Tele Vue NP101is User Manual

®

Tele Vue

-NP101

is

Operating Guide

540mm f/5.4 IMAGING SYSTEM

4-ELEMENT APO REFRACTOR

Thank you for purchasing the Tele Vue-NP101is. It has been our pleasure to craft this fine instrument for
you. Thirty years ago Al Nagler took Petzval’s portrait lens concept using widely spaced doublets, and
patented a fast telescope design version for the purpose of testing eyepieces. The 5” f/4 MPT (Multi­Purpose Telescope) with its fast speed, wide and flat field, led to a series of continuous improvements,
primarily in color correction. The “Halley Commemorative,” 4” f/5.5 started the parade where more
advanced glasses including special dispersion, fluorite and fluorite substitute glasses brought steady
improvements. The 4” f/5 Genesis employed fluorite in the rear doublet and the SDF version at f/5.4
and subsequent Tele Vue-101 version brought us closer to perfection. Maintaining the f/5.4 speed while
reducing tube length in a totally new design with new glasses allowed virtually ideal color correction and
improved field flatness in this, the ideal form culminating the 30-year refinement toward perfection with
the Nagler-Petzval 101. Al’s “spacewalk” dream from his 1960’s NASA simulator days is yours to live.
Tele Vue’s “is” designation denotes instruments capable of accepting Imaging System photographic
accessories. Tele Vue has designed this series of accessories in conjunction with each optical system
so you are ensured of compatibility and maximum performance. While the NP101is maintains all the
visual prowess of the standard NP101, the larger rear elements and larger focuser along with a host of
proprietary Imaging System accessories, make it ideally suited for the CCD imager.

WARNING: NEVER try to look at the sun or point the telescope toward or near the sun without professional
solar observing equipment rigidly secured in front of the objective lens. When observing the sun with the

proper filters, remove any finding devices such as Starbeam from the telescope. Instant and
permanent eye damage may result from viewing the sun directly, even during a solar eclipse,
or when viewing through thin clouds, or when the sun is near the horizon.

2” Accessory Adapter (left)
Imaging System Adapter (right)

Optical Tube Assembly

Lens Cap

Case

Standard Features - Optical tube assembly includes: captive sliding dew shield, 2.4” focuser with 10:1
Focusmate reduction, tilt adjustment end ring, screw-on metal lens cover, 2” Accessory Adapter, Imaging
System Adapter, custom hard-shell case, Allen Keys for end ring tilt adjustment.

Tele Vue

Visionary

®

32 Elkay Dr., Chester, New York 10918 [phone]. televue.com

Getting Acquainted with the Tele Vue-NP101is

1.1 Optical tube assembly

The optical tube consists of an air-spaced doublet in the front cell, which attaches to the tube via three
alignment screws. (Never touch the alignment screws in the front lens cell.) The rear doublet, making up the
rest of the objective, is larger in diameter than the standard NP101 and provides additional illumination
at the edge of the field. This benefit is especially useful for large format CCD chips which are extremely
sensitive to light fall-off. The rear lens group is housed in the cell that threads between the back of the tube
and the focuser. Never stick any long objects into the focuser or you will hit the rear-most lens surface.

1.2 Focuser

The 2.4” output side of the NP101is focuser is designed to pass all of the field rays exiting the rear ele­ments of the objective, as the forward end of the draw tube has a 3” internal diameter. A larger focuser,
therefore, lends no additional illumination benefit.
The telescope is shipped in its “visual” configuration. The 2” Accessory Adapter sits within the 2.4”
inside diameter of the drawtube. Thumb screws pass through both the drawtube and adapter to cinch a
brass clamp ring around 2” accessories. With three thumb screws there is enough holding power for the
heaviest of visual accessories!
The two tension screws on the top of the focuser body can be adjusted to add resistance when using
heavy equipment. These tension screws tighten against a brass clamp ring, which then cinches down
on the Teflon sleeve in which the draw tube slides. For photography it is not necessary to tighten beyond
the need to keep a camera stationary but we do recommend to tighten them in unison to avoid any focus

Digital Indicator Kit
Mounting Points

Jack Screws (typical)

Drawtube Tension
Screw (typical)

shift. Note that even when sufficiently tight,
the focuser knobs can still drive the draw tube.
The end ring can be adjusted (and
locked) to compensate for any tilt effects seen
in CCD imaging. Lock screws in the end of

Lock Screws
(typical)

Jam Screws
(typical)

2” Accessory
Adapter

the draw tube tighten against either the taper
of the Imaging System Adapter or brass clamp
ring within the 2” Accessory Adapter.
The threaded holes on top of the focuser body
accept the Digital Indicator Kit.
Operation of the rack and pinion focuser is
via the 10:1 ratio Focusmate on the right side
or either of the 1:1 knobs. You might consider
the optional Focusmate Driver for vibration-free
focus control.

