We all own a lens or two or five. Not everyone knows how modern camera lenses work. So I thought I’d write a short post going over some of the basics. Some newbies might find this interesting. Even though I am no newbie, I still enjoyed preparing this post.
Compared to the best lenses we had 30 years ago, the lenses of today are extremely high quality. The glass and parts are all precision made and extensively tested. Making matters more complicated, today – most lenses includes sophisticated electronics that do everything from aid in autofocus to vibration reduction. 30 years ago, a zoom lens that didn’t crap out on you at the long end was considered a great lens!
The basic parts of a lens are:
1. the mounts
2. the barrel
3. the focusing ring
4. the aperture
5. zoom ring (if applicable)
There are two mounts on most lenses. The front mount accommodates filters and lens caps. The rear mount attaches the lens to the camera. It often also houses the electrical contacts that allow the camera’s computers to interface with the lens’ electronics.
The barrel acts as a housing for all the various parts that comprise the lens.
The focusing ring (not present on some less expensive or point and shoot cameras) allows the photographer to manually focus the lens. It also may drive the optics or work a servo motors that drives the lens elements.
The aperture moves in one-stop increments to allow more or less light into the lens. More sophisticated cameras offer fractional stops between aperture openings.
The zoom ring is found on zoom lenses and allows the photographer to change the focal length of the lens.
Most lenses come with lens hoods and front and rear caps. In my opinion, you should always use your lens hood and use front and rear caps when the lens is not in use.
More expensive lenses come with carrying bags. If possible, it’s a best practice to leave your lens in the carry bag when not in use. This provides a maximum of protection.
After the basics come the important characteristics like focal length – which impacts angle of view, minimum focal distance, minimum and maximum aperture.
The “faster” a lens – the larger the aperture. Meaning a fast lens has a large aperture or a small f-stop number. Another important factor when choosing a lens is its minimum focal distance. Most photographers don’t have a great deal of experience with 600mm (and up) lenses and are surprised to find that these lenses often have minimum close focus distance of 20 feet or more.
The quality (and usually price) of a lens will often impact the lens flaws or lack thereof. And all lenses have flaws. 99.99999 percent of the flaws are untraceable by the human eye. But there are flaws we do see such as chromatic and spherical aberrations, coma and light falloff. The more expensive lenses are corrected for these problems. The less expensive lenses are not. But don’t worry. Even the consumer-level, kit lenses you can buy today are pretty good to great compared to the lenses we bought 30 years ago.
There are special lenses like macro lenses – which allow you to work very closely to your subject, or fish-eye lenses, which allow you to get a super wide field of view that will often be distorted in a circular manner. These specialty lenses offer unique characteristics and qualities which make them a must-have for some photographers, and a not important acquisition for others.
This is a very basic, and very quick rundown on camera lenses. Hopefully this post will spur you on to learn as much as you can on your own about lenses and how they impact your photography. In the end, buy the best lens you can afford. But don’t miss sleep over it. 98% of all lenses are better than 99% of all photographers anyway.