johnnycamra Loc: Hackettstown, NJ

I was wondering what causes noise with higher iso levels and with today's technology why can't someone make a camera that can produce photos without noise at any iso level? Just like cd's did for lp's. Maybe that is something that will happen in the future? Thanks.

tdekany Loc: Oregon

What iso do you normally shoot at?

But to answer your question directly, google the Sony A7sII. King of high iso.

BebuLamar

The noise is always there even with CD and digital audio but it's very low to be noticeable. Today sensor has very low noise that is virtually not visible at base ISO. But if you boost the ISO up then regardless how low the noise is if you boost it enough you will see the noise.

JohnSwanda Loc: San Francisco

The camera manufacturers have done a great job of lessening noise at high ISOs on the latest high end cameras, and I'm sure they will continue to do so. But you may have to wait quite a while for high ISO captures to be noise free, or have the same IQ as low ISO.

warrior Loc: Paso Robles CA

Take a look at Topaz software "De Noise"

DirtFarmer Loc: Escaped from the NYC area, back to MA

Noise is a natural process. There is noise in all photos, but when there's plenty of light the noise is just too small to notice. There is noise in the audio from a CD also, but it's too small for most people to notice. Here's the deal for photos. Your camera takes in light and converts it to an electrical signal. Electrical signals are made up of electrons. When there is lots of light, it generates lots of electrons. When the light is dim, it generates few electrons. Since electrons are discrete individual particles, they are not infinitely divisible. And when you are counting individual particles there is a natural variability. For a random process (like converting light to electrons) the variability is basically given by the square root of the number of particles counted. So if your light generates 100 electrons, the variability is 10 electrons, or 10%. That's noise. When you have lots of light, you might get a million electrons so the variability is 1000 electrons, or 0.1%. That's noise too, but it's much smaller than what you get in dim light.

When you have low light levels you get few electrons on your sensor. In order to convert that into a useful image you have to multiply the number of electrons you count so you have an image that is bright enough to see. The multiplication factor is related to the ISO level in your camera. Low light, few electrons, high ISO, large multiplication factor. But just multiplying the number of electrons also multiplies the variability in the count by the same factor so if your 100 electrons are multiplied by 10,000 to get it to a million, the variability of 10 electrons is also multiplied up to 100,000 so your noise level is still 10% of the signal.

The square root relationship between signal and noise is only an approximation for large signals. For very small signals there is still variability in the number of electrons counted. So if you have no light at all, there may still be countable electrons in your sensor. These are generated by thermal motions of the atoms in the sensor. They add to the counting noise described above. So there is inherent noise in the image for very dim light levels. Raising the ISO (multiplying the electrons by larger numbers) also multiplies the thermal noise.

Joe Blow

Noise is caused by low light. High ISO doesn't cause noise, it only amplifies the noise already there.

TriX Loc: Raleigh, NC

Noise in modern DSLRs is caused by every link in the digitizing chain: the sensor, the amplifier (which typically sets the ISO). and the A/D. As you raise the ISO setting, the noise from each of these sources is increased in the final image. I’ll be glad to detail the specific source in each of these components if you’d find it useful

f8lee Loc: New Mexico

So as I understand it, a large component of noise is actually the heat that comes off the electronics (in the form of infrared photons, which the photo sites cannot distinguish from visible light photons) - when you set the ISO higher those unavoidable heat photons become more apparent.

Meanwhile I believe the real kind of high ISO is the Nikon D5, at 3+ million: https://petapixel.com/2016/01/12/this-is-nikon-d5-image-quality-at-iso-3280000/

TriX Loc: Raleigh, NC

If you really want to understand the mechanism that various components play in the noise of an image, the manner and which ISO adjustments in-Camera are made, and the effects of underexposure or ETTR, let me suggest the following read: http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p2.html

TriX Loc: Raleigh, NC

Yep. Also: http://www.photonstophotos.net/Charts/PDR.htm

davyboy Loc: Anoka Mn.

Noise is when you guys write so loud

telepro21 Loc: Fort Worth, Texas

Best explanation of noise that I have ever read, DirtFarmer, many thanks for your clarity and detail.

repleo Loc: Boston

It is worth remembering that 'back in film days', ISO 400 (or 400 ASA) was considered fast or high speed and usually came at the price of grain. Todays cameras are capable of producing low noise images at 4 or five stops higher. Relatively speaking that is pretty close to 'without noise at any level'.

LarryFitz Loc: Beacon NY

The sensor records information (data) from the available light. The more light that reaches the sensor the data collected is better an more precise, the less light the data collected is not as good. The less precise data collected causes the noise.