NYI Student Advisor Rachel Neville shoots weddings nearly every weekend. Lots and lots of weddings, and she's been doing it for a number of years, starting with film and through the digital era. There are lots of different workflows for different photographers, so we asked Rachel to comment on dust and sensor cleaning from her perspective.
Certainly the best way to avoid sensor dust is to limit the number of times one changes lenses, whether in studio or out on location. However, for many photographers, that is just not an option.
Whether using prime or zoom lenses, one or two camera bodies, there are many circumstances where a photographer needs to change lenses frequently. Wedding photography, for instance, is a great example of this. Here is a situation where the demands on the photographer require a fairly constant swapping of lenses to create the numerous types of shots a modern event will need. Typically, good fast lenses should be in several ranges of focal lengths to meet all artistic needs, such as; a 17 - 55mm, a 28 - 70mm, a 70 - 200mm, 105mm macro for detail work, fixed 50 and 85 mm for fun and picking up extremely low ambient light in evening or reception situations. Indeed, many seasoned pros carry as part of their 'kit' a separate bag that is designated 'the lens bag'. This is a light weight, easy-to-carry over the shoulder case that is designed to hold the three or four lenses most used in a day for easy access.
If we were to dissect any given hour of work at a wedding, and considering some hours will be more high action than others, a photographer may change lenses upwards of 10 - 15 times! Let's look at the first hour of 'Bride getting ready' time. The photographer may start with one lens (or have a separate camera set up) for candid shots, switch to a macro lens for detail shots of the shoes, flowers, hair ornaments and jewelry, switch back to a wide lens for full shots of the dress, change to a zoom for the 'getting into the dress' moment, switch up to a portrait lens for tight headshots, back to a zoom for some candid's, over to the 28 - 70mm for family portraits, wider zoom for full length shots, 70 - 200 for some creative close-ups, back to a zoom for candid's, ...you get the idea! To do the job well, one can not be limited to the focal length of just one or two lenses.
What, then, do wedding photographers do about sensor dust? If we had to send our cameras into the shop every time we picked up a particle or two we'd never have enough machines to shoot on. On the other hand, when you are processing thousands of images from a weekend of shooting (here in New York, shooting two or even three weddings a weekend is not uncommon, and often a photographer will shoot anywhere from 800 - 1800 images a job), you really don't want to have to deal with dust on each image. So...
First, we take precautions. Try never to put a camera body down without a lens on it. This may seem a little silly and simple, but when you are working quickly and trying to accomplish much within a short time period, it can happen, particularly if you are shooting with more than one body. Second, when changing lenses, try to make sure to hold the open face of your body in a direction where wind and other contaminants are not going to enter. Sometimes this may mean downward (not if you are in a field with high grasses or on a beach with sand!!!), sometimes towards you, and yes, sometimes you will feel like you just want to move away from the crowd to do it. Third, make sure to safe guard your lens and/or camera bag against dust and grit; try to remember, even when shooting quickly, to keep the top of the bag closed.
Next, many photographers 'blow' our cameras out before each job, either with a can of compressed air or other similar device. And yes, we often regularly have to clean our sensors with a swab, or for hard to remove particles, send the cameras to be cleaned. Advice then, on how to accomplish this? If you are using compressed air or another blower, test it out on your hand first to make sure you are not going to release any unwanted product onto your sensor, and have the pressure to the point that you think you can control. Follow the instructions in your camera manual carefully as to what your manufacture suggests for your mirror lockup sequence of events. If you are using a cleaning fluid and a swab, camera store bought and recommended is always a better bet than what you can find in your cleaning cupboard at home. Remember, you get what you pay for, and cleaning fluid and swabs are no exception. Finally, use a light touch! Several passes are far safer than to have one mighty go with a huge shot of air, or too much pressure on the swab trying to remove stubborn particles.