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Photographing Night Skies: Part II; the capture

by admin on December 27, 2013
Photographing Night Skies
Part II: the capture.  

Photographing at night can give you dazzling results, but your camera technique had better be spot-on! Using maximum apertures and high ISO’s are one of the techniques and as such require particular care in the shooting and post-processing of the image.

In the last newsletter I discussed the equipment needed to help make the process of night capture a little easier. In this newsletter I will outline the camera technique that I use when I am working after sunset. 

Preparation: 

First; when I get ready to go outdoors at night I make sure that prior to leaving my studio my camera bag is packed with exactly the equipment that I need. I check the batteries in my flashlights and my cameras to make sure everything is in working order. Nothing is more frustrating than being in the field in total darkness with a flashlight who’s batteries have gone dead, or a camera that is worthless because you forgot your extra battery or camera memory card. 

Set-up

Once in the field I identify what I want to photograph and set up the tripod and camera in the appropriate place. Usually when I shoot night skies I use my widest angle lens; that is my 17-40mm zoom lens. It is one of Canon’s sharpest lenses. The reason I choose a wide angle lens is so I can include some foreground and as much of the sky as possible. For star trails, milky way, or aurora images this gives the viewer context and scale for the image. Many times the foreground is a single pine tree or perhaps a clump of trees. 

Focusing

The trick for including foreground is to make sure it is sharp. Nothing is more frustrating than downloading your images from a nights hard work and discover that none of the images are sharp! To make sure that the foreground is sharp you must focus the lens on the chosen foreground element. This is where your large flashlight will come in real handy. Shine the flashlight on the foreground element, check where in the frame the spot-light lands. You can check your framing to make sure you have not included too much foreground (remember your foreground will most likely just go black–particularly with milky way or aurora type images.) If your camera is equipped with live-view I use the live-view mode to focus the lens. In live-view mode magnify the area that you are illuminating with the spot light and simply focus the camera. Experience has shown me that Canon cameras tend to have a better live-view focusing system than Nikon. This is not a judgement of one brand over another simply an observation. Depending upon the camera you own it make take some practice to use the live-view focus.  If your camera does not have live view you will need to focus by looking through the lens. Either way the camera and lens must be set to manual focus. For many night situations your exposure is made at the maximum lens aperture so focus is critical! 

Calculating and Making the Exposure:
The correct exposure is dependent upon the effect you are trying to achieve. Milky way, and aurora image are best shot at a maximum aperture and shortest shutter speed possible. A good starting point would be f4@30 seconds at ISO 1600. Once you have made the initial exposure you can check your histogram and adjust as necessary. A word about the histogram–night photography is typically a mostly black subject so most of your histogram will be over on the left side, this is normal and in many cases desirable. Over exposing will result in over-blown highlights that can’t be processed back into a useable range. Underexposure will result in an image with excessive noise and poor tonal range. Exposure for star trails is very different a good starting point for a moonless night would be f5.6@30 minutes at ISO 400. The longer the exposure the longer the start trails. Depending upon how much ambient light there is, and how your specific camera reacts to long exposures will determine your exact settings. You will need to make some test exposures and find out what works for you. Remember using a cable release is essential for long exposures. 

Night Histogram
Typical histogram for night 

Camera Settings:
Night photography is best done in Raw format. Post processing is critical to good results and the Raw format gives you the most options. Turn off all “noise reduction” settings and “long exposure noise reduction” settings. If you shoot in Raw format these settings are redundant and just take camera processing time.

Summary:
The above process is one method of capturing night images, it is not the only method. Using a series of short exposures made one right after the other is another method. I choose not to cover that here because it can require additional software, or equipment, the above approach is the simplest method. 

A critical aspect of night photography is how much ambient light is present either because of the moon or light pollution. To get night images with a strongly pronounced star trails or auroras requires a minimum of ambient light. If you are shooting in an area of high ambient light you may want to factor that into your choice of subject matter and approach to night image making. Have fun and stay awake!  

In the next newsletter I will cover post processing your night shots.           

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