Care and maintenance
Cameras
The latest EOS professional digital cameras offer excellent water and dust resistance. Seals and O-rings are used extensively, and when a water-resistant EF lens is attached the entire camera-and-lens outfit becomes water resistant.
Even so, it is sensible to take precautions. After using the camera in adverse conditions, the body should be wiped clean and dry with a soft cloth before it is put away in a well-padded case or bag.
Apart from this, there is little user camera maintenance which is needed, or indeed, possible. An annual service at a Canon Service Centre is recommended for cameras that are being worked hard.
Cold conditions
The specifications for EOS digital cameras suggest that conditions below 0°C are unsuitable. In practice, this does not seem to be the case. There are many reports of the cameras being used successfully in sub-zero temperatures.
Where there is a problem is with the lithium-ion batteries. These are good for a lot fewer exposures in the cold than in more normal temperatures. The solution to this problem is to have several fully-charged batteries available. Use one in the camera and keep the others warm in an inside pocket. As the power drops, swap the batteries around. The warm battery will keep the camera going, while the cold battery will regain some of its power in a warm pocket.
Condensation
A major problem when shooting in low temperatures is not the cold, but condensation. To understand this, you need to know a little about humidity.
Humidity is the amount of water vapour in the air. This vapour comes from the evaporation of rivers, lakes and the sea. Rainfall also increases the humidity.
Absolute humidity is a measure of the amount of water vapour in the air (usually quoted as grams per cubic metre). This is not a value you will see very often.
When most people talk about humidity, they are actually referring to relative humidity. This is expressed as a percentage. It is the amount of water vapour in the air relative to the maximum amount of water vapour the air could hold at that temperature. So a relative humidity of 75% means that the air contains three-quarters of the maximum water vapour it could hold.
The total amount of water vapour the air can hold varies with temperature. Air at higher temperatures can hold more water vapour than air at lower temperatures. Below freezing point (0°C), the air can hold very little water vapour.
The final term you need to know in relation to humidity is dew point. As a mass of air cools, its relative humidity increases. There is no increase in the actual amount of water vapour in the air; instead, there is a decrease in the maximum amount of vapour the air can hold. If the air continues to cool, you will reach a point where the relative humidity is 100% - the air is fully saturated with water. This is the dew point. Further cooling of the air means that there is more water vapour present than it can hold. This water condenses onto the nearest surface.
Outdoors, this condensation often takes place as the warm air from the previous day cools down during the night. The condensation takes place on the ground. We call it dew.
What has condensation to do with photography? Simply this. If you carry a cold camera into a warm atmosphere, the camera may cool the surrounding air to below its dew point. This air will no longer be able to hold all of its water vapour. The excess vapour will condense on your camera and lens, covering the surfaces with a fine film of water.
After a while, the camera will warm up and the condensation will evaporate back into the surrounding air. However, if you move back into the cold air before the condensation has had time to evaporate, the water will remain on the camera and lens. And if you move into air that is below freezing point, the water will turn to ice. Trying to shoot through a film of ice covering the front of your lens is not recommended. There are four solutions:
- Wait until all the condensation has evaporated before moving back into freezing air;
- Use a soft cloth to wipe all the moisture off the camera body and lens before moving back into the freezing conditions;
- Leave your camera outside in the cold when you go into warmer air (this will only be safe in isolated areas where there is no risk of theft);
- Before going from a cold to a warm environment, put your camera and lens into a sealed container - if the equipment is sealed in with the cold air, there will be no moisture to form condensation as the camera warms up, and you will be able to remove the equipment safely once it is at room temperature.
Condensation is not a problem limited to working in very cold conditions. It can occur whenever you move from cool air into warm air - as people who wear glasses will know!
Lenses
You may have been attracted to EOS cameras by the reputation of their lenses. And it is true. EF lenses can give you outstanding images − but only if you look after them. If a lens is not in good condition, the quality of your photographs may suffer.
On a more mercenary note, a lens that has been well looked after will hold its value better than one that looks as if it has been heavily used and abused.
Here are a few basic tips that will ensure that your valuable lenses are well protected. Much of what follows is common sense − but how many of the ideas do you actually put into practice?
Lens caps
Every new EF lens is supplied with two lens caps.
The front cap should always be in place when the lens is not in use. Even if you have a screw-in filter attached, it’s a good idea to use the lens cap as well − a new cap is cheaper than a new filter. Most lens caps will attach to the front of a filter in just the same way that they attach to the front of the lens.
