The 500 Rule for Star Shooting
Knowing What the maximum exposure times are before you start to see star trails, when photographing the Milky Way, depends on your sensor size and focal length, using the commonly termed '500 rule' (500 / Your focal length in 35mm terms).
This handy chart provides the most common focal lengths and their respective exposure times for photographing the Milky Way. These are maximum exposure times you can use before you start to see star trails.
Keep this chart handy when going out to shoot at night! (Downloadable version below)
This handy chart provides the most common focal lengths and their respective exposure times for photographing the Milky Way. These are maximum exposure times you can use before you start to see star trails.
Keep this chart handy when going out to shoot at night! (Downloadable version below)
| The 500 Rule |
Focal Length (mm) |
Full Frame Sensor Size (35mm) |
Maximum Exposure Time (Seconds) |
Crop Frame Sensor 1.5x (mm) (Nikon) |
Maximum Exposure Time (Seconds) |
Crop Frame Sensor 1.6X (mm) (Canon) |
Maximum Exposure Time (Seconds) |
8 |
8 |
63 |
12 |
42 |
13 |
39 |
10 |
10 |
50 |
15 |
33 |
16 |
31 |
11 |
11 |
45 |
17 |
30 |
18 |
28 |
12 |
12 |
42 |
18 |
28 |
19 |
26 |
13 |
13 |
38 |
20 |
26 |
21 |
24 |
14 |
14 |
36 |
21 |
24 |
22 |
22 |
15 |
15 |
33 |
23 |
22 |
24 |
21 |
16 |
16 |
31 |
24 |
21 |
26 |
20 |
17 |
17 |
29 |
26 |
20 |
27 |
18 |
18 |
18 |
28 |
27 |
19 |
29 |
17 |
19 |
19 |
26 |
29 |
18 |
30 |
16 |
20 |
20 |
25 |
30 |
17 |
32 |
16 |
21 |
21 |
24 |
32 |
16 |
34 |
15 |
22 |
22 |
23 |
33 |
15 |
35 |
14 |
23 |
23 |
22 |
35 |
14 |
37 |
14 |
24 |
24 |
21 |
36 |
14 |
38 |
13 |
25 |
25 |
20 |
38 |
13 |
40 |
13 |
26 |
26 |
19 |
39 |
13 |
42 |
12 |
27 |
27 |
19 |
41 |
12 |
43 |
12 |
28 |
28 |
18 |
42 |
12 |
45 |
11 |
29 |
29 |
17 |
44 |
11 |
46 |
11 |
30 |
30 |
17 |
45 |
11 |
48 |
10 |
31 |
31 |
16 |
47 |
11 |
50 |
10 |
32 |
32 |
16 |
48 |
10 |
51 |
10 |
33 |
33 |
15 |
50 |
10 |
53 |
9 |
34 |
34 |
15 |
51 |
10 |
54 |
9 |
35 |
35 |
14 |
53 |
10 |
56 |
9 |
