Basics of Photographing Star Trails By Rick Graves November 15, 2016 1
What are Star Trails? Night sky images with foreground elements that show the passage of time and the motion of the stars 2
Which way to point the camera? Typically point north to get the north star in the image North star is stationary Star trails revolve around the north star Causes more full circles to be in the image rather than streaks Any direction is OK, though Be aware of city lights and light pollution 3
What lens is best? Wide angle lens It s up to you Recommendations 16 mm or wider on full frame 10-14 mm on APS-C crop 5-10 mm on Micro 4/3rds Large maximum aperture Lets in more light to get brighter stars f2.8 or larger 4
Capture Methods Single long exposure Multiple exposures, stacked in software 5
Basics Manual Exposure (shutter speed, ISO, aperture) Manual focus Manual White Balance - sunny Bulb mode or long time exposure setting Sturdy tripod A locking cable release Wide angle lens Long exposure noise reduction off Ideally a dark night, no moon, no clouds Experiment with this you may like moonlight on your foreground Proper clothing to keep the photographer comfortable Capture format Recommend RAW Plan to spend an hour or more outside to get one final image Go sit in the car or bring a chair Start about an hour after sunset or end about an hour before sunrise 6
Single Long Exposure Determine exposure Find the composition Focus manually Capture Post process 7
Determine Exposure Select shutter speed to capture desired star trail length Bulb mode, locking cable release 30 minutes minimum, longer can be better Be sure you have a fully charge battery Select lens aperture Typically select wide open or nearly wide open Select ISO to finalize the exposure Lower ISO = lower noise Sky should be dark (it is night after all) Long exposure noise reduction If you leave it on, the camera will take another 30 minute exposure to average out noise, etc Doubles the time you have to wait More risk of running out of battery power! 8
Composition Determine where in your image you want the north star Determine what and how much foreground you want in your image Be aware of camera tilt Horizons Water level Buildings etc 9
Manual Focus Not easy in the dark More like really difficult! Can shine bright flashlight on a distant object to get close to infinity focus Stars are at infinity Foreground may not be at infinity Most lenses go past infinity so you can t just turn the focus ring as far as it goes The infinity mark may not be infinity If you can see the moon, then focus on it Tape the lens so it won t move Consider live view and zoom in for critical focus Start before sunset, set up and focus when you can see then don t move the tripod and wait During the day, focus at something about a football field away & mark this spot as infinity 10
Image Capture Using the locking cable release, lock the shutter open Time your exposure Check watch Set timer Somehow keep track of the time Wait for time to end (exact end is not that critical) Start with a 30 minute exposure, check results and adjust to suit your taste in star trail length 11
What if all I have is a wireless remote? Infra red wireless remote Set camera to Bulb Set camera shutter release to infra red remote Click the remote one time Shutter opens starting the exposure Wait the proper amount of time Click the remote a second time Shutter closes ending the exposure 12
Post Processing Post process in your usual software Check for color noise and adjust in post processing Hot pixels will show up They do not move like the stars Clone them out 13
Single Long Exposure -Wide ISO 100, f4.0, 45 minutes, 10 mm 14
Single Long Exposure - Normal ISO 200, f1.8, 30 minutes, 28 mm On a crop sensor 28 mm isn t a wide angle lens 15
Practice Long Exposure Set camera to manual (M) Shutter speed Bulb or B Aperture Wide open a faster lens is better ISO Low 100-200 Focus Manual White Balance Sunny RAW Long Exposure Noise Reduction Cable release with a lock Time your exposure 16
Multiple Exposures, Stacked Multiple images taken and stacked in software to produce a complete photograph 50 to 100+ images Lots of images = start with empty memory card and fully charged batteries Dark frames Requires more post processing Why stack images? Lower noise in final image Can result in darker foreground 17
Startrails Software Free Software Donations accepted Web page: startrails.de See resources at the end There are other stacking software options 18
