Tele Vue NP127is User Manual

®

Tele Vue

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Operating Guide

660mm f/5.2 IMAGING SYSTEM

4-ELEMENT APO REFRACTOR

Thank you for purchasing the Tele Vue-NP127is. It has been our pleasure to craft this fine instrument for you.
Nearly thirty years ago, Al Nagler received a U.S. patent for a fast, refracting telescope design based on
Josef Petzval’s portrait camera lens concept. Petzval’s design uses widely spaced doublets to produce a
flat focal plane over a relatively narrow field of view, just the sort of field a fast telescope can see. Nagler’s
combination of flat-field, fast focal ratio, and unobstructed system lent itself perfectly for testing eyepieces.
The 5” f/4 MPT (Multi-Purpose Telescope) with its fast speed and wide, 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
subsequent SDF and Tele Vue-101 versions at f/5.4 brought us even closer to perfection. Maintaining
this fast 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 20 year refinement
toward perfection with the Nagler-Petzval 101, and NP127 with an even faster f/5.2 speed.
The Tele Vue-NP127is refines the original NP127 with the addition of a more robust, larger focuser
now standard with 10:1 reduction. The “is” designation denotes Imaging System, Tele Vue telescopes
with specific mechanical advantages for photography. Tele Vue offers a series of accessories in conjunc­tion with each optical system so you are assured of compatibility and maximum performance. While the
NP127is maintains all the visual prowess of the previous NP127, 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 sighting devices such as Star­beam from the telescope. Use only the Tele Vue Sol
Searcher to find the sun. 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.

Standard Features - Optical tube assembly includes:
captive sliding dew shield, 2.4” focuser with Focus­mate 10:1 reduction, tilt adjustment end ring, screw­on 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

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

Optical Tube Assembly

Lens Cap

Case

1.0 Getting Acquainted with the Tele Vue-NP127is

Focuser Body

Draw Tube Tension

Draw Tube

Lock Knob

End Ring

Rear Lens Cell

Main Tube

127mm Front
Lenses and Cell

Fine Focus

1.1 Optical tube assembly

Focuser Pinion Assembly

Coarse Focus

Dew Shield in
retracted position

The NP optical design contains four elements consisting of two widely spaced, air-spaced doublet groups.
The forward group of lenses are contained in a stainless steel lens cell. The cell attaches to the main tube
via three alignment screws. The front cell is encased within the sliding dew shield. The rear doublet, mak­ing up the rest of the objective, is larger in diameter than the previous NP127 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 NP127is 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 NP127is is shipped in its “visual” configuration. The 2” Accessory Adapter sits within the 2.4”

inside diameter of the drawtube. Thumb

Digital Indicator Kit
Mounting Points

Jack Screws (typical)

Drawtube Tension
Screw (typical)

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

Lock Screws
(typical)

Jam Screws
(typical)

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,

2” Accessory
Adapter

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 shift. Note that even when sufficiently
tight, the focuser knobs can still drive the draw
tube.

1:1 Knob

Focuser with 2” accessory adapter in place

1:1 Knob

10:1 Knob

The end ring can be adjusted (and locked)
to compensate for any tilt effects seen in CCD
imaging. Lock screws in the end of the draw
tube tighten against either the taper of the

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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.

2.0 Mounting Options and Set Up

The telescope tube diameter is 5”. The dual ring MRS-5000
is suited for photography and CCD imaging with a variety
of adapter plates that can be bolted to the base plate.
The base plate also bolts to the Tele Vue Gibraltar5 Alt-Az
mount if a more travel-friendly, visual use mount is desired.
Each tube ring has two machined channels with #10-32
threaded holes for mounting accessories. A central bar
spans across the top of the two rings for added stability.
The bottom of the tube rings have ¼-20 holes to accept
mounting studs or screws. Telescope balance is achieved
by unlocking the “bat handle” screws and sliding the tube
fore or aft. Once the O.T.A. is repositioned, retighten the

MRS-5000

bat handle screws.

3.0 Visual Observing Set Up

As previously mentioned, the NP127is is shipped in its “visual” configuration. If you have removed the 2”
Accessory Adapter and would like to re-install it, loosen the three end ring lock screws sufficiently to remove
any accessory that may be in place. However, do not retract them fully into the end ring. By allowing them
to protrude into the body (note photo below), they act as locators. Looking at the 2” Accessory Adapter,
note the three grooves with holes machined 120° apart. The grooves help index the holes in the adapter
to the three thumb screw arrangement in the end ring. This will ease installation in the dark. 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

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

Slip a Tele Vue 2” Everbrite diagonal into the focuser

Adapter.

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.

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”

Focuser set to accept 2” Accessory Adapter

3.1 Eyepieces

accessory adapter.

With its wide, highly corrected, flat field and fast f/ratio, the NP127is puts eyepieces to the test. This
scope demonstrates the superiority of Tele Vue eyepiece performance and, with a range of 12x to 330x
(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 the “Choosing Your Eyepieces” article.)

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