CHAPTER 13: Digital Astrophotography — What’s New?Chapter_13__Digital_Astrophotography.htmlChapter_13__Digital_Astrophotography.htmlshapeimage_1_link_0
 
Exposure Tables With the instant results of digital cameras, exposure tables aren’t as necessary as they were in the film days. But for those who may wish some guidance, here are the tables we presented in earlier editions of our book, designed for 35mm film but good for DSLRs. Exposure Guidelines: Camera-on-Tripod Subjects

Subject


Constellations

Twilight Scenes

Lunar Haloes

Auroras

Zodiacal Light

Star Trails (short)

Star Trails (long)

Meteors

Lens


28 to 50mm

20 to 135mm

15 to 28mm

8 to 50mm

8 to 28mm

15 to 50mm

15 to 28mm

28 to 50mm

ISO


400 to 3200

50 to 200

200 to 400

200 to 400

400 to 1600

100 to 200

100

400

Focal Ratio


f2 to 2.8

f2 to 2.8

f2 to 2.8

f2 to 2.8

f2.8

f2.8 to 4

f5.6 to 8

f2 to 2.8

Duration


10 to 30 sec.

2 to 10 sec.

4 to 16 sec.

5 to 40 sec.

60 sec+

5 to 60 min.

1 to 8 hours

5 to 20 min.

Lens



28mm

50mm

105mm

Celestial

Equator


25 sec.

12 sec.

6 sec.

Dec. of

45° N or S


40 sec.

20 sec.

10 sec.

Near Celestial

Poles


90 sec.

50 sec.

25 sec.


Exposure Guidelines: Maximum Exposures To Avoid Trailing

ISO

Speed


3200

1600

800

400

200

100

50

25

Full

Moon


1/2000

1/1000

1/500

1/250

1/125

1/60

1/30

1/15

Gibbous



1/1000

1/500

1/250

1/125

1/60

1/30

1/15

1/8

First

Quarter


1/500

1/250

1/125

1/60

1/30

1/15

1/8

1/4


Exposure Guidelines: Prime Focus Lunar Photography (f16*)

Thick

Crescent


1/250

1/125

1/60

1/30

1/15

1/8

1/4

1/2

Thin

Crescent


1/125

1/60

1/30

1/15

1/8

1/4

1/2

1

Earthshine



2 to 5 sec.

5 to 10 sec.

10 to 20 sec.

20 to 40 sec.

40 to 80 sec.

N/A

N/A

N/A

* Use one shutter speed faster around f11, two shutter speeds faster around f8, and so on. As a general rule, though, always bracket exposures one or two shutter speeds either side of values given to allow for atmospheric absorption and other vagaries. Use a lunar-rate drive for longer Earthshine photos.

Partial Phases


Totality:

Diamond Ring


Prominences


Outer Corona


Inner Corona


Wide-Angle Scene

1/500 second



1/250 second


1/500 second


1/2 second


1/30 second


2 to 4 seconds at f4

Exposure Guidelines: Solar Eclipse Exposures (assuming ISO 100 at f5.6)

... with safe solar filter in place over lens or telescope at all times for partial phases

These applied to “full-frame” 35mm film cameras, but won’t be too different for APS-sized DSLRs, with their equivalent 18mm wide-angle, 35mm normal, and 70mm short-telephoto lenses.