155mm f7 StarFire EDF, 900GTO German Equatorial Mount, 48" Portable Pier, one 10 lb. and one 18 lb. Counterweight and other accessories
This 155mm f7 StarFire EDF (6.1" aperture) was designed to be the ultimate astrograph while providing uncompromising visual performance. Outstanding photographs published in Sky & Telescope, Astronomy and various international astronomy magazines can only hint at the detail of the original prints and negatives. The 30" x 40" prints of the Lagoon/ Trifid and Horsehead Nebulas that are on display in our showroom show incredible pinpoint star images from one side of the print to the other with no sign of image degradation. Truly amazing! Photographic spot diameters measure 15-20 microns over a 5 degree field (4" circle). The fast f7 focal ratio captures elusive and faint deep-sky objects easily with incredible detail. This lens has outperformed mirror type astrographs twice its size, as we had predicted.
The EDF is superb as a visual instrument as well. It is easily capable of high-power observations of the moon and planets. Secondary spectrum is nearly absent at any power. Deep-sky views are equally impressive due to the very high transmission of the three glass types.
In the astrographic configuration, the lens is a 5-element design in 2 groups (3 elements in front, 2 in rear). The heart of the front triplet apochromatic lens is an ED glass and 2 crowns. This combination essentially eliminates all secondary spectrum, coma and spherical aberration. The rear lens is a 2-element field flattener that eliminates astigmatism and field curvature. In the visual configuration, the rear 2-element lens is removed and replaced with a standard visual adapter. This adapter allows all our usual accessories to be attached, as well as all standard 2" and 1.25" oculars.
The tube assembly comes fully baffled for a 5 degree 4" field. The giant 4" focuser is silky smooth and can be locked for long time-exposure astrophotography. Although it is possible to attach your own custom-made film holder, we have determined that the most practical camera back is the Pentax 6 x 7cm medium-format camera. Field coverage is 3 x 3.5 degrees. After many years of field research, we chose this camera because it holds the film critically flat without the use of special vacuum attachments. This is not the case with other, less expensive film backs. The Pentax allows the user to critically focus directly on the ground glass with a high-power magnifier, assuring the highest possible resolution.
Another feature is the extra-large opening and minimum back distance to the film plane which minimizes the inevitable vignetting of the light in the extreme corners of the format. All the important color and black/ white films are available in the 120 format, which is not the case with larger formats. It is for these reasons that we have standardized on the Pentax 6 x 7 and offer all the attachments necessary to use with the 155mm EDF.
The Astro-Physics giant 4" focuser is truly versatile. The 4" ID of the drawtube will allow maximum coverage of the Pentax 6 x 7 cm negative for medium format photography. The inside of the drawtube has a series of knife-edge baffles for maximum contrast. When you wish to use your 35mm camera with the field flattener you can attach the camera adapter (67RT--, specify the t-ring) directly to the bayonet and you are ready to go. You can use our special CCD adapters to couple your favorite CCD camera to this field flattener as well to obtain exquisite images, especially with the large chips available today.
For for even faster exposures (f5.2), use our Telecompressor (27TVPH) and Camera Adapter (PFCT--, specify the t-ring). Note, the Telecompressor cannot be used with the field flattener; they are separate and distinct optical designs. The 2" and 1.25" adapters will allow you to use all of our standard accessories to maximize your visual and photographic applications.
The 900GTO or 1200GTO German Equatorial are recommended for astrophotography, depending on your requirements for portability and the amount of wind you are likely to encounter at your photographic site.Specifications
|Color correction||Less than 0.01% focus variation from 405nm to 706nm (r to h wavelengths). Color correction curves.|
|Clear aperture||155mm (6.1")|
|Focal length||1085mm (43")|
|Resolution||0.74 arc seconds|
|Coatings||Multi-layer, overall transmission greater than 97% in peak visual wavelengths|
|Magnification range||20x to 600x|
|Tube assembly||White, 6.5" aluminum tube, baffled, flat black interior, push-pull lens cell, engraved retaining ring|
|Focuser type||4.0" I.D. Astro-Physics rack & pinion focuser, 4.15" travel; 2.7", 2" and 1.25" adapters; 2.5" extension|
|Telescope length||1041mm (41") w/ dewcap fully retracted|
|Weight with dewcap||27 lbs. (12.3 kg)|
|Field flattener||4" diameter, 2-element with multi-coatings|
|Carrying-case type||Wood case with grey vinyl covering and foam-lined interior|
|35mm Photographic field at prime-focus||1.3 x 1.8 degrees @ f7|
|35mm Photographic field with telecompressor||1.7 x 2.4 degrees @ f5.2|
|35mm Photographic field with 2x Barlow||0.6 x 0.9 degrees @ f14|
|6x7cm Photographic field at prime focus||3.2 x 3.7 degrees @ f7|
Reviews and Related Articles
Author Unknown. "One Amateur's View of the Heavens", SkyWatch '99, pp. 110-112, featuring Carl Weber.
Dyer, Alan. "Astro-Physics Big & Small", Astronomy, September 1993, pp. 62-67.
Hallas, Tony and Mount, Daphne. "Fuji's Miraculous Super HG 400, Astronomy", September 1990, pp. 62-64.
We have prepared some pertinent support documents relating to this scope and many of our other products on our Technical Support page. Please check there first to find the information that you need.
Upgrades and Spare Parts
Check out our Astro-Physics.com website to find accessories, replacement parts or learn about possible upgrades for your scope.
Copyright © 2004-2019 Astro-Physics Inc. All
Last modified: March 11, 2019
11250 Forest Hills Road, Rockford, IL 61115, U.S.A.
Phone: 815-282-1513 Fax: 815-282-9847