zondag 8 september 2013

Blog 6: Different lenses and their applications.

Different lenses, different applications.

Hello and welcome to my sixth blog entry. Today I would like to tell you something about different lenses and when to apply which type. Keep in mind that these are general applications. There is no one stopping you from using your lens in different fields.

Before we dive into the actual lens types, I want to tell you something about the science behind these lenses. Photography is writing with light (freely translated) and light is bound by natural laws. The most important part is the so called focal length. Light is reflected on an object and taken in by the lens on the camera. The image however, is always in reverse because of the glass that resides inside the lenses. The point where the light “crosses” is called the focal length. It is the length between that point and the sensor.

All lenses work according to this principle. In this example, a 24-105mm zoom lens was used. 

This picture shows a shorter focal length (24mm in this example).
 Because the focal length is closer to the sensor, the camera will capture “more” of the surroundings. This is what we call a wide angle lens. 

The zoom lens is able to shift the focal length from 24mm to, for example 105mm, capturing less of the surroundings and more of the object of interest. This is what we call zooming.

The amount of “zoom” is indicated on the lens. For this example, a 24-105mm zoom lens was used. This lens can vary between 24 and 105mm and everything in between, making it zoom approximately 4.5 times. Lenses that range from 18-200mm have 11x optical zoom. Keep in mind however, that lenses with a greater zoom range generally take less sharp photos (the reason why not everyone is running around with mega zoom lenses). 

Now that we have had a look at the basic physics of lenses, let’s move on to their application.

In general, there are four basic categories in which we can divide lenses. They are:

- Prime lenses

- Wide angle lenses

- Standard zoom lenses

- Tele/supertele lenses

All these types of lenses have their own general application. I will discuss each and every type in this blog. There are some other lenses on the market, like fisheye lenses, tilt-shift lenses and lenses with adjustable depth of field like Lensbaby. I will not discuss these lenses in this blog but might do so in the future.

Prime lenses

The first category is lenses with a fixed focal length. In normal language this means that the lens is not capable of zooming. 

In the photo on the left you can see one of these prime lenses, the Canon EF 50mm F1.4. The pros of these lenses are the unsurpassed image quality, speed and autofocus speed. Primes are usually fast, which means they have small F values (like the 1.4 on the photo). Smaller F values mean more light entering the lens and reaching the sensor. The actual application is determined by the focal length, depicted as the amount of mm on the lens. A 24 mm lens is mainly used in landscape or street photography. A 50mm lens is mostly seen as the standard lens (because our eyes operate at approximately 50mm). At 50mm your camera sees what you see, making it suitable for almost anything! The larger focal lengths, i.e. 85mm, 100mm etc are mostly used for portrait photography and macro photography. 
Needless to say, the biggest con of this lens is the inability to zoom. If you change application, you have to change the lens.

This photo was taken at night, without the use of a tripod, using the speed (F1.4) of the 50mm F1.4 prime, a 1/100s shutter speed at ISO 400. The depth of field and shutter speed would not have been possible without the speed of this lens. I love it!

Summary for prime lenses:

- Unsurpassed image quality, speed and autofocus speed

- Application is determined by focal length

- No zoom means changing lenses when switching objects

Wide angle lenses

Wide angle lenses have a short focal length. The wide angle lenses range from approximately 10 to 40mm. Because of the short focal length, the lens will capture more of the surroundings (as in the example). This makes wide angle lenses the preferred choice for landscape- and street photography.

For landscape photography, the speed of the lens is unimportant. Landscape photographers usually aim to capture the entire landscape in one sharp image. This means that a high F value is required (i.e. F22). For street photography, the speed is more important, especially when shooting indoors. Think train stations, subways, bars, restaurants, dense urban locations etc. Because of their nature, wide angle lenses tend to cause barrel distortion. Barrel distortion is where the outer corners of the image are bent, like a barrel. Be careful around butts and thighs, they will look bigger than they actually are!

This photo was taken using a 16-35mm lens at F8. Without the short focal length, I would never have been able to capture so much of the sea, since I was standing a few meters away from it! I used the F8 to make sure the beach and water were sharp.

Summary for wide angle lenses:

- Short focal length (approximately 10 to 35mm).

- Used in landscape, street and architecture photography.

- Speed is unimportant for landscape or architecture photography, but more so for street photography.

- Be careful with barrel distortion. People may look bigger than they are.

Standard zoom lenses

The next category is the so called standard zoom lenses. Standard zoom means the range between approximately 50mm and 105mm. The lenses that utilize the standard zoom range however, mostly also cover a part of the wide angle range. Therefore, these are the most versatile lenses one can own. 

For example, I own the Canon EF 24-105L F4 (see photo).

This lens allows me to capture landscapes (wide angle) and make portraits (standard zoom) and everything in between, while still maintaining great optical quality and autofocus speed. When using one of these lenses, you hardly have to take if off the body.

Standard zoom lenses like this one are best to take on a holiday when you don’t want to carry different lenses with you. Albeit not having the large zoom range of an 18-200 lens, the image quality is far superior. As for the speed, 18-200 lenses usually slow down considerably when zoomed in. For example, one of those lenses might be able to reach F3.5 on 18mm but slows down to F5.6 when zoomed above 120mm. This 24-105mm has F4 across the entire range. This is my most used lens!

This photo was taken on the NDSM wharf in Amsterdam. The 24mm allowed me to capture the entire sculpture.

This photo was taken using the same lens as the Amdock photo. Because of the 105mm, this lens is also suitable for portrait photography.

Summary for standard zoom lenses:

- Versatile lenses because of both wide angle and standard zoom ranges

- Most standard zoom lenses remain fast even when zooming

- Almost no changing of lenses because of wide application

Tele/supertele lenses
The last category is the tele/supertele lenses. These lenses are usually very long and range from approximately 120mm to 1700mm. The biggest supertele is a whopping 5200mm (it is really a prime)! 

This photo shows a supertele lens on the body of a Nikon camera.
Tele and supertele lenses are mostly used for animal photography, sports photography and voyeurism.
Because of its large focal length, images lose depth and there is no real distinction between object and background. They do allow you to take that photo of a lion in Africa, or the winning goal of your favorite soccer player while standing on the sideline. 

This photo was taken using a 70-200mm lens on F4 during a visit of a zoo in Alphen aan de Rijn. The bird was pretty far away so I had to use the full 200mm to get a crop of its head. Because of the F4, the background got nice and blurry (we call this effect Bokeh).

Summary for tele/supertele lenses:

- Mostly large, expensive and heavy lenses

- Used in animal- and sports photography

- Allows you to “snipe” shy animals and winning goal scoring soccer players

Well this concludes my blog on different lenses and their application. Like I said in the intro, this blog describes general applications. Of course you can use a supertele for landscape photography, or a wide angle lens for portraits. You might get some surprising results!

If you have any questions, suggestions, complaints or compliments, please contact me at info@photojitsu.nl.

Also, come visit me at www.photojitsu.nl, www.facebook.com/photojitsu and follow me on Twitter @photojitsu_nl.

Thanks for reading!
Maarten Kuiper
owner of Photojitsu.nl

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