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ZWO ASI294MC Pro - Need help with straight vs diagonal setup

astrophotography
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#1 hobbes

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Posted 14 November 2019 - 06:25 PM

Currently, I'm working with UV filter to f6.3 focal reducer/corrector to 1.25" visual back. If I attach the asi294 to the visual back with the 21m adapter + 1.25" attachment, the camera can't slew 90 degrees because the camera/USB cord jams on the mount. I also removed the UV filter, and it still couldn't slew 90 degrees without jamming into the mount.

 

gallery_227714_11766_68516.jpg

 

 

Unfortunately, I've been using a diagonal to

resolve this problem. But I'd like to run it straight to remove the added glass.

 

gallery_227714_11766_31499.jpg

 

Do you have adapters from ZWO that can allow for my asi294 to attach directly onto my focal reducer/corrector, and something that will maintain a 55m back focus range (and allow for 90 degree slew)?

 

gallery_227714_11766_164633.jpg

 

Any help would be greatly appreciated!



#2 donstim

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Posted 14 November 2019 - 06:53 PM

I'm afraid it may be worse than you think.  From what I could glean in a quick Google search, I think the correct back focus distance for the Antares .63x reducer you are using is 82 mm, not 55 mm.  If your spacing only provides 55 mm, then adding an additional 27 mm will make the clearance issue even worse.

 

I have a Celestron 0.63x reducer/corrector, which has a back focus distance of 105 mm.  With my Celestron 8" OTA moved forward as far as I can get it on the rails, I can only get to something like 62 degrees or so of altitude without hitting the mount.  Above that, I have been using a diagonal, and I haven't really noticed any problems in the resulting images, except that I am doing short exposure EAA imaging, not long exposure astrophotography imaging.

 

One solution to the mount obstruction issue would be to get a Hyperstar, so the camera is mounted on the front rather than the back.


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#3 kathyastro

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Posted 14 November 2019 - 07:19 PM

You need a GEM.


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#4 descott12

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Posted 14 November 2019 - 07:39 PM

And the cooled version of the camera is much longer than the non-cooled. A new mount or hyperstar is the only way to go. I have the Hyperstar and I love it.

A GEM will work and there are also a few Alt-Az mounts like the iOptron AZ Mount pro that have the OTAs off to the side and you have all the space you would ever need.

Forks are tough for cameras on the backside unfortunately.

 

Edit: People do use a diagonal in this setup to solve this problem but that always seemed like a very insecure way to dangle a very expensive camera off of....


Edited by descott12, 14 November 2019 - 07:40 PM.

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#5 hobbes

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Posted 14 November 2019 - 07:44 PM

One solution to the mount obstruction issue would be to get a Hyperstar, so the camera is mounted on the front rather than the back.

 

I'm looking on the starizona site at their Hyperstar 8 v4. So this will allow my ASI294 to mount to the front at f/1.9? That would be incredible.

 

How does cable management work, if the cable goes across the scope glass?


Edited by hobbes, 14 November 2019 - 07:48 PM.


#6 descott12

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Posted 14 November 2019 - 07:49 PM

I'm looking on the starizona site at their Hyperstar 8 v4. So this will allow my ASI294 to mount to the front at f/1.9? That would be incredible.

Yes it is really awesome and you can still use the OTA at prime focus for other things. Also, as I mentioned, the uncooled cameras are quite a bit smaller so you could get something else and still use it back there for planetary work or when you still need f10 or f20 with a barlow.


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#7 hobbes

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Posted 14 November 2019 - 09:49 PM

Thank you everyone for all the advice.

 

I think the HyperStar 8 is the way to go. I notice that online, you can choose the camera you're going to use it for. What are the differences, do they supply the appropriate back focus for the camera? What if I wanted to use both my cooled, and non-cooled cameras on the HyperStar?

 

Will I need to buy any additional adapters to accommodate other cameras?



#8 descott12

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Posted 14 November 2019 - 09:55 PM

If you look at the spec sheets for some of the ZWO cooled vs uncooled cameras, they do have  different back focus. But I bought my Hyperstar for my 294 cooled and it works fine with my 178 mono uncooled.

They must have different adapters but in my case it didn't seem to matter. Just my dumb luck too because I had forgotten that it wasn't technically supposed to work.


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#9 GoFish

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Posted 14 November 2019 - 09:58 PM

Yes, you will need different adapters for ZWO cooled and ZWO non-cooled. 


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#10 richorn

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Posted 14 November 2019 - 11:54 PM

Don't you have to get different filters if you are shooting below f/4?



#11 TelescopeGreg

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Posted 15 November 2019 - 12:14 PM

But, you still need a GEM-type mount in order to get the most out of your scope and camera, regardless of how the camera is attached to the telescope, or what type of telescope you have.



#12 hobbes

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Posted 15 November 2019 - 02:17 PM

But, you still need a GEM-type mount in order to get the most out of your scope and camera, regardless of how the camera is attached to the telescope, or what type of telescope you have.


For what it's worth, I'm using an ASIAir for plate solving and ASI120mm for tracking which has helped accuracy. And have an EQ wedge as well.

#13 Michael Harris

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Posted 15 November 2019 - 04:31 PM

When you order the Hyperstar be sure to tell them you are using a ZWO Cooled camera and they will include the proper adapter. If you want to use uncooled versions you will need to order additional adapters. I am using this system now and it is very good for wide field images. Here is the set up and an image taken with it.

C8 Hyperstar Setup
Gamma Cygni - Flat corrected

 I used the diagonal setup for the Mercury transit this week because I was using my Evolution AltAz mount, and it worked okay but I didn't need to elevate the tube much so clearance wasn't an issue. Here is how that looked.

Solar Photography Setup (White Light)
Mercury transit screen shot

Good luck with developing your set up. You can do a lot with your scope.


Edited by Michael Harris, 15 November 2019 - 04:33 PM.

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#14 hobbes

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Posted 15 November 2019 - 05:08 PM

A question I had about the HyperStar; if I get one for my Non-EdgeHD scope, then upgrade to a bigger EdgeHD scope, what's needed to convert it?


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#15 Michael Harris

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Posted 15 November 2019 - 05:23 PM

A question I had about the HyperStar; if I get one for my Non-EdgeHD scope, then upgrade to a bigger EdgeHD scope, what's needed to convert it?

Starizona’s web site says the lens designs are different between the normal and Edge SCTs so you need different Hyperstar units for each. Can’t convert between them. Expensive hobby.



#16 TelescopeGreg

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Posted 16 November 2019 - 01:26 AM

For what it's worth, I'm using an ASIAir for plate solving and ASI120mm for tracking which has helped accuracy. And have an EQ wedge as well.

Ah, sorry.  Missed that you were using the Wedge.  That qualifies as an GEM scope...



#17 kathyastro

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Posted 16 November 2019 - 07:27 AM

Ah, sorry.  Missed that you were using the Wedge.  That qualifies as an GEM scope...

A wedge qualifies as an equatorial mount, but not a German equatorial mount (GEM).  The distinction is relevant to this thread because the issue is having the camera clear the forks.  A wedged fork mount still has the fork clearance issue.  A true German equatorial mount does not have the problem.


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