Archive for November, 2009

Know How to Zoom

Experienced photographers who have been around for a while, often prefer prime (fixed focal length) camera lenses over zoom models. Photography magazines always suggest the sharpness of fixed focal length lenses far outway the flexibility of zoom lenses.
Before looking at the advantages and disadvantages of both, we first need to know ‘what is a zoom lens or prime lens’.
What is a zoom lens?
A zoom lens is one that has a retractable zoom ring, making it easier to get in as much or as little of the scenery as you want, without the need to physically move yourself. If the lens name has a hyphen between two mm extreme’s, then it is a zoom lens. For example, a Canon EF-S 17-85mm f/4-5.6 IS USM is a zoom lens. The focal length can be set from 17mm to 85mm.
What is a prime fixed focal length lens?
A prime (fixed focal length) lens is set to one mm focal length. In other words, the focal length cannot be adjusted. If you want to get more or less of the scenery or object in the photograph, then you need to physically move yourself in or out. For example, a Nikon AF-S VR Micro-Nikkor 105mm f/2.8G IF-ED lens is a prime lens because it has a fixed focal length of 105mm.
Other differences between zoom and prime camera lens
Prime lenses take sharper photographs than their zoom counterparts, because from a design point of view they have fewer compromises. It makes sense that if a lens is designed to zoom from between 17mm and 85mm, then it’s going to be harder to make than one that has a fixed 105mm focal length. A good example of compromises found in zoom lenses, can be seen in the distortion problem many of them have.
While it’s true a zoom lens may not be as sharp as a prime lens, they are however cheaper. Therefore the tradeoff for sharpness, is price cutting costs.
As explained earlier, a prime lens requires the photographer to physically move themselves closer or further away from the subject depending on the situation. Many amateurs find this annoying, therefore opting for zoom lenses.
Should you buy a zoom lens or a prime fixed focal length lens?
Personally, I think both have their place when it comes to good photography. If sharpness is the main concern and you are photographing a subject where you can easily position yourself physically, then a fixed focal length lens (prime) is the way to go.
However, there are times when physically moving yourself closer or further away from the subject isn’t a possibility. For example, if you were on a whale watching cruise, the restrictions of a prime lens would be useless. For times like this, a zoom lens would be more beneficial.

Experienced photographers who have been around for a while, often prefer prime (fixed focal length) camera lenses over zoom models. Photography magazines always suggest the sharpness of fixed focal length lenses far outway the flexibility of zoom lenses.
Before looking at the advantages and disadvantages of both, we first need to know ‘what is a zoom lens or prime lens’.
What is a zoom lens?
A zoom lens is one that has a retractable zoom ring, making it easier to get in as much or as little of the scenery as you want, without the need to physically move yourself. If the lens name has a hyphen between two mm extreme’s, then it is a zoom lens. For example, a Canon EF-S 17-85mm f/4-5.6 IS USM is a zoom lens. The focal length can be set from 17mm to 85mm.
What is a prime fixed focal length lens?
A prime (fixed focal length) lens is set to one mm focal length. In other words, the focal length cannot be adjusted. If you want to get more or less of the scenery or object in the photograph, then you need to physically move yourself in or out. For example, a Nikon AF-S VR Micro-Nikkor 105mm f/2.8G IF-ED lens is a prime lens because it has a fixed focal length of 105mm.
Other differences between zoom and prime camera lens
Prime lenses take sharper photographs than their zoom counterparts, because from a design point of view they have fewer compromises. It makes sense that if a lens is designed to zoom from between 17mm and 85mm, then it’s going to be harder to make than one that has a fixed 105mm focal length. A good example of compromises found in zoom lenses, can be seen in the distortion problem many of them have.
While it’s true a zoom lens may not be as sharp as a prime lens, they are however cheaper. Therefore the tradeoff for sharpness, is price cutting costs.
As explained earlier, a prime lens requires the photographer to physically move themselves closer or further away from the subject depending on the situation. Many amateurs find this annoying, therefore opting for zoom lenses.Should you buy a zoom lens or a prime fixed focal length lens?
Personally, I think both have their place when it comes to good photography. If sharpness is the main concern and you are photographing a subject where you can easily position yourself physically, then a fixed focal length lens (prime) is the way to go.
However, there are times when physically moving yourself closer or further away from the subject isn’t a possibility. For example, if you were on a whale watching cruise, the restrictions of a prime lens would be useless. For times like this, a zoom lens would be more beneficial.

Focus Tips in Taking Pictures

Many digital camera lenses now come with the option of autofocus (AF switch on the side of your lens) or manual focus (MF switch on the side of your lens). For ninety percent of the time, photographers can set the lens on AF and let the camera focus itself. However, there are times when your lens won’t focus easily. For example, on a windy day when you’re trying to focus on a flower, or if you were photographing a moving insect, you could find your lens will erratically move and not stabalise on the object long enough for you to take the shot. It’s times like this, where it’s more effecient to set your camera lens to manual focus (MF).

Camera: Canon EOS 400D / Rebel XTi
Lens: Canon EF 100mm f/2.8 Macro lens
Shutter Speed: 0.005 sec (1/200)
Aperture: f/11
Focal Length: 100 mm
ISO Speed: 200
Exposure Program: manual
How this shot was taken
For this shot, the camera lens wouldn’t focus properly when set to AF autofocus, due to the fly hovering and constantly moving. Therefore, the photograph was taken with the lens set on manual focus using a method similar to the tips shown below.
Manual focus tips
First set your lens to autofocus (AF) and focus on the closest object near the one your trying to photograph. For example, in the hover fly image above, I firstly set the autofocus on the flower, then turned the lens switch to MF for manual focussing. In other words, focus automatically on something that isn’t moving, near the object you are wanting to photograph. This helps give a good starting point from which to manually focus.
Hold your camera body with your right hand, while you position your left hand underneath the lens. This will enable you to easily rotate the lens focal ring with your fingers, similar to the photographer in the image below.
The photo above demonstrates how you should hold your camera for manual focusing. He is holding a Nikon Micro-Nikkor 105mm lens, however most camera lenses have the focal ring in a similar position.
Above all else, shooting with manual focusing takes practise. The more you practise, the easier it will become. There are many photographers who prefer to use manual focusing instead of automatic focusing for most of their shots.