There is a lot of talk about cameras and therefore lenses are overlooked. With competing priorities when you’re shopping for lenses, here are some things that may influence your decision of which lens to buy.
In photography, there is always a reward. Whatever benefits a particular choice brings, there will be disadvantages. Furthermore, any rule in photography must be taken as if we mean “as a rule” and not as a self-evident truth. There are always exceptions. So, as a rule, if we consider buy a lens we want it to help us get the best quality photo possible. So we’ll start by thinking about what we want to avoid.
Aberrations and how to avoid them
Chromatic aberration
Aberration is a lens defect that prevents the lens from creating a perfect image. Typically, this means that some of the light entering the lens will be focused too close or too far from the focal plane. Sometimes this can be light of a specific wavelength, so the light is split, causing color fringing that is most visible around high-contrast edges. That effect is called chromatic aberration.
Lens flare
Visible lens flare is an aberration in which light enters the lens and bounces off the inner surface. This is usually undesirable. However, it can be used as a creative effect. Think of JJ Abrams movies and the horizontal lines of flare created by anamorphic lenses used in cinema. Good quality lenses have coatings on the inner lens elements that help prevent light from reflecting from their surfaces.
There is a second type of lens flare in which image contrast is reduced due to light hitting the front element of the lens. This can be avoided by using a lens hood to cover the lens.
Distortion
Barrel distortion is a lens aberration that stretches the image around the edges. Therefore, the square becomes barrel-shaped because the magnification decreases toward the edge of the lens.
In contrast, pincushion distortion is more likely to be seen on telephoto lenses. In that case, the edges of the scene are distorted inward, toward the center.
Pattern
Pattern is darkened at the corners and edges of the frame. The reason is that light at extreme far corners is blocked by the lens barrel. Sometimes this can be avoided by zooming in, cropping out the vignette, or reducing the aperture. A smaller aperture reduces the overall amount of light and the angle at which light enters the lens is also reduced. Therefore, light from the center of the lens is visible at the corners.
Many fast prime lenses have vignetting that quickly disappears as the aperture size decreases. However, one must also note that small apertures can yield softer photos as light refracts (bends) around the aperture blades, scattering the light before it hits the sensor. .
Breathing lenses
Lens breathing is the unwanted change in focal length as the focusing distance changes. Even expensive prime lenses can show it, but cheaper lenses tend to show it more, thus making image stacking more difficult.
Beauty defects
Beauty defects are cosmetic defects that are visible in the lenses but do not adversely affect the image. When you buy used lenses, retailers will mention that dust may be visible inside the lens but this will not affect image quality.
So what are we looking for in a lens?
Whatever you sow, you will reap
When purchasing equipment, price may be an important factor for you. However, the more you pay, the better. Which framework should you choose? Unless you have a disdain for image quality and only take selfies to post on social media, buy the best you can afford.
Lenses typically fall into one of three quality frames. Low-end hobbyist lenses are cheaper and don’t perform as well as mid-range enthusiast lenses. On the contrary, they are not as good as top quality professional lenses. What it takes to create a high-end lens is a far cry from the standard, mass-produced kit lenses on entry-level cameras. That doesn’t mean those cheap lenses are necessarily bad, although some are, but the more expensive lenses are better.
Prime lens
Although this was not their original definition, prime lenses are now considered lenses with a fixed focal length. Zoom lenses can change their focal length. The quality of zoom lenses is much better today than it was twenty years ago and can have excellent image quality. However, prime lenses with the same quality frame will often give better image quality but they do not have the versatility of a zoom.
Optical quality
Optical quality is often an important consideration for photographers. A good lens will minimize distortion and aberrations, resulting in sharp, clear images. To achieve this, the lens requires meticulous design and manufacturing. That’s why the best lenses are often the most expensive. Premium lenses feature aspherical elements made of higher quality glass. That glass requires extremely precise grinding and polishing. They will likely contain one or more low dispersion elements that help reduce chromatic aberrations and high refractive index elements that help manufacturers make lenses smaller and lighter. This type of glass has a number of different proprietary names depending on the manufacturer, but you will often see them mentioned in the lens specifications.
Counting the Number of Lens Elements
Looking at the specifications, you may notice that lenses have different numbers of elements. Fewer elements result in better light transmission. However, that doesn’t necessarily result in better image quality. More factors can help correct aberrations. Furthermore, more complex designs, such as those found in zoom lenses, require more elements to function.
Does length matter?
