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24" f/2.75

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#1 opticsguy

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Posted 24 July 2017 - 09:59 AM

First no pics but it DID happen. My friend got some pics so maybe can post something later.

 

The Table Mountain Star Party was held this last week, about 300 people and every night was clear although a few clouds on the third evening. 

There were several interesting scopes on the filed and there was one OUTSTANDING scope on the field.

 

A 24" f/2.75 with Lockwood optics, Zambuto coatings, TOTALLY automated in EVERY aspect.  This scope is mobile and controlled remotely, yes mobile meaning it drives to and from the observing site. Scope obviously tracks and go's to.  The OTA has a handle you reach for and when your hand breaks the laser beam all locks are disengaged and you are free to move the scope manually and when let go, locks into place and tracks.  This scope was "home made" but obviously designed and built by a very very smart engineer! The amount of design work and technology were simply overwhelming.!!! There is a built-in coma corrector but i forgot to ask the design.  My time was spent at the EP of this scope and while others were chatting about the design and specifications, I was observing so was not listening. Now I wish I knew more......

 

The images were "perfect" at least for me. I am not a testing guy, I am an observing guy. Had about 5 hours total at the scope to chase down several remote and special objects off the beaten path and was very successful in locating and seeing all the chosen optics.  I had been trying observe one object up near NGC 205 and observed in many scopes up to 41" and the object was not seen. I did locate and observe the remote galaxy in this scope. Seemed no matter what magnification I used, the images were pinpoint stars.  I greatly enjoyed using my ES 9mm x 120 with wonderful views of the skies!!

 

Eyepiece height was perfect for me at the zenith, I am 5' 8".  

 

I have been thinking about a larger scope at one point and was looking at something around 30", an expensive proposition and an instrument that could be bulky and heavy and not used much. After seeing the performance of the Lockwood optics and the resulting physical size of the OTA I am coming to believe a 24" f/2.75 scope could be the very very best scope a person could own.  

 

So, simply put, this is by far the VERY best scope I have ever used!!!  Period!!!


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#2 IVM

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Posted 24 July 2017 - 10:38 AM

Nice to hear it was put to critical use, not just talked about ;) Thanks for the report.

 

"Drives" means "is hauled like a trailer", right?



#3 NiteGuy

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Posted 24 July 2017 - 10:39 AM

Great report, thanks for posting. I'd be very interested to also hear about collimating challenges, how well the scope holds collimation from horizon to zenith and if it needs to be collimated every session. That does sound like it just might be the perfect scope.



#4 opticsguy

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Posted 24 July 2017 - 11:21 AM

"Drives" meaning it is self powered and drives like a remote controlled electric powered lawnmower.  The owner of the scope drove it up about 200 feet to the observing location, up a hill.  This is not a lightweight scope (300? pounds) but it is almost the perfect scope.  And I have observed through one heck of a lot of scopes. The owner designer is brilliant.

 

Someone asked about collimation from horizontal to vertical.  Answer;  PERFECT!!


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#5 turtle86

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Posted 24 July 2017 - 11:40 AM

Sounds like an ingenious scope. I'd be curious to hear how Jupiter and Saturn looked through it, though I realize a scope like this is primarily intended for deep sky observing.

 

Look forward to seeing some pictures!



#6 MitchAlsup

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Posted 24 July 2017 - 11:50 AM

"Drives" meaning it is self powered and drives like a remote controlled electric powered lawnmower.  The owner of the scope drove it up about 200 feet to the observing location, up a hill.  This is not a lightweight scope (300? pounds) but it is almost the perfect scope.  And I have observed through one heck of a lot of scopes. The owner designer is brilliant.

 

Someone asked about collimation from horizontal to vertical.  Answer;  PERFECT!!

I am planning on making my 30" F/3 drive as if it were an Radio Controlled car but closer to 1-2 MPH than 60 MPH:: Drive the trailer to the observing site, open the tailgate, unlash the scope tiedowns, press a few buttons and the scope drive out of the trailer and sits itself on the ground. Assembly is still yogurt powered.

 

Good to know others are thinking similarly.

 

Since I am also building some other scopes, I wonder if your friend has thought of electronically combining the drives of several scopes so that if you find something in one scope, a few pushes of a button, a few seconds of movement, and the object is centered in some other scope.


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#7 Mike Lockwood

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Posted 24 July 2017 - 01:28 PM

Good to hear some reports about that telescope, I'm happy to hear that it made it out to a star party!

 

I am hoping to get some photos from the owner/builder and would like to feature it in a short article if he is agreeable to that.  I've heard enough about it from him and seen enough of it in some under construction photos to know that it's something quite special (in terms of design and features) and I think people should see what the owner/builder has accomplished and appreciate the planning and time that went into it.

