Night Photography Test Answers

If you took our test (here), then you were likely sent your score and a link to this page.

We haven’t perfected the scoring at the moment, so your emailed results (if you filled out a correct email) will only indicate whether you got the question correct or not, not which answer you chose.  Here are the questions, and the correct answers along with a brief explanation why.

1. Which of the following is the HARDEST to get a decent photo of *WITHOUT* special expertise or equipment?
A. The Milky Way
B. Meteors / meteor showers.
C. Stars of magnitude 3 and dimmer
D. The Pinwheel Galaxy (M101)

The Pinwheel Galaxy is small and is found in Ursa Major (the Big Dipper). The galaxy is not visible to the naked eye. You need to track the sky (do true astrophotography) to get a good exposure.

2. Which of these camera settings are most likely to capture details in the face of a FULL Moon.
A. This is a trick question. It depends on the time of day or night!
B. f/9 ISO 200, 1/200 of a second, 150mm
C. f/2.8, ISO 1000, 3 seconds, 1500 mm
D. f/5.6, ISO 100, 20 seconds, 350mm.
E. ALL of the above except item 1.

All except B will grossly overexpose the moon details – and the “B” settings will properly expose the face of the moon regardless of the time of day or night.

3. Which of these causes the greatest INCREASE in digital noise?
A. Increasing ISO from 800 to 1600
B. An 25 degree Celsius Increase in the air temperature
C. Double the brightness by changing the exposure in post processing
D. Use a telephoto lens instead of a wide angle lens

D is clearly a red herring. A and C will display more noticeable noise, but the biggest factor in photography is the temperature of the sensor used to capture the image.

4. You are in Chicago and you desperately want a photo of the Galactic Center of our Milky Way. Which strategy is most likely to pay off:
A. In December, leave Chicago to the the darkest skies you can and wait until at least 2 hours after sunset.
B. In October, go on the shore of Lake Michigan so that there are dark skies to the north and look up at 4 am
C. Get on the top of the tallest building in Chicago and look any time it is at least 2 hours after sunset.
D. In June: Leave Chicago to find dark skies in the south. Look up and south at about 11 PM

The Milky Way (Galactic Center) is not visible in December, and it’s barely visible at the end of October – but not to the North.

5. You encounter a photo of the half full moon near the horizon with starry skies and the fading glow of twilight. What can you conclude?
A. The photo is a forgery.
B. It must be the first quarter moon
C. It must be a last quarter moon
D. There is nothing to conclude. You’re being tricky, aren’t you Mr. Question guy!

Anytime you see a moon that is not eclipsed, you cannot get stars, too because of the huge dynamic range between the moon and stars. And only a FULL moon can be eclipsed.

6. The most effective way to get a star trail that is at least an hour long is to:
A. Take a single 1-hour exposure, duh!
B. Take a sequence of exposures and stack them in lighten mode.
C. Take a sequence of exposures and stack them in Screen mode in Photoshop
D. None of these.

While you might manage a single hour-long exposure, that will only work if the sky is REALLY dark. A lighten stacked sequence will work under any lighting conditions.

7. You set your Intervalometer to take ten 58-second exposure with a 2 second intervals between each. You start the intervalometer, hear the first shutter click and return after 10 minutes to discover 10 shots, but they are only 20 seconds each! What did you probably do wrong?
A. Left long exposure noise reduction on.
B. Accidentally used your slowest speed memory card
C. Didn’t connect the intervalometer properly
D. Forgot to set your camera to Bulb mode

No matter what you set the intervalometer to do, it is the camera settings that win. Had you left long exposure noise reduction on, the most likely result would be only 5 photos.

8. You want to capture a shot of a dark, distant mountain peak on a dark night with as little noise as possible. Which of these strategies will produce the best result?
A. Push the ISO high and use strong noise correction
B. Open the aperture to f/2.8
C. Take several dozen exposures, average and then brighen them
D. Make a long exposure: of 30 minutes or so at a lower ISO (e.g. 400)

Actually any of these would work. But to keep the noise low you will need lots of exposures that you average. It will be hard to get detail in a dark, distant mountain peak since it would be too far away to light up with your own light.

9. You want to shoot a multi row panorama featuring the Milky Way in the South East sky. What panorama shooting strategy will work best?
A. Shoot in landscape mode South to North, land then sky.
B. Shoot in portrait mode, North to South sky first, land last.
C. Shoot as short as possible exposures, land to sky, then North to South
D. Wait for strong moon light to brighten the landscape then the shooting order wont matter

To figure this one out, think about the motion of the stars. Stitching will fail if the stars move significantly between the shots… so using landscape mode pointing at the fastest moving part of the sky (southeast-east) then the slower moving part of the sky (north) will minimize stitching issues. And, if you make it a multi-row panorama, the “sky” portion of the shots will have only stars which should stitch together without a problem.

10. The rising moon or stars appear dim when low in the sky. Why?
A. Because there is often a lot of light pollution near the ground that drowns them out.
B. Because of atmospheric “extinction”
C. They aren’t dimmer. It’s an optical illusion.

Atmospheric extinction is the same thing that causes the sun to rise or set reddened. There is so much more atmosphere looking toward the horizon than straight up that light gets “extinguished” significantly.