Multiple Exposures Stacked Determine exposure Shutter speed ISO and aperture Find the composition Focus manually Turn OFF long exposure noise reduction Capture the images Post process an image, make all of the rest match Stack the images Save resulting output 19
Determine Shutter Speed Select shutter speed to capture stars as points Determine based on sensor size, lens focal length to get points 500 Rule Maximum Exposure Time = 500/ ( Focal Length X Crop Factor ) Example: Canon 7D (1.6x crop), focal length = 10 mm 500/(10x1.6) = 31.25 seconds (round down to 30 or even 25 seconds) Set to a shorter time if you don t get stars as points Reference - http://www.davemorrowphotography.com/p/tutorial-shooting-night-sky.html#exposure 20
Determine Aperture and ISO Set aperture to wide open or close to wide open (f2.8, f1.4, etc) A fast lens is better here Set ISO to obtain a good exposure Keep sky dark Higher ISO if your lens maximum aperture is f4 or smaller You want bright stars 21
Composition Determine where in your image you want the north star Determine what and how much foreground you want in your image Be aware of camera tilt Horizons Water level Buildings etc 22
Manual Focus Not easy in the dark More like really difficult Can shine bright flashlight on a distant object to get close to infinity focus Stars are at infinity Foreground may not be at infinity Consider live view and zoom in for critical focus Start before sunset, set up and focus when you can see then don t move the tripod and wait 23
Capture the Images Be sure long exposure noise reduction is turned off If you leave it on, you will get gaps in your star trails Camera shutter release Set your camera shutter release mode to a continuous setting Multiple shots with one press of the shutter button Attach the cable release to the camera Use the cable release lock button Because you locked the cable release button, the camera should continue to automatically take one exposure after another until you unlock the remote release After 30 minutes to an hour, unlock the cable release lock button to stop the captures Place lens cap on the lens and take 5-10 more dark frames These are used by the Startrails software to average out the noise Use the exact same exposure settings as used for the image files Need to take at the same ambient temperature as image captures If you forget this step you will get more noise in the final image 24
Practice Multiple Exposures Set camera to manual (M) Shutter speed 500/ ( Focal Length X Crop Factor ) Aperture Wide open a faster lens is better ISO 400-800+ to achieve exposure you need Focus Manual White Balance Sunny Shutter release on continuous Set long exposure noise reduction OFF RAW Cable release with a lock 25
Preparation for stacking in Star Trails Post processing Lightroom: Export images as full size jpg or tif Other software: save as full size jpg or tif Tif is recommended More data for later editing of final stacked image Put all of your captured images and dark frames in one separate folder on your hard drive You need to be able to distinguish the dark frame files from the image files they are loaded separately in Startrails 26
Process in Startrails Start Startrails software Open the images Open the dark frames Stack Save output Optional create a time lapse movie too 27
Open Files in Startrails List of image files shows up here List of dark frame files shows up here As stack is being created, the final image forms here 28
Stack Images Click the Startrails button I select the lighten- Screen-Blend button Click OK and watch the image build 29
Watch and Wait 30
When Complete Save the image Save as tif is recommended Edit final image in your favorite software Save final edited image 31
Multiple Exposures, Stacked ISO 400, f2.8, 25 seconds, 96 subject frames, 10 dark frames, 17 mm Approximately 42 minutes of exposures 32
Multiple Exposures, Stacked ISO 800, f4, 25 seconds, 62 subject frames, 10mm Approximately 25 minutes of exposures 33
Time Lapse Video in Startrails Make a time lapse video with your image frames 34
Startrails Timelapse Video 35
Resources http://startrails.de http://deepskystacker.free.fr/english/index.ht ml http://www.lonelyspeck.com/ http://petapixel.com/2015/01/06/avoid-startrails-following-500-rule/ http://www.davemorrowphotography.com/p/t utorial-shooting-night-sky.html#exposure http://www.lightstalking.com/how-tophotograph-star-trails/ 36