Which Lens is Best For Me?

Today I want to talk about camera lenses, the effects they have, and hopefully help you choose which lens (lenses) you'll need for your photography.

I want to first start by giving an explanation of crop factor. What is crop factor?

Crop Factor - is the ratio from a standard 35mm film size to the size of a digital cameras image sensor (measured diagonally).

What this means is that a 35mm camera would give you a certain image with a certain lens. With a digital camera, many have what is called a crop factor because the sensor size is smaller than the standard 35mm film size. Pretend the circular image above is how the camera sees the scene. The example above is what the translated photo area would look like with a 35mm film negative as compared to a digital camera with a crop factor. This is assuming you stood in the exact same spot and use the exact same lens on both the 35mm and digital camera.

Below is how the resulting images would look:

35mm

Digital Crop Factor

Notice that the image taken with the same lens from the same spot appears to have more of a zoom effect. The key word is appears. While it appears to be more zoomed, in reality, it's just losing more off the edges. This works out well for images shot at a distance, but if you're a landscape photographer and you want a really wide angle, you're losing a considerable amount of image with a digital camera.

To make up for this, one can either buy a full framed digital camera (sensor is the same size as the 35mm film negative) or you can buy a wider lens. Since the introduction of crop factors, manufacturers have been producing lenses wider than normal to makeup for the crop factor. 28mm focal length for a 35mm film camera is considered wide. However, on a digital camera with a crop factor, it's not. Lenses with as low as a 10mm focal length have been developed to cope with the crop factor. Why not just buy a full framed digital camera? Well, if you can afford it, please do...however, these cameras are seldom found cheaper than $2500.00. A few years from now, someone may read this blog and think that price is to high, but lets just remember the price of consumer electronics drops considerably over time.

To figure out your cameras crop factor, the manufacturer has included a multiplier to give you an idea of what your lens is effectively producing on your digital camera. Below is a list of crop factors for common camera manufacturers:

Nikon - 1.5x

Canon - 1.6x

Sony - 1.5x

Pentax - 1.5x

Olympus - 2.0x

To use this information, just take the lens focal length and multiply it by the number associated with your camera above. My camera is a Canon EOS 50D. Therefore if I were to look at my 28-135mm lens, the crop factor would in effect give me a lens that appears to have a focal range of 44.8-216mm (28x1.6=44.8 and 135x1.6=216).

For the rest of this blog post, and likely throughout future blog posts, I'm going to just assume everyones digital camera has a crop factor.

So what types of lens options are available to me?

Wide Angle - Anything less than 24mm is considered a wide angle lens (less than 39mm full frame)

Normal - 25mm-37mm (40mm- 58mm full frame) On a side note, the human eye sees at approx. 32mm (50mm full frame)

Telephoto (Zoom) - Anything greater than 37mm is considered a telephoto lens (58mm full frame)

Macro - A lens that allows extreme short focus on the subject allowing for close-up photography.

Fisheye - Allows for a distorted and extremely wide angle view of the world up to 180 degrees

Teleconverter - A piece of glass that attaches between the camera body and another lens allowing you to increase the effective zoom range of your camera. A 2x teleconverter for example would double the focal length of the lens that is attached

Image Stabilized - Lenses with image stabilization use a series of gyros to detect motion from hand holding the camera, and attempts to stabilize the motion to produce a non blurry image.

all information in the definitions above are assuming you are using the 1.6x Canon crop factor. If your camera uses a different crop factor, you would need to adjust accordingly by dividing the provided 35mm film focal length by the crop factor for your manufacturer.

So lets start from the top of the list:

Wide angle lenses are great for landscape photography. They allow one to capture more of a scene into one single image. The problem with them is that the images will likely be distorted to an extent. For example, if you took a photo of someone with a wide angle lens and they were close the the camera, it will make there body look distorted. If it's a closeup of the face, the nose may seem extremely huge.

Wide angle lens - Photo courtesy of Will King Photography - All Rights Reserved

Normal lenses would be the focal range between wide and telephoto. Images in this range will be the closest to what the human eye sees. As stated above, the human eye sees at about 32mm (50mm full frame or on 35mm film). A great time to use normal lenses would be for portraits. This allows for the least amount of distortion.

Telephoto lenses are used when you can't get physically closer to your photo yet you have a need to make the subject bigger in the frame. An example might be if you were on an safari and you saw a lion in the distance. For obvious reasons, you don't want to get physically close to the lion. The telephoto lens will allow you to get closer to the subject via zoom.