When is the lens not in use? You could argue that it is when you are not looking through the viewfinder or pressing the shutter release. It would certainly be good if you could clip the cap in place at these times. However, we need to be practical. If you are shooting a sports event with two cameras, each with a different lens, you need to be able to switch between them with the minimum of delay. You don’t have time for lens caps.
However, if there is rain in the air, or you are at risk of being splashed with water, then put the cap in place at all possible opportunities. Water evaporates, but it often leaves behind dissolved impurities that can mark the surface of a lens.
Put on the lens caps − front and rear − as soon as the lens comes off the camera. And use a body cap on the camera if you are not putting another lens on right away.
The second lens cap fits the rear of the lens. It should always be put in place the moment the lens is removed from the camera − no exceptions. This will protect the rear element from damage when you put the lens down. Just as important, it will help to keep the electrical contacts clean. These contacts are the only link between the lens and the camera. If they become dirty, all manner of things can happen − or fail to happen − when you try to take photographs. For the same reason, it is important to fit the body cap to the front of the camera whenever there is no lens attached. Not only will this protect the gold electrical contacts on the camera side, it will also prevent dust and dirt reaching the reflex mirror and the focusing screen.
Lens and body caps are easily lost, but most of them are also relatively cheap to replace. Next time you need one, buy two and keep the spare in your gadget bag.
Use a filter
The glass used for making optical lenses is often much softer than other types of glass. Once marked, it is not easy to clean.
Most lenses have a coating applied to the surface of the front element. The main purpose of this is to reduce the risk of flare, but it also provides a harder surface. However, the term ‘harder’ is relative, and it is still quite easy to damage the surface of the lens. Rain, dust, flying stones, foliage and fingers are among the potential dangers.
Fingers in particular are a risk. Your fingertips exude an acidic grease which can, over a period of time, eat into the surface of the lens. The result may not be very noticeable, but it can increase the effect of flare. For this reason, if you touch the surface of the lens with your fingers, you should polish it gently with a soft, dry cloth to wipe away the grease.
You can protect the surface of the lens from fingers and other perils by attaching a filter. This screws into the mount at the front of the lens, forming a virtually dustproof seal between the surface of the lens and the outside world. Any dust or damage is then sustained by the filter, rather than the lens. If the damage is beyond normal cleaning methods, it is far cheaper to replace the filter than the lens.
Canon produces a filter specifically for protection. The Canon Regular filter (previously known as a Protect filter) is made from perfectly clear glass that does not alter the light passing through it.
Although the Regular filter is ideal in situations that require an accurate colour balance − studio photography or copy work, for instance − an Ultraviolet (UV) or Skylight filter can be just as good for protecting a lens. These block ultraviolet light that can cause a blue haze over distant landscapes. In addition, a Skylight filter has a pinkish tint that reduces the blue cast in shadow areas under blue skies. In most situations, however, an Ultraviolet or Skylight filter has no noticeable effect on your photographs.
If you use a Regular, ultraviolet or skylight filter as protection on a wide-angle lens, do not add further filters. The mount of the front filter may intrude into the image area and cause vignetting.
Lens hoods
If you drop a lens − with or without a camera attached − there’s a good chance it will land on the exposed filter ring, denting it. Or, even worse, the front element of the lens may impact on a sharp stone.
You can reduce the risk of dropping the camera by using a neck strap and always slipping it over your head whenever you pick the camera up. You can’t attach a strap to the lens, but you can reduce the risk of any damage by holding the lens close to a flat surface when you attach or remove it. Then, if the lens does slip out of your grasp, it will not have far to fall. Outdoors, you may have to crouch or kneel so that the camera is close to the ground as you attach or remove a lens.
If the worst happens and your lens is launched into free fall, the risk of damage might be reduced if it is fitted with a lens hood. A hood protrudes from the front of the lens and may take the brunt of an impact.
Lens hoods offer some degree of protection to your valuable lenses while you are shooting − and reduce the risk of flare.
Canon produces hoods for most of its lenses. Apart from protection, there is a good argument for using the correct hood all the time − it can help to reduce the risk of flare from the sun or other bright lights in front of the camera.
Lens cases
It is all very well looking after your lens while it is mounted on the camera, but it is equally at risk when off the camera − even when stored in a camera case or bag.
The safest way to store a lens is in a hard case or pouch. This can then be placed inside your camera bag or case.
If you do not have a case or pouch to hand, a cheap but effective way to protect your lens is to wrap it in a clean, lint-free duster. This will reduce the risk of scratches and dents if the lens rolls around in a case and bangs into another lens, or the camera body.
