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Monday, March 29, 2010

••◊ 5D audio made simple...or is it?

Some of the major complaints I hear from "traditionalist" videographers is the form factor of the 5D mark II (or any DSLR really). They just can't wrap their heads around the lack of immediately available controls and no real world audio inputs. OK, so they have a point that the form factor is less than ideal but not totally unworkable. With the new 5D firmware upgrade that allows for manual audio levels I decided to try to use in camera audio with my lavs; which highlighted the audio input issue previously mentioned. ...the solution? ...a trip to Radio Shack for some common components.

A picture of the resulting home brew project is below along with the simple to build schematic. Nothing special right? The schematic is fairly dead brain simple and it's not like I needed XLR inputs or anything fancy for lavs. Anybody can figure this out and build it. So why blog about it? Well, this wasn't the difficult part.

The real issue to discuss here is gain structure; the arch nemesis of any audio engineer. Really you have three points of audio amplification when using a lavaliere microphone. There's amplification at the transmitter where the mic plugs in, amplification at the receiver, and amplification in the camera. At any point in the chain the audio signal can clip and you won't know where the distortion is coming from without a full triage.

I put on my scientific thinking cap and came up with the following scheme. I wanted to take 2/3rd's of the gain structure out of the equation at any one time because fiddling with buttons in the middle of the shoot doesn't give anyone a warm-fuzzy. Here's what I did...

First I determined that if the lav transmitter and the camera distort at the exact same time, then effectively that removes the lav receiver and camera as a source of distortion in the first round of triage. So how did I determine the correct gain levels for each device? I simply moved the lav microphone closer and closer to a speaker playing a 1kHz tone (earplugs highly recommended) until the lav transmitter lit up an LED showing distortion. At the same I was recording the output of the lav receiver into the camera. After importing the recorded sound into Adobe Soundbooth I could visually see when the distortion occurred (see pictures below). If the distortion appeared before the signal was clipped at 0dB, then I knew that the amplifier gain was too low in the lav receiver or camera (precedence given to the receiver, then camera). If the signal was clipped at 0dB before I saw any pre-distortion from the transmitter then I knew the gain was too high from the receiver or camera. When the transmitter and camera audio distorted at the exact same time then I knew I had the gains set correctly. The theory being if the camera was distorting at 0dB, then the lav mic transmitter was also distorting. Gain from the transmitter was arbitrary, as long as it allowed signal clipping to occur.

Camera gain too low. Receiver gain=-12dB, camera=4 clicks above mute. Note how the audio clips before the camera distorts.

Just what we want. The lav audio distorts at exactly the same time as the camera. Receiver gain=-12dB, camera=5 clicks above mute.

Too much camera gain. The camera is clipping the audio before the lav distorts. Receiver gain=-12dB, camera=6 clicks above mute.

Yeah, yeah, yeah...so what do I set the gains to, right? Well, this only works for the G3 lav system into the 5D. The process is same for other audio inputs devices as well. My gains were set as follows: receiver=-12dB, camera=5th step (counting up from mute).

Now this is just a starting point. If I start here and don't see enough audio signal the first thing I do is turn up the lav transmitter. If that's not enough then I turn up the lav receiver. ...and as a last resort I turn up the in camera amplification. Simple troubleshooting, yes? Now, if the opposite is true and you have a distorting signal then the only thing you need to do is turn down the lav transmitter - in fact that's all you can do to keep from distorting since the lav and camera signals look exactly the same time in this configuration.

So how did my interview lav audio sound? Excellent in my opinion. I'm editing it into interviews right now.

Wednesday, March 24, 2010

••◊ Waz up grrrrrrl?

Last Saturday I spent the day interviewing a group of bgirls in Hollywood. No, you haven't experienced Internet induced time travel back to 1982. Break dancing, you ask?... Well these girls would be quick to correct you that the dance style is actually called "b-boying" and is very much alive.

