Audio noise of the cameras

[Patrick Tresch]

Hello

Not a scientific test but just to get some notions of the fan noise of different cameras.

Test performed with the F65, Epic, Alexa (ProRes mode) and Aaton Delta

The sound level meter was set to 30cm of the film plane pointed to the lens.

The acousitic minimum of the setting (sound level meter and room) was at 27.7 dB. (there fore not very scientific).

There was mainly two camera position mesured :

- front toward the optic

- and we turned the camera 90 degrees to get the mesurement of the side of the camera (where the wents are often located).

It's written in french, if you need any translation tell me.

See you.

Pat

[JesseF]

Gotta love the Alexa .

[Patrick Tresch]

The Alexa is not noise less. It performs slightly better (less than 0.2 dB) than the Epic set @ 25% fanspeed.

The Alexa test was setup with the "shitty" Prores recorder mode... (Ok for TV/series but a no go for big screen movies IMHO). They didn't have the Raw recorder on set so I couldn't test it.

The best performer was the Aaton. But it looks like the camera heats up a bit more when in record mode. Didn't test it in record mode as we didn't have the Delta Pack (it was off loading @ the DIT station). But the camera is impressively quiet in Stby mode.

The F65 is the big looser of this test. Turn the mecanical shutter off to get better performance.

Pat

[Patrick Tresch]

Easy rool of thumb:

If you set the fan speed of the Epic at the dB level of the room, you won t hear it.

Pat

[tourtelot]

Easy rool of thumb:

If you set the fan speed of the Epic at the dB level of the room, you won t hear it.

Pat

Not true of course. Inverse square law says that the closer you come to the noise source, the louder it will be. Mics are more often than not close to the camera.

D.

[LarryF]

The difference between the room noise and the camera noise at 25% is too small to make any meaningful comparisons. If the camera noise were equal to the room noise (27.7 dB) the sum would be 30.7 dB. The fact that the room plus camera noise is below this value says that at the 30 cm distance , the camera is quieter than the room. The noise measurements of 35 dB and up are meaningful.

Also, no one should give any credence to noise differences of 0.2 dB. That measurement is literally down in the noise.

One thing not mentioned here is that a whine is very discernible at levels far below random noise levels. Specifically, a whine at 50 dB can easily be heard below white (random) noise of 60 or 70 dB. If these cameras whine (fan), they will be very audible above room noise even if they measure at the same or lower levels. Mid pitched noises (fans) will also be heard above low frequency (room rumble) noise of the same level or higher level. (Not trying to tell sound guys the facts of life here, by the way.)

Best Regards,

Larry Fisher

Lectrosonics

[Patrick Tresch]

Well, I'm not a sound guy and you are surely all better qualified as I am.

I was just comparing Epic fan speed in % (indecated by RED) with the sound level I could hear in the speaker box. Not very scientific for the least.

I just wanted to hear and measure the different noises of the cameras. As there are a lot of speculations in this particular field.

I conducted my tests as a DP to be able to talk about the audio camera noise. To have a slight clue even if not THE definitve one.

Now I'm curious to hear from your tests. I'm sure you'll conduct them with all due attention as you have more sound knowledge as I have.

Best Regards,

Pat

[David Waelder]

There is a smart phone app called "dB Meter Pro" that can give you a read-out in decibels of whatever sound is in the immediate vicinity of your phone. It's available for iphone.

There's also a version for Android that looks like the same application (graphics are very similar but layout a bit different):

https://play.google.com/store/apps/details?id=kr.sira.sound&hl=en

I think the results are reasonably accurate - always keeping in mind that this is a phone app and not a calibrated professional instrument. In any event, measurements made of different cameras are likely to yield comparatively useful information if you take care to conduct the tests carefully. Make sure that the environment is the same and use a measured distance between the lens and the phone. Traditionally noise measurements are made at a distance of one meter from the front of the lens. Ideally, the cameras would have similar lenses mounted. If the meter is insufficiently sensitive, or your test area is not an anechoic chamber, you might need to make the measurement at a closer distance to get meaningful data.

If you have access to the cameras, it's probably easier for you to purchase the app than for one of us to secure the cameras. I think the app from Apple is only $0.99.

David

[Marc Wielage]

Yes, another vote for dB Meter Pro:

The guys over on GearSlutz have compared it to the $50 Radio Shack meter and said it's within a couple of dB in terms of accuracy. Certainly close enough for jazz.