46 cm (18") homemade reflector      Updated on November 8, 2015
                                                                                                              
Multifunctional stepladder was added
Old version is here (updated in 2008) 


Outline
Assembling
Takedown & loading
Primary & Secondary mirror

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Outline


The entire view
Aperture 18" (459 mm, Effective aperture: 455 mm), F 4.5, f: 80.2" (2037 mm). The secondary mirror is 3.1" (79 mm) with 17 mm thick. The optics have recoated in June 2015 by Galaxy Optics, Colorado, USA. The reflectivity of the primary and the secondary are 96% and 97%, respectively.
A wood bar suspending from the top ring is used to move the telescope down ward: I grab it and push down when I sweep the sky vertically. The light shroud was renewed in 2010: the present shroud was made by AstroSystems, Colorado, USA.The light shield is attached over the eyepiece.






Left: Secondary cage.
A piggyback ride Regal Quick-Finder on a 50 mm right erect finder, and a digital setting circles, Nexsus DSC. The eyepiece, I usually use for comet hunting, is Ethos 21 mm with 97x and 1.0˚ actual field of view (FOV). A light shield is placed over a white plastic part on the eyepiece. Another eyepiece that I use is Planocular 30 mm, manufactured in Germany with 88˚ apparent FOV, which is combined with Parracor with 78x and 1.1 ˚ apparent FOV. Once I used Planocular 30 mm alone with 68x and 1.3 ˚ actual FOV. The dew shield made by insulator for water supply pipe (white colored) is placed on the Quick-Finder and the eyepiece of the 50 mm finder. Only when I peer into finders I remove the dew shields. A long dew shield hood is placed for the objective of 50 mm finder.
Center: Nexus DSC (left) and iPad mini2 (right) that displays SkySarari 4 Pro. iPad receives signal from Nexus DSC via WiFi and the FOV of my comet-seeker links with SkySafari 4 Pro (a digital map). Since the FOV always links to the map, it is very easy to identify DSOs. A red transparent plastic sheet on iPad mini2 can be flipped up by picking up gTeleVueh sticker with fingers (see photos below).
Right:
Rear view
The power line extends from the rocker box where the battery is placed to the secondary cage via the heater controller. There are two heaters; one is applied to the secondary mirror and another is to the eyepiece. Kendrick Dew Remover System is installed in the secondary mirror and can be attached on the eyepiece.

Multifunctional stepladder

Left: iPad mini 2 is placed on the stepladder using an attachment with flexible arm (not detached every session). LED lamp is fixed using Velcro and rubber string. Note that the clipboard is not vertical but inclined to avoid dew or frost condensation on the paper (not seen).
Right: Close-up of iPad mini 2. Red plastic cover is flipped.





 
 Left: Front view of the secondary cage
Right:
Rear view of a mirror cell. There is a cooling fan at the center. Two vertical wood blocks are to protect three light collimation knobs, when the mirror box is placed on the ground.


 
Top view of 18 point flotation cell.
A primary mirror and trusses are removed. The photo was taken in 2003.

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Assembling

 
 
 
Left: Installing truss-tube poles.
Center: Connecting truss poles and the secondary cage.
Right: Pulling on the light shroud. White counter weight, which is metal chain covered with white foam, is in the secondary cage. At this stage, it is bottom heavy. The counter weight is removed after the finders and other gears are installed on the secondary cage.
Photos were taken in 2003



 
 
 
 Left: Each wedge is stuck inside of the cage using Velcro.
 Center: The wedge is screwed between a pair of poles.
Right: Inside view of the pole seats and wedge. Velcro is placed on the surface of the wedge and inside wall of the secondary cage.
Photos were taken in 2003

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Takedown & loading

 
 

 Left: Loaded primary mirror and truss-tube poles
   1: primary mirror, 2: plastic bag with chuck, 3: silica gel in paper bag, 4: truss-tube poles, 5: cleaner to vacuum air in a plastic bag,
   6: eyepiece boxes, 7: homemade PVC primary mirror cover, 8: ladder, 9: parts box, 10: plywood plate (lifted)
Center: Loaded mirror box
   11: step for loading
Right: Completion of loading
   12: clothes box, 13: white form for shock absorbing


 
 
 Left: All the components are covered with insulation sheets in summer.
Right
: My new car is Toyota NOAH. Even though the telescope occupies the third row seats, four persons can ride in total including a driver: two persons each on the first and the second row seats, respectively.

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Primary & Secondary mirror: Galaxy Optics

 
 
Left: 18-inch primary mirror RMS: 0.032 Lambda, P-V: 0.22 Lambda
        Serial number: SN01797-PS#1

Right: 3.1" secondary mirror RMS: 0.011 Lambda, P-V: 0.086 Lambda
I have ordered a premium mirror: they make ten mirrors per one lot, and this is the best of them. The performance is superb!
The optics were polished in April, 2001.



 

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