CCD Imaging Optics for the 160 StarFire EDF,
the 155 StarFire EDF and the 140 StarFire EDF

With the advent of ever larger CCD chips, starting with the STL11000 by SBIG, it became clear that some special optics would be nice to take full advantage of both the Astro-Physics 4" Giant Focuser and the new, larger (and ever growing!) chip sizes. All of the earlier StarFires that came with the 4" Focuser: the rare 6" f7.5 StarFire EDF, the 155 f7 StarFire EDF, the 180 f7 StarFire EDF, and the 206 f8 StarFire EDF each had their own unique dedicated 4" Prime Focus Field Flattener optimized for use with medium format 6 x 7 film cameras. Likewise, the recent 160 f7.5 StarFire EDF has its own dedicated Prime Focus Field Flattener (160FF) shown below. Unlike the earlier field flatteners, however, this one was designed with CCD imaging in mind rather than film photography. Its design allowed the fabrication of special adapters to achieve the critical distance between optics and focal plane for optimal performance with the STL series cameras from SBIG, especially the STL11000. These adapters also allow full illumination of the chip by eliminating the camera's 2" nosepiece with its restrictive T2 camera threads that caused vignetting on the larger chips. Owners of the 160 f7.5 StarFire EDF and SBIG STL11000 can now enjoy round, pinpoint stars all the way to edge of the chip.

To increase the flexibility and imaging potential of the 160 f/7.5 StarFire EDF even further, Roland also designed a customized, telecompressor corrector for the instrument that would compress the field and increase the 160's native f7.5 photographic speed up to f5.7. This highly corrected optic provides a reasonably flat field while also taking advantage of the 4" Focuser and new large CCD chips. The result was the 160 f/5.7 Telecompressor Corrector (160TCC). This telecompressor was so highly praised, that owners of the 155 StarFire EDF soon began asking whether it would work on their scopes as well. The answer was no - but yes. The precise configuration that had been arrived at for the 160 at f7.5 was not quite ideal for the 155 at f7, but only a relatively small modification was needed to make it work. The two TCC versions are close, but they are definitely different, and are NOT interchangeable. The 155 f5.3 (0.76x) Telecompressor Corrector (155TCC) got its initial test during one of the Rockford area's legendary winter cold spells. It was tested on a Mach1GTO mount atop a 6" Eagle Adjustable Folding Pier, and the performance of all the components was so impressive that a special "performance" web page was produced. The page was written primarily to showcase the mount's performance, but it does an equally impressive job of highlighting what the 155TCC can do. Click on the images of IC405 & 410 & cropped IC410 to see them at their full resolution glory!

Then, when the 140 f7.5 StarFire EDF was designed, part of the design goal was to produce an instrument that could be used with existing optical accessories. The 140 f7.5, when equipped with the 4" Giant Focuser (140EDF4), uses the same field flattener as the venerable 155 f7 EDF, namely the S155EDFFF 4" Field Flattener. This instrument was designed originally for the Pentax 6x7 camera, so it will easily put pinpoint stars out to the edge of current large CCD chips. This Field Flattener now also has adapters for direct coupling to the STL Series of CCD cameras. The 140 f7.5 StarFire EDF also uses the 155TCC Telecompressor Corrector, but it operates at f5.7 with this pairing because its native f-ratio is f7.5 instead of the 155's f7. Those who purchased the 140 f7.5 StarFire EDF with the 2.7" focuser (140EDF27) also have options for both field flattening and compression as outlined on our main Photographic and CCD Accessories Page.

Finally, many of our customers image with digital SLR's, and the Canon EOS line is especially popular. Canon was the first to offer a widely available full format sensor in their DSLR cameras. We have therefore introduced a special adapter for using the 160 Field Flattener and the 160 and 155 Telecompressor Correctors with the Canon EOS DSLR's (ADATCCEOS). This adapter has the full 1.875" available opeining of the large Canon bayonet. At this point in time, we are only producing this adapter for the Canon cameras. Nikon also now has full frame DSLR's, but the Nikon Bayonet itself is smaller than the Canon and is only very slightly larger than the opening of a T-ring. The Nikon cameras would therefore see very little benefit from a dedicated adapter that did not use the standard T-ring.