1:1 Knob

Focuser with 2” accessory adapter in place

1:1 Knob

10:1 Knob

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1.3 Case

When opening the case, we recommend always lifting
the lid while holding the handle. The lid opens a full 180°

Optional Accessories Shown

and holding the handle will give you a better grasp to insure that the lid doesn’t slip out of your hand. The
interior of the case was designed to store your scope with the optional Starbeam, Focusmate Motor Driver
and Digital Indicator Kit installed. To fit the Starbeam, you may have to slide your ring mount so that the
Starbeam fits in the lid of the case between the accessory bags.

The two accessory bags within the case lid are removable. IMPORTANT: Whenever carrying

your telescope in the case, the accessory bags must be
in place as they act to hold the telescope down. Failure
to do so may result in the telescope rolling into the lid of
the case and damage to the telescope may occur. These

bags are held in place by Velcro and can be easily
lifted out. Each bag will hold a variety of accessories,
so remove the foam inserts as your needs require. The
right side bag is where you’ll find the Imaging System
Adapter. There is also an cutout for an optional Everbrite

diagonal with 2” to 1¼” adapter inserted. Remember
to zipper the bags closed before closing the case lid!

Optional Accessories Shown

2.0 Mounting Options and Set Up

The telescope tube diameter is 4”. Tele Vue has two mount ring options available. The single ring (RS4-

8004) and the dual ring (MRS-4011). The single ring is fine for visual and photographic use. It contains
two machined grooves that accept the Starbeam (SFT-2003) unit power finder and the Piggy-Cam (PGC-

1001) piggy back camera adapter. The RS4­8004 is recommended for use with all Tele Vue
Alt-Az mounts as it allows greater balancing
opportunities than the MRS-4011.
The dual ring MRS-4011 is best suited
for critical photography and CCD imaging.
It also has grooves for mount accessories. A
central bar spans across the top of the two rings
and permits varying the spacings between the
rings in order to fit a variety of mount heads.

MRS-4011 - Heavy duty tube ring set with
slotted spreader bar to adjust ring spacing for
a wide variety of equatorial mounts.

However, if you wish to use these tube rings
on a Tele Vue Alt-Az mount, you will need to
order the BPL-1098 adapter plate as a base.

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For Alt-Az mounting, Tele Vue recommends the Gibraltar or
Gibraltar5 due to their sturdy legs. You will receive the necessary
attachment hardware and complete mount assembly instructions
with the mount. Tele Vue makes various adapter plates for popular
German equatorial mounts. Please consult your dealer.
The bottom of both mount ring systems have ¼-20 holes to
accept mounting studs or screws. The thread size in the accessory
groove is #10-32. Telescope balance in both systems is achieved
by unlocking the “bat handle” screws and sliding the tube fore or
aft. Once repositioned, retighten the bat handle screws.

3.0 Visual Observing Set Up

In order to use the scope visually, the 2.4” diameter of the draw­tube needs to be reduced to 2”. This is achieved by installing the

RS4-8004 - Slotted for accessories, three
¼-20 tapped holes for attachment.

included 2” Accessory Adapter. Note the three grooves with holes
machined 120° apart. The grooves will help index the holes in the adapter to the thumb screws in the
end ring. This will ease installation in the dark.

To install the 2” accessory adapter,
loosen the three end ring lock screws sufficiently
to remove any accessory that may be in place,
but do not retract them fully into the focuser body.
By allowing them to protrude into the body, they

Lock Screws threaded
partially in to use as
guides for inserting
the 2” Accessory
Adapter.

act as locators. Insert the 2” Accessory Adapter
into the end of the focuser. If it does not go all the
way in, rotate the adapter. When the grooves in
the adapter align with the protruding screws, the
adapter will seat fully into the focuser. Tighten the
three screws a few turns so they enter the holes in
the adapter. The lock screws will now act against
the brass clamp ring in the 2” Accessory Adapter.

Slip a Tele Vue 2” Everbrite diagonal into
the focuser and tighten the lock screws. You will
now be able to reach focus with any Tele Vue
eyepiece.

IMPORTANT CAUTION: When replacing the orange plastic plug into the 2” Accessory Adapter, push
it in far enough to seat. Do not use the lock screws to clamp the plug in place as the clamp screws will
distort the brass clamp ring in the 2” accessory adapter.

3.1 Eyepieces

With its highly corrected wide, flat field and fast f/ratio, the NP101is puts eyepieces to the test. This
scope demonstrates the superiority of Tele Vue eyepiece performance and, with a range of 10x to 270x
(if the atmosphere allows) there is a magnification for all purposes. See chart at the end of this manual or
call Tele Vue for recommendations. In general, we suggest choosing low and medium power eyepieces
in ratios of field stop diameters. For example, factors of 1.4 or 2.0. When choosing higher power eye­pieces, use ratios of magnification. (See reference chart in “Choosing Your Eyepieces”)

3.2 Finders

We particularly recommend using the Starbeam reflex sight (part# SFT-2003), which attaches to the Ring
Mount or Tube Rings. The case has a cutout for the Starbeam. The Quick Release Universal Finder Bracket
(QFM-1008) can hold a traditional 50mm finderscope and also attaches to the mount ring channels.

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