Astro-Physics 105mm F/6 Traveler EDT APO Refractor

I met Astro-Physics, Inc. owners Marge and Roland Christen shortly after the total solar eclipse of July 11, 1991. Roland's photos of that event shot with a new prototype 4-inch refractor he designed and built were nothing short of stunning. I was eager to order one as soon as it went into production. I purchased the new Astro-Physics 105mm f/5.9 Traveler EDT APO refractor through Company 7 in early 1992. Astro-Physics, Inc. is world reknowned for its premium quality refractors and uncompromising German equatorial mounts so I was fortunate to get an order in the first production run of the new 105mm Traveler refractor.

The Traveler was the first advanced 4-inch Apo refractor designed to fit in an airliner carry on bag. This made it a most attractive portable instrument for travel on solar eclipse expeditions. In fact, I brought the Traveler with me on eclipse trips to India (1995 Oct 23) and Aruba (1998 Feb 26). I even took it south of the Equator in 1997 to image the southern heavens from Bolivia during the Southern Skies Star Party. Unfortunately, new airline weight restrictions (from 70 lbs. to 50 lbs.) ultimately made the Traveler impractical to take on air travel because of its heavy 9 lbs. (4 kg) weight which required a correspondingly heavy equatorial mount.

Nevertheless, the Traveler is still one of my favorite telescopes and is occasionally used in Bifrost Observatory, but more often on portable mounts and tripods. Recent uses include total lunar eclipses in 2007 and 2008 as well as a stunning occultation of Venus in 2009.

The tables below gives the techincal specifications and eyepiece data for the AP105 Traveler.


AP105 Traveler Telescope Specifications
Clear Aperture: 105mm (4.13")
Focal Length: 616mm (24.3")
Focal Ratio: f/5.9
Resolution: 1.1 arc seconds
Color Correction: Focus variation <0.01% from 405nm to 706nm
Coatings: Multilayer, overall transmission >97% in peak visual wavelengths
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 (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

The the AP105 Traveler is the baby brother of the Astro-Physics 130mm StarFire EDF Refractor.


Plössl Eyepiece Data for AP105 Traveler
Focal
Length
(mm)
Eyepiece
Design
Apparent
Field
°
True
Field
°
Power Power
Per
Inch
Exit
Pupil
(mm)
55 Plössl 50 4.5 11.2 2.7 9.4
40 Plössl 43 2.8 15.4 3.7 6.8
32 Plössl 50 2.6 19.3 4.7 5.5
26 Plössl 50 2.1 23.7 5.7 4.4
21 Plössl 50 1.7 29.3 7.1 3.6
17 Plössl 50 1.4 36.2 8.8 2.9
13 Plössl 50 1.1 47.4 11.5 2.2
10.5 Plössl 50 0.9 58.7 14.2 1.8
7.4 Plössl 50 0.6 83.2 20.1 1.3

Wide Angle Eyepiece Data for AP105 Traveler
Focal
Length
(mm)
Eyepiece
Design
Apparent
Field
°
True
Field
°
Power Power
Per
Inch
Exit
Pupil
(mm)
40 Wide Field 65 4.2 15.4 3.7 6.8
32 Wide Field 65 3.4 19.3 4.7 5.5
24 Wide Field 65 2.5 25.7 6.2 4.1
19 Wide Field 65 2.0 32.4 7.8 3.2
15 Wide Field 65 1.6 41.1 9.9 2.6
35 Panoptic 68 3.9 17.6 4.3 6.0
22 Panoptic 68 2.4 28.0 6.8 3.8
13 Nagler 82 1.7 47.4 11.5 2.2
9 Nagler 82 1.2 68.4 16.6 1.5
7 Nagler 82 0.9 88.0 21.3 1.2
4.8 Nagler 82 0.6 128.3 31.0 0.8


Bifrost Observatory Index

Bifrost Astronomical Observatory