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Tour Notes (please know this is currently a work in progress)
I have been a photo tour guide in Haines Alaska for a few years, and clients often ask if there is a summation of points that I have covered available. Well, here it is! I am happy to receive any suggestions or questions as this page evolves. The very first thing you should do is to set your camera's ISO. ISO refers to how fast your camera records an image of the light coming through the lens. In the days of film, the "speed of the film" was referenced by the ASA number. Digital camera manufacturers have corresponded the "speed" of the digital camera to the old ASA number with the ISO. The higher the ISO number, the faster your camera will record light, and this can give you an advantage with respect to shutter speed. While a higher ISO will allow you to shoot faster, or obtain better exposure in low light situations, it does come at a cost. The higher the ISO number you use, the more noise (aka grain in film vernacular) you introduce into your picture. There is software to eliminate noise, but this too comes at a price. Noise reduction software will reduce detail in your picture (not always a bad thing in terms of water, sky, or wet fur on a bear in the river) and adds one more step of processing to your digital image (the prevailing thought being the less processing a picture needs, the better.) In the low-light environment of Alaska I generally recommend an ISO of 400. A bright sunny day might suggest a lower ISO, but I like the advantage of the slightly faster shutter speed and 400 ISO is a very safe setting with regard to noise artifacts. Camera manufacturers are claiming astronomic ISO capabilities of their cameras, but I don't trust the claims. I have done testing on a Nikon D300 (DX, or cropped sensor body) and a Nikon D700 (FX, full-frame sensor) and feel comfortable pushing the DX up to 800 ISO, and the FX up to 1600 ISO without much introduction of noise in the picture. I do NOT recommend leaving your ISO set to automatic. You will find the results of your photography are unreliable if you do leave your camera to determine what is best. I have seen results where the camera's metering system determined two radically different ISO requirements for subsequent shots of the same scene with unhappy results. I DO recommend leaving white balance on automatic, as I find it far easier to correct color temperature in processing digital photos than worrying about that setting in the field. A question you might want to consider is what is the intent of your photography? Are you making a record of a trip, telling a story in recording an event or events, or using photography to create art. This may well determine if you want to shoot in jpeg, or RAW. JPEG files are smaller in size, but they also contain less information than a RAW file contains. JPEGs use 8-bit color depth, and apply editing parameters that you set (or some unknown engineer has set) in your camera and throws out the rest of the information your camera has recorded, never to be seen again. Any change you make on a JPEG involves throwing away any original data unless you save the file with a new name. (Contrary to rumor, just opening and closing JPEGs does not cause file degradation.) RAW files on the other hand apply no camera parameters to an image other than those defined by ISO and white balance. RAW files can record images in higher color depth (up to 14-bit depth) thereby giving you a file that has about 30% more information. (This results in larger file sizes. Hard drives are cheap!) Any change you make to a RAW file is completely reversible. Perhaps the strongest recommendation I can make is that RAW files give you much more editing headroom than JPEGs. RAW files will allow you about 2 stops of exposure adjustment, so resolving overblown highlights or underexposed areas is far more responsive in RAW images. Not everyone can open RAW images, so you will be well advised to save RAW images as JPEGs before sharing them. RAW processing takes a little more time, but once you dial it in, the workflow can go rather quickly with current RAW editing plug-ins. My recommendation: if you are embracing photography seriously and want the most control of your images, RAW files are "money in the bank," even if you aren't processing everything today, or have yet to learn the nuances of RAW processing. If your interest in photography is more casual, JPEGs may well be the best suited format for you. If you type in RAW vs JPEG in your favorite search engine, you will find a wealth of articles that discuss this debate further. Aperture Priority mode & f-stops What is aperture, and what is a stop? Aperture refers to the opening, or hole, through which light travels through your lens to your camera's film or sensor. Aperture is measured in f-stops, sometimes simply referred to as 'stops.' They are often referred to as f/numbers, for example f/2.8, f/4, f/5.6, f/8, f/16, f/22, etc. A stop refers to doubling or halving the amount of light that travels through the lens when you take a picture. Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens, and hence the amount of light that travels through. We use aperture mode to control depth of field. Depth of field (DOF) refers to that range of distance that objects in your photo are in focus. It is often used to isolate the subject of your photo from the foreground or background. If you're not careful, you can also inadvertently have part of your picture (in the foreground or background) be out of focus when you didn't want it to be out of focus. A large depth of field means that the foreground and background are going to be in focus relative to each other. A small depth of field means the object you are focusing on (presumably the subject of your shot) will be isolated and objects in front of, or behind your subject, will be blurry. This perspective control is a powerful compositional tool. Simply stated, the smaller the f-stop number (i.e., f/2.8) then the smaller the DOF. The larger the f-stop number (i.e., f/22) then the larger, or greater DOF. (The confusing aspect, and one that I often ignore in explaining aperture choices to clients in sake of simplicity and clarity, is that a small f-stop number indicates a large aperture, while a large f-stop number indicates a small aperture.) Another consideration in choosing which f-stop to use is in overall picture sharpness. Generally, the larger the f-stop (smaller aperture), the sharper the picture will be. There is however a serious consideration that needs our attention here, and that is with respect to shutter speed. While your camera is in aperture mode, it is still operating in an automatic function, in that your camera's metering will adjust your shutter speed based on your aperture choice to obtain what it considers to be the proper exposure. It is time to carefully consider what is happening at this point to see how three basic settings on your camera come together. The smaller the aperture (large f-stop) the more time it is going to take to allow the required amount of light through the lens to obtain a good exposure. This means a slower shutter speed. Now, if you bump up your ISO setting to a higher number, for the same aperture the camera will be able to increase the shutter speed to get the proper exposure because the ISO has made your "film" faster. (Conversely, as you use larger apertures (smaller f-stop) for any given ISO the camera will be able to take the proper exposure at a faster shutter speed. Take some time to let your head get around this balancing dance between aperture, shutter speed, and ISO. In summation, use aperture priority mode to control depth of field and overall picture sharpness. Shutter Priority mode Having come to the understanding that aperture settings and ISO can affect shutter speed, we need to be aware of the possibilities and limitations of shutter speed, and when we might want to switch from aperture priority to shutter priority. Shutter speed indicates how much time your lens stays open, allowing light to pass through the aperture. I use shutter speed to freeze motion. But what if your scene isn't moving? Even if your scene is stationary, maybe your hands are not. Telephoto lenses are more susceptible to camera shake since small hand movements become magnified. Try looking through high powered binoculars and you will see the same effect. Longer focal lengths require shorter exposure times to minimize this blurring caused by shaky hands. So how fast is fast enough? The old rule of thumb was that you need to use a shutter speed which is the reciprocal of the focal length of your lens. For instance, if you are using a 200 mm lens, you would need to shoot at 1/200 of a second to attain a sharp shot that doesn't have any blur. A 500 mm lens would require a faster shutter speed of 1/500 of a second. With today's vibration reduction and image stabilization built into lenses, manufacturers claim we can shoot 4 stops down with safe results. (Half of 1/500th is 1/250th, half of that is 1/125, half of that is 1/60, half of that is 1/30 ... that's four stops. I would NOT feel safe shooting at 1/30 of a second with a 500 mm focal length.) So what is a safe speed to shoot at? VR (IS, OS) will give us a good edge on reducing camera shake, but I don't like pushing the limit any more than I have to. I like sticking to old rules of thumb. On a static scene, I'm happiest if I can shoot at 1/250. I am okay with 1/125. I will go to 1/60 if I need to, but I am starting to get a bit nervous, and look to rest against a tree or set my camera on a pack or some other object to help me stabilize. OR, we can use a tripod, which is always my best recommendation. With a tripod, you can shoot at any speed with good sharp results, assuming you are shooting a static scene. While VR (IS, OS) will reduce blurring caused by camera shake, it will do nothing to reduce movement within your scene. It seems the breeze is always active when we are trying to take pictures of wildflowers. Hopefully the eagle will take flight. Bears are always moving from one fish to the next. When the scene is in motion we need to set our camera to shutter priority (TV ... time value ... on a Canon). On wildflowers, your setting will depend on the amount of breeze. Experiment. I would suggest starting at 1/250 to start, and move it up or down as results indicate. As to wildlife, let's move to the next topic. Wildlife photography If I am shooting wildlife, I always go to shutter priority or manual mode to fully control the exposure parameters of my camera. Wildlife moves, and if you are not ready for the action, you will end up with a blurry picture and a memory card full of regrets. When I am photographing bears or similar animals, I find that a shutter speed of 1/500 of a second is pretty ideal. Take some test shots when you get to your location to make sure you are happy with your exposures. In the poor light of Alaska, or with the onset of evening lighting (pretty common when shooting wildlife) you want to make sure you have a reasonable exposure. Adjust the ISO if necessary, or bump up your camera's exposure compensation (I often do both). Remember if you are shooting RAW, you have more editing headroom, but increasing the exposure value in the editing software often increases the noise/grain of the picture and we don't want that if we can avoid it. Set your camera's auto focus mode to continuous servo and dynamic area auto focus in anticipation that the scene will be moving. I like to set my metering on spot or center-weighted, but usually the former. Next: eagles
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Email: tom @ majorproduction.net