I have no idea how to lenses

S

Spock

I'm about to dive into serious filmmaking, and I'm about to make a large camera purchase. My problem is that I know about the camera bodies but NOTHING about lenses, which will affect my camera purchase substantially.

So, please, any recommendations would be very welcome. I also have some very newbie questions about them. What do their specs even mean? How many lenses should I get to shoot with, and what should each be used for? I don't even understand what is meant by the "angle" of a lens. Any advice? Or could you guys at least point me to an article that would answer my questions, as I'm sure telling me everything about lenses ever would take quite a bit of writing.

Thanks guys.
 
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As always, Uncle Bob has to chime in with "What are you doing about your production sound and post sound needs?"

Your project will only look as good as it sounds because
"Sound is half of the experience."


Besides sound, great visuals are also dependent upon great lighting; how are you addressing that need?
 
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You don't need to know everything about lenses, here's the basics - it's hard to give any specific recommendations without knowing what camera you are getting and how you intend to use it:

The 'focal length' of the lens is the number expressed in millimeters - 28mm, 50mm, 85mm, etc.

In general, when comparing lenses, the smaller the focal length the wider the 'field of view' - how much of the scene in front of the camera is visible in the shot.

Focal length alone isn't enough to determine the actual field of view - it's a combination of focal length and sensor size that affects this. On DSLRs the sensor size is usually represented as a 'crop factor' relative to a sensor that is the same size as a 35mm still picture frame.

So on a "Full Frame" sensor (same size as film, Canon 5D series, etc) a 28mm would be a 'wide' angle, 50mm is considered "normal" (close in perspective to the human eye), 85mm is a slight telephoto (often referenced as a 'portrait' lens), 100mm+ would be telephoto.

An APS-C sized sensor (Canon Rebel/T3-4-5-etc series) has a 1.6x crop factor - so you multiply that by the focal length to determine the equivalent on a full frame lens. Now your 28mm lens becomes your 'normal' lens, 50mm is your portrait lens, and 85mm+ gets into the telephoto range. To get a wide angle shot you'll need something in the 17mm range.

A micro-4/3 sensor has a 2x crop factor. The blackmagic pocket has almost a 3x crop factor. When deciding which lenses you'll need you want to start with the sensor size and determine the focal lengths that will give you the types of shots you are trying to achieve, based on the typical distance of your camera from the subject. Naturally, you can change the composition by moving the camera closer or farther from your subject, so you'll want to take into account how you plan to set up your shots when considering the focal lengths you need.

A 'prime' lens is one with a single focal length (i.e. 50mm), a 'zoom' lens just lets you adjust the lens anywhere between two different focal lengths (i.e. 24-105mm).

The 'aperture' is an iris inside the lens that can be opened and closed to control the amount of light passing through the lens to the sensor.

The size of the aperture is the "F-stop", and is a ratio of the aperture's diameter to the focal length of the lens. The higher the F-stop, the smaller the iris opening, the less light passes through the lens. As you go down the scale each 'stop' on the aperture ring represents a doubling of the light passing through.

Lenses will typically be labeled with the largest aperture setting they have - i.e. an f/2.8 lens has a maximum aperture of f/2.8, but can be stopped down to smaller apertures - f/4, f/5.6, f/8, f/11, f/16, f/22. The larger the F-stop number, the smaller the opening, the less light enters the lens.

The 'speed' of a lens refers to it's maximum aperture (and thus how much light it lets in). A 'fast' lens will generally have an aperture in the f1.2 to f/2.8 range, a 'slow' lens will generally be f/4 or above. It's more difficult, and thus more expensive, to make fast lenses. It's even more difficult to make a fast lens that zooms, so zoom lenses tend to be relatively slow compared to primes. The most difficult thing is to make a fast lens that zooms and maintains the same aperture setting at all focal lengths. Cheap zoom lenses will generally be both slow and variable aperture - they're faster at the wide angle setting, but the aperture closes down at the telephoto setting. If you plan to zoom during shots this can cause a visible darkening of the scene as you zoom, so it's generally desirable for video use to get a zoom with a constant aperture (but also more expensive).

In addition to controlling the amount of light entering the lens, the aperture setting determines how much "depth of field" the lens has. Depth of field ("DOF") is the distance in front of and behind the focus point in a shot that is still in focus. The wider the aperture, the shallower the depth of field, and the narrower the slice of your shot that will be in focus. A smaller aperture will result in greater depth of field or 'deeper' focus and more of the scene in focus.

Depth of field is also affected by the distance between the camera and the subject you are focusing on. Focusing on something closer to the lens will result in shallower depth of field, while a subject farther away will have greater depth of field - even if the aperture is the same in both shots.

All else being the same, a wide angle lens will have greater apparent depth of field (more of the scene in focus) than a telephoto one.

Sensor size also plays into the depth of field you can achieve in a given composition. Since a smaller sensor crops the shot relative to a larger sensor you will be forced to use a wider-angle lens to maintain your composition and field of view. Since wider angle = greater depth of field, you'll generally have a more difficult time getting shallow DOF with a smaller sensor camera. Camcorders have very small sensors compared to DSLRs, requiring very wide lens focal lengths to get normal shots - often in the 6-7mm range - and thus will generally have very deep DOF in most situations. If you want to achieve shallow depth of field with a small-sensor camera you'll need to use a telephoto lens and just move the camera much farther back from the subject in order to achieve the desired field of view.
 
