Whether you look at them as the most expensive photographs you've ever taken, or the least expensive souvenirs you've ever purchased... whether you "take snapshots" or "create images"... travel photography is one of the most popular activities for those who travel.
The single most important choice to make is what kind of camera to purchase and/or bring along. There's no single "best" camera – or even kind of camera – for travel photography. The kind of pictures you want to take, how much flexibity or ease-of-use you want, your budget, and even how much you want to carry all factor into it.
Regardless of media type, cameras tend to fall into three categories of ease-of-use and features; an increase of one tends to decrease the other:
How your camera records images – digitally or on film – is probably the biggest choice in selecting a camera today. Fortunately, either of them is a good, viable choice for most people. It used to be that a film camera only got you prints you could pass around, and a digital camera only got you files you could use on a computer. If you wanted them in the other format you had to scan them or print them yourself. But photo processors increasingly offer the option of getting files on a CD from your film negatives, or high-quality prints from your digital files.
The price of digital cameras has fallen significantly, and the quality of the images they capture has increased, to the point that they're rapidly replacing film cameras in many travelers' luggage. They usually have the advantage of allowing instant review of the shots taken and deleting/repeating those that went wrong. Digital storage can hold far more pictures in a smaller amount of space; you may be able to take hundreds of photos without reloading. The storage cards can also be reused from one trip to the next, and you save the cost of buying and developing film.
However, digital cameras still tend to be more expensive than film cameras with comparable features, and high-end digital cameras with interchangeable lenses still command a substantial price premium over 35mm SLRs. They demand much more power (requiring frequent battery recharges or replacing expensive disposable batteries) than film cameras. While digital cameras are suitable for most applications, if you want good enlargements you'll still want a film camera (and for wall-size prints, larger-format film).
The various storage media (xD, SD, Memory Stick, Compact Flash, SmartMedia, etc.) all work pretty much the same; all that really matters is the capacity of the little cards you buy. Longer trips will require more memory, unless you bring along a laptop or another way to backup your pictures and clear your memory card. For some travellers, periodically getting the pictures burned to a CD works out well. This is easiest if you use a 512MB memory card, which fits neatly on a single CD. For example, in China this service is available in any big city or tourist town for under a dollar. For safety, get your pictures burned twice – at different shops – before you erase them from the camera.
You could also consider buying additional memory cards, especially if your camera came with only a small capacity card or if you are visiting somewhere like Singapore where they're cheaper. Note that the price increase for storage capacity isn't linear; you can get twice as much storage for less money than two smaller cards. The exception is for really large capacity cards which may use scarce parts and command a premium price. There's some danger in putting all of your eggs in one digital basket, however.
Digital cameras usually have different quality modes available which use more/less storage space for each picture. They have confusing names like SHQ, HQ, and SQ1, and different resolutions (how many pixels). Experiment ahead of time to figure out what quality setting you want to use. Keep in mind that you don't need multi-megapixel images to fill a computer screen or make a pocket-sized print, and you'll be able to fit a lot more photos on the same card with lower settings. Don't use the in-camera display to determine what setting to use, because it can't show you how much detail you're losing; look at the final results in a print or on the computer screen (depending on how you plan on viewing your photos). The ability to switch to lower quality settings can also be useful if you're running out of storage space in the middle of nowhere: better to have the last couple dozen pictures taken at a less-than-ideal quality setting, than to run out of exposures before you reach home.
Film cameras still have a slight edge in image quality, which is noticeable if you want any of your pictures enlarged. Not only do they tend to be less expensive in general, you can get real bargains buying used equipment from owners who have decided to switch to digital models, and a cheap camera is less of a loss if broken or stolen. Many models will run for months of use on the same little battery. Standard 35mm film can usually be replenished easily and cheaply if you run out, and offers resolution roughly equivalent to a 10 to 22 megapixel digital camera.
Film can be fogged – or even ruined – by x-rays. Most modern airport x-ray machines use low enough intensity beams that a dose or two probably won't show up in your photos, but it's better to be safe than sorry. Also, older x-ray machines used in some countries might not be as film-safe. As a general rule-of-thumb, most x-ray units used for carry-on luggage are film-safe, while most units used for checked luggage are not. When flying, keep your camera and your film in your carry-on luggage, and give it to security to inspect by hand instead of running it through the x-ray machine. Note that in many airports, all carry-on material including films must be x-rayed.
Film comes in different film speeds, referring to their sensitivity to light, and therefore the shutter speeds you can use with them. Relatively "slow" film varieties (ISO 100-200) produce the highest quality images, but don't work as well indoors or in other low-light situations, where they require either the use of a flash or slow (blurry) shutter speeds. Higher speeds (ISO 400-800) are better in low light, but the images can look more "grainy". Since you probably won't have the luxury of changing film depending what conditions you're in at the moment, try to anticipate how much you'll be in each; if you're going to be in low-light situations much, a high-speed film will be more flexible... but a little more expensive.
There are also different types of film: color print, color slide, and black and white print film.
