Apertura DT Series Configuration guide

DT Series
Dobsonian Telescope
Assembly Instructions and User’s Guide

CAUTION!
NEVER ATTEMPT TO LOOK AT THE SUN WITH
YOUR APERTURA™ DOBSONIAN TELESCOPE
UNLESS YOU HAVE A FULL-APERTURE
SOLAR FILTER (NOT INCLUDED WITH
TELESCOPE) INSTALLED OVER THE OPEN END OF
THE OPTICAL TUBE. NEVER USE AN EYEPIECE-
MOUNTED SOLAR-FILTER ALONE AND ALWAYS
COVER THE FINDERSCOPE EYEPIECE WITH A
PLASTIC DUST CAP. WITHOUT A FULL-
APERTURE SOLAR FILTER INSTALLED, YOU RISK
SEVERE EYE DAMAGE AND PERMANENT
BLINDNESS!
Please take a few minutes to read over
the assembly instructions to familiarize
yourself with the individual parts and
procedures before attempting to
assemble your Apertura™ DT Series
Dobsonian Telescope.
X

Unpacking your Apertura™ DT Dobsonian Telescope
Parts List:
Optical Tube Box (package 1 of 2)
•Telescope optical tube with 2" focuser 8x50
finder scope & bracket
•Two tension adjustment springs
•Two black altitude knobs with hardware
•25 mm Plossl Eyepiece - 1.25"
•2" to 1.25" Adapter (shown in focuser)
•Dust cover for front of telescope

Base Mount Box (package 2 of 2)
Wood Components
1 small panel – front
1 large panel – right
1 large panel – left
6"-10" DT - 2 large round base plates
12" DT - 2 large base plates, 1 round & 1 triangle
1 Four-hole eyepiece tray
1 handle
3 black plastic feet
1 Allen wrench
1 bolt with knob head
1 large washer
1 small bearing washer
1 small washer
1 axle sleeve
10 long black Allen screws (8 for 6"/8" model)
2 medium silver Allen screws
3 medium Phillips screws
2 short black Phillips screws
Hardware
Adjustment Knob Assembly

Assembling the DOBSONIAN BASE HOUSING
Attach handle to the BASE FRONT with
two medium silver Allen screws. The
curved edge of the board is the top of
this part when vertical.
! IMPORTANT ! Make sure the flat
face of the embedded T-nuts are on
the BACK side of the board (opposite
the handle).
Attach BASE RIGHT to BASE FRONT
with two long black Allen screws.
(The BASE RIGHT is the one with
two smaller pre-drilled holes for
the eyepiece tray)
Attach BASE LEFT to BASE FRONT
with two long black Allen screws.
Be sure all three sides are secure.
BACK

Locate the BOTTOM BASE
PLATE.
The BOTTOM BASE PLATE for
the 6" - 10" DT is round as shown
and has 3 holes around its
edge and a brass fitting in the
center hole. The BOTTOM
BASE PLATE for the 12" DT is
shaped like a triangle.
Attach the 3 feet to the BOTTOM
BASE PLATE’s bottom side with
3 medium Phillips screws, with
the wider side of the feet facing
the board. (The bottom side of
this plate has the brass fitting
almost flush with the surface – see
inset picture)
Locate the TOP BASE PLATE. It
has several holes around its edge
(not counting center hole).
Model DT6 & 8 = 4 holes
Model DT10 & 12 = 6 holes
Turn the completed BASE
HOUSING upside down.
Align the holes of the UPPER
BASE PLATE with the
holes of the BASE HOUSING.

Screw long black Allen screws through
the BOTTOM BASE into the BASE
HOUSING making sure the side with
the recessed holes is facing away from
the BASE HOUSING.
Place BOTTOM BASE PLATE
with feet facing down.
Insert AXLE SLEEVE into the
Center hole and place Teflon pads
on plate as shown in next photo.
Place some of the AZIMUTH AXLE
SPACERS over the AXLE SLEEVE.
These washers will control the "feel" of
the azimuth motion. Telescope
movement is a very important aspect of
using a telescope but preferences as to
what that motion should feel like varies
from person to person. The use of the
spacers allows you to set the amount of
resistance you like best. Use fewer
spacers for a stiffer motion and more
spacers for a more fluid motion with less
resistance. It really is that easy.

