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CFF 300 f/15 First Light -- Well, Sort of...

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#1 MJB87

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Posted 23 April 2019 - 10:36 AM

It's here. Assembled and on the mount.  No, the A-P 130mm GTX next to it is not a glorified finderscope. I now have a choice of instruments, one tailored for big dim things (refractor) and the other tailored for small bright things (Cassegrain).

 

631080DE-1F9A-4F25-AAD4-A08844F26989.jpeg

 

The shipment arrived in two days in excellent condition. It was well packed.  The only glitch is that my finderscope holder is fitted for a A-P bracket so I'll need to pick up the normal Baader bracket. Electrical connections (fan, heater) all seem to work normally.  The handle on the top of the OTA makes it relatively easy to install it on the mount but I'd still say it is a two-person job. Mechanical fit and finish is superb.

 

To my surprise -- not knowing if the alignment model still worked or if I was anywhere near proper focus -- we were able to easily "find" Sirius before sunset. Over time, I'll need to better align the two OTAs, though a star centered in the CFF 300 is also in the FOV of the 130mm refractor, albeit not centered.

 

Since seeing was not at all good at the time, we limited the number of tests. It was also clear that I need to tweak collimation a bit. Here is Propus at about 400x magnification with focuser racked out

 

33F478BF-37AE-4C7C-9C92-F5B9CBA84CFF.jpeg

 

Collimation will be a job for the next clear night.  I'll also need to build a new T-Point model to get more precise GOTOs with the new telescope.  Once this is done, I'll send images.

 

Marty

 

 

 


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#2 Wouter D'hoye

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Posted 23 April 2019 - 10:44 AM

Congrats on the new scope waytogo.gif



#3 Eye stein

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Posted 23 April 2019 - 10:54 AM

OK ..how many Kilos are your counter weights (please notice I used metric)  tough for me since I grew up and still use English units.

Nice set up in any language!

Joe



#4 MJB87

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Posted 23 April 2019 - 01:01 PM

The telescope setup weighs about 40-42kg, including cameras, saddles, dovetail bars, rings, focusers, etc.. The counterweights are 57kg .  The arm of the counterweights is less than the arm of the telescope assembly, which explains the difference.  

 

The mount seems to handle to load just fine. However, took a lot of time to get the side-by-side setup balanced properly.

 

Marty


Edited by MJB87, 23 April 2019 - 01:02 PM.


#5 Wjdrijfhout

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Posted 23 April 2019 - 02:59 PM

That’s a beautiful and impressive setup, congratulations!
Looks like CFF is making some really great scopes. I’ve been tempted by an RC10/f8, but not pulled the trigger yet.
How important is for you the alignment between both? Given the large difference in FOV, do you foresee them both imaging the same target simultaneously? One of the options I had in mind for the RC10 was to combine with 130mm refractor, make camera selections such that FOV and image scale were in similar range and combine images, for example luminance with RC and RGB with refractor. That would essentially double observation time.


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#6 MJB87

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Posted 23 April 2019 - 05:34 PM

I don't really see a scenario where I'd image one target with both scopes.  The 130mm GTX is great for wide FOV and long-duration imaging of large DSOs. I wanted to also have the ability to image planets which requires higher focal length.  Since I have only one pier and since I do not want the hassle of switching out OTAs, I went with the side-by-side.

 

This screenshot from Sky Safari shows the different FOVs with the cameras I have installed, without Barlow or focal reducers.

 

1AB842A5-0641-4E59-B937-D5D98C069E07.png

 

However, I would like them to be coaxial so that I can use the same mount alignment model.  It is "good enough" now and I may move to plate-solving for DSO imaging anyway.

 

Marty


Edited by MJB87, 23 April 2019 - 05:36 PM.

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#7 Wjdrijfhout

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Posted 23 April 2019 - 05:40 PM

Ah, it’s for the mount model, that explains. Yes, I would have expected the FOV’s to be widely different.
Again, congratulations with your new fantastic setup, and please share the photo’s, I’m sure they will be beautiful.



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#8 rcg

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Posted 23 April 2019 - 06:45 PM

Looks like the best of both worlds … nice setup!



#9 gnowellsct

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Posted 24 April 2019 - 10:47 AM

However, I would like them to be coaxial so that I can use the same mount alignment model. It is "good enough" now and I may move to plate-solving for DSO imaging anyway.

Marty


I think it would be phenomenally difficult to have them perfectly aligned and stay that way. I know people who have struggled to get a 70 mm apo aligned with a 9.25.

The practical choice might be:

A. Do a plate solve when you switch scopes, have a cup of coffee OR
B. let the big scope with narrow field be dominant and figure out a rapid way to realign the gt130 when you move the rig OR
C. Store two complete models in memory and load the one you want to use

I went with B for portable visual use. But I think A or C would be best for you.

I hope you enjoy your cff as much as I'm enjoying my tiny one.

Greg N

#10 MJB87

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Posted 24 April 2019 - 01:22 PM

I think it would be phenomenally difficult to have them perfectly aligned and stay that way. I know people who have struggled to get a 70 mm apo aligned with a 9.25.
 

You are almost certainly correct here, Greg. I will build the mount model around the CFF 300 with its much smaller FOV. Stars centered there so far are well within the FOV of the refractor, even with a 7mm eyepiece. So it is "good enough." Eventually I will just plate solve for the refractor, as you suggest. So "good enough" is probably going to be the objective anyway.



#11 R Botero

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Posted 25 April 2019 - 06:13 PM

Dream set up! Congratulations! Don’t use Propus as test for collimation of such a long focal length instrument...it’s a double star :wink:
Roberto

#12 MJB87

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Posted 27 April 2019 - 08:00 AM

Thanks, Roberto.  Good advice.  It was just a star of convenience at the time to check alignment. Collimation will have to wait until the next dark night with decent seeing.


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