# My f/4.9, 1500 mm



## KmH

I have mentioned before I had new lenses put in my eyes and can see very well at a distance again.

That re-sparked my interest in astronomy, so UPS delivered 3 big boxes Monday afternoon that contained my new, fast, 12", f/4.9, 1500 mm Newtonian telescope and Dobson type altitude-azimuth mount.

The 2 biggest boxes weighed 90 lbs together so the UPS guy had to use a hand cart to get the boxes to the back door.






Tres cajas (3 boxes)
The 12" mirror in it's mirror cell was very well packaged by itself in a double box (22 lbs). It's the box on top of the biggest box. The flat box (42 lbs) has the base/mount parts in it. The biggest box (48 lbs) holds the 14" optical tube sections and sundry other parts.





The main telescope mirror all snug, cozy, and safe in it's shipping box.





Here is the base all assembled. The Altitude and Azimuth bearings have electronic magnetic position encoders on them that report to a 9v battery powered, hand-held object locator computer that plugs into the center of that white circle on the near side panel. The silver disc on the far side panel is the altitude position encoder. Because of the grass you can't see the lower part of the base that has 3 feet on the ground. The part of the base you can see is the azimuth bearing and it rotates on that lower base.
Once an telescope alignment sequence has been completed, the object locator computer gives directions for moving the telescope in altitude and azimuth





To aid portability the optical tube assembly (OTA) has 3 sections.
The lowest section has the main mirror in the bottom of it. Here I have the tube section cover on so nothing can fall onto the 12" wide main mirror. This section of the OTA has 2, 8" altitude bearings on the sides and 4 truss rod brackets around the top of it.
We cannot see here is a fan on the bottom of the mirror cell to help get the thick Pyrex mirror to the same temperature as the ambient air temperature. The mirror cell fan is powered by 8, D-cell batteries.





Here I took the tube cap off for an oblique look down at the mirror. The surface of the mirror is not flat. It has been ground to the shape of a parabola that causes light to focus 1500 mm from the mirror. You can see 2 of the 3 edge clips that hold the mirror in it's 9-point flotation cell. The shot also shows the top of the altitude bearing on the side of the tube and the bolts and nuts inside the tube that mount the 2 bearings to the tube.





Down the tube.







Here the 8 truss rods have been attached to the 4 truss rod mounting brackets on the lower tube section.





The top tube section with it's 2"/1.25", 2-speed (11:1), Crayford style eyepiece focuser and 9x50 finder scope now secured to the top of truss rods. I have moved the telescope in altitude
Also the object locator computer is plugged in and stuck to the side panel w/Velcro.





Here is a shot that shows the flat, oval, tilted at 45° secondary mirror that deflects the light from the main mirror 90° and out the side of the tube to the focuser. If you look in the focuser without an eyepiece in it, the tilted, flat secondary mirror looks round. To the right of the focuser you can see the mount for the finder scope - without the finder scope in the mount.





To give a sense of scale, I got some overweight, 5' 10" tall old guy to stand next to the telescope.


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## 480sparky

So, when exactly did Aperture Fever take hold?


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## D-B-J

That's monstrous. I'm assuming you can attach a dslr/mirror less to it, yes? Can't wait for some images!


Sent from my iPhone using Tapatalk


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## Designer

He looks happy to have the new telescope!  Congratulations!


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## KmH

480sparky said:


> So, when exactly did Aperture Fever take hold?


"Go big! Or go home!" It's cloudy tonight so the mosquitoes are going to starve without me outside to suck blood out of.

For a time when I lived in Tucson I was a volunteer at the Flandrau Planetarium on the campus of the University of Arizona.

I leveraged that association to garner some observing/photography time on several Steward Observatory telescopes in and around Tucson.

Back then I had a 6" Meade Newtonian on a motor driven EQ mount, and an 8" Celestron Schmidt Camera on a Celestron motorized EQ mount. With the Celestron I could expose 1 frame of film at a time. An exposure of the Andromeda galaxy that imaged the outer reaches of Andromeda took about 45 minutes, and no auto-guiders.

