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What Actually Happens When You Stop Down a Lens

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I got an email the other day that got me thinking. A guy simply asked “How far do I have to stop down a lens to get maximum performance. I’ve heard two stops from wide open. I’ve heard down to f/8. Which is correct?”

I asked him which lens he was referring to, and was he talking about the center point, corners, or overall. He didn’t realize that it mattered. He thought all lenses were the same and had this idea that eventually there was an aperture where the lens was maximally sharp and the corners were as sharp as the center. At this point, I realized there was no way I could tell him everything he needed to know in an email and I decided to write a blog post about it.

For purposes of this post, I’m not going to get into diffraction softening very much. That’s discussed all over the place. I’m simply going to look at what’s going on with your lens and explain why different lenses are going to improve differently when you stop them down.

For those (and you are many) who don’t like to read here’s the quickest summary:

The general rule that lenses get much sharper stopped down two stops from wide open is generally true.

And here’s the not quite as quick summary:

Center sharpness is usually nearly as good as it gets two stops from wide open.

Edge and corner sharpness often continues to improve for 4 stops or more.

Edge and corner sharpness is not as good as best center sharpness even stopped down (it may be close enough, but not as good).

BUT, Edge sharpness may equal center sharpness as diffraction softening occurs and center sharpness drops a bit. Or it may not.

Let's Look at some MTF Curve Examples

This is just an example of what happens when we stop down different lenses. I picked two 35mm f/1.4 lenses: the Canon 35mm f/1.4 (Mk I version) and the Sigma 35mm f/1.4 Art. Canon fanboys, save your 'Not fair, you should use the Canon 35mm Mk II' complaints. This isn't a contest, I'm just trying to make a practical, everyday point, not fuel your silly 'my lens is better' arguments. (Those of you who do thorough graph analysis will notice a little weirdness between f/1.4 and f/2 because the f/1.4 curves are 10-lens averages, while the stopped down MTF curves are each single lens examples.)

f/1.4

Wide open it's pretty clear the Sigma has the better MTF curve. (Learn how to read an MTF chart here)

Olaf Optical Testing, 2016

 

 f/2.0

Stopped down to f/2 both of the lenses improve, but the Canon much more than the Sigma. Notice particularly how the Canon makes a huge jump in center sharpness with just one stop of aperture.

Olaf Optical Testing, 2016

 

f/4

Two stops further down both lenses are even sharper. If you look you'll see the Canon is improving most in the central area of the image circle. Away from the center, the sagittal and tangential curves are improving differently. If you look about 14 mm from the center (0 on these MTF charts) you'll notice astigmatism is actually increasing.

Olaf Optical Testing, 2016

 

 f/8

By f/8, you actually start to see a bit of a drop in the center of the lenses, but they are still improving off center, although in slightly different ways.

Olaf Optical Testing, 2016

 

f/16

At f/16, we are starting to see a slight drop in resolution across the image but the MTF is now fairly even from center to edge. Even at f/16, though, there's still a difference between the two lenses way out in the edges with the Canon still having a bit more drop-off in the tangential curves.

Olaf Optical Testing, 2016

 

One other example I want to show is the Canon 16-35 f/2.8 Mk II lens stopped down. A lot of people think a not-so-good lens stopped down becomes just as good as a good lens stopped down. The f/8 and f/11 MTF curves below shows that the zoom never becomes quite as good as either of the primes, at least on the edges of the image. It may be just fine for what you're shooting, but that doesn't mean it's just fine for what Joe's shooting.

Olaf Optical Testing, 2016

 

Aberrations and Aperture

The reason that different lenses behave differently as they are stopped down is one of those 'so obvious we never think about it' things. All lenses have aberrations, and aberrations are the main reason that a dot in real life is a fuzzy, distorted dot on the imaging sensor. In other words, aberrations affect the MTF of the lens. Lens designers try to minimize aberrations but they can't be completely eliminated. Depending on the purpose of the lens, goals of the design, and other factors, different aberrations may be prioritized in different lenses.

Each kind of aberration responds differently to change in aperture and to the distance from the center of the lens. Table 1 lists some of the more common aberrations. (There are a lot more. In some complex lenses, 7th and 9th order aberrations are sometimes as significant as the aberrations I've listed here.)

