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My new StarStructure/Lockwood 20" dob

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#101 stubeeef

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Posted 27 October 2020 - 08:06 PM

More than anything I'm just glad you got time off to enjoy an evening of viewing. Thats the big news. Yipppeeee!

 

I'm curious have you tried a mask during times of high mag bad seeing?


Edited by stubeeef, 27 October 2020 - 08:38 PM.


#102 starzonesteve

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Posted 27 October 2020 - 08:43 PM

More than anything I'm just glad you got time off to enjoy an evening of viewing. Thats the big news. Yipppeeee!

 

I'm curious have you tried a mask during times of high mag bad seeing?

I haven't, but I would be curious to hear others chime in as to whether or not an aperture mask has helped them.



#103 stubeeef

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Posted 28 October 2020 - 06:25 AM

check post 267 here https://www.cloudyni...-6#entry9742749


Edited by stubeeef, 28 October 2020 - 06:26 AM.


#104 Mike Wiles

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Posted 28 October 2020 - 11:45 AM

Some of the resolution was lost, except for the 10 or 15% of the time when the atmospheric turbulence would die down enough to let the fine surface details come into focus. It was clear to me that any loss of resolution I was seeing came from seeing issues. Those rare moments when seeing became still for 30 or 60 seconds at a time were truly jaw dropping. My Lockwood mirror was clearly up to the task and the StarStructure scope and drive kept me comfortably and smoothly locked in.

Great report Steve!  It echoes my own experience in moments of good seeing with my 20" (also made Mike Lockwood).  My report on Mars from the week of October 11th is almost the same as yours above.  When the seeing settled I was frozen in place by the amount of surface detail that pops out and how much subtle variation there was in the Mare coloring across the surface of the planet.  I found too that the optics provided enough contrast to make viewing Deimos without an occulting bar in the eyepiece quite easy.  Phobos was much more difficult, but also accomplished.  

 

I had a couple of sessions last spring with the optics where I simply "ran out of eyepieces".  The seeing had become so steady that I didn't an eyepiece capable of providing "too high" magnification - my highest powered eyepiece being 'only' a 2.5mm Nagler providing 708x.  It's those moments when the optics/structure really shine and I understand what all that cost was about. 

 

Looking forward to more reports.  Starstructure was my first choice in the build structure, but Mike Z said he'd not be able to get to even start it for 18 months at the time.....and well, I'm not that patient.  :)  

 

Mike


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#105 Mike Lockwood

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Posted 28 October 2020 - 12:14 PM

I haven't, but I would be curious to hear others chime in as to whether or not an aperture mask has helped them.

I've never found it to help.

 

An aperture mask decreases resolution and image brightness while making the seeing appear better.  For a Newtonian, to miss the spider and secondary, this is more than a factor of two in resolution reduction and more than four in brightness reduction.  This is a big difference.

 

Alternatively, your practiced brain filters out poor seeing and you remember the good moments of seeing with the full resolution of the telescope at your disposal.

 

If the image is too bright, use a good neutral density filter or use more magnification.

 

Allan's use of the off-axis mask was to reduce brightness and distributed spider diffraction to make a faint moon of (very bright) Jupiter, located near the planet, easier to see.  In this case, reduced resolution has no effect on the task at hand.  However, that is not true for normal planetary observing.

 

I've got a client doing full-aperture planetary imaging with a 32" and the results are great.  No aperture mask there, either.

 

Nice report Steve, I hope you get some more observing time on some clear winter nights.


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#106 starzonesteve

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Posted 28 October 2020 - 07:32 PM

I had a couple of sessions last spring with the optics where I simply "ran out of eyepieces".  The seeing had become so steady that I didn't an eyepiece capable of providing "too high" magnification - my highest powered eyepiece being 'only' a 2.5mm Nagler providing 708x.  It's those moments when the optics/structure really shine and I understand what all that cost was about. 

A Couple of years back I met Bob Shilling to buy his Teeter/Zambuto STS. He had a couple of extra items to sell. One was a a Televue 4x Powermate. I told him I didn't need it as it was probably redundant and overkill. He smiled and said that that was probably true 99% of the time. However, when you get a night of incredible seeing you never want to to run out of magnification before the seeing degrades. He told me that if I run into a night like that and have to reach for the Powermate it will more than make up for lugging it around the rest of the time. Still waiting to be able to pop the 3.7 Ethos into the 4x Powermate and observe at over 2000x...


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