Focal length is the distance from the optical center of the lens to the sensor when the lens focuses at infinity. Without getting too focused on physics, the longer the lens, the narrower the field of view and the closer objects will appear. Therefore, distant objects appear more magnified with a long lens because they fill the frame. A wider angle lens means a wider field of view will appear in the photo, so the subject will appear smaller.
Focal length also changes the appearance of the scene in other ways. A wide-angle lens will make objects close to the lens appear much larger than objects a little further away. You may have seen photos of kittens and calves with their noses appearing unusually large. These photos were taken with a short wide-angle lens, close to the animal’s face. It’s cute to small animals but unsightly to humans. Meanwhile, long telephoto lenses appear to compress images and can flatten subjects making them look like cardboard cutouts. They make distant objects appear closer to objects in the foreground of the scene.
There are no hard and fast rules here, and the numbers may vary depending on the sensor size of the camera you use. But to generalize, a typical wide angle lens can be between 7-30mm, depending on the camera. They are great for landscaping. Telephoto lenses typically have a focal length of 60mm or longer, although often in the low to mid hundreds. They are used for photography where the subject is further away from the camera, such as sports and wildlife. In the middle are standard lenses, commonly used for portraits.
One mistake many beginners make is buying cheap, long lenses. Bigger is better, right? Wrong! The longest possible lens is not necessarily the best solution. Unless you pay a lot, long lenses will be slower and have poorer image quality. Getting closer to your subject will always give you better results. Additionally, zoom lenses with a limited range perform better across all focal lengths than lenses with a smaller range. A 70-200mm lens will be better than a 70-300mm lens.
Does aperture matter?
The size of the aperture determines the amount of light entering the lens. Wider apertures (i.e. lower f-numbers) allow for better low-light performance, so faster shutter speeds at lower ISOs are possible. They also give you more scope to control depth of field.
The number of aperture blades and their shape will affect the nature of the out-of-focus area or blur effect. Smooth bokeh is often the result of high-quality lenses with multiple rounded aperture blades. That will also create circular balls of light in a blur effect, while the six-bladed aperture will create a hexagonal shape. What is considered undesirable are asymmetrical balls of light.
Build quality
Construction and durability are important factors. I recommend lenses with at least one metal bayonet mount. All-metal lenses withstand wear better, ensuring longevity. They are often more expensive than their plastic counterparts. However, plastic lenses are lighter.
Fast focus
Autofocus performance is also important. Fast and accurate autofocus enhances usability. Low-end cheap lenses are not capable of tracking fast-moving subjects.
Older lenses use a screw drive mechanism to adjust autofocus. Cheaper lenses have replaced those with a micro-motor, which uses tiny gears to drive the lens. Higher quality models use faster piezoelectric motors. They have many different names such as Super Sonic Motor (SSM), Voice Coil Motor (VCM), Ultrasonic Motor (USM), Silent Wave Motor (SWM), Hyper Sonic Motor (HSM) , etc. This type of mechanism is both fast and quiet. Although their designs may vary, they are all based on piezoelectric materials that can change shape when receiving an electric current.
Weather sealed
Let’s look at the water and dust resistance. There’s no point in buying a weather-sealed camera if the lens isn’t similarly protected. However, with one exception, there is no legal definition of weatherproofing, and I know people whose cameras and lenses were supposed to be splashproof who died after a rainstorm. Ideally, you want a camera system with an ingress protection (IP) rating, but only one manufacturer offers this.
Third-party lenses
There are many third-party lens manufacturers. Sigma and Tamron produce a number of high-quality and consumer-grade lenses, and Sigma is often subcontracted to produce lenses for camera manufacturers. In general, their equivalent lenses are cheaper than the manufacturer’s own models but may or may not have completely equivalent performance, do your homework.
Other manufacturers such as 7Craftsmen, Artisan Center, Meyer-Optik Gorlitz, Lensbaby, SamyangAnd DSLR camera produces many types of lenses. Some are high quality, while others are quirky and interesting.
You can also purchase an adapter to mount classic lenses from film SLR cameras to most cameras. These give a completely different feel to your photos.
Compatibility
Make sure the lens fits your camera mount and sensor size. Lenses from the same brand don’t necessarily fit all of that brand’s camera bodies, and the recent switch to mirrorless cameras from DSLRs has caused a lot of confusion for people.
Ultimately, decide what you need and research whether the lens meets your needs. Then, if possible, take your camera to a camera store and try it out with that lens. Take some test shots and see how it works before you part with your cash.
If you are considering buying a camera for the first time, Please see my article about that.