Macro lenses allow you to focus extremely close to the subject. A true macro lens will have a 1:1 ratio. This means that the image is taken life size. With macro photography, you can get extremely close detail of something. An example might be the inside of a flower. You'll be able to see each piece of pollen with a macro lens.

Fisheye lenses are often times less of a necessity, and more of a luxury that is usable to give a cool creative effect. One example where they do prove very useful is shots of airplane cockpits. My good friend Michael Davis is a well known aviation photographer that sometimes uses fisheyes to capture the entire cockpit environment. You'll notice with fisheye lenses, the majority of the distortion is on the edges. The further from the center of the photo, the greater the distortion

Fisheye Lens - Photo courtesy Michael Davis AirTeamImages - All Rights Reserved

A Teleconverter allows you to add a multiplier to your current lens. If your teleconverter is 2x and you're using a 70-300mm telephoto lens, the effective focal length is now 140-600mm. With these lenses, you are reducing the amount of light reaching the sensor, thus requiring you to make up for it with a longer shutter speed, a larger aperture, or a higher ISO setting.

Image stabilization is a great thing to have on a lens. It helps prevent motion blur thus allowing you to handhold the camera at shutter speeds that are slower than previously possible. They say a good rule of thumb is to use the same shutter speed or greater for a given focal length to prevent motion blur. For example if you are shooting at 110mm, you should use 1/110th of a second. However, cameras don't use 1/110th sec, so you would round up to the next shutter speed of 1/125th. By adding image stabilization, one may now be able to handhold as slow as 1/80th of a second. This is all dependent on each person. If you naturally hold the camera steadier than the next guy, you'll be able to hold the camera at slower shutter speeds than him or her with or without image stabilization. This is a great feature if you have Parkinson's disease or some other disorder that causes hand shakes or tremors. Image stabilization will often greatly increase the cost of the lens. Often times the IS (image stabilization) feature of a lens will double its price to a similar lens without the feature. Different brands refer to IS using different terms. IS is the Canon term for the feature. Nikon uses VR (vibration reduction). Sony is a brand that includes the feature in its camera bodies, eliminating the need for it on the lenses. However, the Sony lens brand often costs more in general, so it makes up for the fact that you don't have to buy the feature on each lens.

So here's the deal: BETTER GLASS (lenses) = BETTER QUALITY

I'm not saying you can't take good photographs with lower quality lenses, but the quality of a lens definitely reflects in the final photo. Sharpness, color, fringing, distortion, etc will all be better with higher quality glass.

When buying lenses, it makes since to buy a lens first that you will use the most. If you're a nature photographer, you'll want to buy a wide angle first.

Some people don't want to lug around 3 or 4 different lenses for different functions. For this, they have designed lenses with greater focal ranges. For example, Sony now makes a lens with a focal range of 18-250mm. This lens gives you a nice wide angle, and with the turn of a ring, you can be zoomed into 250mm.

Another thing to note is to read a lot of reviews before buying a lens. Better yet, find a photo shop that rents out lenses. This will allow you to test the lens before investing the big bucks. Different lenses have different "sweet spots." A lens will usually be softer at its extreme focal lengths (18 or 250mm on the example above). This lens focal length sweet spot may be between 50 and 200mm. The other sweet spot will be in the lenses aperture. It will likely be softer at the largest and smallest aperture, and sharpest somewhere in between.

With that said, other things to consider are the lenses aperture, build quality, zoom type, color quality, distortion, color fringing, etc.

Some lenses have a fixed aperture. For example my 70-200mm Sigma lens will stay at F/2.8 throughout the entire focal range. My Canon 28-135mm on the other hand has an aperture range of F/3.5-F/5.6. This means that at its widest angle, the lens will shoot as large as F/3.5, but as you zoom, the camera changes the aperture so that by the time you reach 135mm, the smallest aperture achievable is F/5.6. The constant aperture is a great feature, but often cost more money.

Some telephoto zoom components are completely internal, meaning as you zoom, nothing happens on the outside. My 28-135mm on the other hand has external zoom components. This means that as I zoom, the lens itself actually gets longer.

All of these are factors to think about when purchasing a lens. I hope this entry helps with your future purchases. Hey! If you are photographing the Empire State building anytime soon, either stand close to it with a wide angle, or stand far away with a normal or telephoto, and you'll capture the entire building "From the Ground Up!" :)