This is a big as I could justify from an ease of portability perspective.
Orion makes a 14" f/4.6 that isn't much more costly, but just enough more unwieldy that I went with the 12".
Assembled my XX12i weighs 86.5 lbs - 34 lbs for the base, 49.5 lbs for the assembled OTA, and 3 lbs for the finder and 2 eyepieces that are included with the telescope.
The base, 2 tube sections, and truss rods all fit in the back of my car with little room to spare.
I have to tilt the base to get the side panels in and then they barely clear the roof.
The short upper tube section sits on the bottom of the base.

I didn't get the GoTo version of this 12" truss rod telescope because with the GoTo motors and beefed up base it weighs 128.75 lbs.



D-B-J said:


> That's monstrous. I'm assuming you can attach a dslr/mirror less to it, yes? Can't wait for some images!


12" is a good size but there are bigger amateur telescopes.
Teeter's Telescopes in Rockaway, NJ make fast dobsonian mount telescopes with up to 22" f/3.3 mirrors (only $11,050). They make it f/3.3 to keep the eyepiece about the height of an adult man.
Yes some photos, but with a couple of serious limitations:
1. This telescope is optimized for visual use. Telescopes of this type (Newton telescope) optimized for doing astrophotography (they are known as astrographs) have the prime focus outside the telescope tube. Other telescope types make even better astrographs, but they are heavier and require a more substantial mount.
2. Telescopes for astrophotography have a motorized mount that counters the earth's rotation on it's axis. This telescope is moved manually. The computer object locator with this telescope is a PushTo system that just shows the telescope operator -me- which way and how much to push the telescope in altitude and azimuth. The initial numbers displayed get smaller the closer to the selected object I get. Some of the things I want to look at are quite dim and pretty small even with a bunch of magnification. By the way, the more magnification you use the dimmer the object appears in the eyepiece.

I will be able to make photos of the Moon and some other bright objects that can be imaged before the would get blurred by the earth's rotation making them move in the telescope's view. At high magnifications I will have to continually 'bump' the telescope in both altitude and azimuth to correct for earth's rotation and keep my subject in the eyepiece.

One of the things I want to look at and make photos of is the sun. To do so I will need a solar filter. Good glass solar filters have a nickel-chromium stainless steel alloy vaporized onto the glass to block most of the sunlight yet keep the sun a natural color.
With a 12" mirror I will be able to see, and photograph, granulation on the visible surface of the sun.


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## 480sparky

KmH said:


> 480sparky said:
> 
> 
> 
> So, when exactly did Aperture Fever take hold?
> 
> 
> 
> "Go big!Or go home!" It's cloudy tonight so the mosquitoes are going to starve without me outside to suck blood out of.................
Click to expand...


Don't tell me about the cloudy skies and skeeters..... I ain't far from ya.  

Someday, I should get my CPC1100 out.


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## jkzo

Congratulations.....looking forward for  awsome pictures of celestial bodies......


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## KmH

480sparky said:


> Don't tell me about the cloudy skies and skeeters..... I ain't far from ya.
> Someday, I should get my CPC1100 out.


Yep, you should. 
Does your 2800 mm folded optical path f/10 OTA weigh about 30 lbs?

The DMAS club skips public nights in July at the Ashton-Wildwood County Park because of the clouds, heat and late sunset times.
The local club (I sent a check to join) has a public night at  there observatory Friday July 24. That gives me time to get familiar with my telescope.



jkzo said:


> Congratulations.....looking forward for  awsome pictures of celestial bodies......


Look way forward.
I'll need to get accessories that will let me mount a DSLR to the telescope to make photos.

I haven't yet found a full aperture solar filter big enough to fit the 14" tube my 12" mirror is in so I can observe/photograph the sun
There are other accessories I need that have a higher priority.


