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Equipment Discussions >> Reflectors

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johnnyha
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5576742 - 12/18/12 02:07 AM

Be-yooo-tee-full!

Is that going to have a SIPS installed Bob?


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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: johnnyha]
      #5576791 - 12/18/12 03:42 AM

Quote:

Be-yooo-tee-full!

Is that going to have a SIPS installed Bob?




Johnny, A SIPS is indeed a part of the system. Do not know if it will work with the Mallincam and sure know it will not work with my binoviewers. I also have a HUGE 3" Starlight Instruments fine focusing knob for the SIPS that should make focusing a cinch with the native focal ratio of f/3 and it being more relaxed witht the SIPS. Bob


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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5580160 - 12/20/12 07:30 AM Attachment (117 downloads)

Well Astro Buds, The 20" JPA finally got first light under Florida skies last night. The seeing was only about 6/10 and transparency was about 7/10 under an almost 1/2 moon. I was able to test the SIPS (Starlight Instrument Paracorr System) which worked wonderfully with my Ethos EP's presenting pinpoint stars to the edge on 17mm Ethos ep's. I think it was equally comfortable with the 21mm Ethos in terms of coma but did not spend enough time with the ep to determine how precise the starpoints were at the periphery. Jupiter was looking pretty decent with 8 and 10mm Ethos ep's.

After doing a non-critical two-star initial alignment, I did subsequent align on stars procedures with the Argo Navis and the scope with a 10mm Ethos was putting Jupiter and Uranus which were about 180 degrees apart right smack dab in the center of the eyepiece. I will include a couple of real-world pics since all of the others were in the shop.


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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5580166 - 12/20/12 07:34 AM Attachment (111 downloads)

Here is a view on the focuser side of the scope. You will notice in the picure above that the whole scope is powered by one electrical cord. It turns out the that computer dew heater was pulling so much power that it caused my 5 amp regulated power supply to shut down due to overheating when I was running everything. I went to my 111 amp/hour marine battery and the scope ran like a charm. I left the front fan blowing on the face of the mirror on at the lowest setting after turing off the rear sucking fan. The mirror had equilibrated quite rapidly and there was no need for the rear fan.

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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5580168 - 12/20/12 07:37 AM Attachment (103 downloads)

It was a bit chilly last night and so I kept the wireless handpad in my coat pocket and directed the scope while pushing the buttons by feel. Gary Myers of ServoCat had made the handpad tactile friendly and it was easy to do. The integrated wheel system allowed for rapid deployment and return of the scope to the garage with a minimum of fuss and bother. Simply closed two latches on the back of the mirror box, tightened the turnbuckle on the front of the mirrorbox/rocker box, set the pin in the foot that correctly aligns the scope to the feet and tilted the scope over and rolled it in and out of the insulated garage. Could not be an easier way to begin viewing with a large scope. All systems so far are working well. Next step is to play with a Mallincam Hyper Plus directly connected to the 3.5" color LCD monitor positioned on the UTA and see how it works and if it will work with the SIPS in place? The rubber-backed carpet seems to prevent thermals from the driveway coming up much around the scope. However, I am eyeing that patch of grass in the picture as a likely more ideal setup spot to take advantage of the Northern sky and also to get off of the concrete. I have all my scopes able to roll rather than trying to carry anything which is a pain in the butt. The scope ergonomically is a dream. John Pratte tried to think of every way in which the scope would be user friendly and require the least amount of fiddling. We certainly accomplished all of the original design goals and a host of others almost too numerous to list. The 8 month collaborative effort produced some very interesting and unexpected features that neither of us would have dreamt of until we got into the build of the scope. I have had a tendency to buy and sell scopes over the years but this scope will be my permanent large aperture scope for now and into the future. As I age, utility and ease of use trumps many other potential options/benefits.

Edited by Bob S. (12/20/12 08:00 PM)


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Jarad
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5581419 - 12/20/12 08:36 PM

Congrats!

Maybe this will be the scope that finally permanently captures your heart.

And if not, I call first dibs!

