By Eugene Struthers
The key to narrowing down your search criteria for a suitable lens. It is knowing what to look for and why you require that particular lens. The decision to either purchase a Prime or Zoom lens must be made after you have decided on the type of focal length you require. This will make the whole process of searching for a lens a lot easier, whilst also highlighting the advantages and disadvantages each lens has.
Knowing what you want to photograph and how to use your camera. Assists in the decision process of what type of lens you will require. This can be influenced by cost and how suitable the lens is to use. And how often you will use a particular lens.
If you make your main income from photography as a wildlife photographer. You can justify the purchase of an expensive super-telephoto lens. As the lens will serve its purpose as an aid in increasing the quality of the images you capture and the profits you make. Is it a requirement for a wildlife photographer to have a telephoto lens if he is out in the middle of Africa photographing a pack of lions? Yes, it is. These are for obvious reasons. The first is safety, and the second is the ability to capture images at a far distance away whilst zooming in to give the impression of being amongst a pack of lions. So getting the heavy, bulky lens out into the bush in the middle of Africa is extremely inconvenient. The benefits of the lens characteristics make up for this, by being convenient to use when capturing the lions some distance away.
You need, to ask yourself: What do I want to photograph? How can this lens assist me to achieve this? If I purchase this lens, will it serve a dual or single purpose? Is there a lens that will allow me the benefits of both a "Prime and a Zoom lens"? Is it worth purchasing this lens on my budget? Do I eventually want to go professional and make all my income from photography? All of these questions will be influenced by your budget and your photography requirements.
So what is a Prime and Zoom lens? What distinguishes them apart from one another? What are the technical characteristics of each?
A Prime lens has a Fixed focal length.
This means that the focal length of the lens is fixed and set to one number and cannot be adjusted, and you cannot zoom onto a particular subject. If you need to change your angle of view, you will need to get up and move the camera toward or away from your subject. They have one focal length with very few moving parts, which makes the lens very precise.
To achieve different focal lengths, you will need a variety of different prime lenses. Each prime lens will serve its purpose and field of view. To capture images at say 10mm, 35mm, 85mm, 100mm, or 300mm you will need to purchase five separate lenses for each focal length.
Fixed focal length lens Advantages
The simpler optics of a fixed focal length lens means that it has a larger maximum aperture (smaller f-numbers). A lens aperture is the opening through which light travels; the larger the opening, the smaller the f-number. A larger aperture allows for photography in lower light and photos with a shallow depth of field. Depth of field refers to the area of the photo that is sharply visible in comparison to the area that appears blurry. For example, in a shallow depth of field, the subject of the photo will appear sharp, but the background will appear blurred. In a photo with a deep depth of field, most or all of the photo will be in focus. This is covered in more detail in the Depth of field course.
Fixed focal length lenses are faster because of the wider aperture. That is, a wider aperture allows the photographer to comfortably use higher shutter speeds to capture high-action photos in quick succession in lower-light situations. A focal length of the lens is often the first choice for photographing dark, indoor, highly active situations such as indoor sports and live theatre. This lens allows for photographing indoors without using a flash.
The images produced with a fixed focal length lens are very sharp and vivid. Colours tend to be more accurate because there are fewer glass elements between the subject and the image sensor.
Fewer glass elements also translate into a lighter weight. Should portability be an issue, prime lenses are much lighter than zoom lenses. A lighter lens is easier to carry and transport, particularly for shooting on location.
The focus ring on prime lenses is more sensitive. Although there may be times when a photographer uses autofocus, having the ability to manually focus with a super-sensitive ring allows for as much latitude as possible for a sharp image. The dynamic focus of a prime lens allows for more variations and control.
Prime lenses are a more budget-friendly option. Because there are fewer moving parts in a prime lens, they are priced lower than zoom lenses of the same calibre. There is often not a comparable zoom lens that can be found for the same amount of money that produces the same, high-quality, precise, vivid images as a prime lens.
Fixed focal length lens Disadvantages
Single Angle of View
The major disadvantage of a fixed focal length lens is that there is a single angle of view. Therefore, to get the composition that is most fitting for the subject, the photographer may need to get closer to the subject. Many times, this isn't a problem, as a photographer will select the proper lens for a subject ahead of time with an understanding of the desired composition. However, if, for example, a photographer is using a macro prime lens to take close-ups of flowers, and then unexpectedly sees a bald eagle soaring above, there's no way to capture the bird in flight without changing the lens. With a zoom lens, the photographer could go from petals to wildlife in less than a second.
Photographers who use prime lenses must change lenses each time they require a different focal length. Not only does lugging multiple lenses around become impractical when shooting outside a studio, but each time a lens is changed, a photographer risks getting dust on the camera's image sensor, as well as the lens itself.
A zoom lens comprises an assembly of various lens elements to allow for a range of focal lengths, from telephoto to wide angle. Photographers can take advantage of the varying focal lengths without having to switch the lens on their camera. A true zoom lens, also called a par focal lens, is one that maintains focus even when the focal length changes. The varifocal lens loses focus when zooming in and out.
The range of focal lengths is used to describe a zoom lens. A zoom lens that ranges from 100 mm to 400 mm, for example, ranges from the closest focal length of 100mm to the further focal length of 400mm. This range can also be described as 4:1 or 4x zoom, offering four times the zoom from the minimum to the maximum focal length. Professional photographic lenses can zoom as high as 100x. For beginning photographers, the telephoto zoom lens will be most practical for a range of subjects. A lens that zooms from the "normal" focal length of 55 mm to the longer focal 200 mm is a good place to start.
Various Focal Lengths
One zoom lens can do the work of multiple prime lenses to achieve the same range of focal lengths. Therefore, it is not necessary to bring along lenses that achieve other focal lengths when a zoom lens can accomplish the same task.