Photo Credit: Clarence Legaspi

Lead instigator in this group is Amy "Catfox" Campion, who runs a dance troupe called Antics Performance in L.A. She brought in "Peppa the Host Steppa", "Asia-1", "Chronic", and "L-boogie." for the shoot. Clarence assisted and did b-cam work with his K-7, which we quickly found out has major jello-cam issues (i.e. rolling shutter). Clarence was shooting at 300mm and this was his first shoot, so he didn't know to lock the tripod head down during the interview. We were sitting in a local tea shop the next day reviewing the footage and all we could both do is shake our heads and laugh. Clarence...lock down that wobbling camera! - as we both laugh on. Oh boy. I was manning my own camera and didn't have time to review the footage on set...however we did get a few seconds of usable footage from the K-7 that will go into the edit.

This shoot gave me a chance to check out the new manual audio controls and 24p firmware for the 5Dm2. I gotta say that the audio control is a blessing. This is the first time I've captured 5D audio and found the results desirable. The downside is that the audio meters aren't available in record mode (major mis-oversight on Canon's part). My audio interface box will be a topic for an upcoming post. 24p is still up for discussion. I found that it really didn't make much difference for this production. 30p would probably have worked just as well.

This also allowed me to use my newly procured Marshall field monitor, which I quickly learned not to trust alone for exposure. I really need to combine that with a 18% gray card. The Marshall has a "false color" filter that acts like a colored IRE meter to quickly set exposure. Unfortunately I trusted the documentation...which got me semi- close, but tended to over exposure the image a little. Nothing I can't fix in post. However it's going to take a little more work to establish a better way to set exposure.

We used the Mole-Richardson FAY lights bare, mostly because we didn't have the budget for good powerful HMI lights. The FAY's aren't really daylight balanced, but much, much better than tungsten. Probably in the 4500-5000K range. So the view out the balcony windows is a little more blue than it should be. Not completely bad, but not completely good either. The lighting was also a bit flat since we didn't have the power to use light shapers like a soft box or reflector card. That's my biggest concern going into post.

Photos from the shoot can be found on Clarence's flickr page (aka Lumpyfree1001).

My next two weeks... transcribing footage, writing the storyline, editing, mastering... augh. The idea is that this will be a 3-5 minute extra on Amy's instructional DVD titled "How to Bgirl." Three hours of footage for a 3 minute video. Yep, seems about right.

Thursday, March 18, 2010

••◊ sharpness, contrast, saturation,...rinse, lather, repeat.

Last night I made another visit to a class taught to my colleague, Oreste, at the UCSD extension campus. This time he was teaching an intro to printing course, for which I'm not an expert. Being part of the digerati, I've kind of given up on printing photos except for my own fine art collection. However, working for a printing company I was bound to pick up more than a few pieces of useful information about print quality and image reproduction issues.

Like last time, I had to come up with a class picture. This concept came to me because I have my brain inundated with hip-hop at the moment. Yep, wide angle, not quite fish eye lens, top lighting. Notice the "UC" gang sign for his printing posse - the CMYK's of room 134. Vignetting and color adjusted in post. Now...about Oreste's look. I told him to give me gangsta. He gave me more of a "Weird" Al Yankovic Cuban gangsta. Sorry Oreste, you don't have a future in male modelling.

So...print quality. It really comes down to three things once all the obvious image flaws are taken care of. 1. Sharpness - your eyes are drawn to whatever is sharp. 2. Contrast - Don't blow the highlight or kill shadow detail. 3. Saturation - Even Tim Burton refrains from pure candy colors. I often had to bring the students back to these three topics because just like most photogs, including me, our first inclination is to look at the composition. That's a different class.

Off to a hip hop dance shoot tomorrow. Hells yeah baby.

Saturday, March 13, 2010

••◊ Lumpy and Renata

Just got back from a shoot with Renata Damone and Clarence Legaspi (aka Lumpy on flickr). I was there mainly to get some practice with the Steadicam Merlin for next weekend's shoot. Toward the end I gave in and took some quick pics and thought I would toss these up on my blog to share. No special purpose for the pictures, just fun.