Jarad


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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Jarad]
      #5582675 - 12/21/12 03:22 PM

A significant proof of concept occurred today. I placed a glass of water on top of the front mirror fan frame that is mounted on Sorbothane mounting pads in the mirror box and turned the Maglev fan on at full to low speed settings and there was no vibration detected in the glass of standing water. I then turned on the much larger rear Maglev main sucking fan that is completely isolated in Sorbothane at full speed with the front fan going at full speed and rested it on the edge of the mirror box and there was no detectable vibration in the water. I then placed the glass of water with both fans going at full speed up on the ring of the UTA (upper tube assembly) to see if there was any harmonic vibrations being transmitted to the upper cage and there was no detectable vibration noted in the glass of water. This lack of vibration is likely attributable to the Maglev fans and mounting techniques. It is a very welcome finding suggesting that the relatively extreme measures that John Pratte of JP Astrocraft took to isolate the fans from causing vibration paid off handsomely.

Jarad, As the scope took shape and Mike Lockwood figured the primary mirror, at the completion of the mirror figuring, I had him inscribe my three initials with another set of three letters "RIP". My spouse will unfortunately have to have one of my buddies sell the scope when I die, become disabled or get out of the hobby

Edited by Bob S. (12/21/12 04:54 PM)


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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5583741 - 12/22/12 09:06 AM Attachment (92 downloads)

A second significant proof of concept occurred earlier this morning of December 22. I equilibrated the scope from 5:20 until 6 a.m. using both front and rear fans of the CBLMS (Comprehensive Boundary Layer Mitigation System) and then proceeded to get first light of the year on Saturn which started at about 30 degrees above the horizon and by 7:30 a.m. was at about 60 degrees above the horizon. Saturn is a great target to test resolving capabilities and this morning's task was to ascertain how the fan systems would work with improving/degrading the image of the planet. I had my 10mm Ethos in the SIPS system which gave me 175x magnification. Seeing was about 6/10 and as the planet climbed higher in the sky continued to show more fine detail culminating in views with the Sun coming up but still presenting decent images until about 7:35 a.m.

In Illinois a month before the scope was completed, we only had the rear fan operational, on the first light night, we found that the image of Jupiter from an unequilibrated mirror cleaned up instantly when we turned on the enclosed sucking fan. We also found that using that fan at high speed by itself caused the primary mirror to shift into an overcorrected state per Mike Lockwood as he tested the mirror during the session. We all figured that adding the front fan would eleviate the overcorrection problem by not only cooling around the edges of the mirror but equally cool the center mass of the primary thus maintaining the neutral figure of revolution that Mike had put into the mirror.

This morning, my first task was to run the front fan only at the lowest speed which creates a gentle breeze on the front surface of the equilibrated 1.25" thick primary and the views of Saturn were good and getting better as it rose higher in the sky. I experimented with turning the front fan on and off and each time I turned it back on, the images were more detailed. So, that part of the CBLMS was proving itself to be additive.

Now, the big question in my mind and that of Lockwood and Pratte was if the rear sucking fan that is fully enclosed in the back of the mirrorbox coupled with the annulus that is in front of the primary mirror and about 1/2" larger in circumference than the front mirror would indeed draw air off the boundary layer and thus contribute to an improved image? I am VERY happy to report that it indeed worked. The most detail seen in the Cassini Division and other parts of the ring structure including the surface detail of Saturn were when the entire CBLMS consisting of the front blowing fan and the rear sucking fan were operating at their lowest rpm settings. Below is a picture of the scope pointing at Saturn this morning at 7:30 a.m.


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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5583758 - 12/22/12 09:20 AM Attachment (107 downloads)

Now, there is another side-story that continues to evolve and is making this for me, the finest visual scope that I have ever used. As many of you know, I elected to incorporate the Starlight Instrument Integrated Paracorr System as the f/3 seemed to dictate the need for this as well as to not have to fiddle with Paracorr II settings in the conventional Paracorr. With the SIPS system, any eyepiece used is corrected best for coma by the system. The second neatest feature of this system is the large 3" brass focuser knob that Starlight Instruments sells for their SIPS system that made focusing the most pleasant experience that I have EVER had! I cannot even begin to figure what the ratio is but with gloved hands this morning, just a light touch of the knob and the focus was at the pinnacle of perfection. As many of you know who own fast systems, focusing with a very limited depth of field can be a little bit of a challenge. Couple that to the changing seeing conditions and fiddling with the focuser knob even in a conventional Feathertouch focuser is a bit demanding. With the large 3" knob, all of these challenges fall to the wayside. It is so simple to lightly touch the wheel to get best focus that I was almost hoping for seeing changes just to play with the large knob. It is sooooooooo easy. Here is a picture of the 10mm Ethos in the SIPS with a dew strap on the ep and the 3" focuser knob that operates the fine-focus of the Feathertouch.

