Eyelens
Your eye pupil positioned too
far in or too far out will cause
edge darkening & field loss.
Ideal match for
your eye pupil
INSNAGLER
4-0399
NAGLER TYPE 4 EYEPIECE INSTRUCTIONS
WARNING:
Be alert that the weight of the Nagler Type 4 is enough to extend the eyeguard if you pick up your eyepiece
by the black barrel. The eyepiece cannot fall out of the Instadjust housing so do not be alarmed!
Thank you for purchasing a Tele Vue Nagler Type 4 eyepiece. Each features long eye relief along with an 82 degree
apparent field. By using new glass technology, we were able to improve eye-relief, contrast and ghost suppression, and
linearity (freedom from pincushion distortion) for any speed (f/#) telescope, while keeping size and weight down.
Our unique new “Instadjust” eyeguard housing allows maximum eye relief for eyeglass wearers in the down position.
Pulling the housing up will permit click-stop setting of the eyeguard height allowing for an ideal match between your eye and
telescope pupils. With this much eye relief available, it is important to learn your own optimum “click stop” position.
If you don’t wear eyeglasses, start with the eyeguard housing pulled out all the way. You can fold the soft rubber
eyeguard up or down, whichever is most comfortable for you. You may not see the full field with the eyeguard housing fully
extended; just keep “clicking down” until you find the most comfortable position where you still see the entire field (this is much
easier to do than to explain how, thank goodness). You will also find that this system minimizes extraneous outside light,
giving you the highest contrast for those “faint fuzzies”. The generous eye- relief also minimizes eye lens fogging due to eye
moisture in cold weather. See other side for description of pupil guide operation.
Following is a table of all Nagler Type 4 focal lengths and their corresponding effective field stop diameters. To
determine the true field in degrees for an eyepiece on any given telescope, simply divide the field stop diameter of the
eyepiece by the focal length of the telescope (in mm) and multiply the result by 57.3 degrees (a radian).
Warning: to avoid getting dust and dirt into the eyepiece, do not unscrew the chrome barrel. Also, do not unscrew
the identifying ring; this ring prevents removal of the “instadjust” housing. Re-assembly requires a special tool, so don't try
it no matter how curious you are. The eyepiece might have to be returned to us, with a service charge required.
The 12mm Nagler Type 4 eyepiece can be used with 1¼" AND 2" holders or focusers. Since it is designed as a
1¼" eyepiece, there is NO optical benefit from using a 2" holder. The 2" barrel is included just for convenience, but is also
threaded to accept the EBX-2120 extension tube which allows use of 48mm filters.
For 1¼" Holders:
1) Back off lock screw in the 2" barrel section of the eyepiece so it can be fully inserted into the holder.
2) If the holder has a lock screw, rotate the eyepiece so that the screw slips into the slot in the 2" section of the eyepiece barrel.
Your holder lock screw clamps to the 1¼" barrel of the eyepiece, while the eyepiece lock screw clamps to the outside of
your holder for maximum safety.
3) If your holder doesn't have a lock screw, be sure to clamp the eyepiece lock screw onto the outside of the holder. This
eyepiece is heavy, and can fall out of holders with slip fits, unless the lock screw is used!
For 2" Holders:
1) Remove the eyepiece lock screw. (Don't lose it.)
2) Use the lock screw on your 2" holder, being careful not to let it slip into the slot in the 2" barrel of the eyepiece.
3) The eyepiece will not "bottom" on Tele Vue 2" diagonals. Be careful if using other diagonals.
We wish you years of exciting viewing with these eyepieces, and welcome comments on your experiences with them.
Proper Eyeguard Positioning
Center Field
Edge Field
Nagler Type 4 F.L.
Field Stop Dia.
Eye Relief
Elements
Barrel Size
Weight (lbs.)
22mm
31.1mm
19mm
7
2"
1.5
17mm
24.3mm
17mm
7
2"
1.6
12mm
17.1mm
17mm
6
1¼"/2"
1.1
Extend eyeguard
by pulling up on
outer housing
32 Elkay Dr., Chester, New York 10918 (845) 469-4551 www.televue.com
Tele Vue
V i s i o n a r y