 

The telescope uses the Starlight SIPS for coma correction.  This works pretty well at f/2.75, but that is as fast as I recommend for high-quality visual use.

 

As for collimation of an f/2.75, to paraphrase Mark Twain, reports of the difficulty of collimating fast instruments has been greatly exaggerated.  The owner/builder had Aurora Precision make a mirror cell that follows my mirror cell recommendations (whiffletree/roller edge support), and it is very solid and well-made.

 

Finally, with the right eyepieces, there is no reason you can't enjoy planetary observing with such an instrument.  This 24" has a 6.5" secondary and a 27% obstruction and will still produce very good views of planets when conditions are good.  24" is a lot of light and resolving power.


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#8 turtle86

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Posted 24 July 2017 - 02:09 PM

I hope that a short article about this scope (with pictures!) comes to fruition.  The engineering that went into it really sounds cutting edge.

 

Plus, the 24" mirror has nearly twice the light grasp of my 18", yet the scope is still nearly a foot shorter. 



#9 PEterW

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Posted 25 July 2017 - 02:02 AM

The speed bug seems to be gaining on aperture fever as the most dangerous affliction in these parts.

Peter
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#10 Tom Masterson

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Posted 25 July 2017 - 12:35 PM

Here's some pictures of Elvira, the scope I describe as a love child of NASA and Tesla. She's part Mars rover part exotic sportscar.

 

This is the FIRST telescope he's ever made! It's seems as if he has literally thought of everything. The attention to the tiniest detail is superb. It's not only innovative, but every detail has been thought through. As an example, please note the mirror cover in the photo. It's not just simply a cover, the large knob on top twists, locking the cover in place, but that's not all! The cover is also vented. When you twist the locking knob, it also opens or closes vents in the cover allowing fan driven, filtered air to be blown from the back of the mirror, through special baffles, around a specially curved part of the mirror box, that directs the air around the mirror's edge, and across it's face. Since the air blows across the mirror face from many directions, the flow meets in the center and turns upward to exit the vent. This pre-cools the mirror without removing the cover, and the design also disrupts the boundary layer at the mirror's surface when observing.

 

Unfortunately, I wasn't able to get any photos of the scope free from its docking and transport cart. Yes, the red, U-shaped wheeled base doesn't stay in place after the scope is set-up, it's only for charging and transport. (NOTE: The safety wheely wheels on the base he says the cart can really move and these provide additional safety when going up a ramp) When it's time to observe, there's three small hydraulic jacks in the telescope base that lift it up off the cart, at which time the cart is driven away from the scope, the jacks are then used to level the base. The only physical lifting involved, is inserting the carbon fiber truss tubes in their sockets, placing the thin rotating case base on the truss tubes, and attaching the secondary cage. The mirror is stored in the scope even during transport in a ramped cargo trailer, cushioned by the transport cart's soft rubber tires against shocks. No heavy lifting is involved unless servicing of the drive components hidden in the base is required. Sounds like the perfect large scope for us "older" astronomers or others with lifting limitations. 

 

As for the question of collimation, it can be done remotely from the eyepiece using a small push button keypad which can be seen above the focuser in the photos.

 

This scope not only is driven in push-to mode as described above, it also can be run in go-to mode wirelessly from a tablet. In either case, it is running in a closed loop feedback system to the tablet running Sky Safari software via encoders.

 

For me, the innovation I enjoyed the most, was the handle on the upper cage that could be used for push-to operation. Because the scope's axis are locked in drive mode, it doesn't make any difference what eyepiece you put in the focuser. NO rebalancing is required! You must learn a proper technique for pushing the scope to a new location because as mentioned above, when you close your fingers around the handle, they break an infrared beam which then unlocks the clutches releasing the drive. If you have a heavy eyepiece in the focuser, this can send the scope slipping downward. My first trick for preventing this was to place one hand on the top of the cage as you would when using a dob, then taking my other hand to grasp the handle. A very soft click tells you the clutches have released and light upward pressure stops the scope from dropping in altitude. After a while with the scope I even up doing it one handed using only the handle. I found myself cupping the handle with slight upward pressure before closing my fingers around it, breaking the beam on the backside. It sounds like something you have to think about, but I assure you, within a short time it becomes very natural and transparent. I loved that innovation! I had asked what kind of sensor he used to detect your hand, speculating it was capacitive touch sensor. He replied he had tried that at first and found it didn't work with gloves, so he switched to a simple ir led emitter and photo eye on the mount of the handle. Regarding the clutches themselves, he moves them with linear actuators that only draw power for about 3/10ths of a second when moving the clutch disks, not continuously like solenoids would to save power. Everything is run off internal lithium-ion batteries in the scope's base which are good for three nights observing, and these are charged from the transport base without wires when the scope is "docked" in the base.

