I followed these instructions and written down the steps I understood to be important, that is:

shutter speed = 600 / focal length * crop factor (1.5 for APS-C sensors)
ISO = 6000 * f-stop^2 / shutter speed

So, I made my first photo of the Milky Way using the formulas to determine the exposure settings.
Now I'm undecided whether to go on or to throw myself off from a highway bridge :)

Is the problem with the photos below that there is too much light pollution (photo taken at 200 meters above the city), or did I do something wrong?

Here is the EXIF data:

Body: Nikon D7000 
Lens: Tokina 11-16mm F2.8 
Focal length: 11 mm 
F-stop: F2.8 
Shutter speed: 35 seconds 
ISO: 1250

Here you can see the result:

The disaster !!!!

For completeness I've also attached the lower part of the photo, just to let you see what the light was (real light)

Real Light

Note that the first photo (the wrong one) shows the upper part of the sky of the second photo.

  • 17
    \$\begingroup\$ With that many city lights, yes, the problem is pretty clearly light pollution. \$\endgroup\$ Jul 27, 2014 at 16:49
  • 2
    \$\begingroup\$ Next time, find a place where you see no artificial lights, not even as a glow against the horizon, and try again :) \$\endgroup\$
    – JohannesD
    Jul 27, 2014 at 16:51
  • \$\begingroup\$ I only would like to be sure it was not an arror from me. In some other groups (italy) i've been told to have used too much iso ;) \$\endgroup\$ Jul 27, 2014 at 17:04
  • 1
    \$\begingroup\$ That looks a lot like light pollution. Try using a light pollution map next time to find if a location is sufficiently dark. \$\endgroup\$ Jul 27, 2014 at 17:23
  • 4
    \$\begingroup\$ I'm curious if you could see any indication of the Milky Way with the naked eye in that environment. If the light pollution washes out what the eye can see, it will most certainly wash out the camera too. \$\endgroup\$
    – user13451
    Jul 27, 2014 at 18:00

2 Answers 2


Yes, you have way too much light pollution. It looks like the sky is Bortle class 7 or worse

Class 7: Suburban/urban transition. The entire sky background has a vague, grayish white hue. Strong light sources are evident in all directions. The Milky Way is totally invisible or nearly so. M44 or M31 may be glimpsed with the unaided eye but are very indistinct. Clouds are brilliantly lit. Even in moderate-size telescopes, the brightest Messier objects are pale ghosts of their true selves. The naked-eye limiting magnitude is 5.0 if you really try, and a 32-cm reflector will barely reach 14th magnitude.

You need to move at least 50 km away from big cities to get dark enough skies to see the Milky Way well. Even at that distance away, you will still have a lot of light pollution causing the sky to turn blue in long exposure pictures. The milky Way will then be visible in the picture, but it will look like you somehow shot the picture during daytime or dusk.

A truly dark sky is only possible when you are at least a few hundred km away from cities, when the Moon is not in the sky and when the Sun is at least 18 degrees below the horizon. E.g. at 50 degrees Northern Lattitude around 21 june, the Sun does not sink far enough below the horizon, at local midnight you'll still have astronomical twilight. The sky may appear to look very dark with many faint stars visible, but weak nebulae will be drowned out.

  • 2
    \$\begingroup\$ Many years ago, I was in Death Valley (Father Crowley Point) and I could see two dim domes of light - one to the south, one to the east... and while the sky was full of stars, those two domes were enough that they took careful positioning of the frame to avoid contamination of a long exposure. \$\endgroup\$
    – user13451
    Jul 27, 2014 at 20:37
  • 1
    \$\begingroup\$ I dispute the 50km suggestion. On a clear night you can stand on a beach on east Hayling Island, UK and see the Milky Way with excellent clarity. The City of Portsmouth is 15km away. This may be because the city limits are the sea, limiting urban sprawl and providing a higher proportion of well controlled lighting fixtures. \$\endgroup\$
    – Gusdor
    Jul 28, 2014 at 9:19

If you can see as little as the glow of lights of a small town over the horizon, you're going to suffer from light pollution to some extent. Light pollution is the reflection of the "glow" of cities off the atmosphere, brightening it, so dimmer stars can't be differentiated. If you see the clouds in your first picture, they're so bright because of the reflection from the city lights bellow. If you had taken the picture without a city beneath it, then the clouds would have been black.

From a quick glance, you're settings seem good, but with a city in your photo, it's not going to work without cheating, save maybe a freak blackout.

Quick note, it's also worth noting that moon light is also a major contributor to light pollution. Probably not so much in this situation, but it's worth noting in the future.

  • 1
    \$\begingroup\$ Perhaps unintuitively, sunlight may also be a major contributor at night. At even moderately high latitudes nights are way brighter in the summer than in the winter. \$\endgroup\$
    – JohannesD
    Jul 27, 2014 at 17:06
  • \$\begingroup\$ there wass no moon. here it's new moon. but of course, i see, too city lghts \$\endgroup\$ Jul 27, 2014 at 19:19

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