For professional and prosumer cameras with interchangeable lenses, the choice of lenses to bring along becomes crucial. Often the best choice is the standard kit lens that covers the range from wide-angle to short-telephoto. For a high-end digital SLR this might be in the range of 18-70mm; for a 35mm SLR 28-100mm would be equivalent. (The magnification strength of lenses on digital SLRs varies from that of 35mm film, and even from camera to camera.) However, due to their moving parts zooms are more prone to breaking, and a sturdy and fast 50mm prime lens is a popular (and compact) backup.
If you intend to photograph far-away objects – typical examples include going on safari or birdwatching – you will also need a strong telephoto lens. If space is at a premium, you may be tempted to ditch the kit lens and instead go for a superzoom lens that covers the full range from wide-angle to to 200 or even 300mm; however, picture quality on these will suffer noticeably and you'll be stuck using a physically big lens all the time. A smaller-range 75-200mm or a fixed-focal length telephoto will offer better quality.
At the other end of the scale, if you expect to take a fair amount of panoramic landscapes or want to be able to fit a busy city square into the frame in close quarters, supplementing a normal-to-tele zoom with a strong wide-angle lens (e.g. 24mm or less for 35mm film) might be useful.
People with several interchangeable lenses sometimes carry two or more bodies with different film, or even a digital and a film body. A camera body that uses film can be an advantage for wide-angle lenses, because the larger format widens the angle that lens captures. Put a lens from a film camera on most digital bodies and the angle of view decreases; a 24mm lens on a digital camera might have the limited angle of view of a 38mm lens on a film SLR. Why not load some film into another body and use the lens as real wide-angle optics? This may give pictures that your digital rig can't capture.
Consumer-grade cameras usually handle focusing in one of two ways. Fixed-focus snapshot cameras are quickest and easiest to use. They have a lens that's pre-set to get everything more than a meter or two away roughly in focus. They rely on bright light and/or flash to pull this off. Auto-focus cameras tend to produce sharper images and allow you to work in somewhat dimmer light, but can be a little slower to react. This can be a problem when taking pictures of quick-moving subjects like your boyfriend running with the bulls in Pamplona. Professional- and prosumer-grade cameras usually offer the choice of manual or auto focusing.
Film cameras may include zoom capability, which is handy for getting a closer shot of something in the distance. (One of the most common errors of inexperienced photographers is not getting close enough.) Digital cameras usually have zoom, but only one of two kinds they feature is "real". Digital zoom doesn't capture any additional detail at high magnification; it reprocesses the same information for a larger image, or just crops off the edges for you. If you have photo editing software on your computer, you can do a better job of that at home. Optical zoom (the kind film cameras use) actually changes the magnfication of the lens, and is better for getting sharp close-up shots of distant subjects. This is the kind of zoom worth paying extra for, and a built-in high-ratio optical zoom (e.g. 10x) distinguishes some prosumer-grade digital cameras.
Most photographers today use at least a zoom lens or two, but some feel that the extra weight, extra complexity, and the drop in image quality are not worth it. Consider a 70-200 mm zoom vs an 85 mm fixed lens. The 85 will be considerably smaller and lighter, will take sharper pictures at 85 mm, and will be probably be much faster, so usable in lower light. As for the photos where you want a 200 mm lens, either use a teleconverter (85 *2 = 170) or just shoot at 85 and enlarge it more. You may lose some image quality this way, but may be better off overall in terms of weight and reliability.
Batteries are an important thing to think about, because it can be extremely frustrating to run out of battery power right in the most exciting part of your trip. With some cheap digital cameras, running out of power can mean losing all of your images; avoid these completely. If your camera uses a non-standard battery type (especially common with digital cameras), be sure to bring extras or a recharger. Some cameras normally use higher-capacity batteries (CR-V3 lithium are common), but can run on standard AAs (with more frequent changes) if needed. The ability to use AA batteries – readily available anywhere from Tibet to Togo to Tuvalu – is a great safety net.
Battery chemistry makes a big difference, and even something as standard as AA batteries come in several varieties. A rechargeable NiMH battery usually lasts longer (even without recharging) than even the best lithium battery, and its reusability will pay for itself in the long run. The main drawback of rechargeables is that they lose their charge even just sitting for a few weeks. Don't use alkaline or NiCd batteries in a digital camera (except in emergencies); they simply won't last.
If you're leaving civilization behind altogether, consider an old-fashioned mechanical film camera that can be run without battery power, or a not-quite-so-quaint electronic film camera which uses so little battery power (e.g. for the light meter, to time the shutter speed) that it can run for months on a single button-size cell. Most manual-exposure 35mm cameras from the 1970s and earlier will run battery-free; auto-exposure 35mm cameras from the 1980s merely sip from their batteries, and a few (e.g. Pentax ME series) can even continue working (on manual) without.
Many serious photographers carry along a tripod, and even a little pen-sized model can come in handy if you want to set up timed shots of yourself and yours. If weight is an issue (e.g. when hiking), consider a monopod instead. Bogen/Manfrotto even makes a line of well-regarded monopods that double as hiking sticks, although they're rather pricy. Alternatively, shop for hiking sticks with camera mounts hidden under the top knob. However, bear in mind that many (if not most) museums and tourist attractions do not permit tripods or monopods. Sometimes breaking out the tripod will put you in the "professional" category, and you suddenly need copyright permissions for what the owners of the place now consider commercial photography.
