The Basics
1.
2. Exit Pupil: the circle of light where you
place your eye.
3. True Field of View: angle in sky in
degrees.
4. Apparent field: the angle the field stop
circle appears in your vision, when you
look through the eyepiece.
5. Eye relief: distance from center of eye
lens to exit pupil.
Some General Thoughts
1. Choose a range of eyepieces in
low/mid power in ratios of 1.4 to 1.7
field stops.
2. Limit low powers to exit pupils of 7mm
or less for reflecting telescopes.
3. Limit high power to 200x - 300x (at-
mospheric limits) or to a 0.4mm minimum
exit pupil.
4. If you need to wear eyeglasses to
correct your eyesight astigmatism, select
eyepieces with at least 15mm of eye
relief or consider using DIOPTRX instead
of eyeglasses.
5. In general, large apparent field eye-
pieces are more spectacular and permit
more magnification, darker sky back-
grounds and smaller exit pupils (minimiz-
ing eyesight limitations) than narrow field
eyepieces having similar field stops.
Of course everyone has their own needs
and preferences in eyepieces. Keep those
factors in mind when choosing between
eyepiece types.
For data specific to your telescope visit the
Tele Vue Eyepiece Calculator at Televue.
com.
Eyepiece Reference Data
To Assist in Building Your Collection
32 Elkay Dr., Chester, NY 10918 (845) 469-4551 www.televue.com
Telescope Magnification =
Telescope objective F.L.
eyepiece F.L.
Exit Pupil Diameter =
eyepiece F.L.
telescope f/#
TFOV =
eyepiece field stop dia.
telescope obj. F.L.
x 57.3°
Focal
Length
(mm)
Type Product Code Apparent
Field (deg)
Field Stop
Dia. (mm)
Eye Relief
(mm)
Dioptrx
Ready
Pupil size in mm for various f/ratio telescopes
f/4.5
f/5.2
f/7
f/10
f/14
2" Eyepieces for Wide True Fields
55
Plössl
EPL-55.0
50
46.0
38
Y
12.2
10.6
7.9
5.5
3.9
41
Panoptic EPO-41.0
68
46.0
27
Y
9.1
7.9
5.9
4.1
2.9
31 Nagler 5 EN5-31.0
82
42.0
19
Y
6.9
6.0
4.4
3.1
2.2
35
Panoptic EPO-35.0
68
38.7
24
Y
7.8
6.7
5.0
3.5
2.5
21
Ethos
ETH-21.0
100
36.2
15
Y
4.7
4.0
3.0
2.1
1.5
22 Nagler 4 EN4-22.0
82
31.1
19
Y
4.9
4.2
3.1
2.2
1.6
27
Panoptic EPO-27.0
68
30.5
19
Y
6.0
5.2
3.9
2.7
1.9
17
Ethos
ETH-17.0
100
29.6
15
Y
3.8
3.3
2.4
1.7
1.2
17 Nagler 4 EN4-17.0
82
24.3
17
Y
3.8
3.3
2.4
1.7
1.2
1¼" Eyepieces for Wide True Fields
40
Plössl
EPL-40.0
43
27.0
28
Y
8.9
7.7
5.7