Please note: The spacing between these optical components and the focal plane / CCD chip is critical. It is also different from all our earlier Prime Focus Field Flatteners! Please be careful if you try to produce a custom adapter.

160 f7.7 Field Flattener for 160 f7.5 StarFire EDF (160FF)


Covers on

 

The 160 f7.7 Field Flattener is made specifically for the 160 f7.5 StarFire EDF with its 4" focuser. The effective speed of the 160EDF will be f7.7 with this accessory. The maximum fully illuminated field coverage is a 76 mm (3") circle. (Camera nosepieces, filters etc. may further reduce the fully illuminated circle.) The distance from the back of the field flattener to the optical focal plane (film plane or CCD chip surface) is 80.8 mm (3.18"). It is critical that this distance must be maintained within 6 mm (0.25"). Click here to see diagram.

Correction is essentially diffraction-limited over a 76 mm (3") circle, encompassing 3.5 degrees of sky. Stars will be pinpoint into the extreme corners of the field. The special adapters for the STL cameras ensure minimal vignetting of the corners of the format (vignetting is unavoidable in these cameras due to the limitations of the filter size).

Field size:
Fully Illuminated Circle - 3.0" (76 mm) 3.5 degrees
ST10 - (14.9 x 10mm) - .68 x .46 degrees
STL6303 - (27.7 x 18.5mm) - 1.27 x .85 degrees
STL11000 - (36 x 24mm) - 1.65 x 1.1 degrees

 

 

The 160 f7.7 Field Flattener comes with beautifully machined anodized aluminum covers: protection befitting the fine optics.

 

 

We offer several different adapters for various SBIG (Santa Barbara Instrument Group) cameras and filter wheel combinations. We also offer a large diameter adapter for the Canon EOS line of film and digital SLR's and an adapter for the QSI WSG camera.

Please read the descriptions below to determine which of the adapters for the field flattener is correct for your application. Please note that you must purchase one of the adapters below, or have a custom adapter made, in order to use your 160 f7.7 Prime Focus Field Flattener. We do not currently have adapters available for other types of CCD cameras or film/digital cameras.

Note: You can gain an additional 0.72" (18.3 mm) of back spacing by removing the rear adapter (seen in the photo at the left) for a total of 3.90" (99.1 mm). This would require custom adapters to be made.

160FF with ADATCC1 - 160 Prime Focus Field Flattener for 160 f7.5 StarFire EDF and SBIG STL Cameras with 5-position filter wheel. Adapter includes four 6-32X1/2 socket head cap screws. The ADATCC1 is featured below.

160FF with ADATCC2 - 160 Prime Focus Field Flattener for 160 f7.5 StarFire EDF and adapter for SBIG ST8/10/10XE cameras. We recommend that you substitute our Tapered 2" Nosepiece (AP16T) for the nosepiece that comes with the camera. Unless you are extraordinarily picky, the field flattener is not really needed for these cameras due to the limited size of their chips.

If you are not using an ST8/10/10XE camera, you MUST ensure that the 3.18" (80.8 mm) distance to the camera's chip is precisely maintained (+/- 0.25" or 6 mm ). The ADATCC2 is featured below.
160FF with ADATCC3 - 160 Prime Focus Field Flattener for 160 f7.5 StarFire EDF and SBIG STL Camera with 8-position filter wheel. The adapter includes four 6-32x1/2 socket head cap screws. The ADATCC3 is a shorter version of ADATCC1 that maintains the critical spacing with the thicker SBIG FW8-STL filter wheel. The ADATCC3 is featured below.
 

160FF with ADATCCEOS - We also have a special adapter for the Canon EOS line of auto-focus film and digital SLR's. This adapter provides the full 1.875" available clear diameter of the Canon EOS bayonet. (ADATCCEOS) The ADATCCEOS provides the perfect spacing to the sensor or the film for all the optics on this page. It is featured below.

160FF with A3513 - We also have a special adapter for the QSI WSG line of CCD cameras. This adapter attaches via the 2.156" optional adapter plate. The A3513 provides the perfect spacing to the sensor for all the optics on this page. It is featured below.