An ultraviolet filter comes in handy, not just for blocking ultraviolet (which can cut down on distant "haze" in landscape photos) but also for protecting your lens from dust, grime, and scrapes.
With expensive photography gear, packing it properly becomes an issue. Specialized cases specifically for packing cameras and lenses are available, but they are bulky and inconvenient. If travelling light, it's better just to bring along the original leather pouches for your lens and camera. A T-shirt folded and wrapped around a lens provides some impact protection and guards it from prying eyes.
Wipe down your camera and lenses with tissue after use, before you put them away. In particular, zoom lenses in dusty environments should be extended fully, wiped off, and allowed to dry before packing them, as grit will wreak havoc on the delicate mechanisms inside.
With fragile Super-8 film cameras and bulky VHS cameras receding into ancient history, compact videotape and digital cameras have made it more practical than ever to take moving pictures of your travels. These can be more entertaining to look at (for you and your friends), and better capture the grandeur of a panoramic view or the excitement of a helicopter ride. But video is also harder to do well than still shots, and bumpy recordings that cut abruptly from one scene to the next can be more disorienting than informative. Movie-editing software can help turn your raw footage into a slick presentation, but it's additional work after you get home.
Some digital still cameras advertise the ability to record moving pictures, but this sounds more useful in the product literature than it is in actual usage: the movies are typically low-resolution and highly compressed, and have poor (if any) sound. If you want to take movies, buy or borrow a movie camera.
Be aware that people in other cultures may view being photographed differently from you. In some countries, it is illegal to take pictures of individuals without their consent. Some Brazilian indigenous groups, for instance, believe their souls are captured when they are photographed. Members of some religious sects (e.g. the Amish) consider having their picture taken an act of impious vanity, and although they may permit it they don't welcome it. Cameras may also not be welcome during some religious rituals or other cultural events. Such particular views on photography should always be taken into account when deciding whom and when to photograph.
There are various situations in which flash photography may be inappropriate. Sometimes it will not be permitted, either to preserve a solemn atmosphere, or to protect antiquities from the damaging effects of bright light. Keep in mind that flash usually won't illuminate things more than a few meters away, so taking flash photos of the roof of a cathedral would be both distracting and ineffective. Flash also tends to spoil the natural appearance of the things you're trying to photograph, and if the object is behind protective glass, then your camera may end up blinding itself with the reflection of its own flash. So if you can disable your camera's flash and shoot by natural light (holding the camera very steady to compensate for slow shutter speeds), it may very well be worth the effort.
Photography equipment can be expensive and the pictures you've already taken at any point in your trip are effectively irreplaceable, so it's always wise to consider their safety when traveling. Besides theft and accident human-caused damage, natural issues like extreme heat and cold may have a significant impact on your equipment. If rain is likely, a weatherproof camera might be a good investment.
Don't flash your camera around any more than necessary. If you take it out of your bag, wrap the strap around your wrist a few times and hold it firmly in your hand. Walking around with an expensive SLR hanging from a neck strap is an invitation to motorcycle thieves. When walking in a city, keep not just the camera but also the bag holding the camera on the side of you facing away from the road. Brand-name camera bags advertise what's inside them. You may be safer carrying your camera in an old rucksack or even a shopping bag, perhaps padded with some clothes.
Avoid photographing government buildings (other than obvious tourist landmarks), military installations, or other plausible targets of political violence. In areas with ongoing military conflicts and/or heightened alertness for terrorism, this can get you unwelcome attention – or worse – from anxious security personnel.
Some people get their family or other travel companion(s) into every picture. Others focus exclusively on the places. Try to strike a balance. Including members of your group (especially if they're your kids) can add some fun and personality to your photos. But a litany of "Here's Stan standing in front of the Eiffel Tower. Here's Stan standing in front of Notre Dame. Here's Stan standing in front of..." can get tedious, not just to say but to look at. Try to capture your human subjects in the process of exploring the environmental subjects; a shot of Stan gazing into the sunset captures the experience better than him standing in front of it.
Similarly, share the camera, so that sometimes Stan is behind it and you get in some of the pictures too. Asking another camera-toting traveler to snap a picture of both/all of you (with your camera, not his), in exchange for returning the favor, helps to establish that you were in fact there together (though it puts you at the mercy of their ability to work your camera). Likewise, if you're traveling alone, either get someone to take a shot of you at various locales, or if that's not practical, at least try setting up a shot or two with a self-timer to prove to everyone that you really went there.
One of the most practical things to remember with a camera, is that you are capturing "light". If you are photographing outside, make sure the sun is to your back. If you are shooting into the sun it will throw off the automatic settings on your camera and you will have a very dark image. The same applies to shadows. Sitting someone in shadows and standing in the light to photograph them will likely be disappointing. The same applies to inside photgraphy. Taking a photo with an outside window in the frame will throw off the automatic settings and result in a dark image of what's in front of the window.