Howcome Red/Arri being with small sensor look so good in low light ?

[Blaise Douros]

The answer is dead simple: noise doesn’t depend on sensor size. Noise depends on noise-reduction algorithms and the camera’s overall high-ISO performance. So some cameras are better at it, and some are worse.

[Soumendra Jena]

Of course sensor sensitivity is different topic.

My understanding is higher the ISO< more noise you are going to get.
And since Super 35 is much smaller than full frame, means it doesn’t get enough light like FF sensor, so to compensate you have to bump up your ISO and that eventually gets more noise.

So do you mean, RED/ARRI super 35 sensors will see better and sensitive to ISO better than a full frame sony a7s2 keeping the lights same ?

[Todd Terry]

“Full frame” has nothing to do with it.

I always laugh at the “full frame” fanatics, anyway. “Full frame” means the frame size is the same size as a frame of film shot with a 35mm still camera… where the film traveled horizontally, so the frames were bigger than a motion picture film frame, where the film travels vertically. I think most will agree that the S35mm frame is the standard for cine work. That’s all that means… it has nothing to do with noise.

It has to do with the sensor itself, not the size. And all are not created equally. You have to remember that the sensor alone in an Arri Alexa is probably 10 times as costly as the entire a7s2 camera, if not more.

Comparing those two cameras is apples and oranges. A decent but pretty inexpensive consumer-grade apple, compared to a pretty darn expensive and very very high-end uber-professional orange.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com

[Soumendra Jena]

Ok that answers it.
Thanks.

I just wanted to understand that.

[Blaise Douros]

This is such a big topic, and requires so much background knowledge, that I pretty much have to tell you that you need to go research the history of film sizes, sensor technology, noise reduction, codecs, and processing for a while before we can even begin to have an intelligent discussion on it.

For example: the a7sII has such a great reputation for low-light performance because it processes the video like crazy, and uses slightly different back-illuminated sensor technology than RED and ARRI. So while RED and ARRI may not get super clean video at super-high ISOs, they will get much BETTER results at normal ISOs, and really, the a7sII is just applying tons of noise reduction at high ISOs anyway, which doesn’t depend on sensor size, plus the codecs capture differing levels of detail, so you could argue that there is room in RED and ARRI footage for post-processing of low-light footage that the Sony doesn’t offer, and…and…and…

You see what I mean. There’s a lot to learn, and nobody here realistically has the time to take you through the (quite extensive) amount of knowledge that it will take for you to understand all the whys behind the answer to your question. So for now, you’ll need to accept the short answer, which is that low-light performance does not depend on sensor size.

[Todd Terry]

Ok, this is not totally related (although somewhat), but I was just in a non-COW forum where someone there didn’t have a good grasp on what “full frame” actually means, and why it may or may not necessarily be a good thing. Again, this has nothing to do with noise… but rather frame size.

They were also disparaging on anything less than “full frame” cameras, such as the various flavors of APS-sized sensors.

So… I took a bit of my very valuable time (actually a little bored today) to make this diagram for them, drawing it out with my bare hand like an animal, and I’ll share it here too.

Some people can’t grasp why “full frame” is not the same as Super35mm. That is because, obviously, a still film camera runs the film horizontally whereas a cine camera runs it vertically. Yes, that Pentax K1000 you shot yearbook candids in high school shoots a bigger frame than a Panavision Gold GII.

Secondly, there’s no call to be wary of some of those other sensor formats because they are not “full frame.” They are still big. The Canon APS-H sensor is actually bigger than an S35mm frame, and the Nikon and Sony APS-C sensors are almost as big… they are perfectly adequate for almost any job, size-wise (and there are actually two sizes of APS-C, the Canon version is slightly different than the others. Obviously Micro Four-Thirds is a fair bit smaller, but even that is still bigger than a 16mm film frame.

Also, old school film guys like me don’t want to shoot “full frame” because that’s not what we are used to, and have completely different fields of view than S35mm. If I put my eye to the viewfinder of any S35mm camera in the world I know exactly what a 50mm lens will look like, what an 85mm will look like… and so on. If I’m using a “full frame” camera, the FOV is completely different. If I were a still photographer by trade and had been doing 35mm-format portraits for the last 30 years instead of cine work, it wouldn’t bother me… but that’s not the world I come from.

Just getting all that off my chest.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com

[Rick Wise]

And a might good chest it is, Todd.

(Sent from my new home in tiny Amador City, Ca, where two cars on the road at the same time is a traffic jam, and we count up to 186 good souls, excluding dogs, cats, chickens, wild turkeys, and deer.)

Rick Wise
Cinematographer
MFA/BFA Lighting and Camera Instructor Academy of Art University
San Francisco Bay Area
https://www.RickWiseDP.com

[Mark Thompson]

I thought I would chip in and add to the confusion ☺

I believe the main factor is the size of the photosite, the bigger they are the more photons they can collect. That gives the best chance of lower noise when when that photosite is read. So in theory a Full Frame sensor should do better than S35. Of course all the other things that affect photon count come into play, for example shutter angle and of course the lens you put on. You are more likely to put an expensive prime lens on an ARRI.
Full Frame sensors often have more photosites, so the photosites are not necessarily bigger.
I think ISO is just a courtesy to the film guys, that circuit is really just an amplifier. So if you have a noisy chip the amplifier will increase the noise along with the picture.

Noise reduction is just remediation for the noise. It may work well, or it may not. Look at the instructions for Neat. They sometimes help but sometimes do not.
Some manufacturers are putting electronics next to the photosites. That can reduce the noise upon readout (Sony). RED use a different way of encoding the picture (Wavelet compression).
There is also “native iso”, a setting that gives the camera the best performance at that gain/iso.

The best approach is to do a camera test with the rig you intend to use.