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ASI-120MM with Orion 50MM Guide scope

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#1 dcollier

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Posted 15 January 2020 - 08:47 AM

I am having issues getting an Orion 50mm guide scope ( Base model) to come to focus with an ASI-120 MM camera. Anyone else Have this issue? Can you share what solves it? 

Thanks 

 

          -Dave 

     



#2 Huangdi

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Posted 15 January 2020 - 09:14 AM

There were a couple small extension tubes that came with the camera. You have to attach these to the camera to be able to move the sensor further away from the scope in order to achieve focus!

Once you got good focus you can screw on the small ring that came with it and lock the focus with it.

Edited by Huangdi, 15 January 2020 - 09:15 AM.

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#3 dcollier

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Posted 15 January 2020 - 10:30 AM

I got the camera used without the extensions about how much extension is needed. I am using the supplied 1.25" T eyepiece adapter.

 

 -Dave 



#4 Huangdi

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Posted 15 January 2020 - 10:44 AM

I'm afraid you'll have to buy those then. Reaching focus without enough spacing is impossible!

 

I attached two images of my setup and as you can see, the camera needs to be roughly 1.6cm (0,6 inches) away from the connection of the scope.

 

 

Attached Thumbnails

  • WhatsApp Image 2020-01-15 at 4.41.47 PM (1).jpeg
  • WhatsApp Image 2020-01-15 at 4.41.47 PM.jpeg

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#5 dcollier

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Posted 15 January 2020 - 11:40 AM

My camera is the ASI-120 MM  not the Mini.  Sorry for the confusion.

 

           -Dave 



#6 Huangdi

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Posted 15 January 2020 - 12:17 PM

My camera is the ASI-120 MM  not the Mini.  Sorry for the confusion.

 

           -Dave 

That's fine, however it won't change the fact that you need extension tubes. The sensor is still the same size and it requires more distance to the lens in order to achieve focus at infinity.



#7 Aurneth

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Posted 15 January 2020 - 04:57 PM

The Orion has a focal length of 162 mm, so measure off 162 mm (6⅜") from the front objective and see where it ends up. That's where your sensor needs to be, so you have to make sure that between extension tubes and adjusting the front objective (loosening the ring and rotating the objective in or out) you can get to that point.


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#8 Stelios

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Posted 15 January 2020 - 05:50 PM

Hmmm--I don't have the minis, but the SSAG has the 50mm guidescope and a camera which comfortably comes to focus without extension tubes (other than the 1.25" adapter). I thought distance to sensor is distance to sensor and independent of what the sensor is. 


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#9 Ultron

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Posted 16 January 2020 - 08:24 AM

I am having issues getting an Orion 50mm guide scope ( Base model) to come to focus with an ASI-120 MM camera. Anyone else Have this issue? Can you share what solves it?
Thanks

Hi Dave,

I had the same camera and same guide scope and was able to get it into focus by just adjusting the lens on the guide scope. The 120MM should have a small extension tube that came with it (comes with an all sky lens and the tube) and this allowed some adjustment of the position of the camera as well.

-Dave



#10 dcollier

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Posted 16 January 2020 - 09:10 AM

Actually, I have the ASI-120MM-S and not the Mini as my camera. (It does not come with any extensions) I was able to get it to focus finally.  But the camera needed to be pulled almost all the way out to get it to focus as described by Haung. So it needs a 1" Filter Thread Barrel Extension.  Further research on Cloudy Nights indicated that not all of the 50MM guide scopes are physically the same length. Some may require more or less of an extension to reach focus. So, problem solved and as with most things astronomy, there is always something else to buy to get it to work.  Kind of like doing a home DIY plumbing project!  Thanks for all the help!

 

                             -Dave 

 

              -


Edited by dcollier, 16 January 2020 - 09:12 AM.


#11 klaussius

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Posted 16 January 2020 - 10:54 AM

Actually, I have the ASI-120MM-S and not the Mini as my camera. (It does not come with any extensions) I was able to get it to focus finally.