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In simplest terms. "Angle" is the same as "Field of View" ... in other words, how much to the left, right, top and bottom of the world in front of the camera is seen by the lens.

You can imagine an invisible cone, projecting from the lens out into the world, the point of that cone would be inside your camera. The base of the cone out in front of the camera.. extending outward the further it extends away from the camera.

Wider angle lenses mean that the image seen by the camera/lens is wider than narrower telephoto lenses. The angle is inversely proportional to the "length" of the lens.

A "long" lens, telephoto, has a much narrower view into the world than a wide lens. This is represented by the millimeter value of the lens.. so, a 14mm lens is wide, a 200mm lens is narrow. Essentially.

Things get a little more complex than that when you take into account sensor cropping and whatnot, but a 200mm lens will always give you a tighter angled view of the world than a 14mm lens. The difference for sensor cropping would be that those same lenses on a so-called "full-frame" sensor and a "cropped" sensor will show different images.

https://www.youtube.com/watch?v=eCa1dfl5o7k

Ideally you'll want primes (single focal length lens, not a zoom) that are "fast" ... meaning their aperture opens very wide.. the lower the f-stop number the faster the lens. So an f1.4 is faster than an f4. This means a few things; First, a faster lens requires less light for proper exposure. Secondly, a faster lens can produce a shallower depth of field (less in focus at any given time) -- but that depends on the aperture being open farther... an f1.4 lens stopped down to f4 isn't going to have shallower depth of field than a lens that will only open up to f4, until you open the fast lens up to a wider aperture/lower f-stop value.

Besides lenses, you'll also want to get some nice neutral density filters, which will let you decrease the amount of light hitting the sensor without having to close the lens aperture. This will allow you to get shallow depth of field in even very bright conditions.

https://www.youtube.com/watch?v=dGmpNslYuiY

The reason you primarily want primes is because they generally (not always, but the exceptions are usually quite spendy) have better optics and faster speeds than zooms. There's certainly nothing wrong with zoom lenses, and they do provide a great deal of flexibility, but for various reasons can be more difficult to work with... it can be more difficult to maintain focal length with a zoom lens while pulling focus for a shot, that's really the biggest issue. And, again primes tend to be faster.

The other reason to favor primes -- old nikon and canon (and compatible) manual prime lenses are readily available at pretty low cost at camera shops, thrift stores, garage sales, flea markets, and online (ebay, etc). Saving money is always a good thing :)

Note: Some of this is my opinion, but it's based on fact.. :)

Here's a few other people's opinions on good lenses to start your kit with:
https://www.youtube.com/watch?v=UekU93GzpI8
https://www.youtube.com/watch?v=paDcaG5CiME
https://www.youtube.com/watch?v=mQ_zhe78x-M
 
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Wow, guys. Thanks for the novels. That was hugely informative.

@Alcove Audio: I do have some nice shotgun mics that I think will do nicely. I only have work lights and a homemade reflector for lighting so far but I'm thinking about getting at least one nice light with barn doors to serve as a key light.

@ItDonnedOnMe: Wow, that's a load of information. Thank you so much. I read it, but it I'm going to have to read it again later because that's a lot to digest. Very informative and very helpful though, thank you.

@Will Vincent: Same to you, very helpful. Thanks for the videos too I'll take a look at them. What's more is that you covered things ItDonnedOnMe didn't, so you were helpful as well. Thank you.

Also, Will and ItDonnedOnMe, you're the same people who helped me out in some of my other threads. I can't thank you enough for the time you've taken to help me out and answer my many questions.

@sfoster: Thanks for the resource, I'll check into it.

Much appreciated guys. For anyone who's wondering, I'm torn between the Canon 5D Mark III and the Panasonic GH4 as far as the camera goes.
 
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If you're shooting on a DSLR you'll need some way to record the audio - you can't plug the XLRs directly into the camera. There are adapters for doing this, but the onboard audio hardware in the camera is very low quality and it's often difficult to set/monitor audio levels. In general you'll be better off with an external audio recorder.

The most popular low-end recorders are the Zoom H series and Tascam DR series - these will run $3-500 each and will be much better than the built-in camera audio. They're still low-end devices though - as you step up to more expensive hardware you'll get much better preamps and build quality. You can easily spend thousands of dollars on a good audio recorder, but it whether it's necessary or not will depend a lot on your goals for your intended projects. Personally I'd say if you're at the point of considering high-end recording hardware you're probably better off hiring a dedicated sound person who has the necessary hardware and knows how to get the most out of it.
 
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Oh, yeah I know I'm going to need some external recorder to plug the mics in now. Previously I'd shot with a dedicated video camer that had XLR ports. Thanks for pointing out some specific recorders though!

But I figure now is as good a time as any to ask this: I'm thinking of getting the GH4, so do you think the YAGH attachment would be worth buying? On one hand it saves a lot of hassle with syncing audio and such, but on the other hand it seems like it's not really worth 2 grand for that.
 
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Plural eyes, huh? I can't imagine how one would begin programming that, but if it exists then I guess I'm good to go! Thanks everyone!

E: Just so I have something to go off of, what would be an example of a "high end" audio recorder and shotgun mic setup?
 
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