the world-renowned standard of excellence against which all others six inch Apos are measured
155mm f7 STARFIRE EDF APOCHROMATIC REFRACTOR ULTRA-PORTABLE WITH 2.7" FOCUSER
Originally introduced with the avid astrophotographer in mind, the 155mm f7 StarFire EDF (6.1 inch
aperture) astrograph features the gigantic focuser and included the Field Flattener lens option accommodating up to Pentax 6x7cm camera format with full field illumination. It made an astounding versatile visual telescope too; capable of extraordinarily wide fields of view at lower magnifications, with the capacity to reveal subtle features on the planets at high magnifications that few other 25 lb. telescopes can show. The astronomy community came to appreciate the
versatility of this instrument and at the urging of our customers, we now offer the same excellent 155mm f7 lens in a lighter weight tube assembly incorporating the highly regarded Astro-Physics 2.7 inch focuser.
We continue to be amazed at the compact size of this instrument. At
last, a 6.1 inch Apo refractor with an overall length of 40 inches (with dewcap
retracted). This is less than half the length of an fl5 and
approximately a foot shorter than an f9! In fact, it is about the same
length as our 130mm f8, but with an inch more of aperture! You can
transport it in a smaller car, store it in less space, invest in a smaller
mount and shorter pier/tripod. This instrument is the fulfillment of
the astronomer's dream for a truly portable 6.1 inch refractor.
The EDF is superb as a visual instrument. It is easily capable of
high-power observations of the moon and planets. Secondary
spectrum is totally absent at any power which allows you to
discriminate the subtle color variations on the surface of the planets.
Deep-sky views are equally impressive due to the very high
transmission of the three glass types. Performance will rival larger
obstructed systems because the contrast is excellent. Stars snap to focus. Individual
stars of globular clusters are sharply etched as intense diamonds against black velvet
background. A beautiful sight!
This refractor can, of course, be used photographically with a 35mm
camera at prime focus with only a simple camera adapter or at a
fast f5.2 with the optional flat- field telecompressor. A single element
field flattener is available for the Pentax 6 x 7 medium format camera,
however the field is vignetted in the corners due to the restrictions
of the 2.7" focuser (full coverage requires the 4"
focuser/4" field flattener combination). The 2.7" focuser is
interchangeable with the 4" model should you choose at some time
in the future to upgrade to the full EDF 4" package.
ASTRONOMY TEST REPORT
In the test report entitled "Astro-Physics Refractors Big & Small", in
the September 1993 issue of Astronomy, Alan Dyer described the
performance of the 155mm f7 EDF during his winter observing
sessions. Please note that the article in error referred to this instrument as our EDT.
"Optical performance of the 155EDT was impressive. It produced
nary a trace of false color even on Venus. Equally impressive, this
scope provided superb images as soon as it was set outside. Even
in sub-freezing temperatures, image quality, though not perfect at
first, was surprisingly sharp from the start. In cold weather, after a
modest settle-down time of 30 minutes, in-focus star images were
textbook Airy disks with a well-defined first diffraction ring and a
trace of a second outer ring. There was no sign of spherical
aberration, lens figure changes, heat plumes, or distorted Airy disks
due to tube turbulence."
We could not have said it better ourselves.
For 2004 Astro-Physics has developed a new specially designed dual-speed pinion fine dual speed geared focuser assembly. Incorporating a 9 to 1 geared reduction knob, this is the Feather Touch® Micro Focuser option. It is available as an retrofit kit for existing compatible Astro-Physics focusers. Or you can order it factory installed in your new Traveler telescope.
Right: Feather Touch® Focuser option on Astro-Physics 155 mm EDF Apo telescope, optional Astro-Physics 8x 50mm Finder also shown (54,384 bytes).
Click on image for higher quality, enlarged view (125,877 bytes).
||Less than 0.01 %focus variation from 405nm to 706nm (r to h
wavelengths) see table at right
| Clear aperture:
| Focal length:
||1085mm (43") efl
||0.74 arc second
||Multi-layer, overall transmission greater than 97% in peak
| Magnification range:
||20x to 600x
| Tube assembly:
|| White, 6.5" aluminum tube, baffled, flat black interior,
engraved push-pull lens cell
||2.7" I.D. Astro-Physics rack & pinion focuser, 4.5" travel,
2.7", 2" and 1.25" adapters, 2.5"
||1041mm (41") with dewcap fully retracted
||Foam-fitted, vinyl-covered plywood case
|Carrying Case dimensions:
||44-1/2 x 10.5 x 10.5 inches
|Carrying Case weight:
||15.5 lbs (7 kg)
|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 .9 degrees @ fl4
|6 x 7 cm Photographic field at prime focus:
||3.2 x 3.7 degrees @ f7 (vignetted)
Left: Color correction of the Astro-Physics 155 mm EDF Apo telescope (69,285 bytes).
Click on image for higher quality, enlarged view (178,123 bytes).