Please explain: ISO setting: Digital - vs - film

05/25/2007 06:01:48 PM · #1

I do notice grain in higher ISO film photos, but I don't notice grain in digital photos when comparing 100 to higher settings. I was told to shoot 100 as often as possible with my digital to avoid grain. Why is that?

When I think about it, film cameras allow the light to come in and hit the film chemicals that are made of silver grains - the lower the ISO - the smaller the grain. Higher ISO has bigger grains of silver which gives the photo a grainy look.

However, in digital format the light enters the camera and hits a sensor...so where would the grain come from? Does have to do with the camera's pixel count?

robs

Canon EOS R6 Mk II

Canon RF 24-70mm f/2.8 L IS

05/25/2007 06:07:11 PM · #2

Originally posted by dsterner:

so where would the grain come from?

It's not grain but noise - I know people still use the film word but they look different. The higher ISO is basically just amplifying the signal from the sensor [even low ISO requires a lot of amp from the sensor] and that creates random noise as you amp up. Not a great analogy but; Think of the clipping an amp will do when played at full power.

Message edited by author 2007-05-25 18:08:14.

kirbic

Canon EOS R5

05/25/2007 06:07:18 PM · #3

Digital sensors create noise in a number of ways, and though the noise doesn't look exactly like film grain it does increase at high ISO values. Try shooting the same scene at 100, 200, 400, 800, and 1600 ISO, maintaining exposure by changing shutter speed. Look at the results and you'll see the difference.
Bottom line, digital SLRs have much lower noise at high ISO than film. That's especially true of the more recent Canon cameras.

fotomann_forever

05/25/2007 06:08:05 PM · #4

In digital it's called noise. Boosting ISO of a digital sensor boost the gain of the sensor. In effect it's like turning up the volume on a stereo. The more you turn it up the more noise you will have, especially if you have a weak signal (low light) to start.

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

05/25/2007 06:19:07 PM · #5

WOW! your responses really clarified my understanding of ISO settings...even helped my vocabulary - grain/noise application. Many thanks!

strangeghost

Canon EOS-7D

05/25/2007 07:08:06 PM · #6

Here's a fun series of test shots I did awhile back to gauge the increase in noise in my 30D:

Pbase gallery noise test

05/25/2007 07:44:12 PM · #7

Very cool! Thanks for posting - I understand even more

Originally posted by strangeghost:

Here's a fun series of test shots I did awhile back to gauge the increase in noise in my 30D:

Pbase gallery noise test

Artifacts

Canon EOS-5D Mark II

05/25/2007 09:09:38 PM · #8

Originally posted by strangeghost:

Here's a fun series of test shots I did awhile back to gauge the increase in noise in my 30D:

Pbase gallery noise test

It is a hard to see noise until you get to the higher ISO numbers and then it does not loolk like much. Is that 100% crops? Does not look like it.

Btw... nice book collection. Richard Feynman is one of my all time personal heros.

gaurawa

Canon EOS-5D Mark II

Canon RF 24-70mm f/2.8 L IS

05/25/2007 09:57:21 PM · #9

Originally posted by strangeghost:

Here's a fun series of test shots I did awhile back to gauge the increase in noise in my 30D:

Pbase gallery noise test

I don't suppose its 100% crop. Atleast my 30D isn't that clean viewing 100%.

Also what were the shutter speeds?

kirbic

Canon EOS R5

05/25/2007 09:59:55 PM · #10

On John's test shots, you have to open the "original" size. I believe those are the complete full-resolution shots.

gaurawa

Canon EOS-5D Mark II

05/25/2007 10:05:49 PM · #11

Originally posted by kirbic:

On John's test shots, you have to open the "original" size. I believe those are the complete full-resolution shots.

I need to look carefully before posting !