OM System LS-P5

​1.1. Connecting to a Camera

The LS-P5 can be used as a separate recorder as well as an external microphone. For this you may want to consider a shock mount, like the Movo SMM5-B[c] to minimize handling noise from the camera. The OM System tutorial[d] skips over a few things, though. First, to actually get any sound going from the LS-P5 to your camera, you need to press the recording button. Second, since you are sending the headphone output from the LS-P5 to the microphone in connection on the camera, you need to set the microphone recording level on the camera and the headphone volume on the LS-P5. For this I recorded a test tone and then just clicked around until the VU meters on the camera and the LS-P5 looked about the same, and found that setting microphone sensitivity to 15 or auto on a Nikon D3200 and a Nikon D600 corresponded to a headphone volume of 03. Sensitivity 10 had a matching headphone volume of 07. Your mileage may vary, so do run a sound check on your own camera, and I'd treat the camera recording as a backup the way the tutorial recommends. For a recorder that is intended for and marketed for use as an external microphone, it's an omission that there isn't a button to automatically set the headphone output level to mic level; especially as too high an output can actually damage the camera.

​4.1. Recording Levels

With digital cameras you can control the amount of gain using the ISO setting, and basically higher ISO means brighter image. However, you also amplify the noise to a varying degree, with lower ISO gains amplifying the noise a little, and higher ISO values more. In almost all modern cameras there is a point at which your camera turns "ISO-less" - when increasing the gain amplifies the noise as much as it amplifies the image. At this point, you are better off brightening the image in post-processing.

For the LS-P5 I wanted to know what the signal to noise ratio was as I turned up the recording level. If I wanted to record a faint sound outdoors, would I be better off keeping the rec level low and turning the volume up in post, or should I crank the rec level up as far as it would go? Or something in-between?

This is not a pro-level experiment. I recorded silence by wrapping the recorder in a blanket and putting it in the quietest room in the apartment. It was far from silent - I could see my steps on the VU meter when I walked away from the bundle - but just like measuring the sharpness of a camera and lens combo it gets you a rough idea of how things work. I then compared the silence with a recording of a 440 Hz tone obtained by shoving the LS-P5 into a set of headphones, by using Audacity[f] to measure the RMS dBFS for the recordings. Note that this is not a measurement of the noise floor or dynamic range of the recorder - it is strictly a test of how the recorder behaves as the recording level is changed. These measurements are only valid when compared to each other.

I interpret the above as the recording quality being pretty much flat as long as you get it above the noise floor, and that over rec level 30 there's an amplification that actually reduces the SNR.

​4.2. Pickup Pattern

The Tresmic II microphone system has a directional zoom feature that lets you change the width of the field in 21 steps, with zero being the widest and 20 being the narrowest. This is done by mixing the signal from the center capsule with the signals from the two side capsules. Since I couldn't find any actual measurements of the pattern I did a quick test on my desk with a 440 Hz test tone. Again, this is a quick test to get an idea of what is going on, not a professional in-depth look at the characteristics of the Tresmic II system.