What specs should I look at when shopping for a lens to take talking-head-at-a-desk and closeup shots?

Question

I want to purchase a lens for my Nikon D750 that can zoom in and out, and will be good for taking selfies/vlogging at a desk. It would also be nice if this lens could also be used to shoot words on a page. What do I need to look for in the lens's specifications to figure out if it can do these things?

Answer 1

My first recommendation is that you need to know your space.

The main thing to understand is 1. The distance from the camera to your face, and 2. How much do you want to capture your surroundings, your background.

a. If the camera is too close the result could not be too flattering, so define if you can put the camera a little further away and get a better perspective.

b. If the focal length is too big, the space you can move could be more restrictive than a wider lens.

c. If you want to show more of a room you are in, use a wider lens. If you do not want distractions try a longer focal length.

I am assuming that you have at least one lens. The best option is to actually use your camera and see what limitations are presented in your setup. I believe a 24-120mm is commonly sold with that camera.

Try different well-defined focal lengths.

One possible limitation of your current lens could be that needs more light. Then it would help to decide to actually add more light or to get a faster lens.

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If your camera does not have a lens, I found a post to make some tests for framing using cardboard.

Framing shots before purchasing cameras?

Answer 2

Things to look for:

Mount system

The lens has to match your camera for you to be able to attach and use the lens. In your case, a Nikon D750 is in the Nikon F mount dLSR lens system. So you need to look for lenses that are for Nikon F. Nikon does also make a mirrorless system, Nikon Z, and those lenses would not be compatible.

Sensor coverage

You also want to get a lens that covers your sensor with its image circle. While you can get a crop (DX in Nikon terms) lens and use it on a full-frame (FX in Nikon terms) body, the resulting image will be cropped down to crop dimensions, reducing resolution. If you didn't shoot Nikon, you could look up the specific manufacturer designations for full frame or crop on this Q&A:

What do all those cryptic number and letter codes in a lens name mean?

Focal length range

If you want a lens that zooms in and out, you need to look for a lens that has a focal length range, which will be specified as a numerical range in millimeters (e.g., 18-55mm). If the lens only has a single focal length (e.g., 50mm) then it's a prime lens that does not zoom.

Focal length distances

The focal length numbers themselves will tell you how the lens frames and what working distances are most likely to work for you. The shorter the numbers are, the wider the view on the lens will be, and the closer you can get to a subject.

Most vlogging/selfie shooting is done from fairly close (arm's length for shooters holding their camera in their hand), and people typically want to get the context of the space they're in into the shot with a wider field of view, so the most common lenses used for this are ultrawide or even (in the case of action cameras) fisheye lenses. But these can do perspective distortion when used in so close and may also exhibit barrel distortion from being so wide.

If you have more room, want to frame more tightly, or would prefer less distortion, a longer lens might do the trick, something in the wide to short telephoto range favored by portrait shooters.

In general, full-frame equivalent focal lengths boil down like this:

• Ultrawide: under 24mm
• Wide: 24-50mm
• Normal (not wide/not tele): 50mm
• Telephoto >50mm
• Supertelephoto >300mm

Figuring out how that would work with a specific camera depends on the sensor size being used. On a full-frame camera like the D750, you can just go with those equivalent numbers. But on something like an APS-C mirrorless camera, say a Sony a6100, then you'd have to divide that number by the crop factor of the sensor (1.5x), and 24mm would be more like 16mm.

IOW, you probably want something like the Nikon 14-24, but you can probably afford something more like the 28-70 or 24-120.

Minimum focus distance / macro

While shorter focal lengths help you take images with the lens closer to the subject, most lenses for larger-format sensors will also have a minimum focus distance. If the lens is closer than that distance to the subject, it cannot focus.

For extreme closeups with a full-frame sensor, you may need a specialized macro lens. And a "true" macro lens (one that gives you 1:1 magnification, where the size of the image on the sensor is the size of the subject) will always be a prime, and typically be in the normal to short telephoto range in focal length. Most full-frame true macro lenses are around 100mm.

Cinema/video-specific features

Additional cinema features you might want in a lens for video (but that may cost a ton):

• Silent autofocus motor
• Lack of focus breathing (when the lens changes focal length as you change the focus point)
• Focus rig gearing
• Clickless aperture for continuous, rather than stopped adjustment

Answer 3

Your D750 is a full frame! That means the dimensions of the image sensor is approximately the same as a film camera accepting 35mm film. The size of the image recorded by this camera is 24mm height by 36mm width. Additionally, the diagonal measurement of this rectangle is 43.3mm.

Knowlege of your cameras format size is important because these dimensions are key factors as to what focal length lens are appropriate.

First, every format size as a "normal" focal length based on the diagonal measurements. If you mounted a lens with a focal length approximately equal to the diagonal, the angle of view realized is 53 degrees. Note: is the diagonal angle of view, the one most often published. I always thought this is crazy, because I think what you really want to know the horizonal angle of view which works out to 45 degrees. Such a lash-up is considered the "human perspective".

Now the industry has rounded what it considers "normal" up to 50mm. In other worlds, 35mm photographers consider 50mm as "normal".

Now what is wide-angle? The realm of wide-angle is 35mm and shorter. What is telephoto for this format? Telephoto is deemed 100mm and longer.

How about portrait lenses? The biggest mistake made is working in too close. If you do, things close to the camera reproduce too big. In other words, the nose is reproduced too big and the ears too small. This can be subtle, the sight errors may not be noticed but the subject will say "I don't photograph well". Anyway, the cure is just to step back.

Most portrait photographers, using this format, gravitate to a 105mm. This focal length will force the photographer naturally step back when composing. I suggest a zoom that allows a 105mm setting.