11. The Galactic Center of Our Milky Way Galaxy can be found in which constellation:
A. Andromeda
B. Big Dipper
C. Orion
D. Sagittarius

Orion is on the Celestial Equator and pretty far from the Galactic Center. Spot the teapot (a group of stars in Sagittarius) to find the Galactic Center of our Milky Way.

12. You want to create a great image of a starry night landscape against a delicious foreground. Which of these conditions offers the best hope?
A. The stars are twinkling brightly
B. The area is very dark in all directions
C. The moon is nearly full
D. None of the Above

We give credit for B, or D. The problem is when it is “very dark”  (B) it is hard to get a foreground unless you do light painting.  Twinkling stars actually mean there are atmospheric disturbances and by themselves are both a problem, and not sufficient. A full moon implies that stars in the sky will be mostly  washed out.  Best time, a partially lit moon or very dark and supply your own foreground light.

13. The moon appears much larger when it is low in the sky. Why?
A. It’s an optical illusion.
B, Atmospheric distortion stretches the moon to make it look larger
C. The moon diameter changes as it rises.
D. It doesn’t appear bigger, what are you talking about!?!

When the moon is nearer to identifiably sized objects, it looks larger. Atmospheric distortion actually squashes the moon slightly.  You could argue that you are not swayed by optical illusions and vote for D.

14. You set your camera for a 10 minute exposure at ISO 100, f/5.6 and 15mm on a dark night. Looking at the result you discover a streak through the stars. Which of these is the LEAST likely explanation for the streak?
A. An airplane
B. A meteor
C. A satellite

f/5.6, ISO 100 will capture satellites and airplanes… but only a brilliant fireball (meteor).

15. You want a shot with starry skies and you want those stars to be *dots* that are smeared no more than two pixels across the sensor. Assuming you are using a 1.6 crop camera with a 20mm lens, what is the longest exposure you can make to avoid “dashes”?
A. From the 600 rule: 600/20 = 30 seconds.
B. Apply the 600 rule, but use the crop so 30 / 1.6 = 18 seconds
C. It depends how many pixels are in each row, but assuming 5200 pixels then 8 seconds is the maximum.
D. Use the 500 rule. 500 / (20 * 1.6) = 15 seconds

We have extensive writing on this particular subject. The width of the streak is mostly related to sensor geometry, however.

16. How long does it take the moon (or sun) to move it’s diameter in the sky?
A. 10 seconds
B. one minute
C. two minutes
D. ten minutes

If you know the angular diameter of the moon, you can figure this one out. 360 degrees is a day, 15 degrees is an hour. The moon is only 1/2 a degree in angular diameter. In an hour it moves 30 times its diameter. Doing the math that works out to moving its diameter in two minutes.

17. If the moon rises tonight at 10 PM local time. About what time will it rise TOMORROW night?
A. 10:10 PM
B. 9:10 PM
C. 10:50 PM
D. 1:15 AM

The answer depends on your  latitude, but on average the moon rises 48 minutes later each night.

18. My lens has 7 blades in the aperture iris. How many spikes will I have radiating from a bright light source if I stop down to f/11?
A. None. You need a star filter to get those spikes.
B. Four
C. Duh, 7!
D. 14

Curiously, even numbered blades produce matching numbers of spikes, but odd number of blades produces double the spikes.  Good thing to know if you like those diffraction spikes.

19. The brightest star in the night sky is
A. Polaris, (the North Star), in Ursa Minor
B. Sirius, in Canis Major
C. Neptune, in the Eclipitic Plane
D. Proxima, in Centaurus

Proxima is the closest star to our solar system, Sirius – in the “Big Dog Constellation” is the brightest star. Sirius’ apparent brightness is because it, too, is very close to us. Anything in the sky brighter than Sirius is a planet.

20. Do these settings have anything in common: f/2.8, ISO 200, 20 seconds; f/4, ISO 100, 80 seconds
A. No.
B. Yes. The settings collect the same amount of light

21. Pictures of Galaxies and Nebulae may require exposure bracketing to capture them well.
A. True
B. False

True. The Orion Nebula, for example, has a bright core that is several stops brighter than the surrounding nebula, and several stops more bright than the outer expanses of the nebula.

22. Your 5-second exposure is very dark. If you increase the exposure time to 20 seconds, what is the most likely outcome? *
A. There won’t be a dramatic difference.
B. It will be blown out. 20 seconds is a very long exposure
C. It depends on the conditions.

We are talking two stops here. Not a huge difference despite the large number of seconds of additional exposure.

23. You want to get the “star burst” effect visible around the lamps above. Which of these is the least expensive way to achieve this? *
A. Get a starburst filter for your lens
B. Under expose the shot
C. Stop the aperture down (e.g. from f/4 to f/9)
D. Phone a friend

Stop down. That creates more diffraction. You  will have to increase the exposure time or ISO to compensate, of course.

24. The most effective way to get a proper exposure at night is to… *
A. Use the automatic metering mode of your camera.
B. Adjust exposures based on the histogram
C. Apply a standard rule
D. Adjust settings until the image on the LCD looks right

If only the image on the LCD was as helpful as it seems. Check that, but the histogram will tell you a lot more.