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Bill Barlow
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5583868 - 12/22/12 11:03 AM

I'm envious, Bob. Would love to get a few looks through the eyepiece of this fine instrument. Enjoy!

Bill


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Relativist
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5584328 - 12/22/12 04:22 PM

Quote:

A significant proof of concept occurred today. I placed a glass of water on top of the front mirror fan frame that is mounted on Sorbothane mounting pads in the mirror box and turned the Maglev fan on at full to low speed settings and there was no vibration detected in the glass of standing water. I then turned on the much larger rear Maglev main sucking fan that is completely isolated in Sorbothane at full speed with the front fan going at full speed and rested it on the edge of the mirror box and there was no detectable vibration in the water. I then placed the glass of water with both fans going at full speed up on the ring of the UTA (upper tube assembly) to see if there was any harmonic vibrations being transmitted to the upper cage and there was no detectable vibration noted in the glass of water. This lack of vibration is likely attributable to the Maglev fans and mounting techniques. It is a very welcome finding suggesting that the relatively extreme measures that John Pratte of JP Astrocraft took to isolate the fans from causing vibration paid off handsomely.

Jarad, As the scope took shape and Mike Lockwood figured the primary mirror, at the completion of the mirror figuring, I had him inscribe my three initials with another set of three letters "RIP". My spouse will unfortunately have to have one of my buddies sell the scope when I die, become disabled or get out of the hobby




Very nice. If you have an iPhone you could use iSeismometer (or similar app) as well. The best measurement would be to use a laser, that said if you don't notice any difference visually then I wouldn't worry about it further.


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nsldvd
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5584498 - 12/22/12 06:42 PM Attachment (66 downloads)

Quote:

The second neatest feature of this system is the large 3" brass focuser knob that Starlight Instruments sells for their SIPS system that made focusing the most pleasant experience that I have EVER had!




That's a great addition to the SIPS. A while back we could see the light bulb turning on when John Joseph was at Chiefland. It's really just a big plus for any focuser w/or w/out SIPS, fast or slow...


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johnnyha
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5585020 - 12/23/12 01:55 AM

Bob that's the first I've seen the Jumbo Knob. I'd really like to know how much more it sticks out than the original little fine focus knob but I can't find the dimensions - can you estimate approximately how much?

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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: johnnyha]
      #5585360 - 12/23/12 10:46 AM

Quote:

Bob that's the first I've seen the Jumbo Knob. I'd really like to know how much more it sticks out than the original little fine focus knob but I can't find the dimensions - can you estimate approximately how much?




Johnny, The original gold fine focuser knob's diameter is 13/16". The new focuser knob which is $49 from Starlight Instruments is 3" in diameter. They list a 1.75" brass knob for $29. The 3" knob is pretty intrusive and frankly can only be used when the SIPS is in place. I would suspect that the 1.75" knob might have more clearance for some applications? I am thinking that I would like to try the 1.75" knob and see how that feels. Bob


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johnnyha
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5585782 - 12/23/12 03:11 PM

Bob thanks. What I was wondering though, is what is the total thickness rather than the diameter? In other words how far extra does the jumbo knob protrude outwards? The jumbo knob looks to stick out at last 1" whereas the original fine focus knob is about 1/2".

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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: johnnyha]
      #5586036 - 12/23/12 05:55 PM

Quote:

Bob thanks. What I was wondering though, is what is the total thickness rather than the diameter? In other words how far extra does the jumbo knob protrude outwards? The jumbo knob looks to stick out at last 1" whereas the original fine focus knob is about 1/2".




Johnny, The 3" large fine-focus knob protrudes out from the attachment point 1 3/8" as opposed to the 1/2" of the stock fine-focus knob. Bob


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johnnyha
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: Bob S.]
      #5586382 - 12/23/12 10:26 PM

Bob thanks, so it sticks out an extra 7/8", thats about what I thought. Anyway... that is one masterpiece of a scope you have put together, truly. Kudos.

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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft new [Re: johnnyha]
      #5586617 - 12/24/12 03:07 AM

Quote:

Bob thanks, so it sticks out an extra 7/8", thats about what I thought. Anyway... that is one masterpiece of a scope you have put together, truly. Kudos.




