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Astro-Physics 105 Traveler Telescope with optional Maxbright Diagonal, eyepiece, on optional Model 400 GTO mount (185,898 bytes)

105 mm f6 TRAVELER EDT REFRACTOR (4.1" aperture)

Right: Astro-Physics 105 Traveler Telescope with lens shade extended, and with optional Maxbright Diagonal, eyepiece, on an optional Model 400 GTO "Go-To" German Equatorial mount (185,898 bytes)

Since 1991, the standard against which all other 4" Apos are measured

Imagine a refractor with a 105mm (4.1") aperture, a versatile focal ratio of f6, in a tube assembly that has an overall length of 19 inches! The 105 Traveler EDT is the culmination of years of optical research by Roland Christen of Astro-Physics. This project aimed at developing a very fast and portable telescope that will allow you to enjoy sharp, high-contrast images wherever you go. The first two prototype Travelers were completed in 1991 (one of the original two remains on display at Company Seven's showroom/museum collection, the other with Astro-Physics), after years of study and evolution of the Astro-Physics product line. Even at first glance, we knew the Traveler was a landmark achievement in Apo technology development; one can argue it remains today years ahead of its time since no one has been able to equal the overall optical and mechanical performance, and versatility of this telescope and its superbly engineered accessories.

The 105 EDT has a fully machined tube assembly with a permanently aligned lens cell. Its construction is extremely rugged to allow it to withstand all the handling that is typical of airline travel. The lens uses a special new Super ED glass (ED stands for extra low dispersion, Vd> 90) that allows color free performance at the f6 focal ratio. Images of stars and planets are presented in their natural colors, and daytime objects appear sharp and contrasting without annoying purple fringes.

The optical design of the 105mm objective is identical to the StarFire EDF refractors. It consists of a positive element of Super ED glass surrounded by two matching hard crown meniscus lenses. The two outer elements are chosen so that the combination is free of coma, spherical aberration and other higher-order aberrations. All surfaces are spherical, which results in a very smooth overall figure. Under steady viewing conditions, you will see a hard white Airy disc at focus surrounded by the first diffraction ring. Inside and outside of focus, you will see an evenly illuminated, expanded disc with concentric Fresnel rings, the outermost ring brighter and wider than the rest. The two air-glass surfaces have a multilayer antireflection coating that results in overall light transmission greater than 97% in peak visual wavelengths. On most nights, the settling down time for the lens is between ten to fifteen minutes, and even in subfreezing conditions it rarely takes more than forty five minutes to stabilize.


The 105 Traveler is an awesome performer both at night and during the daytime since it is capable of operating at magnifications as low as 12x or as high as 400x. Based on light gathering area alone, the Traveler has 36% more light grasp than a 3.5" Maksutov and 10% more light throughput than a 100mm refractor. During the daytime, delicate detail and vivid colors of flowers and wildlife are a true joy to observe. During the night, the high light transmission of the extremely pure optical glass becomes immediately apparent. With an optional well designed 2" wide angle eyepiece, we have seen the entire Veil Nebula including the very faint inner region, all in one eyepiece field of view. The North American Nebula region is so bright and clear, it looks much like a deep-sky astrophoto. Pop in a high power eyepiece, and you will be rewarded with truly stunning views of the Moon and planets. Jupiter will amaze you with sharp resolution of the bands, festoons, white ovals and the Great Red Spot. This scope shows detail on Saturn and Mars that rival views in much larger instruments.

The Traveler is a fabulous astrographic instrument too. With an optional Pentax 6 x 7 cm medium format camera, you can capture areas 5.6 x 6.6 degrees wide of stunning star fields, clusters and nebulas at f6! If a faster focal ratio in a 35mm format is desired, then you may use our optional Telecompressor for operation at f4.5, or a 2x Barlow for f12 exposures.

Whether traveling to exotic eclipse locations, to your favorite camping spot, to bird watching expeditions, or simply in your backyard, this little gem will provide you with years of observing pleasure.


The mechanical construction of the Traveler provides this scope will be completely trouble-free, and the optics will remain permanently aligned unless it suffers some catastrophic injury. The gorgeous tube assembly is precision machined in the Astro-Physics shop with the most modem CNC equipment available; there are no fragile die castings in this telescope. Expert machinist transforms solid, aircraft-quality aluminum stock into a fully baffled tube assembly with no less than twelve knife-edge baffles in the focuser draw tube alone. Astro-Physics has has endeavored to achieve the highest absorption of stray light possible to give you the maximum contrast. The black exterior finish of the tube and dew cap will retain its deep. lustrous beauty for many years. You will appreciate the unique design and fine craftsmanship of this telescope.

