stop moving please

In the last Blog i talked about increasing the amount of night photography time.This one is about a different type of time. If you have ever taken a night photo you will know that the stars move (really its the earth that's moving) and cause streaks so you have to calculate the exposure time based on the lens and camera that are used. Often the calculation is based on the 600 or 500 Rule which i think is better for more rounded starts.

                                                                                                                                                                  That's unless you want a star trail effect as above

Shutter Speed Using the 500 or 600 Rule

Use this table to help you calculate the maximum shutter speed you can use before you’ll start getting noticeable star trails in your nightscape photos.

Use the 600 rule for longer exposures and web images where slight trailing won’t be noticeable, or

Use the 500 rule if you’re more conservative or plan to print your images at 30” or higher.

                      1.5x Crop Sensor                   1.6x Crop Sensor                  Full Frame

                               NIKON                             CANON

Focal Length 500 rule 600 rule                  500 rule 600 rule             500 rule 600 rule

8 mm                42 s     50 s                            39 s        47 s                       63 s        75 s

14 mm              24 s     29 s                            22 s        27 s                       36 s        43 s

17 mm              19 s     23 s                            18 s        22 s                       29 s        35 s

24 mm              14 s     17 s                            13 s        16 s                       21 s        25 s

35 mm                9 s     11 s                              9 s        11 s                       14 s        17 s

50 mm                7 s      8 s                               6 s        7.5 s                      10 s        12 s

70 mm                5 s      6 s                               4 s         5 s                          7 s          9 s

For custom focal lengths, simply divide 500 or 600 by the focal length of your lens.

Example, for a 20 mm lens: 600 / 20 = 30 seconds on full frame, or 600 / (20*1.6) = 19 seconds on a Canon crop camera or 600 / (20*1.5) = 20 seconds on a Nikon/Sony crop camera.

  

For a 2 x crop sensor (bridge or 4/3rd camera)

            500 rule

14 mm  17 s

20 mm  12.5s

30 mm    8s                          

45 mm   5s