 Table 1

Aperture Height from center
5th Order Spherical A5
Spherical aberration A3
Oblique Spherical A3 H2
Elliptical Coma (aka Trefoil) A2 H3
Coma A2 H
Astigmatism A H2
Field Curvature A H2
Axial Color A
5th Order Astigmatism A H4
5th Order Field Curvature A H4
5th Order Distortion H5
Lateral Color H
Distortion H2

 

The aperture and distance from the center of the image affect each type of aberration mathematically, and for many aberrations the mathematics are exponential. A fifth order spherical aberration, for example, changes to the 5th power with a change in aperture, while 3rd order spherical aberration changes to the third power. Distance from center doesn't affect spherical aberration at all so the effect across the entire image is the same. Stopping down by even one stop makes a dramatic difference in spherical aberration, by two stops it's usually gone, or nearly so.

Some aberrations, don't change at all with stopping down and their severity is simply a factor of distance from the center of the lens. Distortion and lateral color, for example, do not improve as you stop down. Shoot at f/16 and they are no different than they were at f/1.4.

Most aberrations, though, do a more complex dance, improving to various degrees as you stop down, but also being affected by distance from the center. Coma and oblique spherical aberrations improve a lot with a smaller aperture. The effect of distance from the center of the lens also has a large effect, though, so you would notice these improve faster in the mid portions of the lens than they would in the corners. Astigmatism and field curvature get a little better as you stop down, but the effect of distance from the center is much greater, so these improve just a bit with aperture change.

Every lens has somewhat different aberrations. Different aberrations affect things in different ways. Some might have more effects on high frequency (40 or 50 line pairs/mm) MTF; others on low frequency. (Just so you are aware, a lot of knowledgeable people call most edge and corner blurs 'coma' even though they are often combinations of coma, astigmatism, and most commonly oblique spherical aberration. Unless you know a lot of optical theory and examine the blur of points of light at various distances and apertures, you can't tell exactly which aberrations are causing this so-called 'coma'. Why does it matter? Because stopping down improves that 'coma' by varying degrees depending upon what it actually is.)

The bottom line is stopping down improves center sharpness greatly - after all distance from the center point is nearly 0 so there is very little effect from the distance. A lens with a lot of spherical aberration, like most wide-aperture double gauss designs, will make massive improvements within a stop or two from wide open. Other lenses improve more slowly. Away from the center, though, things are more complex. The edges will never get exactly as sharp as the center, but they will get close. Depending upon the lens and what you are shooting, 'close enough that you can't tell the difference' might be within two stops or might be never.

Some Light Point Demonstrations

Of course, what matters is what it looks like when you take a picture. But pictures are complex things with lots of variables. To simplify things a bit we took the two lenses from the MTF charts above, the Canon 35mm f/1.4 Mk I and the Sigma 35mm f/1.4 Art and put them on our Olaf machine. This basically shoots 5-micron wide pinholes of light through the lens and lets us examine what that pinhole looks like on your sensor.

Olaf Optical Testing, 2016

While the dots are never absolutely perfect, you can see that at f/4 they are pretty close, with just a bit of halo around the edges. At f/8, the halo is largely gone but the dots have gotten a bit larger.

Now let's look at that same dot about halfway between the center and lateral edge of the image.

Olaf Optical Testing, 2016

It doesn't look much like a tiny, white dot, does it? And really between f/1.4 and f/2 you have to look pretty closely to see any improvement. At f/4 it's clearly better, but still not very 'dot-like'. At f/8, the Sigma is getting rather dot-like, and the Canon is pretty close, although it is providing us with a great example that stopping down doesn't improve lateral color very much. (Just so you're aware, the dot is smaller than a pixel when you take into account Bayer filters and such, so even a slightly smeary dot on OLAF may be a sharp dot on your camera.)

And finally, here's the dot way over on the edge of the image. I should point out that with these images my intent was to crop a single dot's aberration; doing so moved the center of the dot a bit in the f/8 images.

Olaf Optical Testing, 2016

 

The point that should be taken from these edge images isn't so much the specifics. It's that you see certain aberrations improving by f/4 although even at f/8 we still have some obvious aberrations left. It should be apparent, when you look back at the table, that there are aberrations that are much more affected by distance from the center than by stopping down the aperture.