Our superb Astro-Physics focuser is a very finely crafted unit with several unique features. The components are machined to extremely high tolerances, assuring that there is no wiggle between the draw tube and housing. More than a dozen knife-edge baffles are machined into the wall of the draw tube and painted flat black in order to maximize contrast by essentially eliminating any internal reflections. The inside diameter (I.D.) of the draw tube is 2.7", this allows the avid astrophotographer to employ a medium-format camera to capture images in a 6 x 7 cm format with minimal vignetting. You can use standard accessories with the 2" and 1.25" adapters. Recessed brass locking rings are installed at each thumbscrew location. As you tighten each thumbscrew, the brass locking ring clamps onto the part that has been inserted. Consequently, your focuser draw tube and 2 and 1.25" accessories are held securely in place. This is particularly important considering the heavy and expensive accessories that you may use. As an added advantage, the brass will not mar the surface of your accessories.

We invite you to compare the optical performance and mechanical construction of any other scope of comparable size on the market today. You will find that the Astro-Physics 105 Traveler is the finest, most versatile scope of its size.


This was the first four inch Apo in the world that is so advanced in its optical design that it can be made short enough to carry on to an airliner assembled and in its provided carrying case. The design of this case was arrived at by Company Seven, and we used to have "Tenba" an excellent fabricator make these for Astro-Physics. After a couple of years of early Traveler production, Astro-Physics elected to have a less sophisticated and less costly simile of the original which is now made by another vendor. This padded case is made of black ballistic nylon, with padded rigid panels sewn into the lid and to the base, other areas incorporate flexible padding, and spacers which can be arranged to suit the observers preference. The zip open lid incorporates a sip open pouch suitable for storing paperwork, or a thin document. Sewn on carrying handles, and a clip-on adjustable length shoulder strap are provided.

Right: Astro-Physics Traveler with lens shade retracted stored in current model provided padded bag.
Note textured, painted finish now provided with the AP Traveler optical Tube.

Also shown left to right are optional Universal Astronomics UniStar Light Deluxe Alt-Az Head and Aluminum Post,
Astro-Physics Maxbright 2 Inch Mirror Diagonal, and (58,267 bytes).
Click on image to see enlarged view (173,595 bytes)


Color correction: Less than 0.01% focus variation from 706nm to 405nm
Clear aperture: 105mm (4.13")
Focal length: 610mm (24") (actually f5.8)
Resolution: 1.1 arc seconds
Coatings: Multilayer, overall transmission greater than 97% in peak visual wavelengths
Magnification range: 12x to 400x
Tube assembly: Black finish, 19" aluminum tube; fully baffled, permanently aligned cell construction; engraved focuser
Focuser type: 2.7" Astro-Physics rack and pinion focuser, 4.5" travel; 2" and 1.25" adapters; 2.5" extension
Telescope length: 43 cm (19") with dew cap fully retracted
Weight with dew cap: 9 lbs. (4 kg)
Carrying case type: Custom padded bag
Case outside dimensions: 21"x 10.8" x 7" (53 cm x 27 cm x 18 cm)
Weight of empty case: 3.5 Ibs. (1.6 kg)
35mm prime-focus field: 2.3 x 3.2 degrees @ f5.8
35mm telecompressor field: 2.9 x 4.1 degrees @ f4.5
35mm field with 2x Barlow: 1.1 x 1.6 degrees @ f11.6
6 x 7 cm prime-focus field: 5.6 x 6.5 degrees @ f5.8
* Specifications are subject to change without notice.


  • Very high correction of spherical and chromatic aberrations
  • Visual and photographic focus is identical, eliminating the need for light absorbing filters
  • Clear, color free glass types result in brighter, more contrasting images
  • Stunning lunar/planetary and deep-sky views
  • Ideal for 35mm and medium-format deep-sky astrophotography
  • High-resolution optics are a good match for fine-grained Technical Pan emulsions


  • Low profile and lightweight mounting rings (pair)
    these rings accept optional piggyback dovetail hardware
  • Felt lined dew cap slides over cell for compact 19-1/2" storage
  • Fully baffled tube and focuser assures highest contrast
  • Giant 2.7" focuser allows coverage of 6 x 7 cm formats, or optional photo visual telecompressors
  • 2" and 1.25" adapters with non-marring brass locking ring
  • 2.5" extension tube included
  • Beautifully machined parts with lustrous black finish
  • Machined aluminum lens cover to protect against dust
  • Sturdy padded carrying case (21-1/2" x 10-1/2" x 7") will fit in airline overhead storage compartments.
    this case has modular compartments, space for documents, and can be padlocked


  • Universal Astronomics UniStar Light Deluxe Alt-Azimuth Head with a suitable Field Tripod
    This portable mount is perfect for visual and photographic studies in either the Northern or Southern Hemispheres.