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## astroNikon

Neat dobson.  I was looking at those before I got my current (used) Meade LX200 12inch.   I nearly bought a 14incher but the weight & size of those made portability near impossible for me.  So I stuck with the 12 inch. 

Those Orions are very nice scopes.  Hope you have fun with it.


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## KmH

Thanks to you and Designer.
I can slew that dob around like a turret gunner, and zap, zap, zap, zap - one celestial sight after another 
Synta makes the optics for Orion & Celestron.
Synta bought Celestron back in 2005 but had been providing glass to Celestron for a lot of years beforehand.

I don't know where Meade sources their glass, but GSO is the other major provider of telescope glass - mirrors and lenses.
Synta is in China. GSO is in Taiwan.


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## astroNikon

That's what I like about the Orion - a goto feature

The other Dobsons are done by hand.  I nearly bought a 16inch 1829mm Meade dobson instead of my scope but those are slewed by hand, and get kinda big in size.

Meade was sold off in 2013 to  Chinese manufacturer Ningbo Sunny Electronic Co. for $5.9 million - who makes cheap telescope stuff.  So Meade was a known worldwide brand for them.   Ningbo outbid Meade's supplier Jinghua Optics & Electronics Co. from Guangzhou, China.   Jinghua ironically owns Meade's European unit.  But Meade was done for .. they hadn't been profitable since before 2008.

Meade also supposedly, back in the day, provided the assemblies to Nikon for the 500 and 1,000mm Reflex lenses.


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## ruifo

Excellent. Congratulations.
Please keep us posted of you progress and initial photos.


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## Donde

"To give a sense of scale, I got some overweight, 5' 10" tall old guy to stand next to the telescope."

Ha ha ha he looks great and that's a great journalistic piece on the arrival of the telescope. Happy stars to you!


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## JustJazzie

Wow! I honestly thought you were joking when I read the thread title. That is quite the piece of equipment you have there. I am intrigued, and slightly intimidated. I can't wait to see what you create with it!


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## KmH

JustJazzie said:


> Wow! I honestly thought you were joking when I read the thread title. That is quite the piece of equipment you have there. I am intrigued, and slightly intimidated. I can't wait to see what you create with it!


Yep. It is a precision, scientific instrument. If I choose to, I can contribute to the ongoing collection of valuable scientific astronomical research data.
Of course, the f-stop is fixed, can't be changed, and the point of focus distances are, ah, extreme. The moon is the closest sky point-of-focus: at about 250,000 miles away.
No shallow depth-of-field with this puppy.

It doesn't zoom, but I can change eyepieces to get different magnification for my eye. Currently I have 3 eyepieces and a 2x barlow lens, so I currently have magnifications of 43x, 115x, 150x, 230x and 300x.
Saturn at 230x magnification is pretty neat. I need really steady sky to use 300x, or more.
Actually, as you look in the telescope you can see the 'seeing' get better and worse as the air currents you are looking through move about (worse) and settle down (better). Using a good telescope makes you very aware that the atmosphere is always in motion.

As I've said before the telescope is designed for visual use.
Joining the amateur astronomer clubs near me will gain me access to somewhat bigger telescopes the clubs own that *are* optimized for doing photography.
The amateur astronomer club in Des Moines has a $12,000 (for just the optical tube assembly), 16" research grade telescope. (Meade 16" LX-200)
Add the cost of the telescope mount/pier and observatory dome to block stray light, it's like having a $25,000 lens to use.

I need an observing chair that has a variable seat height.
I can buy a nice one on Amazon.com for $150.
Or. I can do DIY and build one.
Today I went out and bought the wood and hardware I need to build a somewhat modified version of a modified Denver Observing Chair.
The wood and hardware cost me $23.
I'll buy white paint and paint it to make it easier to see in the dark and keep it from being weathered.
Call it $35 - total. I figure I'm saving $115 I can spend on some other accessory(s) I need.