Some Final Thoughts

As I mentioned earlier, I picked out these two lenses to just be examples, not to have a contest. We've done stop down testing on a number of other lenses, although not most by any means. I'd love to give you a quick summary of how lenses all behave; something like f/2.8 primes are sharper at f/11 than f/1.4 primes. Or that they are the same. Or anything, really. But the truth is we haven't found any patterns which are that simple, other than the generalities we mentioned above: lateral color and distortion won't be any better stopped down, and astigmatism and field curvature won't be much better. away from the center.

The simple reality is that if you want to find out which 35mm or 50mm is sharpest in the corners at f/8 you actually have to compare them or look at a testing site that has good stop-down data.  Don't make assumptions because assumptions will always end up biting you.

Before you ask, we'll probably do some of this testing and we'll publish it when we do, but remember, we aren't a review site and we can't afford to do everything. For us, every aperture we test at takes just as long as the original wide-open testing data. Lenses are many, and we are few so the choice is usually 'test 5 lenses wide open or test one lens at 5 apertures'.

Roger Cicala, Aaron Closz, and Brandon Dube

Lensrentals.com

January, 2016

How to Use AF Microadjustment on Your Camera

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The most common questions and complaints I hear almost always have to do with AF accuracy, in one way or another, even if they don’t seem like it at first. “I’m trying to focus on this person’s eyes, but the ears are in focus instead,” or, “This lens is front focusing like crazy,” or, “This fast aperture prime was soft the whole time I used it.” Roger has written some rather lengthy, detailed posts about how phase-detection AF works (phase detection being the kind you use on a dSLR in normal, everyday shooting) so I won’t go into a full explanation here. But the gist of his articles is basically this: phase-detection AF isn’t always that accurate. Here’s some light reading, if you feel so inclined:

How Autofocus Often Works

Why You Can't Optically Test Your Lens with Autofocus

Autofocus Reality, part 1: Center Point Single Shot Accuracy

That last link is the first in a 4 part series, but right there in that first part is a really good example of what AF microadjustment can do. You can read that if you like technical stuff, but I’m about to summarize it in the next paragraph.

So what is it and why is it necessary?

Lenses and cameras are made to certain specifications, and those specs fall within a narrow range of tolerances. Because of the way phase-detection AF works and how it relies on physical calibration for accuracy, if lens and camera tolerances stack up in one direction or another and things are off by minute amounts, then you might see consistent front or back focusing with that particular lens and camera combination. It’s important to know that this front or back focusing is a combination specific issue. You can take 20 copies of the same lens and test them on one camera body, and you might find that most of them are pretty close to dead on, one or two will probably front focus varying amounts, and one or two more will back focus varying amounts. You could then take those same 20 lenses and test them on a different camera body and get completely different results. This doesn’t mean the lenses or the cameras are broken. They just need adjustment, and this is something you can probably do yourself in camera.

How do I do it?

The procedure for making the necessary adjustments is pretty simple, and it’s the basically same across camera brands. Here’s a list of things you’ll need:

  • Camera
  • Lens or lenses to be adjusted
  • Tripod
  • Focusing target

 

The target can be something as fancy as a LensAlign, or as simple as a book and a yardstick. All you really need is something with a high contrast, flat face you can stand parallel to the sensor plane, and something next to it that will give you a scale to provide a gauge for the plane of focus.

 

This is a LensAlign.

 

This is how you do it on the cheap.

 

Once you have your target, get your camera set up on a tripod and have it level with your target. If you’re using a LensAlign, there are holes in the front face of the target that line up with red circles on the panel behind. If you’re using the book method, try to get the book and sensor plane as parallel as you can.

 

Here's a 5D Mark III on my trusty tripod, with the image review zoomed in to check accuracy.

 

Then line up your camera, initiate AF and take a shot. Make sure you’re using the center focus point for this. Using outer points can create all sorts of problems if the lens you’re calibrating has any field curvature. I like to focus, take a shot, rotate the focus ring, refocus, take another shot, repeat a few times to gauge consistency.

 

Your test shots will look like this.

 

Zooming in to the image in camera let’s us see how accurate this lens/camera combination is.

 

Zoom way in there to really see how accurate focus is.

 

Look at that! This Canon 135mm f/2L is spot on! But they aren’t always like that. Let’s try another copy.

 

Another 135, another test shot.

 

And this one ain't doin' so good.