Cost Relative to Number of Lenses
Zoom lenses are typically priced higher than prime lenses. While this may seem like a disadvantage, one zoom lens can serve the same purpose as multiple prime lenses. Investing in a single zoom lens that covers a variety of focal lengths may prove to be more cost-effective than purchasing multiple prime lenses to reach the same focal lengths.
Zoom lenses offer more flexibility and creative latitude, particularly when shooting active subjects. Photojournalists and photographers who shoot events such as weddings or sporting events prefer zoom lenses because they allow for quick changes of focal length to adjust for perspective and add variety to each shot within a matter of seconds.
Proximity to Subject
In regard to proximity to a subject, no movement on the part of the photographer is required. Photographers can easily photograph their subjects from a variety of focal lengths without physically having to move. For photographic composition, moving to change angles is still necessary; however, it is not necessary to physically move close to a subject to hone in on details.
Because there is a higher number of optical elements in a zoom lens, the camera is interpreting images based on varying focal lengths. As a result, images are not as crisp, clean, and vivid as they would be without the zoom adjustments. Beyond approximately a 3x zoom, images begin to be degraded, more so than they would be with a prime lens.
Zoom lenses are far more expensive than prime lenses. The various working parts of a zoom lens add to the increased cost. Often to get the same crisp, vivid images achieved with a prime lens, a zoom lens could cost more than £2,000. Again, however, the overall cost is relative to how many lenses a photographer would like to have and how he or she intends to use them. As such, it's important to weigh the cost of one zoom against some prime.
Zoom lenses can be heavier than Prime lenses, making their portability for on-location shooting more challenging.
A Zoom lens has a variable focal length.
This basically means that the lens is able to zoom in and out whilst you maintain your fixed position.
You might have noticed that the lens given to you by the manufacturers when you bought your camera is a Zoom lens (Vary focal length lens) 18-55mm. The main reason being they allows newbie photographers to be more flexible in their approach whilst covering photography which at wide to standard mid range level. Which is really convenient when starting out.
The main downside to purchasing a Zoom lens can be how expensive and heavy they can be. When compared with a prime lens.
You kind of need to way up your options when considering the purchase of a Zoom lens. If you require flexibility and the ease of use whilst looking past the cost and bulky weight of the lens. Then this is the lens for you. It will allow you the creative freedom to capture great compositions while being some distance away.
Zoom Power & Zoom focal length
As a Prime lens doesn't change its focal length. We term these types of lenses a Fixed focal length. Which basically means that you are able to use only one focal length.
The added advantage of having a Zoom lens is the ability of the Zoom "magnification" to cover a range of focal lengths. This is actually indicated on the side of the lens with two reference numbers. These being the wide angle and the telephoto setting.
So if you had a 28-135mm lens
The wide setting would be the 28mm
The telephoto setting would be 135mm.
The Zoom power is indicated by how much of the focal range a lens can cover. The greater the distance between these two numbers the more powerful is your zoom.
Which is kind of reasonable. If you have a 28-135mm lens and you compare it with a 28-300mm lens. The 28-300mm will cover more, focal range as there is a greater distance between the 28mm up to the 300mm. Thus making it more powerful.
How do you determine the strength difference in power between two lenses.
To calculate this difference, we first have to divide the telephoto setting by the wide angle setting. Please check out these examples:
Wide Angle Telephoto Math Zoom Power
18mm 55mm 55/18 3.06 (3x)
10mm 14mm 14/10 1.4 (1.5x)
70mm 300mm 300/70 4.29 (4x)
28mm 300mm 300/28 10.71 (11X)
Types of Zoom lenses
There are four types of Zoom lenses to choose from.
These comprise of:
If you think. Okay, why don't I just purchase a 18-300mm lens and be done with it. That will cover all the focal lengths I need. Well, you could. But the one draw back will be less optical quality in your images. The more elements and optical components in the lens the poorer or inferior the image quality will be. Then again, when I wrote this back in 2004 in Amsterdam. The image quality produced by lenses manufacturers was not as advanced as it is today in 2017.
If you have decided to do glamour-photography, we would recommend you purchase a zoom lens specific to your own requirments. We only use three zoom lenses. The 28-135mm, 35-80mm and the 55-250mm here at Glamour-photography magazine. We could probably get by with just one. The 28-135mm.
Zoom Class Range
Wide angle to Wide angle 10mm - 28mm
Wide angle toTelephoto 28mm - 300mm
Telephoto to Telephoto 100mm - 600mm
Super Zoom 18mm - 300mm
Katja has recently purchased a new Canon 80d digital SLR camera that came with an 18- 55mm
f/3.5 - 5.6 kit lens.
At her local pub, a group of glamour models have found out about her new purchase. And have asked her to photograph them for a charity topless football calendar.
The calendar is for a local charity associated with a local hospice. To help send terminally ill patients to the USA for a holiday.
Katja know's how important this calendar will be to the girls, and she doesn't want to let them down.
She only has her kit lens and knows how to capture a proper set of images for their calendar. She will require a better lens. One more suited with the capabilities and functions to make the day a success.
She knows that she will need to be in the mix with the glamour models as she photographs them from the sidelines. And the only way she will be able to zoom in and out as they run around and across the field as they kick the football. Will be if she has a "Telephoto to telephoto lens". This type of lens will allow her to capture all the actions of the topless players. As the game heats up.
After reading Glamour-Photography magazine. Katja decides that as she has a Canon camera, the lens must be canon as well. She also knows that she will require a zoom lens so that she can get up close to the models as they play topless football on the field.
Katja decides on: Lens mount: Canon
Lens focal length: Telephoto
Lens type: Telephoto to telephoto zoom