FS7: FS7 vs. EX3: Light Sensitivity Question

basspig

basspig

Veteran
Specs are very confusing, given different measuring sticks from one camera to another.

This web site http://www.radiantimages.com/cameras/hd-beyond/sony/296-sony-ex3 claims that the EX3 is ISO 2000. The FS7 claims to be ISO 2000 also. The EX3's stock lens is an F1.9, while the bundled lens with the FS7 is F4.

More confusing is another source quoting the EX3 sensitivity as F10 2000 lux, while the FS7 is T14 at 2000 lux.

'T' or 'F', apples or oranges? So do we need more light to produce the same image brightness with the FS7's bundled lens of F4, over the EX3's F 1.9 lens, or are some of the reported specs in error? I realize that the more pixels you cram onto a sensor, the less light sensitivity you end up with. Just trying to figure out if this will be a problem.

The other night, I filmed a chamber orchestra performing in a church venue, and the lighting was not as bright as a stage performance, hence I was running f 1.9 at 24fps with shutter off. Normally I have 180 degree shutter for stage performances and F 2-2.4, but this was a rather dim venue. Given the extreme cost of an F 1.9 zoom lens for the FS7 (not that one even exists!!), I may have to live with an F4 lens for quite a while.

So how do the relative light sensitivities of the two cameras stack up?
 
That's actually a more complicated question than it seems at first. It really depends on how you are shooting the FS7.
If you're in CINE EI shooting Slog3 then it is nominally 2000 ISO though many people find it noisy at that level and shoot it at lower ISO's However that's because noise reduction is off in CINE EI and you could shoot at 2000 and add noise reduction later. I'm not sure how that stacks up against the EX-3 . However if you shooting Custom , there is noise reduction , and gain can be applied much more liberally to the image. In this case i've found the camera to be very quiet so I generally wouldn't hesitate to shoot at 12DB. Don't remember what the ISO is, but its way faster than an EX-3. You will find that various gammas will change your ISO level so i would just test it out with your preferred looks.

A lot of people will go to Custom for low light shoots.
 
Some non science.

I did some unlit night INT BTS with my EX1 last year at 18db - Totally noisy.
I would expect a lot less noise with my FS7 and a 2.8 lens.

Some psudo science.
EX3 is 1/3 chip (or three?) of 2007 tech colleting photons.. very unlikely to compete with a 2011 chip of S35 real estate?

S
 
Bit of an odd ball off topic question here.... but as it is kinda relevant, how does the Sony PXW-X70 (and CX900 / AX1000) compare in low light vs EX1R / EX3?
 
Andrew Stone said:
On Cine 4 the EX3 is 320 to 400 ISO. You can pull an extra stop by shooting in 720.
Click to expand...


That sounds about right, based on my own intuition, but having read reviews putting at anywhere from 800-2000 ISO, I didn't know what to believe. If that's the case, then the F4 lens of the FS7 package would still be a sliver ahead of the EX3 with its F1.9 lens.

Yeah, S-log is a complication to these calculations. I find the EX3 noise levels to be acceptable at -3dB gain, so that is where I run it all the time. I did tests with encoding to DVD MPEG2 and watched the bitrate ramp up to double when the gain was set to 0dB and the iris was closed down a bit to compensate. Since I add lots of sharpening to my videos, it makes sense that the noise needs to be vanishingly low.

One of the demos of the FS7 at a press conference was notably impressive. The operator shot into the darkened spectator area and cranked the ISO to 6400, making it appear full daylight, but there wasn't any visible noise. That impressed me.

Okay, so the FS7 is roughly 2.2 f-stops faster than EX1, assuming both have equal lens speeds.
 
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