4.0
2.9
32
Plössl
EPL-32.0
50
27.0
22
Y
7.1
6.2
4.6
3.2
2.3
24
Panoptic EPO-24.0
68
27.0
15
Y*
5.3
4.6
3.4
2.4
1.7
13
Ethos
ETH-13.0
100
22.3
15
Y
2.9
2.5
1.9
1.3
0.9
16 Nagler 5 EN5-16.0
82
22.1
10
N
3.6
3.1
2.3
1.6
1.1
19
Panoptic EPO-19.0
68
21.3
13
Y*
4.2
3.7
2.7
1.9
1.4
25
Plössl
EAP-25.0
50
21.2
17
N
5.6
4.8
3.6
2.5
1.8
17.3
Delos
EDL-17.3
72
21.2
20
Y
3.8
3.3
2.5
1.7
1.2
18.2
DeLite
EDE-18.2
62
19.1
20
Y
4.0
3.5
2.6
1.8
1.3
10
Ethos
ETH-10.0
100
17.7
15
Y
2.2
1.9
1.4
1.0
0.7
13 Nagler 6 EN6-13.0
82
17.6
12
Y*
2.9
2.5
1.9
1.3
0.9
14
Delos
EDL-14.0
72
17.3
20
Y
3.1
2.7
2.0
1.4
1.0
20
Plössl
EAP-20.0
50
17.1
14
N
4.4
3.8
2.9
2.0
1.4
12 Nagler 4 EN4-12.0
82
17.1
17
Y
2.7
2.3
1.7
1.2
0.9
15
DeLite
EDE-15.0
62
16.0
20
Y
3.3
2.9
2.1
1.5
1.1
1¼" Eyepieces for Medium Powers
12
Delos
EDL-12.0
72
15.0
20
Y
2.7
2.3
1.7
1.2
0.9
11 Nagler 6 EN6-11.0
82
14.9
12
Y*
2.4
2.1
1.6
1.1
0.8
13
DeLite
EDE-13.0
62
13.8
20
Y
2.9
2.5
1.9
1.3
0.9
10
Delos
EDL-10.0
72
12.7
20
Y
2.2
1.9
1.4
1.0
0.7
15
Plössl
EAP-15.0
50
12.6
10
N
3.3
2.9
2.1
1.5
1.1
9
Nagler 6 EN6-09.0
82
12.4
12
Y*
2.0
1.7
1.3
0.9
0.6
11
DeLite
EDE-11.0
62
11.7
20
Y
2.4
2.1
1.6
1.1
0.8
9
DeLite
EDE-09.0
62
9.6
20
Y
2.0
1.7
1.3
0.9
0.6
11
Plössl
EAP-11.0
50
9.1
8
N
2.4
2.1
1.6
1.1
0.8
1¼" Eyepieces for Higher Powers
8
Ethos
ETH-08.0
100
13.9
15
Y
1.8
1.5
1.1
0.8
0.6
6
Ethos
ETH-06.0
100
10.4
15
Y
1.3
1.2
0.9
0.6
0.4
8
Delos
EDL-08.0
72
9.9
20
Y
1.8
1.5
1.1
0.8
0.6
7
Nagler 6 EN6-07.0
82
9.7
12
Y*
1.6
1.3
1.0
0.7
0.5
4.7
Ethos SX
ETH-04.7
110
8.9
15
Y
1.0
0.9
0.7
0.5
0.3
6
Delos
EDL-06.0
72
7.6
20
Y
1.3
1.2
0.9
0.6
0.4
7
DeLite
EDE-07.0
62
7.5
20
Y
1.6
1.3
1.0
0.7
0.5
3.7
Ethos SX
ETH-03.7
110
7.0
15
Y
0.8
0.7
0.5
0.4
0.3
5
Nagler 6 EN6-05.0
82
7.0
12
Y*
1.1
1.0
0.7
0.5
0.4
8
Plössl
EAP-08.0
50
6.5
6
N
1.8
1.5
1.1
0.8
0.6
4.5
Delos
EDL-04.5
72
5.6
20
Y
1.0
0.9
0.6
0.5
0.3
5
DeLite
EDE-05.0
62
5.3
20
Y
1.1
1.0
0.7
0.5
0.4
3.5 Nagler 6 EN6-03.5
82
4.8
12
Y*
0.8
0.7
0.5
0.4
0.3
3.5
Delos
EDL-03.5
72
4.4
20
Y
0.8
0.7
0.5
0.4
0.3
4
DeLite
EDE-04.0
62
4.3
20
Y
0.9
0.8
0.6
0.4
0.3
2.5 Nagler 6 EN6-02.5
82
3.4
12
Y*
0.6
0.5
0.4
0.3
0.2
3
DeLite
EDE-03.0
62
3.2
20
Y
0.7
0.6
0.4
0.3
0.2
1¼" Zoom Eyepieces for Medium and Higher Powers
6-3
Nagler
Zoom
ENZ-0306
50
5.1-2.6
10
N
1.3-0.7
1.2-
0.6
0.9-0.4
0.6-
0.3 0.4-0.2
