Things aren’t as simple as the days when most video cameras (broadcast and ENG cameras aside) just came with a built-in lens and that was that. Now, between DSLRs, mirrorless cameras being used for video, and cinema cameras that have still-camera lens mounts, one is stuck with the daunting task of picking out a set of lenses.
If I can only choose one lens, what is the best?
First, I would like to dispel any notion that there is one “best” lens. There isn’t. Lenses come in different focal lengths because different shots work best (or at all) with different angles of view. A wide-angle lens might give you the feel you want for a POV shot. A “normal” lens might be best for a medium shot, while a telephoto may be your only option if you’re shooting a nature documentary and the subject is far away. Which lenses to use requires knowing your subject matter and the feel you’re going for.
For those looking for a starter lens, here is my advice. Opt for an inexpensive zoom lens, if one is available for your camera’s format. These won’t be suitable for low light or getting dramatic shallow depth of field, but will offer the widest range of focal lengths with which you can experiment. From there, you can get a sense of what specific prime lenses you may want. Alternatively, meet in the middle with a “normal” lens. The exact definition of normal is debatable—many will tell you it’s 50mm in “full-frame” 35mm format. A more abstract definition is that it is a lens that is neither wide angle nor telephoto. For a full-frame camera, between 35mm and 75mm would fit this range. Normal lenses, being optically simple, are generally inexpensive while being sharp with decent to good low light performance. A normal lens certainly won’t work for every situation, but if you need one prime lens to start with and aren’t sure what your requirements are, it’s your best bet.
What focal lengths do I need?
So, you’ve been convinced you need more than one lens. Now, what lenses do I need? There is no definitive answer that works for everyone. I would start with a normal and work out in both directions along a bell curve. The Sony CineAlta 4K Six-Lens Kit for Super 35mm cameras with a PL Mount is pretty much the dream set you want. It features 20mm, 25mm, 35mm, 50mm, 85mm, and 135mm lenses. For most shots that aren’t pushing things to the extreme, this kit has you covered.
For sports, wildlife filming or other times you will be shooting from afar, a telephoto or ENG-style zoom lens may be called for. In the photo world, the 70-200mm is a popular telephoto zoom. An ENG-style lens gives you maximum versatility and is what you want if you need to be able to zoom in and out freely while recording. ENG-style lenses are bulky and will most certainly require a rod support system to avoid overstressing the lens mount.
You may think 200mm isn’t that impressive, especially considering photo lenses sport focal lengths up to 800mm and beyond. Keep in mind that the more telephoto you go, the better your tripod or camera support needs to be. Any camera shake will by multiplied by the magnification of the lens. Extreme telephoto work (even in photo) will require not only a very stable camera setup, but also a lot of patience, because there will be many retakes.
Low-Light Performance
A big factor in the cost of a lens relates to its f-stop—how wide the aperture will open. The wider, the more optically precise the glass must be to retain acceptable sharpness. This is especially true of zoom lenses. Kit lenses are inexpensive while offering impressive zoom ranges, because they have dismal low-light performance—say f/3.5 to f/6.3, depending on how much you zoom in. Primes are the way to go if low light matters. In photo lenses, f/1.4 or higher is considered good for low-light performance, while cinema lenses measuring performance in T stops around T2 are considered good for low-light capture.
Sensor size typically correlates with low-light performance, so an f/2.8 lens that is respectable on a full-frame camera may come up short on a Micro Four Thirds camera, which has a much smaller sensor. Also, lenses usually aren’t at their best when pushed to extremes. An f/1.4 lens may be mediocre at f/1.4 but really shine at f/1.8 (this is true at the small end of the aperture scale, too).
Depth of Field and Bokeh
Depth of field, like low light, relates to aperture. The wider diameter of the aperture (smaller f-number), the shallower the depth of field. Also, as with low light, sensor size is a factor. At a given angle of view, the larger the sensor is relative to the f-stop, the shallower the depth of field, because the corresponding focal length will be less. Finally, the closer the subject is to the lens, the shallower the depth of field will be. This last is a major problem for macro work, since almost nothing comes out in focus.
Different focal lengths will alter the effect of depth of field. A telephoto lens will compress background elements against the subject, which can make depth of field appear shallower, while wide lenses may create the illusion of deep depth of field.
Bokeh is an artifact that depends on the physical shape of the iris. Since adjustable irises typically have blades, you will see a polygon pattern—even a triangle on very low-cost lenses—rather than a circle. To give bokeh a circular pattern, high-end lenses will use more iris blades.
Specialty lenses like the Lensbaby or tilt/shift lenses can be used to create custom depth of field and bokeh effects.
Native Mount or Adapter?
Adapters are all the rage. Is it better to adapt or use your camera’s native lens mount? It really depends. Using your native mount means electronic functions like autofocus and auto iris will still work (how well they work in a video context is another story). But if you plan to operate your lens manually, which is usually your best bet for video, then electronic communication is less of a concern. And since you don’t care about electronics, you may be able to take advantage of quality second-hand lenses made for legacy formats, such as Canon’s deprecated FD mount.
Besides electronic interfacing, there is the question of sensor format. A Nikon AIS lens, for example, is made for a full-frame camera. Placed on a Micro Four Thirds camera, such as the Panasonic GH5, that 50mm becomes about a 100mm equivalent, thanks to the Micro Four Thirds system’s much smaller sensor size. Not only does this make the lens seem more telephoto, the full-frame lens may not be optimal from an optics perspective. Lenses tend to perform best with their native format, though some lenses do exhibit falloff (at least in certain settings) which can be mitigated by placing the lens on a slightly smaller format than the one it was designed for. Even so, as a rule, opt for lenses that are made for your sensor size if you can. Alternatively, consider a speed booster, which not only adapts the mount mechanically and electronically but also provides an optical “conversion,” so to speak.
If you are starting fresh and there are suitable lens options in your native format, stick to those. If you have existing lenses you want to use with a new camera, or you want to use second-hand lenses, then adapting makes sense.
Cinema versus Still Photo
Most lens mounts you will encounter will have lenses available either for still photography or as cinema lenses. While this is a topic for a whole other article, here are a few of the benefits of cinema lenses which may apply:
- T-stop aperture measurement
- Gear rings for follow focus
- Hard stops on focus and (where applicable) zoom rings
- Consistent barrel diameters and physical lengths across a series
- Reduced/eliminated “breathing”
- Parafocal design to enable zooming without losing focus
- Rugged, “AC-friendly” housings
This really boils down to cinema lenses being more useable for video, while being bulkier and costlier than their photo counterparts.
Conclusion
There really isn’t one right lens—which is why there are so many. Knowing the projects you will be shooting gives you the best chance of selecting the most suitable lenses.
The Takeaway
- Opt for a “normal” lens or an inexpensive “photo” zoom lens if you can only have one lens in your kit
- A decent lens kit will include a range from wide-angle to moderate telephoto
- For maximum compatibility and optical performance, choose lenses made for your format; but remember that adapting can be a reasonable compromise, in many cases
- Cinema lenses are more usable for video than their photo counterparts but less usable for photo
Feel free to share your own lens-selecting experiences below, in the Comments section.
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