160FF$1,150.00 in stockAdd 160FF To My Cart
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160 f5.7 Telecompressor Corrector (160TCC)

160TCC and ADATCC1 on SBIG STL11000
(Camera not included with either A-P product)

 

This all-new design uses 3 elements of high-index glass to widen and flatten the field while increasing the photographic speed of the 160 f7.5 StarFire EDF triplet refractor. It is designed to be used with either the SBIG STL large format CCD cameras or the smaller ST7/8/10 cameras with the filter wheel installed. Successful operation of this telecompressor depends on the distance of the lens to image plane being held very closely to within 1 mm of ideal (80.8 mm +/- 1 mm). Therefore, it cannot be used with other imaging cameras with the current adapters. We are considering adapters for other cameras in the future. Click here to see diagram.

The 160EDF operating at f5.7 (0.76x compression) is an ideal match for the large format STL series cameras like the STL6303 and STL11000. Extreme detail can be captured in very short time thanks to the fast focal ratio. This accessory is a must for H-alpha imaging where speed and resolution allows one to achieve incredible results. Wide-field images will be highly detailed, which allows the astrophotographer to make very large prints without doing time-consuming mosaics. Even when enlarged to 30 inches, a single image will still have pinpoint stars across the entire frame. The 160 mm aperture is a giant step up, both in resolution and in light gathering over a 4" wide-field astrograph. The resolution of the 160 mm aperture is close to the limit of what the atmosphere will normally allow, and detail will rival that obtained with instruments twice this size.

160TCC with Machined Aluminum Covers

 

In order to preserve the best possible image resolution into the corners of the large formats, a UV-IR filter (provided by SBIG) must be installed in the luminance channel. Without this filter, the distance will be incorrect and the luminance image will have slightly different scale factor from the RGB channels. Therefore, the various channels will not register properly. Also, the IR must be filtered out to prevent elongation in the corners of the STL format due to difference in lateral magnification of the longest wavelengths.

When used with the recommended custom adapters, the image is fully illuminated with the recommended cameras. Only the 2" filters will present a tiny, insignificant amount of vignetting in the very corners.

Field size:
Fully Illuminated Circle - 2.1" (53 mm) 3.3 degrees
ST10 - (14.9 x 10 mm) - .93 x .62 degrees
STL6303 - (27.7 x 18.5 mm) - 1.74 x 1.16 degrees
STL11000 - (36 x 24 mm) - 2.26 x 1.51 degrees

Please read the descriptions below to determine which of the adapters for the Telecompressor Corrector is appropriate for your application. Please note that you must purchase one of the adapters below in order to use your 160 f5.7 Telecompressor Corrector. We do not currently have adapters available for other types of CCD cameras or film/digital cameras.

     
160TCC with ADATCC1 - 160 Telecompressor Corrector for 160 f7.5 StarFire EDF, and ADATCC1 adapter for SBIG STL Cameras with 5-position filter wheel. Adapter includes four 6-32x1/2 socket head cap screws. The ADATCC1 is featured below.
160TCC with ADATCC2 - 160 Telecompressor Corrector for 160 f7.5 StarFire EDF and adapter for SBIG ST8/10/10XE cameras. We recommend that you substitute our Tapered 2" Nosepiece (AP16T) for the nosepiece that comes with the camera.

While the ADATCC2 adapter allows use of a 2" nosepiece, it MUST NOT be used with the 2" nosepiece of the larger STL series cameras. These cameras have a longer nosepiece that will strike the optics of the Telecompressor Corrector. The distance from the optic to the focal plane is EXTREMELY critical (80.8 mm +/- 1 mm or 3.18" +/- 0.04") with the 160TCC. For that reason, we only recommend using an ST8/10/10XE camera. Other cameras are not being supported at this time. The ADATCC2 is featured below.


160TCC, ADATCC2 and SBIG ST10E
(Camera not included with either A-P product)

160TCC with ADATCC3 - 160 Telecompressor Corrector for 160 f7.5 StarFire EDF and ADATCC3 adapter for SBIG STL Camera with 8-position filter wheel. The adapter includes four 6-32x1/2 socket head cap screws. The ADATCC3 is a shorter version of ADATCC1 that maintains the critical spacing with the thicker SBIG FW8-STL filter wheel.
160TCC with ADATCCEOS - We also have a special adapter for the Canon EOS line of auto-focus film and digital SLR's. This adapter provides the full 1.875" available clear diameter of the Canon EOS bayonet. (ADATCCEOS) The ADATCCEOS provides the perfect spacing to the sensor or the film for all the optics on this page. It is featured below.

