Does the Sony F3 Have 5X the Light Gathering Ability of the RED EPIC?
I'm working on an in-depth post comparing the Sony F3 with RED's forthcoming EPIC-S. While the F3 is shipping in limited quantities and the EPIC-S has only been announced, it's possible to compare the two because the EPIC-S shares its sensor with the just-shipping (and significantly more expensive) EPIC-M. In putting together the post, there's one section that I'm not sure of: the pixel pitch of each camera's sensor. Anyone out there want to help me with my math?
UPDATE: see some of the comments below, but it's being reported that the F3 in fact has a 3.4-3.6 megapixel sensor. And from further reading it seems engineers find that, while very small pixel pitches bring with them increased noise, once you reach a reasonable size -- 4-6 microns -- the benefits of larger pixel pitches in terms of noise are reduced. Thanks for the comments -- that's exactly the kind of info I was trying to suss out.
Everyone loves to argue about 4K versus 1080p, and the argument usually centers on whether 1080p is "good enough." I happen to think the answer -- for the next several years at least -- is yes. All things being equal, would I rather have a 4K instead of a 1.9K image? Of course. But all things are not equal, and there are a hundreds of other considerations besides resolution. In fact, there are some situations where 1080p has advantages. For the same reason the megapixel war is waning, there's a downside to packing more pixels into the same-sized sensor: less light sensitivity. And while the consumer megapixel war was always foolish simply because the sensors were so small -- normally in the neighborhood of 1/3" -- the same formula applies to large-sensor cameras. The smaller the pixel pitch, the less light a sensor can gather.
Before we go any further, a disclaimer: I'm sure some RED fans are going to hate all over this post, but I have nothing vested in either company: I'm equally interested in both cameras. I have posted a lot about RED, and I have posted a lot about Sony. If these two cameras were made by Kraft Foods and Yokohama Tires, I'd be writing the same thing. The point of this post is for me to throw some numbers out there and see if the math is right.
No matter how good RED's technicians are -- and RED's Graeme Nattress is a software engineer of the highest order, whose new noise reduction algorithm is apparently something to behold -- the RED is at a physical disadvantage compared to the F3 when it comes to low-light shooting. Why? Thanks to its large sensor and two MP (megapixel) sensor, the F3 is blessed with a pixel pitch that makes it optimal for sucking the most light out of a scene. Four times more than a Canon 5D, by some calculations. This got me to thinking: how much better in low light should the F3 be than the EPIC, simply from a mathematical standpoint?
The F3 has a 2 MP sensor; the EPIC-S has a 14 MP sensor. From a resolution standpoint, the EPIC-S owns the F3. But the larger a pixel is, the more light it can gather. Let's run our own calculation of pixel pitch:
- With a sensor size of 23.6 X 13.3 mm and a resolution of 1920x1080, the F3 has a pixel pitch of 12 microns.
- With a sensor size of 27.7mm x 14.6mm and a resolution of 5120 x 2700, the EPIC-S, EPIC-X, and EPIC-M have a pixel pitch of 5 microns.
When it comes to pixel pitch, bigger is better. Think of the pixels as if they were buckets, and light as if it were rain. If you've got larger buckets (pixels), you'll catch more rain (light). As such, the Sony has more than double the light gathering capability of the EPIC, right? 12 microns verses 5 microns? Actually, I think -- and here's where my math fails me -- that it should be five times as much. This is because pixel pitch is only a measurement of the width of pixels, and we're talking about pixels arranged in a two-dimensional grid -- buckets that are lined up in vertical as well as horizontal rows. The pixel pitch measurement is consistent for the vertical dimension of each sensor -- we're talking about sensors of the same aspect ratio -- so for two dimensions, we'd be talking about double the 2.4X ratio that is 12 microns to 5 microns, which would mean the Sony has pixels 4.8X the size of the RED's pixels. I ran the math a few different ways and always ended up in the ballpark of a factor of five, but given I'm a writer/director/shooter/blogger and not a camera engineer, please feel free to tell me I'm terribly wrong.
Of course, this is all just math. There's more to "light gathering ability" than the size of the pixels, but it is a primary consideration, and in my mind this is nothing to sneeze at. Still, the proof's in the pudding, right? While I'd mentioned previously that the F3 was reportedly terrific in low light, here's a video shot on the F3 solely with candles as lighting, at ISO 6400 (yes, 6400!):
Very, very impressive. I could do without some of the banding seen on her arm at 0:30 -- in fact, the camera's rolling-off of highlights (or lack thereof) is one of my early concerns -- but the camera's low-light capability, both mathematically and practically, is damn impressive so far.
So, about that math -- I know images much better than I know numbers, so please correct me if I'm wrong...