Pick up the BASE HOUSING
with UPPER BASE PLATE
already attached and place it onto
the AXLE SLEEVE of the
BOTTOM BASE PLATE.
Assemble washers onto the
ADJUSTMENT BOLT in this
order:
Small washer
Ball bearing washer
Larger washer
Thread the ADJUSTMENT
BOLT through all of the
assembled base parts.
Tighten the knob until it feels
firm but not too tight.
TIP: Tightening or loosening
this knob is how you will
adjust the amount of effort it
takes to rotate your Apertura™
Dobsonian telescope on its
base.

Attach the 4-HOLE EYEPIECE
TRAY to the BASE RIGHT panel
of the BASE HOUSING
ASSEMBLY using the two pre-
drilled holes and two small black
Phillips screws.
Assembling the OPTICAL TUBE
Attach SPRING SPACERS to each
of the BASE SIDE BOARDS.
Attach ALTITUDE KNOB,
SPACER and SPRING to each
SIDE BEARING, as shown.

Next, place the TELESCOPE
TUBE into the BASE, with
the large SIDE BEARINGS
seated into the
corresponding semi-circular
cut outs in the side boards.
Then attach a SPRING to
each of the SPRING
SPACERS that you installed
on the side boards of your
Dobsonian telescope's base.

Locate the 8x50 FINDERSCOPE and attach it to
the dovetailed FINDERSCOPE BRACKET
BASE on the side of the OPTICAL TUBE,
located near the FOCUSER.
Use the thumbscrew to tighten the
FINDERSCOPE into place.
Continue Assembling the OPTICAL TUBE

Aligning Your Finderscope
When first attached, the finderscope will not be perfectly aligned with the telescope’s
optics. Once the finderscope is properly aligned with the main telescope’s view, the
finderscope’s extra-wide field of view will help you easily center the main telescope on
objects you wish to view.
Start by inserting your 25 mm eyepiece into the focuser and then point the telescope at
a large, distant and stationary object (such as the detail on a billboard at least 250 yards
away). Now look through the finderscope. To focus the finder, first loosen the lens cell by
unscrewing it a half-turn. Then turn the locking ring the other way, to pull it back from
the lens cell and expose the maximum number of threads on the finderscope body. Turn
the lens back and forth to focus your view. Once the lens is focused, then tighten the
locking ring to hold the lens cell in place. You may need to make a slight focus adjustment
the first time you use the finderscope on the night sky, but once the focus is set on the sky
you should not need to adjust it again.
Once focused, align your finderscope by gently adjusting the two thumbscrews on
the finderscope bracket (the silver “knob” contains a spring that gives back-pressure to
the thumbscrews and does not need adjustment). Carefully align the finderscope body
until its cross-hairs are centered on the object that is currently centered in the main
telescope’s eyepiece.
 If you bump the finder during transport or use and disturb its alignment, it will
only require a quick and easy adjustment of the two thumbscrews to realign the
finderscope to the main telescope’s view.
Finderscope Locking Ring
Finderscope Lens Cell
Alignment Screws
Spring Tensioner
(no adjustment)

2" Crayford Style Focuser Your Apertura Dobsonian Telescope comes standard with a 2"
Crayford style focuser and a 2" to 1.25" eyepiece adapter which allows you to use both 2" and
1.25" eyepieces. It is pictured here with the draw tube fully retracted.
The Apertura focuser will accept 2“ and 1.25” eyepieces (with included adapter) and other
common hardware. The amount of focusing required for each eyepiece will vary, therefore
retract or extend the drawtube to bring the image into best focus. For lower power, wide field-
of-view (FOV) eyepieces, it may be necessary to increase the focal length by fitting the 35mm
Extension Tube (sold separately) into the focuser as an adapter to achieve focus.
The movement of the focuser tube is a result of tension inside the focuser which can be
adjusted by the tensioning screw. In general, use the lightest amount of tension that will work
with the installed components for smooth action. But as heavier eyepieces are used, especially
in conjunction with other components, increase the tension to compensate for the extra
weight. Once you achieve focus, you may decide to use the locking screw to hold the focuser
in place even if the adjustment wheels are moved. This is helpful when exchanging parfocal
eyepieces or having other viewers come to the eyepiece, but is not necessary.
Tension Screw
Brass Compression Ring
Compression
Adjustment Screws
Focus Knob
Locking Screw
Focuser Drawtube
Retracted
This image shows the focuser
draw tube fully extended to
4 cm or 1.5 inches.
!! IMPORTANT !!
Locking screw (under tensioning
screw) must be backed out to
allow full drawtube travel.