160TCC$1,520.00 in stockAdd 160TCC To My Cart
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0.76x Telecompressor Corrector for 155 f7 (f5.3) and 140 f7.5 (f5.7) (155TCC)

The success of the 160TCC Telecompressor Corrector left many of our 155 f7 StarFire EDF owners wondering if the almost magical optic could work with their scopes as well. After all, there shouldn't be much difference between a 160 at f7.5 and 1200 mm focal length and a 155 at f7 and 1085 mm focal length. As noted above, the 155 owners were both right and wrong. The combination of focal reduction and substantial field flattening that the 160TCC produced required extremely tight tolerances, and the resulting spacing to the focal plane (CCD chip) had to be precise to within +/- 1 mm. The light cone from the 155's objective was just enough different to require some adjustment. In addition, if we were going to produce a Telecompressor Corrector for the 155, we wanted to be able to use the same adapters to help keep things a bit more affordable. This made Roland's job even more difficult. But of course, you all know that he was successful, and that we are now offering this 0.76x Telecompressor Corrector (155TCC) for the 155 f7 StarFire EDF to bring it to f5.3. If you haven't already seen the performance page that we put together for the Mach1GTO, 6" Eagle Adjustable Folding Pier and 155TCC, here's another link!

An added bonus of this exceptional optical accessory is that it is also perfect for the 140 f7.5 StarFire EDF, if equipped with the 4" focuser (140EDF4). The 140's focal length of 1050 mm was easily within the correcting tolerances of the 155TCC. The only difference is that the Telecompressor Corrector operates at f5.7 with the 140 instead of at f5.3. Follow this link to some 140EDF4 + 155TCC sample images!

155TCC with Machined Aluminum Covers

Many of the details on this Telecompressor Corrector are the same as those for the 160TCC, and we would suggest that you read that information carefully. Take particular note on the filter recommendations that Roland has made.

ALSO PLEASE NOTE: You must have a 4" focuser on your 155 f7 or 140 f7.5 StarFire in order to use the 155TCC. Those of you with the EDFS version of the 155 with its 2.7" focuser or those with the 140EDF27, also with the 2.7" focuser cannot use this optic without first upgrading to a 4" focuser. Of course, you've been wanting to get a greaseless 4" Giant Focuser anyway ...

Field size on the 155 f7 StarFire EDF:
Fully Illuminated Circle - 2.1" (53 mm) 3.7 degrees
ST10 - (14.9 x 10 mm) - .1.04 x .70 degrees
STL6303 - (27.7 x 18.5 mm) - 1.93 x 1.29 degrees
STL11000 - (36 x 24 mm) - 2.51 x 1.67 degrees

Field size on the 140 f7.5 StarFire EDF:
Fully Illuminated Circle - 2.1" (53 mm) 3.8 degrees
ST10 - (14.9 x 10 mm) -1.07 x 0.72 degrees
STL6303 - (27.7 x 18.5 mm) - 1.99 x 1.33 degrees
STL11000 - (36 x 24 mm) - 2.58 x 1.72 degrees

Please read the descriptions below to determine which of the adapters for the Telecompressor Corrector is appropriate for your application. Please note that you must purchase one of the adapters below in order to use your 0.76x Telecompressor Corrector. We do not currently have adapters available for other types of CCD cameras or film/digital cameras. Click here to see diagram.

     
155TCC with ADATCC1 - 0.76x Telecompressor Corrector for 155 f7 StarFire EDF or 140 f7.5 StarFire EDF and ADATCC1 adapter for SBIG STL Cameras with 5-position filter wheel. Adapter includes four 6-32x1/2 socket head cap screws. The ADATCC1 is featured below.

Camera not included

Camera not Included.

155TCC with ADATCC2 - 0.76x Telecompressor Corrector for 155 f7 StarFire EDF or 140 f7.5 StarFire EDF and adapter for SBIG ST8/10/10XE cameras. We recommend that you substitute our Tapered 2" Nosepiece (AP16T) for the nosepiece that comes with the camera.

