the weight of any large camera or eyepieces you may use with it, effortlessly.

 

https://agenaastro.c...cuser-96mm.html

 

 

https://agenaastro.c...user-112mm.html

 

 

...Ralph

I noticed on Agena Astro’s website the 96mm and 112mm will both fit the 120ST. Is there any reason to choose one over the other or just go with the less expensive 96mm?



#10 pdenning

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Posted 23 January 2020 - 09:32 AM

Thanks for all the input.   I went with the GSO with linear bearings .  The fit was spot on and I am able to get tack sharp focus.  The only issue I am having is back focus .  I need to use a tube for visual  

 

 

 

 


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#11 Scott Beith

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Posted 23 January 2020 - 05:35 PM

Thanks for all the input.   I went with the GSO with linear bearings .  The fit was spot on and I am able to get tack sharp focus.  The only issue I am having is back focus .  I need to use a tube for visual  

Are you using a 2" diagonal or a 1 1/4"?



#12 aa6ww

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Posted 23 January 2020 - 10:36 PM

The 120ST already comes with a 112mm Adapter ring which bolts directly to the OTA. Id just get the 96mm one and that would bolt right on the adapter ring on the ST-120. 

 

If you wanted to pull off the stock adapter ring and use the full 112mm model, that would work too. That would be the one on message #8 in here, as shown in his photo he posted.

 

...Ralph

 

 

I noticed on Agena Astro’s website the 96mm and 112mm will both fit the 120ST. Is there any reason to choose one over the other or just go with the less expensive 96mm?



#13 pdenning

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Posted 24 January 2020 - 08:52 AM

Scott I use the 1.25 



#14 Binojunky

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Posted 24 January 2020 - 12:18 PM

I put the 96mm version on mine, three screws out and three in, use both 1.25" and 2" diagonals, I also have an extension tube if needed? find the focuser  is a large improvement over the stock one and its fine for visual use,D.



#15 belgrade

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Posted 24 January 2020 - 03:03 PM

I've received an email from Orion yesterday letting me know that the 120 mm f/5 achromatic OTA is on sale for $229.99 ($20 off).  It's not a huge sale but still something.  Needless to say, I'm not affiliated with Orion in any way (though I did purchase items from them over the years).  I just noticed Amazon lowered the price too, matching the sale.   



#16 Scott Beith

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Posted 24 January 2020 - 03:19 PM

Scott I use the 1.25 

a 2" diagonal might get you where you need to be




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