 

This copy is front focusing on this camera body. Look at the smaller numbers to see the difference. Should be pretty easy to adjust. First go into the adjustment menu. On Canon it’s called AF Microadjustment. On Nikon, it’s AF Fine Tune. On most other camera systems it’s called microadjustment as well. Nikon just likes to be fancy, I suppose.

 

This is what it looks like on the Canon 5D Mark III. Your mileage may vary.

 

You’ll almost always see two options, one for a default setting that affects all lenses universally, and one that’s lens specific. I don’t think I’ve ever used the default setting because every lens will be different.

 

Don't adjust everything by the same amount OR ELSE...you'll just frustrate yourself.

 

Setting the actual adjustment will look like this:

 

The little camera and mountain icons are there for easy reference.

 

If the lens is front focusing, you move the adjustment to the right, away from the camera. For back focusing you go the other way. To get this lens dialed in, I found I needed an adjustment of +9:

 

Number 9, number 9, number 9...

 

Once you’ve set it, make sure the camera shows the adjustment is turned on:

 

ON is good.

 

And here’s what it looks like after adjustment:

 

Looks great, right? Can't you see it?

 

Oh, right. Maybe this will help.

 

Now it matches the first lens! And that’s it. Once you’ve set the adjustment, you shouldn’t have to think about it again.

Is there anything else I should be aware of?

Prime lenses are generally the easiest to deal with. When it comes to zooms, you may be a little more limited. Most current Canon cameras that have the AFMA function can now adjust for both ends of the zoom, with a corresponding W and T setting. If an adjustment for each end is not available in your camera, you can either adjust for the end you use the most, or find a compromise you can live with. I’ve seen zooms where one end was fine, and the other was off, or both ends were off different amounts in the same direction, or both ends were off in different directions. There’s often no universal solution, unfortunately.

When it comes to 35mm and 50mm primes, you’ll often find that making an adjustment at shorter focus distances may cause longer distances to be off. It’s not that other lenses aren’t the same in this regard, but for some reason it seems to be more noticeable on these focal lengths. There isn’t really a good solution to this in camera, unfortunately. You’ll want to make your adjustments fit your needs, which may be difficult with some lenses. But if you have the Sigma Art series lenses and the Sigma USB Dock, you can actually adjust for both closer distances and longer distances. The dock and related software allow for four adjustments at four different distances with those Art (A1) series lenses. On Sigma A1 zooms, you can make those four distance adjustments at four different focal lengths, for a total of 16 possible adjustments! It’s time consuming, but if you want everything as spot on as possible, this is really the way to go.

The example above needed a moderate adjustment, +9. Larger adjustments aren’t indicative of something faulty, though. On very rare occasions you may find a lens is beyond adjustment. I once owned a Nikon 20 f/2.8D that was like that. I ended up selling it to someone who had zero issues with it on their camera. If you own a lens that’s beyond adjustment, you can either do what I did, or you may be able to send your lens and camera to the manufacturer to have them adjust it for you, as long as both lens and camera are from the same manufacturer. Just know that adjustment won’t be free.

Is that it?

Yep, that’s pretty much it. If you’ve never experienced front or back focus issues before, you’re either extremely lucky, or you just haven’t noticed it. It’s incredibly common, so it’s good to be aware of it. I’ve had countless discussions that started off with, “Well, none of my lenses have any problems on my camera, so your lens must be broken.” And 95% of the time the lens just needed a little AFMA to get it right in line. Whether you’ve been shooting for one year or 50 years, you will have to deal with this at some point. If you’re ever in doubt about whether you’re having focus problems or resolution problems, switch to live view and try using manual focus or AF (in live view your camera most likely reverts to contrast detection AF, which is much more accurate but slower). If your images get sharper, the lens is most likely front or back focusing on your camera. And now you know how to fix that.

The Biggest Product Announcements at CES and Their Availability for Rental

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This past week in Las Vegas, was the Consumers Electronics Show (CES), where hundreds of tech companies come and announce some of their biggest products for the upcoming year. While typically for photography and videography, National Association of Broadcasters (NAB), PhotoPlus Expo, and Photokina are the major trade shows where new products are announced, though many other products get their shining moment at CES. Among those products, is a new line of flagship cameras from Nikon, some new products shown off by DJI, and a variety of other tools to help make our lives as photographers and videographers a little bit easier. So, here I'm going to countdown the very best and biggest announcements to come out of CES this year, and when these products will be in our stock house, available for rentals.