Many gadget bags and camera cases allow you to move partitions around to provide snug, padded compartments for each item of equipment. This is a good alternative to a lens case or pouch.
A coat or jacket pocket can also be a surprisingly safe place for a lens. A deep coat pocket (or even better, a padded packet in a photographer’s waistcoat) will cocoon a lens. Whichever method you use to protect the lens, make sure you always fit the front and rear lens caps first.
Storing the lens
Much of the time, your lenses and camera will probably be sitting in a cupboard or drawer at home. Keep the equipment in a bag or case so that it is shielded from daylight.
Make sure the equipment is not near a central heating radiator, and avoid places that may be damp, or have damp air circulating.
The ideal location will have a constant temperature all year round − neither too hot nor too cold. Between about 5°C and 10°C is good.
Climate change
If you bring a lens − or indeed any camera equipment − from a cold outdoor environment into a warm room there is a possibility that condensation will form on the cold glass surfaces. If condensation forms inside the lens you will not be able to use it until the moisture clears, and there is a risk that the delicate internal mechanism will be damaged.
To avoid this happening, seal the equipment in a plastic bag before coming indoors, and then leave equipment for a few hours to warm up gradually before removing it from the bag.
Travel tips
If you are travelling by car, the worst place for your camera bag is on the floor in front of the passenger seat. Here, the equipment will be subject to all the vibrations from the engine, and the shocks as you drive over bumps. Although lenses are surprisingly durable, it is possible for components to loosen or shift position.
Placing the bag on one of the seats will help to protect the equipment from vibrations, but is only safe if you carry the bag with you when you leave the car. A camera bag left in view after you have parked the car is asking for trouble. A thief can break the window, lift the bag and be away within seconds.
If you carry the camera bag in the boot of a car, it is a good idea to reduce vibrations by placing a folded blanket underneath.
How to clean a lens
You should only clean a lens when it is dirty. It is better to try to keep the surfaces clean than to run the risk of damaging them during cleaning.
What you will need:
- Blower brush or compressed air canister
- Lint-free cloth or lens tissues
- A clean, dry, dust-free surface on which to work
1) Take the lens off the camera body and remove any filters or lens hood.
2) Use a lens brush or compressed air can to remove any loose dust or grit. This is important because if there are any particles on the lens when you rub it with a cloth they may scratch the surface. Hold the lens with the surface you are cleaning facing down as you brush, so any dislodged dirt of dust falls away. If using a can of compressed air, be careful to keep the nozzle at least six inches away from the lens, otherwise the any propellant used to expel the air might condense on the glass surface.
3) Use a lint-free cloth or lens tissue to wipe the lens elements. If possible, use a cloth or tissue that is sold for cleaning camera lenses − other materials might scratch the lens coating. Disposable lens tissues are ideal as you can use a fresh tissue for each new lens surface, avoiding the risk of transferring dirt from one lens to another. Also, a tissue can be folded several times into a convenient brush for clearing the lens surface before wiping. However, a clean pocket handkerchief is suitable if nothing better is available. Do not use cloths provided for cleaning spectacle lenses − they often contain impregnated chemicals. Apply a gentle pressure to the cloth or tissue and polish in a spiral from the centre of the lens outwards. This will move any remaining dust or dirt to the edge of the lens, where it will do least harm.
4) If you are using a filter to protect the lens, clean this in the same way.
5) Attach a lens cap to help keep the glass surfaces clean.
Why keep it clean?
Some photographers believe that there is no reason to keep the front element of a lens clean and free of scratches, arguing that the marks will be too out-of-focus to show in the photograph.
While this might be true of minor abrasions, what this argument ignores is the fact that marks on the lens − be they fingerprints, dust or scratches − can create flare.
If you have ever driven a car with a dirty windscreen towards the sun you will have experienced flare − the dirt spreads the light and makes it very hard to see. Clean the windscreen and the sun is much less of a problem.
Exactly the same thing happens with a dirty or marked camera lens. Any non-image-forming light falling on the front element will be scattered by the marks and lead to a degradation of the photograph. The problem can show itself as washed-out colours over the whole image or as small hotspots on just parts of the picture.
If you have to use a lens that is scratched or chipped, you should be aware that flare might be a problem and avoid any direct light from falling on the front element. Using a lens hood will help, as will positioning yourself so that the lens is shaded from direct light. It is often possible to find a viewpoint where the sun is hidden from the camera by a building or a tree. Crouch down to the lens position to check this.
However, scratched lenses will never give you the maximum performance possible and you should consider replacing the lens. If you have a good insurance policy, you may be able to claim for any damage that occurs during the period of the insurance.