 

There's so many more things I could say about this scope, but it would take pages talking about the details and innovations that I know of because there are so many. Believe me when I say, he's thought of everything down to the smallest of details! Yet, for all it's complexity in design, the scope was as easy to use as any simple dobsonian or go-to scope. WOW!

 

 

Attached Thumbnails

  • ElviraGuts.jpg
  • ElviraDocked.jpg
  • Elvira.jpg

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#11 Tyson M

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Posted 25 July 2017 - 10:13 PM

That is seriously amazing. Thanks for sharing the pics and write up.

#12 bvillebob

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Posted 25 July 2017 - 10:34 PM

Honestly, when I read the first post, I kept waiting for the punch line.  I checked the date to be sure somehow April hadn't come around again.  Amazing to see the reality, thanks for the pix.


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#13 ctcables

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Posted 26 July 2017 - 01:37 AM

Wow, very cool telescope, I am using a powered wheel char parts to drive my 34" around with a joy stick.  I would love to talk with the person that made this outstanding setup. I am sure there is much I could learn from him to add to my build. Thank You for posting and I hope to see it at a star party some day.


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#14 Bob S.

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Posted 26 July 2017 - 04:34 AM

I wonder how John Dobson would react to it? Colin Chapman of Lotus 7 car fame was loosely quoted as saying "Simplify, then add lightness". Does not seem to conform to Chapman's cheap approach to building fast race carslol.gif

 

All in all, what a testament to man's ingenuity and creative thinking. An amazing 24" telescopebow.gif

 

I wonder how the owner gets the primary equilibrated and able to track ambient temps with all the metal and machinery surrounding the primary mirror?


Edited by Bob S., 26 July 2017 - 09:43 AM.

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#15 CHASLX200

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Posted 26 July 2017 - 05:13 AM

Kinda reminds me of the Rand RAMO scopes back in the mid 70's.



#16 Tom Masterson

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Posted 01 August 2017 - 11:57 PM

Bob,

 

I don't remember the exact number but he has several fans running behing the mirror. Four maybe? He said he designed the cover to have vents that open so he can start the mirror cooling ahead of time without ever taking the cover off. He then can observe with the fans running. As I mentioned he designed the air-path not only to cool the back of the mirror, but to exhaust out and across the mirror face to deal with the boundry layer. One thing I didn't mention about the fan system is he told me he used a different type of fan, one that doesn't vibrate at right angles to the optical path which could induce vibrations in the image. Any vibrations the fans may produce are along the optical axis of the scope which shouldn't affect the image. He really thought of everything right down to which way a fan would vibrate. There were several times when I stopped by to play with the scope where he'd ask me if I wanted the fans turned off. I never knew they were running in the first place! Of course I never tried viewing a planet at high power to look for vibration, but I couldn't even hear the fans running.

 

I suspect the mass of the mirror is going to be the slowest to shed heat compared to the fairly thin aluminum sheet metal of the lower scope. Although daytime temps were pretty high, the night temps remained pretty stable for the several nights I used the scope. Star images were quite tight which lent me to believe the mirror was tracking temps pretty well but then so was my unventalated 12" sct so these weren't really good nights to tests the cooling system.

 

Also keep in mind the big red aluminum box you see around the base of the scope in the photo is the transport cart which is undocked and moved away from the scope while observing. Unfortunately I was unable to get a photo of just the scope without the transport base. The actual scope base and mirror box are pretty compact.


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#17 Bob S.

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Posted 02 August 2017 - 09:54 AM

Bob,

 

I don't remember the exact number but he has several fans running behing the mirror. Four maybe? He said he designed the cover to have vents that open so he can start the mirror cooling ahead of time without ever taking the cover off. He then can observe with the fans running. As I mentioned he designed the air-path not only to cool the back of the mirror, but to exhaust out and across the mirror face to deal with the boundry layer. One thing I didn't mention about the fan system is he told me he used a different type of fan, one that doesn't vibrate at right angles to the optical path which could induce vibrations in the image. Any vibrations the fans may produce are along the optical axis of the scope which shouldn't affect the image. He really thought of everything right down to which way a fan would vibrate. There were several times when I stopped by to play with the scope where he'd ask me if I wanted the fans turned off. I never knew they were running in the first place! Of course I never tried viewing a planet at high power to look for vibration, but I couldn't even hear the fans running.

 

I suspect the mass of the mirror is going to be the slowest to shed heat compared to the fairly thin aluminum sheet metal of the lower scope. Although daytime temps were pretty high, the night temps remained pretty stable for the several nights I used the scope. Star images were quite tight which lent me to believe the mirror was tracking temps pretty well but then so was my unventalated 12" sct so these weren't really good nights to tests the cooling system.