Nikon D5 DSLR Camera System

The biggest announcement this year at CES came from Nikon with their Nikon D5 Camera. As an upgrade to their Nikon D4 and D4s, the Nikon D5 is a professional level camera system with a plethora of features many have been yearning for in a DSLR system. What features exactly? How about 4K video in a DSLR system, swappable memory card platforms (CF and XQD systems), 14 frames per second still shooting and perhaps most impressively, ISO up to 3.2 million. While 3.2 million is likely unusable for realistic work, we're excited to see what this camera can do when we get it in our hands, and we should have it available for rent in March, and are taking preorders now.

Nikon D500 DSLR Camera System

 

Hiding behind the shadow of the Nikon D5 announcement was their Nikon D500 camera system. With the same processor unit as the Nikon D5, the Nikon D500 is their new standard in their APS-C lineup. The biggest announcement with the Nikon D500 comes in their new autofocus system, which promises accurate focusing on the center point at -4EV. If this news holds true, we're likely looking at the best autofocusing camera on the market today, and an impressive system for wedding photographers working in low light and need the extra reach of a APS-C sensor. Like the Nikon D5, the Nikon D500 also comes with 4K UHD video functionality, catching the DSLR market up to the mirrorless systems that have been promoting these specs for over a year now. The Nikon D500 will be available for renting in March, and is available for preorder right now on our site.

Nikon KeyMisson 360 Action Camera

Nikon wasn't done with their announcements following the two DSLR announcements they made and shook the photography and video community up with. They also showed off something, unlike anything we've ever really seen from Nikon, with the Nikon KeyMisson 360 camera. Meant as a competitor to the popular GoPro systems, the Nikon KeyMisson shakes up the action camera market by offering 360 degrees of coverage in a single camera, allowing you to quickly and effectively create 360-degree videos in 4K and in a single camera solution. The Nikon KeyMission 360 system is also waterproof up to 100 ft, and shockproof from falls up to 6.6 ft. While other information is unknown, such as price or availability, the Nikon KeyMission looks to be an interesting competitor in a market already flooded with options. Sadly, because of the lack of information regarding price and availability, we do not have pre-order links available, but will update once that information becomes public.

Nikon SB-5000 Speedlight

Nikon didn't stop at two DSLR cameras and an action camera. They also announced the latest in their flash systems, with the Nikon SB-5000. Perhaps what makes the Nikon SB-5000 better than it's previous models comes with the power to wirelessly control the flash from nearly 100 feet away, without the need for a PocketWizard or other radio controlling system. However, the downside to that statement is that this feature is only available for the Nikon D500 and Nikon D5 systems, with the feature becoming a standard for other camera bodies in the coming years. Alongside that, comes a new cooling system to prevent overheating, and a battery life boasting 100 full power shots in standard AA batteries. This flash will be available sometime in March, but we're taking preorders on it right now.

Olympus 300mm f/4 IS PRO

Nikon wasn't the only camera company announcing big products for this upcoming year, Olympus also announced the Olympus 300mm f/4 IS Pro for their Micro 4/3rds camera system. With 6 stops of IS, and a focal length equivalent to 600mm after crop-factor, the Olympus 300mm f/4 IS Pro might be the perfect lens for those shooting sports or wildlife handheld. Olympus also promises high-quality optics, rivaling those in a much higher price point, but we'll see how it's able to perform after Roger gets his hands on it for an optics test and lens breakdown. The Olympus 300mm f/4 IS Pro is available for preorder on a first come first serve basis and expected to be available on February 28th.

Panasonic Leica 100-400mm f/4-6.3 ASPH Power OIS

Panasonic also announced their partnership with Leica to create the Panasonic Leica 100-400mm f/4-6.3 ASPH Power OIS, a powerful telephoto lens designed for the Micro 4/3rds camera systems. At 200-800mm after crop-factor, the Panasonic Leica 100-400mm f/4-6.3 ASPH Power OIS is a fast focusing lens with optics designed by Leica, which is expected to show some pretty impressive results, despite being a budget lens from the partnership (By Leica standards at least). This lens is available for preorder though an official release date is not yet available.