Johnny, It has been a lot of fun developing this scope with the help of John Pratte, Mike Lockwood and Gary Myers. I had an interesting conversation with Fast Mike who owns a 28" f/2.75 Lockwood/Webster this afternoon and we were comparing notes on SIPS system performance, eyepiece performance in ultra-fast scopes, cooling fan strategies and secondary mirror holder arrangements. As you may remember, Fast Mike's scope is sporting a 7" diagonal whereas mine is only 5" in the minor axis.

One of the things that we both have found is that the 17mm TeleVue Ethos is very close to bottoming out for in-travel when using the SIPS and gives about 1/2 turn of the fine focuser knob "freeboard" from the bottom of the 1.5" focuser travel to come to focus. He mentioned this is true of the 31mm Nagler which I have not tried using yet in my scope.

An interesting but slightly disconcerting thing we both encountered was that the Leica ASPH Vario zoom with 2" adapter is needing about 1/8" of further in-travel to come to focus with an unmodified adapter from APM. If you shave off the 1/4" ridge on the top of the adapter, the ASPH will come to focus with no problems. Not a big deal but there are always some new things that you discover on the way to the observing field

What was very interesting is that his eyes (Fast Mike) and my eyes found the SIPS position to be relatively similar and I had independently confirmed the amount of "freeboard" with the 17mm Ethos and the SIPS. He pointed out that because the in-travel requirements were the most extreme for the 17mm Ethos and the 31mm Nagler, he uses the 17mm Ethos as the reference for getting proper positioning and sharpest focus of the SIPS rather than the Scotch tape method recommended by the manufacturer and the plastic device they supply. What we both noticed is that that particular method utilizes tape that can vary and requires glasses or a magnifying glass to check best correction when applied and thus potentially throws off the proper tuned position of the SIPS system. Fast Mike has found that the use of the 17mm Ethos is a more reliable method for setting the SIPS and I plan to use the same method.

What the above-mentioned circumstances remind me of is that when you get into faster and faster equipment that is pushing the envelope, there are things to be discovered and accomodated for. Mel Bartels was giving a lecture on the design of Newtonians that I attended out at the Golden State Star Party this past year in California and he noted that the equipment like eyepieces and coma correctors were the limitations imposed for fast optics and that the demand, and manufacturer's response to the demand, helps set the bar as to what our limits will be. I know that there are numerous people that are contemplating scopes in the 40"-70" range that will want their optics to be in the sub f/3 range and as Bartel's pointed out, the only limits are what the optics manufacturers are willing to supply us with. The TeleVue and Starlight Instruments companies among others are helping us to explore ever faster optics that will perform at the levels that some of us demand in our premium Newts. It is a very fun time to be in the hobby and it is a blessing that we have very talented folks that can help us operationalize our dreams. Bob

Edited by Bob S. (12/24/12 03:46 AM)


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cpr1
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft [Re: Bob S.]
      #5586959 - 12/24/12 10:36 AM

Amazing scope Bob. It reminds me of the atomic bomb "fat man" for so reason.

Just curious as to why the argo navis/computer is on the opposite side of the focuser?


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Bob S.
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Re: First Light On My 20" f/3 Lockwood/JP Astrocraft [Re: cpr1]
      #5587013 - 12/24/12 11:10 AM

Christopher, I would hope that the scope would remind you of things much grander and more pleasant than an A-bomb. I was born in Tokyo 4 years after the end of WWII and that was a sad era for the world and a very sad era for our Japanese friends.

On a brighter note, the reason for placing the command center on the other side of the scope is that I wanted to be able to comfortably sit at the eyepiece without the glare of computers/video output being anywhere near the eyepiece area or bouncing off the light path when doing astrovideo. I also wanted an unobstructed sitting area at the eyepiece for the 50% of the time that I will be using the scope visually. The other 50% of the time, the command center houses a laptop computer with planetarium program that will inform the ArgoNavis and also control my Mallincam Extreme astrovideo camera. The control center also houses the wired handpad and allows me to carry the wireless handpad with me wherever I am around the scope. It has a power transformer for the laptop's precise power needs and with all of those wires, it made sense to me to place the command center on the opposite side of the scope. As you can see, the control center is rather large and I did not want it to interfere with the operation of the scope.

Edited by Bob S. (12/24/12 11:11 AM)


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