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## Jasii

That is heavy artillery for me and must say was fun oogling at it 
The read too was lovely. Hoping to see more of it in days to come.
Jasii


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## 480sparky

KmH said:


> ...........It doesn't zoom, but I can change eyepieces to get different magnification for my eye...............



There _are _zoom eyepieces available.  But one word describes them:  *Junk*.


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## KmH

Yep. Kinda like a 10x+ superzoom camera lens.
Convenient, but with a variety of image quality issues.


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## 480sparky

Well, you can always use it to hold your Norton's Star Atlas open.


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## KmH

My observing chair is nearing completion.  Needs a bit more work and when done I will prime the wood and paint the whole thing.
The seat height is variable any where I need it to be from the bottom of the front leg to about 37" high.
I angled a 2x4 block between the seat supports so the 4" face is parallel to the face of the front leg.
I got a 4" long piece of 3/4" fuel line, cut the fuel line length wise, then unrolled, and nailed the fuel line to the face of the block.
The rubber provides traction against the front leg so the seat stays in place when sat on.
I put smaller fuel line on the rear bolt to get a little more traction and to cover the bolt threads so they don't chew up the back face of the front leg.


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## Derrel

This entire set-up looks mighty sweet, Keith! I hope you enjoy the heck out of it for a long time! I'm marveling at the idea of a 1500mm f/4.9 aperture/focal length pairing....that seems mighty fast to me. I mean f/4.9 and fifteen hundred millimeters of length!


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## Woodsman

Just color me green with envy.  Seeing those pics just made my day.  I always wanted to get into backyard astronomy, it is just so fascinating, and have dabbled at it but just cannot justify the cost of a decent setup.  Wonderful to see yours.  Thanks for sharing


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## KmH

You don't need a 12" to have a decent setup.
8" is a decent size and one mounted like mine (dobson mount) costs less than 1/2 as much.
Being a shorter tube and lighter weight you can go with a solid tube instead of truss rods.

Ihave to cover the truss rod section to maintain contrast, postpone dew forming on the main mirror when that can happen, and to keep dropped eyepieces or flashlights from pranging the main mirror at the bottom of the tube.


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## DarkShadow

This is super cool.Good luck and have fun with it.


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## KmH

Got my observing chair done.


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## DarkShadow

Nice but whats the rope for?


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## KmH

While the seat usually stays in place by itself, a bump to the chair can cause the seat to fall.
The 'safety line' prevents that.

The line at the bottom keeps the 2 legs from getting further apart and collapsing the chair.


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## Designer

It's an interesting chair design, but I thought the eyepiece was located at around standing height (average).


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## KmH

When the telescope is pointed near the zenith (straight up) the eyepiece is at my chin.
From this latitude in Iowa, Polaris, the north star (and the close to Polaris north celestial pole) is only 42° above the horizon, not even 1/2 way to straight up. That's when the observing chair comes in handy.

I plan an observing session to look at as much as I can near the zenith and/or near the meridian (a line from the north celestial pole to the south celestial pole), but more often than not the good stuff isn't that high in the sky.
To see some of the good stuff I would need to go down to southern Texas or into the southern hemisphere.

Just as it gets dark the star Vega (in Lyra) is near the zenith. As are a double cluster near Vega, and bit further away from Vega a planetary nebula known as the Ring Nebula (M57). BTW - Vega was the first star (not counting the sun) to be photographed (daguerreotype) - July 17, 1850 - by William Bond.

Saturn is towards the south but lower than Polaris is to the North, and Saturn won't be getting any higher in the sky this year.

I was at the club's observatory site tonight, but we got clouded out before astronomical twilight (2 hours after sunset this time of year).
The humidity was near 100% and dew was already starting to form. Dew sucks if it forms on your optics.


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## Woodsman

The seat should be inflatable.  Whoopeee, for those guests who don't want to vacate the prime viewing spot


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## KmH

Some Moon photos.


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