Eyepiece Selection
Your Apertura™ DT Dobsonian Telescope comes one eyepiece: a 1.25” diameter
medium-power eyepiece with a 25mm focal length. Over time you will want to collect
three or four extra eyepieces to achieve a variety of magnifications. To get the best
results from your telescope, always start with your widest field (lowest power) eyepiece,
then work your way up to the higher power eyepiece, keeping the image centered
throughout.
Deep-sky objects are best observed with low or medium magnifications due to their
dimness at higher magnifications. Astronomical points of interest within our solar
system are good candidates for higher magnification because they are generally brighter
than deep sky objects. Of course, experimentation is always the most rewarding
approach to determining eyepiece selection.
Observation Tips
Your telescope will perform best when local artificial lighting is kept to a minimum.
Nearby streetlights and lighted buildings cause a lot of light pollution and will degrade
the quality of your view with your telescope.
When choosing a viewing location, try to find a spot far away from tall structures with a
wide view of the open sky.
Allow your eyes time to adjust to the darkness before attempting to view any faint
objects in the night sky. Usually 30 minutes is long enough for your eyes to totally adapt
to the dark. Preserve your dark-adapted vision by avoiding looking at sources of light
(street lights, cell phones, computers, etc.). If you are exposed to a light source, the
adjustment period will begin again. After your eyes have reached their dark-adapted
state you’ll want to consider using a red-lens light source for activity in the dark.
Acclimating Your Telescope
Before using your telescope, you should allow its temperature to equalize to that of the
ambient outside air temperature. Larger scopes take longer to equalize and should be
given a half- to one full hour depending on the temperature difference (one hour for a
difference of 40 degrees Fahrenheit is a good rule of thumb). Keeping your telescope
and optics in an outside or non-environmentally controlled building such as a garage or
shed can decrease the time it takes for the temperature differential to stabilize.

Viewing Conditions
The quality of the conditions for viewing are referred to as “seeing,” usually rated on a scale
of 1 to 10, with 10 as perfect seeing and 1 as very poor. There are two major conditions to
notice in evaluating viewing conditions on any given night: atmospheric disturbance and air
transparency. The best conditions for astronomical viewing are when atmospheric
disturbances are at a minimum. Lower your expectations when trying to use your scope too
early in the night or trying to focus on objects close to the horizon as this will impair your
ability to view clearly. Generally, you want to set your telescope up on the highest point
possible as it affords the highest quality viewing and isn’t as subject to atmospheric
disturbances. A good way to determine how well you will be able to see on any given night is
to look at bright stars about 40 degrees above the horizon and look for twinkling of stars.
Twinkling is caused by atmospheric disturbances and is an indicator that quality viewing
may be difficult. However, often stars that twinkle near the horizon will become steadier
later in the evening as they move higher in the night sky.
Also affecting the viewing quality is the transparency (clarity) of the air. Remember that our
viewing of the universe from the ground begins by looking through many miles of air that is
full of particles and water which is in constant motion and changes regularly.
Tracking Celestial Objects
Since the Earth is always rotating, astronomical objects will appear to move across the night
sky. When using your Apertura™ Dobsonian Telescope for a little while, you need to
manually track the observed objects by carefully moving the scope’s tube to keep the object
relatively centered in the eyepiece. Using higher magnification requires you to make more
frequent tracking adjustments than you would when using lower magnification.
A popular method for locating night sky objects is called “star-hopping.” Using a simple
planisphere or star chart, zero in on your target of interest by jumping, or hopping, from one
bright star to another until you reach the closest star to your destination. Then put in a
lower power eyepiece and start scanning the sky around that nearby star until you find the
galaxy, star cluster, or nebulae you are looking for. Learning to star-hop makes object
location much quicker and gets you to where you want to be without much fuss. You can
also experiment with online resources including apps, software you can load on your
computer, etc. Use the method that you like best and then get out there and practice! You'll
be an avid amateur astronomer in no time!