While the ADATCC2 adapter allows use of a 2" nosepiece, it MUST NOT be used with the 2" nosepiece of the larger STL series cameras. These cameras have a longer nosepiece that will strike the optics of the Telecompressor Corrector. The distance from the optic to the focal plane is EXTREMELY critical (80.8 mm +/- 1 mm or 3.18" +/- 0.04") with the 155TCC. For that reason, we only recommend using an ST8/10/10XE camera. Other cameras are not being supported at this time. The ADATCC2 is featured below.
155TCC with ADATCC3 - 155 Telecompressor Corrector for 155 f7 StarFire EDF or 140 f7.5 StarFire EDF and ADATCC3 adapter for SBIG STL Camera with 8-position filter wheel. The adapter includes four 6-32x1/2 socket head cap screws. The ADATCC3 is a shorter version of ADATCC1 that maintains the critical spacing with the thicker SBIG FW8-STL filter wheel.
155TCC with ADATCCEOS - We also have a special adapter for the Canon EOS line of auto-focus film and digital SLR's. This adapter provides the full 1.875" available clear diameter of the Canon EOS bayonet. (ADATCCEOS) The ADATCCEOS provides the perfect spacing to the sensor or the film for all the optics on this page. It is featured below.

155TCC$1,520.00 in stockAdd 155TCC To My Cart
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Adapter for SBIG STL Series Camera with Five-Position Filter Wheel (ADATCC1)

This adapter was developed with two primary goals in mind: to reduce the vignetting caused by the use of a standard 2" nosepiece on the large CCD chip of the STL11000, and to maintain the critical distances to the focal plane required by the sophisticated and complex optics of the 160 f7.7 Field Flattener and the Telecompressor Correctors for the 175, 160 and the 155 and 140 StarFire EDF Instruments. The adapter is machined from a single piece of aluminum for strength and rigidity and bolts directly to the camera. This allows removal of the 2" nosepiece, and the much larger opening of our adapter leaves the camera's own internal filters as the only possible source of vignetting on the edges of the CCD chip. The ADATCC1 is black anodized for a rich finish.

The ADATCC1 adapter includes four 6-32x1/2" socket head cap screws for attachment to the STL series camera. It's depth of 43.4 mm when added to the STL's 36.8 mm backfocus (without the nosepiece and with filters in use) gives the ideal 80.8 mm distance to the optical focal plane.

Note: this adapter is similar to adapters being made for use with all of our other 2.7" and 4" Prime focus Field Flatteners and to use with the 2.7" to 6x7 Outer Bayonet Adapter (ADA2767). These adapters are NOT interchangeable.

Camera not Included.

ADATCC1$70.00 in stockAdd ADATCC1 To My Cart
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Adapter for SBIG ST7/8/10/10XE with Attached Filter Wheel and 2" Nosepiece (adatcc2)

The ADATCC2 was designed to allow owners of SBIG's smaller cameras, the ST 7/8/10/10XE to also use the Telecompressor Correctors shown above. (They can also use the adapter with the Field Flattener, but the smaller chips on these cameras will hardly notice the difference!) The ADATCC2 is machined out of solid aluminum, and is then fitted with our brass compression ring and with three large thumbscrews for a rock solid grip on your camera. For even greater stability, we recommend replacing the camera's nosepiece with our Tapered 2" Nosepiece (AP16T).

Like the other two adapters shown above and below, the ADATCC2 was carefully designed to provide the precise spacing required for successful imaging with the appropriate cameras. The spacing distance when used with the 160FF is 1.7" (43.2 mm) and with the 175TCC, 160TCC or 155TCC is 1.5" (38.1 mm).

The appropriate cameras are the SBIG ST 7/8/10/10XE with close coupled CFW9 color filter wheel attached. (The filter wheel must be attached and it must be the common close coupled version.) Because these cameras all have the exact same distance from the nosepiece shoulder to the CCD chip, we can assure that these cameras will be properly positioned to achieve maximum benefit from the Telecompressor Corrector optics. We cannot make any assurances for other cameras, and cannot support attempts to use other cameras with these components at this time.