DJI X5 for DJI Osmo System

While we've known of this system for a while, CES was the first time the world was able to see the system mounted and ready for use. For those who are unaware, the DJI Osmo is our favorite handheld 3-axis gimbal system on the market, and the X5 camera system promises to bring better sensor quality to the device, by using a Micro 4/3rds sensor system (like those found on the Panasonic Lumix GH4). This will provide higher image and video quality, with the ability to shoot RAW stills from the handheld device. However, no word has been in place on when the mounting bracket will be available, though when they come available, we'll be making them available for you.

Oculus Rift

Alongside photography announcements, we're also excited to announce that we'll be carrying the Oculus Rift available for rental when the product becomes available. For those unaware, the Oculus Rift is a virtual reality device with an open source design, allowing for an unlimited amount of possibilities of use. You can learn more about the system on their website, and you can sign up to rent the Oculus Rift here.

 

Proper Techniques for Using Shotgun and Lavalier Microphones for Video Interviews

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The audio from an interview recording truly is the single most important piece of media you capture. Without a clean, quality recording of your interview subject’s testimonial, your story is lost. No amount of b-roll or text on screen will create the same amount of emotion, drama, or interest that a real person can create when speaking from the heart.

As beginner videographers expand their kits to include audio gear, and photographers start to transition over to the dark side (if they only knew the power, of video production), there’s a lot that needs to be learned about the gear and techniques needed to properly capture audio. Interviews and testimonials are often the backbones to many documentary and corporate video projects, so learning about audio recording is vital to a successful production.

There are three ways to capture audio in an interview setting: using an on-camera mic, clipping a lavalier (or lav) mic onto your talent, and by using a shotgun (sometimes called a boom) mic just off-camera. In the article below I’ll explain how each of these mics are different, the proper techniques for using them, and offer some suggestions on makes and models.

BTS Microphone Setup for Video

Recording Audio From an On-Camera or Built-in Source

Just about every video camera has some kind of microphone built into it, but I would never rely on it for an interview. At best, they are good for reference audio or providing some background NAT (natural sounds) as it will pick up noise from an entire set, with your interview subject sounding very distant.

Video Microphone GH4

A step up from the built-in mic is using a camera-mounted shotgun, like the Rode VideoMic Pro, which is great for DSLR shooters. For cameras with XLR inputs, shorter shotgun mics like the Rode NTG-2 or Sony MKH-60 would make a good choice. Camera-mounted options are great for run-and-gun operations where you don’t have the time to mic someone or budget to hire a boom operator. However, if you’re doing seated interviews, using a mic that is on your camera is simply not the best choice, because it’s so far away from the source of audio (your subject’s mouth, in this example). Whenever you can, you should try to get your mic as close to the source as possible for the punchiest, cleanest recording.

Using Lavalier Microphones

Lavaliers (or “lav” mics for short) are small mics that get clipped onto your subject’s clothes; usually onto the edge of a jacket or between buttons on a button-up shirt. They are easy to set up, and will capture very usable audio when placed about six to eight inches from the talent’s mouth. This is how I mic 90% of the interviews I shoot.

Clipping a Lavalier Microphone

Lav mics might not provide as much tonal range as a similarly priced shotgun mic, but their convenience makes them an industry standard for interview video shoots.

Recording the signal from a lavalier microphone can happen in one of three ways.

Wireless Lav Mic Setup

1. Wireless Transmitters and Receivers
Wireless packs are the most common method of capturing the audio from interviews. The lavalier plugs into a belt pack transmitter, which sends a wireless signal to a receiver that plugs into an audio input on either your camera or audio recorder like the Zoom H4n. Wireless packs are great for convenience, but be careful to use only batteries that are at full strength and select frequencies that are clear of noise and signal interruptions. The Sennheiser G3 series are the standard for most crews I’ve worked with, and I myself have owned the older model of these for years.

2. Wired Directly into the Camera
Wired lavs like the Shure SM93 will plug directly into your camera’s XLR port, and can offer a cheaper alternative to using the wireless method described above. If you’re in an area where there is a lot of radio signal traffic, this might be a safe choice to avoid unwanted dropouts.

