| |
Mirror Size
(mm)
Focal Ratio
Eyepiece |
Magnification |
Field of View (arc-minutes) |
Exit Pupil (mm) |
Focal Length (mm) |
Eyepiece |
x 2 Barlow |
x 3 Barlow |
Eyepiece |
x 2 Barlow |
x 3 Barlow |
Eyepiece |
x 2 Barlow |
x 3 Barlow |
4 |
300 |
600 |
900 |
10 |
5 |
3 |
0.7 |
0.3 |
0.2 |
6 |
200 |
400 |
600 |
15 |
8 |
5 |
1 |
0.5 |
0.3 |
|
9 |
133 |
267 |
400 |
22 |
11 |
8 |
1.5 |
0.8 |
0.5 |
15 |
80 |
160 |
240 |
38 |
19 |
12 |
2.5 |
1.2 |
0.8 |
|
25 |
48 |
96 |
144 |
62 |
31 |
21 |
4.2 |
2.1 |
1.4 |
|
32 |
38 |
75 |
112 |
80 |
40 |
27 |
5.3 |
2.7 |
1.8 |
|
40 |
30 |
60 |
90 |
100 |
50 |
33 |
6.7 |
3.3 |
2.2 |
|
| |
- Exit Pupils below 0.5mm are ususally not recommended
- selections shown in red.
- Exit Pupils above 7mm definitely waste light - selections shown
in red.
- Exit Pupils above 6mm but below 7mm may waste light when the eye
is not totally dark adapted. With increasing age, even the totally
dark adapted eye will have an iris diameter of only about 6mm - selections
shown in orange.
- Field of view estimation is based on Plossl eyepieces with 50° Effective
Field of View
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