••◊ What you don't show.

Last week I found a little insight from cinematographer and author Stu Maschwitz over at his Prolost blog. He was giving a interview and talking about the need for 24p for movies. At first I was like, uh huh, everybody says that. Then he actually gave a good reason why. Cinematography is about what you don't show, or more exactly what you choose to selectively show. 30p gives a very real look to footage. 24p shows less and takes you away from the real look and puts you into a movie. I guess I never thought about it that way before.

His interview is here. Only a couple minutes long, but worth a gander.

Friday, March 12, 2010

••◊ Captain Stubing

Shane Hurlbut has coined the term "man-cam" to describe the apparatus you see me holding. Somehow that nickname seems to be holding in the film community. As you can see, yes, I've been at it in the machine shop again with scrap bin aluminum.

Redrock Micro has a similar camera rig that they call "Captain Stubling." I always mispronounce it as Captain Stubing (as in the Love Boat Captain). So I'm just going to call my configuration Captain Stubing. This camera rig is great when you need to get into tight places quickly and don't mind a little shaky cam, like fast action shots. It's more of a speed boat than a cruise liner like a Steadicam.

The cost? Well, the bicycle grips were about $11 at my local bike shop. They definitely say "welcome aboard" to my hands. Nice and comfy. I already had the D-focus follow focus unit. So all it really cost was my labor - making the unit priceless, of course (ah-hem). Other parts, such as the camera mount and rails were made during an earlier project so I consider them virtually free now.

Below are some pictures of the setup on a tripod. Obviously the tripod mount isn't necessary for the configuration, but I needed to stick the unit on a tripod to take pictures. I only own one camera and couldn't find one to borrow this week. Yes, this is nothing like the Viewfactor rig from my previous post, but nothing is really like that bad boy - including the price tag.

The design can use a little refinement, however it's totally usable right now and that's what really matters. Perhaps I'll start the shoulder rig next. Dunno.

This is your captain speaking. You are now free to cruise about the filming set.

Saturday, March 6, 2010

••◊ Random stuff from Washington DC

This week I just have random stuff to tell you about from my recent visit to the NASA Centennial Challenges awards in Washington DC. After rushing to build my rails and camera mount just a couple days before the trip I decided to take it with me - with the biggest concern being the TSA scratching their heads at it and deciding it was a pseudo-random security risk, while confiscating my hard work and slapping newly fitted rubber gloves against their wrists. Turns out...no problem. You never know. I had a security person in Pisa stop me because he thought my lightweight carbon fiber tripod was some kind of threat.

So, below is proof that the system made it there and filmed the awards ceremony. When am I going to get around to editing it? Dunno. Have too many projects going on as is. I haven't even had time to edit my photos yet. Nick Burrows, one of the Lasermotive team, took the picture on his iPhone so you'll have to forgive the quality.

Another random place I stopped was the Smithsonian Air and Space Museum. I was walking back from the Library of Congress when I happened upon the building and decided to pop in for a look. Unfortunately at this time my feet were barking at me like one of Micheal Vick's pit bulls so whatever I saw had to be quick. In a dark corner of one of the exhibition halls they had a case of NASA historical cameras and thought it would tie in with both the events earlier in the day and this blog in general. I left the image size big, so click on the picture to read the placards. Some of the highlights are Neil Armstrong's Hasselblad film magazine, one of the Apollo 11 Hasselblad cameras with a 70mm lens, a modified 16mm camera to capture Apollo 11, the first RCA television camera sent into space, and the Apollo 11 light meter! Yes, this is ancient in terms of technology, but this was the camera equipment that captured those iconic images of man landing on the moon - on giant leap...and all that!

Tomorrow I'm off to scout a location for a shoot in LA. In happenstance, Philip Bloom is in town and called for a meet up of all those interested in 5D cinematography. I'm going. Should be cool.