ADATCC2$60.00 in stockAdd ADATCC2 To My Cart
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Adapter for SBIG STL Series Camera with Eight-Position Filter Wheel (ADATCC3)

  No sooner than we had finished production of the first ADATCC1 adapters, SBIG came out with a new 8-position filter wheel for the STL series cameras. This filter wheel, the SBIG FW8-STL, was not only bigger around, it was thicker, so we went back to the drawing board and designed a shorter version of the ADATCC1 so that the critical spacing between optics and CCD chip could be maintained. This version, the ADATCC3 has the same robust machined construction and rich, black anodizing of the ADATCC1. Use this adapter ONLY if you have an STL camera with the 8-position filter wheel.
 

The ADATCC3 adapter includes four 6-32x1/2" socket head cap screws for attachment to the STL series camera . It's depth of 34.5 mm when added to the STL's 45.7 mm backfocus (without the nosepiece and with FW8-STL wheel in place and filters in use) gives the ideal 80.8 mm distance to the optical focal plane.

Note: this adapter is similar to adapters being made for use with all of our other 2.7" and 4" Prime focus Field Flatteners and to use with the 2.7" to 6x7 Outer Bayonet Adapter (ADA2767). These adapters are NOT interchangeable.

ADATCC3$70.00 in stockAdd ADATCC3 To My Cart
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Adapter to attach QSI’s 500 series WSG Cameras to the 160 Field Flattener
and the 175/160/155/140 Telecompressor Correctors (A3513)

This adapter is specifically designed to attach the 160 Field Flattener and the 175, 160 or 155/140 Telecompressor Correctors to QSI’s 500 series WSG medium format cameras. It has been precisely machined to maintain the critical spacing to the focal plane at the perfect 80.8mm. It utilizes the larger thread size of the QSI 2.156" adapter plate in order to minimize vignetting when using fast focal ratio telescopes. (2" nosepieces and T-threads are often too restrictive for today’s larger sized detector chips when used with fast scopes.)

It also provides a rigid method of attaching the camera to the optical system. This ensures the elimination of flexure from this part of the system.



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SLR Camera Adapter with Large 1.875" Diameter Canon EOS Bayonet (35mm and digital)
for use with 160 Field Flattener and 175, 160 and 155 Telecompressor Correctors (ADATCCEOS)

This SLR Camera Adapter for Canon auto-focus 35 mm and digital EOS SLR cameras with its large 1.875" (47.6 mm) inside diameter EOS bayonet minimizes vignetting on full frame chips and on 35 mm film by eliminating the restrictive 1.5" (38 mm) diameter standard T-thread interface. Since the introduction of Canon’s full 35 mm frame digital SLR’s, people have been asking for a solution to the vignetting caused by the small clear aperture of the standard T-ring interface that is universally used to connect telescopes to SLR cameras. This was especially true for Astro-Physics telescope owners who were using the 160 Field Flattener or the 160 or 155 Telecompressor Corrector. What good were pinpoint stars to the edge of a wide field when the edge of that field was darkened by the T-ring’s vignetting effect? So, in keeping with our commitment to imagers, we introduced a solution!
  The adapter body is precision-machined aluminum and is anodized black. The bayonet is machined stainless steel, and both the body and the bayonet are baffled and painted flat black on the inside.  

The ADATCCEOS will place the camera's sensor (or film) at the perfect 80.8 mm distance from the mating surface of the 160 Field Flattener, or the 175, 160 or 155 Telecompressor Correctors.

The inside of the adapter has been threaded to accept standard 2" filter cells with 48 mm threads. Be very careful if using filters with any of the TCC Telecompressor-Correctors, as they have very limited clearance to the back optical element. You could stack multiple filters with the 160 Field Flattener (160FF), but DO NOT stack multiple filters with the 175TCC, 160TCC or 155TCC!

Please note: this adapter can NOT be used with Canon manual-focus 35 mm cameras (series FD and earlier lenses).

ADATCCEOS$145.00 early FebruaryAdd ADATCCEOS To My Cart
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This page was last modified: June 12, 2012

Astro-Physics, Inc.
11250 Forest Hills Road, Machesney Park, IL  61115, U.S.A.
Phone: 815-282-1513   Fax: 815-282-9847