175mm f/8 StarFire EDF-4 Triplet Apochromatic Refractor
After extensive testing on the optical bench using interferometers and autocollimation and nights of visual observing and CCD imaging, Roland sums up his impressions:
"I am happy to say that this scope performs up to my full expectations. The design is topnotch using the best glasses available polished to a high degree of perfection. The lenses will be coated with very low reflection multi-layers - less than 0.2% average reflection per surface. The design is broad spectrum correction, for both visual and CCD imaging. The glass is ultra-clear BK7 crown mated to Ohara FPL53 premium ED glass. The result is magic."
Technical specicifactions at a glance:
- Clear aperture 175 mm (6.9"), focal length 1400 mm (55.1")
- CNC machined tube, with multiple baffles reduce stray light to a minimum. Multi-coating technology will provide optimum light transmission greater than 97% (540 nm)
- Compact, lightweight tube assembly
- 4" Rack and Pinio focuser with greaseless drawtube and the dual-speed mechanism of FeatherTouch 9:1 Micro, with 4.15" travel. The drawtube millimeter scale provides position repeatability.
- The rotating focuser collar will enable you to frame your photographs for optimal artistic composition or to keep north up.
- Fully retractable, felt-lined dewshield uniquely designed to aid in dew prevention
- f/8.3 CCD Field Flattener is included
The 175 f/8.3 Prime Focus Field Flattener is made specifically for the 175 f/8 StarFire EDF with its 4" focuser. This f/8.3 CCD Field Flattener provides correction that is essentially diffraction-limited over a 76 mm (3") circle, encompassing 3.0 degrees of sky. Stars will be pinpoint into the extreme corners of the field. Please refer to the original website of Astro-Physics for detailed information, field sizes and spacing requirements diagram. The distance from the field flattener to the focal plane is critical and must be maintained +/- 2.5 mm. If you remove the extension piece, the distance is 114.9 mm (4.5") from rear of housing to the focal plane; plenty of room for rotators, filter wheels, etc.
- f/6.1 CCD Telecompressor Corrector must be purchased separately. This optimized design uses 3 elements of high-index glass to widen and flatten the field while increasing the photographic speed of the 175 StarFire EDF triplet refractor from f/8 to f6.1 (focal lenth 1064mm). This results in a field of view of 2.8 degree at an image circle of 53mm. The distance of the back of the housing to the image plane must be within 1 mm of ideal (80.8 mm +/- 1 mm).
The 1600GTO German Equatorial Mount is recommended fot the 175mm f/8 StarFire EDF-4 Triplet Apochromatic Refractor.
- Tube Assembly with 4" Focuser, Dew Shield and Dustcover
- Dedicated CCD Field Flattener - matched to the 175EDF
- 2.7", 2" and 1.25" Adapters and 4" Focuser Extension
- Wood case
For further information and useful accessories about the 75mm f/8 StarFire EDF-4 Triplet Apochromatic Refractor please visit the original website of Astro-Physics. If you are interested, please send us an email to kontakt (at) baader-planetarium.com or call us.
Astro images taken with the AP 175mm - f/8.3 Starfire with CCD Field Flattener:
|Manufacturer SKU (#)||175EDF|
|Optical Design||Apochromatic Refractor|
|Clear Aperture||175 mm (6.9")|
|Optical Coatings||Multi-layer, broadband, overall transmission greater than 97% in peak visual wavelengths|
|Magnification (x)||25x to 700x|
|Tube (Material)||Cream white, 8.0" CNC machined aluminum tube, baffled, flat-black interior, push-pull lens cell, engraved retaining ring|
|Optical length (mm)||51.25" (1302mm) with dewcap fully retracted|
|Focuser||4.0" I.D. Astro-Physics rack & pinion focuser, 4.15" travel; 2.7", 2" and 1.25" adapters; 4" extension; rotating collar; numerical scale|