This telescope comes collimated from the factory and is ready to use. Should you need
to re-collimate in the future, we have included a basic collimation procedure for a
standard laser collimator (sold separately).
CAUTION: If you use a laser collimator, Do NOT allow the laser to shine in your eyes
(either directly or indirectly off the telescope’s mirrors) as it may very well damage
your eye sight permanently. Do not allow children to use your collimator or any other
laser, and even with adults, make sure and supervise until you are sure they
understand the proper handling of laser products.
1. Remove any eyepiece that may be installed in the focuser.
2. Look into the focuser and confirm that you see the secondary mirror centered in the hole. Reflected
in the secondary mirror, you should be able to see the primary mirror and the three small clips
around the edge of the primary mirror. If not, you will need to rotate the secondary mirror assembly
with your hand (be careful not to TOUCH the reflective surface of the secondary mirror itself) until
the reflection of the primary mirror is centered in the secondary mirror. In addition, although the
shape of the secondary mirror is actually oval, when properly aligned it will appear to be circular as
viewed through the focuser.
3. Insert a 2" laser collimator into the 2” adapter sleeve (or a 1.25" collimator into the 2" to 1.25" focuser
adapter) and then insert that into the focuser. Secure the laser collimator with the thumbscrew. Turn
on the laser collimator and rotate its target face toward the back end of the scope (the primary mirror
end).
4. Hold up a piece of paper in front of the telescope to see if the laser is missing the secondary mirror on
reflection. If the laser isn’t reflected onto the paper, then most likely it is hitting the secondary mirror
as it should.
5. Carefully peer into the tube to see where the laser is hitting the primary mirror below. CAUTION:
Do NOT allow the laser to shine directly into your eye from the telescope’s mirrors. The laser should
be shining in the middle of the small donut ring in the middle of the primary mirror. If it is not,
adjust the tilt of the secondary mirror using the three small screws on the top of the secondary mirror
assembly until the laser is centered in the donut ring on the primary.
6. Now view the target face on the laser collimator to see if the laser is hitting anywhere on the target
face. If not, then this simply means that the primary mirror is far enough out of adjustment that the
laser is outside the target face on the collimator. In either case, you will need to move to the bottom
end of the scope and loosen the large white locking knobs. Then adjust the angle of the primary
mirror with the large black adjustment knobs until the laser becomes centered in the hole in the
middle of the laser collimator’s target face.
7. Once accomplished, lock the primary mirror assembly with the white knobs. This may cause some
minor movement of the mirror, so continue fine adjustments until all six knobs are firm and the laser
is centered on its target.

Keeping your Telescope Clean
Do not touch, rub, brush, wipe or otherwise contact the primary mirror or secondary
mirror. Over time a thin layer of dust will accumulate on the surface of these mirrors. This is
normal and is best left alone. If it is absolutely necessary, use only an optical lens brush and
lens bulb puffer to remove dust from your mirrors.
The outside of your Apertura™ DT Dobsonian Telescope is easily cleaned with a dust cloth
or sponge for fingerprints, dust, etc.
Clean other components ONLY when absolutely necessary and then ONLY with a mild soap
solution and lint-free cloth by gently blotting. Do not use any harsh cleaning chemicals to
avoid damaging the finish on your telescope and components.
Use a dry soft cloth to remove condensation from the outside of you telescope before storing
it. Do not try to dry the eyepiece or finderscope lenses but rather let them dry naturally.
Avoid leaving your telescope in an excessively hot environment such as the inside of a car as
high temperatures can damage your telescope in several ways.