 

Also keep in mind the big red aluminum box you see around the base of the scope in the photo is the transport cart which is undocked and moved away from the scope while observing. Unfortunately I was unable to get a photo of just the scope without the transport base. The actual scope base and mirror box are pretty compact.

Tom, Thank you for this very critical piece of information about the scope. It appears that the owner/builder has really paid attention to critical details that could have derailed this "over-the-top" Newtonian. As you and I know, thermal regulation and proper mirror support coupled with steady skies and good seeing are the keys to optimum performance. It appears that even with all of the incredible amount of detail that the owner has incorporated into the scope that he has paid close attention to the gremlins that most affect a Newtonian's performance.

 

I hope I get to see this scope in person one day. Thanks for the update and maybe the owner is following this thread and will show us some more pictures of the scope without the docking station and tell us about the fans he is using (MagLev fans by Sunon?) Bob


Edited by Bob S., 02 August 2017 - 09:58 AM.


#18 Don W

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Posted 02 August 2017 - 08:12 PM

Ummmm..........Zambuto does coatings now?



#19 Mike Lockwood

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Posted 02 August 2017 - 08:27 PM

Don, he started coating/recoating his own mirrors a few years ago.  He offered to coat my mirrors.

 

He does not do general coating and recoating of other optics.


Edited by Mike Lockwood, 02 August 2017 - 08:31 PM.

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#20 Don W

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Posted 02 August 2017 - 09:09 PM

Wow, I was not aware of that. Thanks.


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#21 SandyHouTex

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Posted 03 August 2017 - 08:33 AM

Ummmm..........Zambuto does coatings now?

I just recently found out that he melts his own Supremax and casts and anneals it!  He has control of every one of his processes for making mirrors.


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#22 Pinbout

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Posted 03 August 2017 - 08:49 AM

 

Ummmm..........Zambuto does coatings now?

I just recently found out that he melts his own Supremax and casts and anneals it!  He has control of every one of his processes for making mirrors.

 

and he can levitate like david blaine

 

https://www.youtube....h?v=pVhJ8pXKaKQ

 

lol.gif


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#23 Mike Lockwood

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Posted 03 August 2017 - 10:44 AM

Well, getting back to the subject of this thread, the 24" f/2.75, this Supremax blank was provided by a very experienced glass company that I work with, and is of superb quality and anneal.

 

This mirror actually came about after a different client ordered one for a scientific use, and I ordered an extra blank and partially finished it.  Luckily it was just what Ed, the client, was looking for.

 

I haven't seen the cooling system, but I know that we spoke about cooling strategies on the phone as he was designing the telescope.  Metal cools much faster than wood, by the way, and thin metal cools extremely quickly.

 

I'm hoping that Ed will participate here in the future.



#24 turtle86

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Posted 03 August 2017 - 01:20 PM

Tom, thanks for posting these pictures. The engineering and level of workmanship are astonishing.  However, even with all the cutting-edge technology incorporated into the scope, what struck me the most is that is still has a humble Telrad for a finder.  I think it says a lot about the simple ingenuity of the Telrad that there is still room for one even on a scope like this.



#25 Bob S.

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Posted 03 August 2017 - 06:16 PM

Getting back to what Mike Lockwood was trying to do about redirecting the thread to the fact that this is a 24" f/2.75 scope, without adding any vendor comments related to marketing (thanks Mike), a 24" f/2.75 scope that produces sharp images is no small feat. I had an opportunity to do a shootout with a 28" f/3.5 Lockwood/Starmaster I owned up against a 28" f/2.75 Lockwood/Webster on two occasions and I have come to believe that the figure on the 28" f/2.75 was just slightly better than my "slower" 28" which I had Mike make a .5" larger secondary for. We are really talking about picking very, very minor nits when I say that there was much of a difference. However, the nod continually went to the 28" f/2.75 in terms of tightness of stars which is really amazing. What is further potentially amazing is that another optician that would join the small handful I was mentioning seems to have made a 28" f/3.58 that I currently own in a Webster telescope that I would dearly love to have go up against the f/2.75 because it anecdotally is showing me the tightest star points I can remember in a large scope. However, as many of us who are super critical know, you have to have the same scopes out on the same night under the same stars at the same magnifications to get a true understanding of the differences in performance at the nit-picking levelshocked.gif

 

That the OP was reporting that he had gotten the best views he had ever had from a Newtonian is truly testament to the art and science that has allowed folks like Lockwood and only a few others that you can count on one hand to produce mirrors that are uber fast and uber sharp. That coupled with what appears to be one of the most complex Newtonians on the planet and it appears that all concerned in the build hit home runs! Kudos to everyone for pushing up the bar and becoming the reference standard that all Newtonians may have to be compared to if things continue to rock along as well as is being reported on this scope.


Edited by Bob S., 03 August 2017 - 06:53 PM.

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