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For comets specifically: 190mm f/5.3 Mak-Newt or 10" f/3.9 Newtonian ?

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#1 Thomas Ashcraft

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Posted 04 January 2018 - 06:35 PM

Specifically for photographing comets and their subtler features:  Is one of these telescopes better than the other?

Orion Premium 190mm f/5.3 Mak-Newt Astrograph Telescope ( around $1500. ) 22 lbs.

Orion 10" f/3.9 Newtonian Astrograph Reflector Telescope ( Around $650. ) 25 lbs.

 

I would be mounting on a CGEM-DX with 50 pound capacity. And using a Canon DSLR or something from ASI like a 1600. I am still researching cameras.

Would I need extra accessories like field flatteners with these scopes to complete them?

Thanks in advance. - Thomas

 



#2 RMannix57

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Posted 04 January 2018 - 06:48 PM

I have the 10" F3.9 Newt. 25 pounds is the naked OTA. With rings, camera, coma corrector, filterwheel, finder, guider,etc it is near 45 pounds.

I have an HDX 110 mount on order to swing that hot water heater around, it is too much for my Atlas EQ-G's


Edited by RMannix57, 05 January 2018 - 07:56 AM.

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#3 sonny.barile

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Posted 04 January 2018 - 07:15 PM

https://www.amazon.c...egon astrograph



#4 Thomas Ashcraft

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Posted 04 January 2018 - 07:16 PM

Oops, Moderator, I think I should have put this question in the reflector forum.



#5 Aaron_tragle

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Posted 04 January 2018 - 07:30 PM

Couldn't the Explore Scientific David Levy Comet Hunter  work? It is 15 pounds. Another plus include the fact that it is relatively cheap at 750. 


Edited by Aaron_tragle, 04 January 2018 - 07:48 PM.

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#6 Ron359

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Posted 04 January 2018 - 07:58 PM

When it comes to resolution of details and collecting as many faint photons in as little time as possible for imaging, its simple;  APERTURE (and low f/ratio) RULES!   The newt would only need a coma corrector for a full frame DSLR unless you want to crop your small comet images down to the basic coma area.  



#7 David_Ritter

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Posted 04 January 2018 - 08:08 PM

I have the Sky-Watcher version of the Orion Mak-Newt.

 

I've only ever taken one comet picture and it was done with that scope:

 

comet_johnson_RGB_large.jpg

 

The camera was an SBIG STF-8300M with RGB filters. So not really an ideal camera for comet catching. But the scope itself worked pretty good. The image shows the comet as being sort of elongated with a dark band in the middle. I think that's because I used DSO long exposure techniques and the comet moved a bit during the imaging session.

 

The stars came out pretty round though, which brings up another point: you do not need a coma corrector or flattener with this scope. The Mak-Newt design incorporates one in the meniscus lens at the front of the scope.

 

For its size, the MN190 is heavy though. It was too heavy for my NEQ6 and this image was done with it mounted on an EQ8. Compared to a Newt, it is nose heavy. The meniscus lens up front is a mighty hunk of glass. The weight distribution may or may not help things, depending on your setup.

 

Edit: One other thing about the Mak-Newt design is the lack of diffraction spikes. This may or may not be a positive thing, depending on how the viewer feels about spikes.


Edited by David_Ritter, 04 January 2018 - 08:44 PM.

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#8 glend

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Posted 04 January 2018 - 08:18 PM

Couldn't the Explore Scientific David Levy Comet Hunter  work? It is 15 pounds. Another plus include the fact that it is relatively cheap at 750. 

Just because Marketing calls it a "Comet Hunter" does not make it any better at that task than another scope.

 

Regarding the MN190, in its several guises (Skywatcher Version 1 &2, and the Orion version), you can count on a couple of things, it is built as an astrograph so it is corrected by the front corrector plate, so no coma and it gives a flat field. The Newt will need s coma corrector and then there is still a question concerning thr flat field (depends on the coma corrector). You need to budget for that. Newts usually do not have baffling in the tube, the MN19 does, this contributes to improved contrast. Consider secondary mirror sizes, at least two sizes were used in the MN190, the original Skywatcher had a smaller secondary than the Orion, and Skywatcher has recently increased rheir secondary size - all due to full size dslr sensors vignetting with the smaller secondary. Hiwever, APS-C sensors work fine without vignetting, on the scope with the smaller secondary. I own the small secondary Skywatcher and it is a wonderful scope, will handle very high EP magnification when used visually, and its a perfect astrograph as well. The small secondary gives you less central obstruction, which improves contrast as well. If you have an APS-C camera, or something lije an ASI1600, then the small secondary is the obvious choice - if you can find one. Neither Skywatcher or Orion use the small secondary any more, and people don't generally sell them. Good luck.


Edited by glend, 04 January 2018 - 08:20 PM.


#9 Richard Whalen

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Posted 05 January 2018 - 08:26 PM

I would recommend a quality MNT. From my experience much better contrast, no spikes, smaller secondary and betterr optics.



#10 Patrick

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Posted 06 January 2018 - 03:23 AM

Specifically for photographing comets and their subtler features:  Is one of these telescopes better than the other?

Orion Premium 190mm f/5.3 Mak-Newt Astrograph Telescope ( around $1500. ) 22 lbs.

Orion 10" f/3.9 Newtonian Astrograph Reflector Telescope ( Around $650. ) 25 lbs.

 

I would be mounting on a CGEM-DX with 50 pound capacity. And using a Canon DSLR or something from ASI like a 1600. I am still researching cameras.

Would I need extra accessories like field flatteners with these scopes to complete them?

Thanks in advance. - Thomas

Given those two choices, I think the MN would be better.  MN's typically have nice flat fields without adding extra glass at the focuser.  The newt will definitely require the use of a coma corrector, adding cost and increasing the height of the camera on the focuser (which exacerbates balance issues).

 

Patrick



#11 Ron359

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Posted 06 January 2018 - 12:07 PM

 

Specifically for photographing comets and their subtler features:  Is one of these telescopes better than the other?

Orion Premium 190mm f/5.3 Mak-Newt Astrograph Telescope ( around $1500. ) 22 lbs.

Orion 10" f/3.9 Newtonian Astrograph Reflector Telescope ( Around $650. ) 25 lbs.

 

I would be mounting on a CGEM-DX with 50 pound capacity. And using a Canon DSLR or something from ASI like a 1600. I am still researching cameras.

Would I need extra accessories like field flatteners with these scopes to complete them?

Thanks in advance. - Thomas

Given those two choices, I think the MN would be better.  MN's typically have nice flat fields without adding extra glass at the focuser.  The newt will definitely require the use of a coma corrector, adding cost and increasing the height of the camera on the focuser (which exacerbates balance issues).

 

Patrick

 

A Baader newt photographic coma corrector goes in the focuser attached to the camera T-adapter same as any 2" prime focus nose.  So it adds nothing to the height, very little weight, so it does not exacerbate any balance issue.  

 

I don't know how anyone can ignore the simple facts of physics of a larger aperture with more resolution for imaging the faint details of comets in favor of a much smaller scope aperture with much lower rez and light gathering and a extra glass corrector in front of the tube prone to dewing and dust collection @ 2x the cost!     

 

There is a lot that can be learned from Chris Shur's comet imaging who is a frequent poster of images on the comets-ml y-group.  

http://www.schursast.../ccdcomets.html


Edited by Ron359, 06 January 2018 - 12:28 PM.



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