Accessory Items
Flat Field Light Box for 12.5" RCOS Ritchey-Chretien



My home made lightbox for the 12.5" Ritchey-Chretien. It consists of three translucent plastic discs and a top opaque disc (left image), spaced and held together with 1/4" all-thread rod. The underside of the opaque disc is lined with aluminum foil and supports a mirror holder to reflect the light back up to the aluminum foil before diffusing down through the translucent plates. The top fixture for the light source is interchangeable between this light box and the one for my FSQ-106. The outer shroud (center image) of the light box is a Kendrick C-14 dew shield lined with chrome Mono-coat, which can be found at most hobby stores. The final product can be seen in the right image.

Mouse over left and right images for different view views.

 

Flat Field Light Box for Takahashi FSQ-106 and FCT-76

This light box is used for both my FSQ-106 and FCT-76 telescopes. It's a nicely constructed piece of equipment, with its outer shell of 6" Schedule 80 PVC pipe turned down on a lathe to match its ID with that of the OD on the FSQ-106 dew shield. Internally there are four translucent plastic discs separated by cylindrical, thin wall acrylic spacers with matching diameters to the ID of the shell, topped with an opaque disc upon which sits the light fixture (right image). The entire inside surface of the shell is lined with chrome Mono-coat to enhance internal reflections and help distribute the light evenly down to the bottom of the light box.

 

 

Flat Field Light Box for Astro-Physics 160 EDF Refractor

8" OD x 0.125" wall polycarbonate spacer and 0.125" thick
x 8.00" OD translucent acrylic disc set. Four sets stacked
atop one another were used in the construction
of the light box (see image to right)
The light box internals prior to assembly include the outer PVC housing (left), four spacer/disc sets with top plate and lamp fixture shown stacked (right), and a PVC ring flange
counte-bored to accept four #6 cap screws (bottom)
The top plate is 0.125" thick x 8.00" OD black opaque acrylic.
A 0.750" diameter hole was cut from the center of the plate
and a custom fabricated lamp fixture was machined to bolt
to the plate with three #6 cap screws.
     


The final assembled product ready for use. Once the internals have been placed in the housing , the ring flange is slipped over the top and fastened to the housing with four #6 cap screws, locking the internals snugly in place.

Looking down the 8.10" bore of the housing. A thin film of chrome MonoKoat lines the ID of the housing, firmly held against the inner wall once the 8.00" OD polycarbonate spacers and translucent discs are installed.

A comparison of the smaller light box built for the Takahashi FSQ-106 (left) and the Astro-Physics 160 EDF (right). Both
lightboxes utilize identical lamp fixtures for interchangeability

 

The Astro-Physics 160 EDF light box is a scaled up version of the one I built for my Takahashi FSQ-106. The housing was fabricated from a piece of 8" Schedule 80 PVC pipe, turned down on a lathe to exacting dimensions. The PVC pipe and polycarbonate spacers were purchased from McMaster-Carr as bulk items (catalog part numbers 48855K43 and 8585K482 respectively) and
cut down as needed for the design. The translucent and opaque acrylic discs were fabricated by a local plastics shop to my specification. The chrome MonoKoat film, an item used by model airplane enthusiasts, is manufactured by TopFlite and is available at serious hobby stores everywhere. The lamp fixture was machined on my Grizzly 7 x 12 mini-lathe from aluminum round
stock procured at a local surplus store. As a final touch, ProtoStar flocking (not shown in any of the above photographs) was used to line the ID of the housing where it slips over the
telescope dewshield, protecting it against possible scratching and wear. The finished light box stands 15.375" tall and weighs in at about 8 pounds.

Click on this A-P 160 EDF Light Box Drawing link (190 Kb) to see a detailed engineering drawing

 

Dimmer Switches for Light Boxes
 
 
Two dimmer switches are required to satisfy all of the light intensities required with all of my telescopes and filter combinations to get proper flat frames. I initially tried a rheostat to meet all of the requirements but found them to be somewhat unreliable, so I designed these two boxes with fixed internal resistors and switching capability to cover all the bases. This arrangement works very well and is a relatively maintenance free solution.
Power Supplies and Related Equipment

12 VDC Gang Box for connecting multiple users. The circuits in this box are not isolated, so special attention has to be given to ground fault issues.

I use 3 each 105 amp-hour Gel-Cell batteries like this to run my mount, Robo-Focus, CCD camera, light boxes and laptop computer. Each battery is housed in a Group 27 battery box complete with a 12 VDC outlet receptacle and battery terminal charging posts. This unit also has a 400W inverter installed.

Mouse over for rear view showing charging terminals

Guest Charge Pro model 2620 20 amp "Smart" charger for the specific charging characteristics of Gel-Cell batteries. This unit is permanently mounted in my travel trailer for recharging in the field. For home use I have a Guest Charge Pro model 2606A 6 amp "Smart" charger.

Mouse over for view of my home charger

Laptop Computer
I use a Dell Inspiron 8500 laptop computer with a 2 GHz P4 processor and 512 MB RAM running Windows XP Home Edition to control the telescope mount and CCD camera during imaging sessions. The Active Matrix TFT WSXGA+ display at 1680 x 1050 resolution allows me to see a large portion of an unbinned frame from my ST-10XME CCD camera without having to do a
lot of scrolling. The single serial port on the laptop itself is used for communications with my mount and a Quatech SSP-100 Serial PCMCIA card gives me the extra port needed to run either
my Robo-Focus or RCOS TCC. USB devices are ganged using an unpowered Dr. Bott T3 Hub. Some of the software that I use includes Maxim DL/CCD Ver 3, TheSky Level IV Ver 5,
Registar, CCD Sharp, RegiStax, AVI2BMP, NEAT Image and Adobe Photoshop CS
Eyepieces

When I was strictly a visual observer, my eyepiece collection consisted of nearly 50 high-end oculars. Since I now primarily do imaging, the eyepiece collection has dwindled as I sold off most of the Naglers, Panoptics and Takahashis. What I decided to keep is my set of Pentax eyepieces, consisting of the following items:

3.8mm smc XP
5mm smc ortho
6mm smc ortho
7mm smc ortho
8 mm smc XP
9mm smc ortho
12mm smc ortho
18mm smc ortho
25mm smc kellner
40mm smc kellner
60mm smc kellner

Toolbox
I learned the hard way that not being prepared while in the field can be a frustrating experience, especially when you're 300 miles from home at a remote location. Now I always carry this toolbox full of goodies with me. Things I have in the toolbox include an assortment of Allen wrenches, screwdrivers, adjustable and open end wrenches, pliers, soldering iron, utility knives, files, digital multimeter, electrical tape, spare wire and connectors, spare light bulbs, twist ties and velcro ties, measuring tape, torpedo level, and a large assortment of screws, bolts, nuts and washers.