night ppt


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night ppt

  1. 1. Night Photography
  2. 2. Night Photography • The first rule of night photography: use manual mode. –Camera meters fail at very low light levels, so any non-manual mode, including Av, will result in bad exposure. • Focus: Autofocus usually fails or is inaccurate in very low light conditions. Ways to focus accurately: –Use manual focus on the lens and use the distance window. Objects like faraway hills or stars are effectively infinite distance away. –Shine a light on your subject, autofocus, then turn off the light and take the image. –Focus while there is still light, setting the lens for later. –Use live view (or equivalent feature) with magnification to focus
  3. 3. Night Photography • RAW mode is good. –.jpg discards image information, reducing the effectiveness of editing. –White balance varies widely at night, especially if there is light pollution. If you are only able to shoot .jpg, experiment with different white balances. –Exposure mistakes are common, and RAW mode allows you to brighten the exposure significantly or recover blown highlights.
  4. 4. Crazy white balance. I didn’t shoot this in RAW, so I can’t get natural colors. Also, the highlights on the water could have been recovered with RAW editing.
  5. 5. General Astronomy Information • Astronomy ≠ Astrology • The Earth rotates about an axis through the North and South Poles. • Polaris, the North Star, lies nearly but not exactly on this axis. • To an observer on Earth, the stars appear to rotate about the North Star, rising in the east and setting in the west. • The magnetic North Pole lies under northern Canada, so compasses don’t actually point in the same direction as the North Star.
  6. 6. General Astronomy Information • The moon has a huge effect on night photography. – A full moon brightens the sky, making it impossible to see dim stars. – A full moon can light up the landscape at night. – New moon = no moon visible, and the most stars are visible at this point in time.
  7. 7. General Astronomy Information • Sky darkness is key. Factors: – Light pollution—cities spew orange light into the skies, blotting out the stars. – Sunrise and sunset. Depending on your location, the sky can be bright up to 2 hours before sunrise/after sunset. – Moon: phase, rise/set times – You can check this information at several websites: • • Google Earth is also incredibly useful.
  8. 8. Night Photography • How to get long exposures: – “Bulb” or B mode takes an image for as long as the shutter button is held down. – Use a remote. Every camera manufacturer makes ones, designs are available online to build your own, and cheap ones are available on ebay for ~$10. • Flip the switch, wait for a while, flip the switch. Your photo is done. • Do a test exposure before committing to an hour (or more). – Try a 30” exposure at your highest ISO and largest aperture (in order to let in as much light as possible in a short amount of time) to check exposure, histogram, focus, framing, level horizon, etc.
  9. 9. Test exposure: 30 sec, ISO 1600, f/2.8
  10. 10. Final exposure: 45 min, ISO 200,
  11. 11. Night Photography • Common problems: – Battery death. A freshly charged battery lasts 1-3 hours, depending on the camera, temperature, and ISO. – Noise. During long exposures, the sensor heats up, and you get thermal noise. This is more of a problem in hot weather. • Dark frame subtraction can reduce this. Some cameras will take a dark frame as soon as you finish an exposure, and then subtract it. 1 hr exposure + 1 hr dark frame = 2 hrs => battery death? = bad. • If you battery dies during the dark frame subtraction, then the photo is lost. • Furthermore, I’ve found that in-camera dark frame subtraction is not always effective. • Taking a second exposure with the lens cap on and then subtracting the dark frame from the light frame in Photoshop is
  12. 12. Night Photography • Common problems: – Light pollution: light from cities is reflected off clouds and dust in the air, creating bright areas where no stars are visible. • Because of this, the best astronomy conditions are far from cities. Source: lighthalo on
  13. 13. Night Photography • More problems: – Condensation. If your lens surface is colder than the air, and the humidity is high enough, water will condense on your camera, totally fogging it. • During night exposures, this most commonly occurs near sunrise. • You can avoid this by putting a foot-warmer-type heating pad on the lens to keep it warm.
  14. 14. Night Photography • More problems: – Airplanes fly across the frame and make blinky trails. These aren’t shooting stars. – Solution: use a smaller aperture or take the photo when few planes are flying (1-5 AM)
  15. 15. Night Photography • General tips: – An interesting foreground gives the photo context and makes it much more interesting. Source: lighthalo on
  16. 16. Night Photography • General tips: – Light painting can bring out detail in a shadow area. – Use a flashlight, etc. to “paint” light onto an object. Source: floris on
  17. 17. Night Photography • General tips: – Light painting can bring out detail in a shadow area. – Use a flashlight, etc. to “paint” light onto an object.
  18. 18. Night Photography • General tips: – Stuff to bring: • Tripod. It holds your camera steady. • Remote. So you don’t have to hold the button down for an hour. • Glowsticks. I frequently set up my camera and tripod and then leave it for a couple hours. It’s much easier to find it in the dark if it is glowing. • Compass. Although it doesn’t point directly toward the North Star, it’s pretty close, and helps locate the North Star. • Warm clothes. If you’re sitting outdoors at night for hours on end, you might get cold. Freezing next to your camera sucks. • Flashlight/headlamp. Trying to set up gear in the dark sucks. • Chair. Because sitting on wet grass or standing for hours sucks.
  19. 19. Stacking • After 30 seconds to a minute, a star will no longer become brighter because its location has changed. Instead, it forms a trail across the image. • Non-moving objects (like empty sky), on the other hand, becomes brighter as long as you expose the image. • Instead of taking one long exposure, you can take many short exposures, a technique called “stacking.” • This increases contrast between the stars and the sky and reduces blown highlights from lights, light pollution, etc. • Instead of taking 1 60-minute exposure, you could do 60 1- minute exposures, 12 5-minute exposures, etc. and then stack them in Photoshop into one exposure.
  20. 20. 1 15-minute exposure
  21. 21. 30 1-minute exposures stacked
  22. 22. Timelapse • You can take a large number of photos at intervals and then play them in rapid succession, a technique called “timelapse.” • If you play images at 24-30 frames per second, it looks like real video.
  23. 23. Timelapse • Tips – Manual everything! • If the camera refocuses in every photo, the video will bounce around, flicker, and have random blurry frames. • If you use auto white balance, the white balance will change throughout the video, causing abrupt changes in color. • The camera must be totally still! Don’t bump it! • Be careful of wind. If necessary, weigh down your tripod or don’t extend it to the max height. – Use an intervalometer to control the camera. • Pushing the button every 5 seconds for an hour is tiring, tedious, and likely to introduce camera movement. • Canon cameras can be controlled from a computer via Remote Capture. • Cheap remotes can be found on ebay for 1/3 the cost of manufacturer-brand ones.
  24. 24. Timelapse • Tips – Chose an appropriate interval for the conditions. • 3-8 seconds for clouds, depending on how fast the clouds are moving and how fast you want them to move in the video. • 30 seconds to 2 minutes for stars – If your battery lasts 2 hours, then 1 image per minute = 120 photos = 4 seconds of video – Don’t worry about high ISO speeds. • When viewing 30 frames per second, graininess isn’t noticed. – Shoot RAW whenever possible • White balance and lighting conditions usually change throughout a scene, and RAW permits more editing flexibility.