I have the 120MM-S and it did include a small extension. My scope needed way more backfocus, which I knew when I bought it, so I bought an extra extension, but in this case the small extension that comes with the camera should be sufficient. I think it's around 1cm long, I would have to measure it.

 

Anyway, if the OP didn't get it, it's all moot. Just noting that it does come with it when new.



#12 OhmEye

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Posted 16 January 2020 - 11:32 AM

I know it's moot, but my new ZWO ASI120MM-S didn't include any extensions either. The box had only exactly what it said it comes with:

 

ZWO ASI120MM-S Super Speed Monochrome CMOS Imaging Camera

    USB 3.0 Cable

    ST4 Cable

    1.25" Cover

    1.25" Nosepiece

    Quick Guide

 

So if somebody gets an extension in a new box, I don't think that's standard. cool.gif



#13 klaussius

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Posted 16 January 2020 - 11:46 AM

I know it's moot, but my new ZWO ASI120MM-S didn't include any extensions either. The box had only exactly what it said it comes with:

 

ZWO ASI120MM-S Super Speed Monochrome CMOS Imaging Camera

    USB 3.0 Cable

    ST4 Cable

    1.25" Cover

    1.25" Nosepiece

    Quick Guide

 

So if somebody gets an extension in a new box, I don't think that's standard. cool.gif

 

I got all that, plus the extension and a CCTV lens.



#14 fewayne

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Posted 16 January 2020 - 12:25 PM

One more vote for just the 1.25" nosepiece with the older-style 120. This is an MC. You probably already know that you can back down the knurled lock ring at the objective end and unscrew the helical focuser (e.g., more distance from camera) to fine-focus, right?

 

https://drive.google...8t2w21Qowp689ej



#15 dcollier

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Posted 16 January 2020 - 12:34 PM

Yes , It takes a fair bit of travel on that as well to get it to focus.

 

        -Dave 


Edited by dcollier, 16 January 2020 - 07:31 PM.


#16 TelescopeGreg

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Posted 16 January 2020 - 02:21 PM

Not sure this issue is limited to the Orion guide scope. 

 

For what it's worth, I just got a ZWO 60mm x 280mm guide scope.  Lashing up my ASI174mm Mini camera required a short extender, and even with the focuser all the way out, the camera had to be backed out of the scope's focusing ring a bit.  You'd think that everything would work perfectly together, since both of these are ZWQ products. 



#17 Aurneth

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Posted 16 January 2020 - 04:09 PM

Actually, I have the ASI-120MM-S and not the Mini as my camera. (It does not come with any extensions) I was able to get it to focus finally.  But the camera needed to be pulled almost all the way out to get it to focus as described by Haung. So it needs a 1" Filter Thread Barrel Extension. 

Well there are more options than that.

 

A cheesy option is to take a short 1.25" barlow (like Orion's "Shorty" if you have one) and just unscrew the barlow lens element. So that'll give you about an inch. Similarly a number of eyepiece projection adapters, just use it without any eyepieces (that might be too much distance, though). Here's an Orion Shorty of interest:

 

https://www.telescop...?keyword=shorty

 

That one incorporates the male M42 T-mount thread that the ZWO units will thread onto, so you can skip the 1.25" nosing entirely. As the ZWO units are threaded for M42 T-mount thread, you can also buy M42 extension rings and attach them to the ZWO before the 1.25" nose adapter, for instance:

 

https://www.telescop...160/p/99591.uts

 

You can also get them from China- and Hong Kong-based sellers on eBay under the name SVBONY as well for not too much, but it may take a month or so to arrive.

 

 

So there are a few options depending on what you already have or what you want to buy for other purposes.



#18 dswtan

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Posted 16 January 2020 - 11:18 PM

@OP: BTW, someone else just posted a pic of their non-helical focuser Orion 50mm guidescope with a ZWO cam, which you may find helpful -- assuming they are getting focus. :-)

 

https://www.cloudyni...ar-field-issue/




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