Zoom Microphone Setup

3. Plug into a Stand-Alone Recorder
If you don’t mind syncing up your audio in the edit, using a “second system sound” is an easy, albeit sometimes risky, way to record your audio. I like to use a Zoom H1, as it’s incredibly small and very simple to use. You plug your lav directly into it, set the levels, hit record, and it will follow your subject wherever they go.

iPhone Rode Lav Setup

A newer, perhaps cheaper option for some, is to use smartphones. The Rode SmartLav+ is specifically sold for this purpose, as it works (and only works) with a smart phone jack, and can be controlled by an app.

The downside of stand-alone recorders is that you aren’t able to actively monitor the signals during the recording. This means that if the battery dies, the mic clip moves or something else happens to ruin the audio, you might not realize it until you’re back at home editing!

Lavalier Models

Most wireless kits will come with a basic lavalier microphone. This will get you an OK recording, but upgrading from a kit model to something like a Countryman B6 or a Sennheiser ME-2 will give you a bump in sound quality.

Lav Mic Placement

 

Techniques for Clipping a Lavalier Microphone

In most interview settings, it’s completely acceptable to see the actual microphone itself, but you should try and “dress” the mic to make it look presentable. This often means hiding the cable inside the subject’s shirt, and making a loop in the cable just below the capsule. The loop actually serves two purposes; it makes the mic placement look neat, and it also creates a small amount of slack in the cable, which will help eliminate contact noise if the mic cable is accidentally pulled or rubbed.

Making the loop is simple to understand, but can be tricky to master, especially when you are in someone’s personal space. First, let your subject know if they need to run the mic up their shirt or not, and be professional about it. Hand them the mic, and ask them to pull out about three to four inches from the top of their shirt or between a pair of buttons. Once they have, take the capsule and use your clip to affix it to an appropriate place, about six to eight inches from their mouth.

Lav Mic Loop SequenceLa Mic Loop Sequence

Open the clip back up, and run the cable back through it in a “U” shape. On the backside of the clip, create a much smaller, upside-down “U” by catching the returning cable into the end of the clip. Use some double-sided spike tape as needed to keep it seated and in place. It can help to practice on a friend, so don’t be discouraged if you don’t get it right the first time. Try to keep the mic pointed in the direction of the talent’s mouth, and keep it clear from rubbing on their clothes or hair.

Using Shotgun Microphones

Shotgun mics, or “boom” mics, as they are called when mounted onto the end of a boom pole, are rod-shaped microphones that are great for capturing interview audio. Shotgun mics are directional, meaning they capture more sound from what they point at, and less from the sides. This is a very general explanation of this style of microphone, as not every shotgun mic is created equal. They can have different pickup patterns from one mic to the next, which is worth looking into before selecting the proper mic.

Shotcun Mic Placement

For controlled interviews, a cardioid or super/hyper cardioid style of a microphone is typically used. The Rode NTG2, Rode NTG4+, Sennheiser MKH-416 and Sennheiser MKE 60, are all solid choices for a quality shotgun mic for interviews.

Shotgun Mix Sennheiser MKH416 Placement

No matter if your interview is a seated one, or captured handheld while on the street, the most important thing to do is to get the mic as close as possible, without it entering your frame. The closer the mic is, the stronger the speaker’s signal will be, which means you’ll get significantly less background noise.

I prefer using a C-stand with an Auray pole holder to sit my K-Tek boom pole in, and positioning it just outside of the upper part of my frame, with the mic pointed directly at the space in front of my subject’s mouth. This will get a great sound, and can be a bit less intrusive to the subject than having to clip a mic onto their clothes.

Boompole Set Up

A Few More Things to Know

Use both shotgun and lavs for your interviews! Best case is you can pick (in the edit) whichever mic sounds better, or if you get signal loss/interference on one mic, you can pick the other without having lost the clip. Building in redundancy is smart if you have an important interview.

If you’re working outside, get “dead cats” for your mics to help eliminate wind noise. They work wonders, and you can get them for both lavs and shotguns.

Pickup patterns are different for each mic, but generally come in one of four patterns: omni, cardioid, hyper cardioid, and shotgun. Don’t get confused by the “shotgun” pickup pattern, as not all shotgun mics have the shotgun pattern.

Also, make sure you invest in a decent set of headphones. In a pinch, you can use earbuds, but a quality pair of studio-grade headphones are well worth the price to monitor your audio, which after all, is the most important piece of your interview shoot.

 

Mike Wilkinson

Guest Contributor

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