    Right: Astro-Physics Traveler in its provided padded bag shown with stored Universal Astronomics
    UniStar Light Deluxe Alt-Az Head and Aluminum Post (52,130 bytes)
    Click on image to see enlarged view (155,880 bytes)

  • 400 German Equatorial Mount with Dual Axis Drive
    This portable mount is perfect for visual and photographic studies in either the Northern or Southern Hemispheres.

  • Diagonals and Binocular Viewers:
    Prism diagonals may introduce aberrations which degrade perceived image quality. Since this is especially noticeable in telescopes with fast focal ratios, we recommend use of the Astro-Physics "Maxbright" 2" Precision Mirror Diagonal for the Traveler. If you use a binocular viewer (which incorporate prisms), then place a Barlow between the focuser and binocular viewer.

  • Eyepieces:

    Astronomers will wish to at least initially set up this telescope with at least two or three 1.25" or 2" eyepieces to address:  

    • Low magnification: for views of the faint deep sky objects a 32mm to 35mm focal length eyepiece.
    • Middle Magnification eyepiece - usually between 80 to 120X, for views of the full Moon, Star Clusters, etc.
    • High magnification: 200X or more for views of the planets

    Plossl, Orthoscopic, Panoptic and older wide field eyepiece designs show sharp images only in the center of the field. These are fine as long as you realize this limitation. If you object to astigmatic images at the edge of the field, or if you require long eye relief (distance from lens to the eye) to accommodate spectacles, then Astro-Physics and Company Seven recommend the eyepieces of advanced designs such as those pioneered by Al Nagler, founder of the TeleVue company. TeleVue's advanced designs include the "Nagler", "Radian", or "Panoptic" series eyepieces. These oculars will provide the widest clear, and flat field images bringing out the most in this (and many other) telescopes. For manually driven mounts in particular, wider field of views are also desirable since as the Earth rotates and objects drift across the field of view, a wide angler ocular shows an object for some time longer before having to adjust the telescope.

      Examples of some popular eyepiece choices:

      Eyepiece Magnification Actual field of view Exit pupil
      41mm Panoptic 15x 4.3 degrees 7mm
      35mm Panoptic 18x 3.8 degrees 5.3mm
      22mm Panoptic 28x 2.4 degrees 3.8mm
      13mm Nagler 48x 1.7 degrees 2.2mm
      9mm Nagler 70x 1.2 degrees 1.5mm
      7mm Nagler 89x 0.9 degrees 1.2mm
      6mm Radian 103x 0.6 degrees 1.0mm
      5mm Nagler 124x 0.65 degrees 0.85mm
      3mm Radian 207x 0.3 degrees 0.5mm

      You may slso consider using our Astro-Physics 2" (2x) Barlow to double your magnification and increase overall versatility.

  • TeleVue Equalizer: A slip fit machined bronze, heavy 2 to 1.25 inch diameter reducer adapter. Helps to keep telescope balance when switching to and from light and heavy accessories and eyepieces. Particularly helpful when using telescope with Alt-Azimuth mounts.

    Feather Touch Traveler focuser knobs (24,150 bytes).

  • 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: Astro-Physics Traveler 4 inch telescope with optional Feather Touch® Focuser Pinion and Gear Reduction Assembly (53,738 bytes).

    Click on image for higher quality, enlarged view (151,858 bytes).

  • "Starbeam" Finder: Beautifully machined and black anodized aluminum, on a quick release machined hardware. Battery powered illuminator is adjustable in brightness; it projects a 10 arc minute diameter red dot onto a transparent 40mm clear aperture window so that the dot appears to be over wherever the scope is pointed. Six arc minute accuracy make "star hopping" easy.

  • Red LED Flashlight such as the Rigel Skylite to help one set up and use a telescope, and to read charts or a planishpere without adversely impacting the observers night vision.

  • Telescopes such as this often put the eyepiece at position that is only about 3 or 4 feet (0.9 or 1.2 meters) from the ground. Since most of our customers are taller than that, they will find it uncomfortable to stand bent over to observe for extended periods. For a much more enjoyable and comfortable observing experience, Company Seven recommends the Observing Chair; this is our most comfortable, flat folding, adjustable height seat. It is not inexpensive, but is so practical and can be used for camping or other times when a comfortable portable seat is desired.

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