[shuttertalk]

Here's an interesting article comparing digital noise vs film noise.
http://clarkvision.com/imagedetail/digit....to.noise/

The comparison in Figure 1 shows that the Canon 1D Mark II has a signal-to-noise at ISO 800 that is still better than fine grained ISO 50 film. At ISO 100, the 1D Mark II has signal-to-noise on the order of 3 to 6 times higher than Fujichrome Velvia, ISO 50 slide film. Higher speed films have greater grain and lower signal-to-noise.

Interesting eh?

[Kombisaurus]

Very interesting Jules,

You always seem to stumble across these interesting little studies..

The only thing I am a bit curious about is how they measured the noise-levels for the film. The author mentioned it was scanned film, but seemed to mention nothing more about it. My experience with scanning tells me that a scanned photo is *never* as good as the photo it was scanned from, and the quality of the scanned image depends a lot on the quality of the scanner, the condition of the source photo, and the settings used. While there may well be a way to measure how much noise is introduced by the scanning process and thus take it out of the equation (similar to some of the in-camera noise-reduction techniques that involve a 2nd shot taken with the shutter curtain closed), I would still imagine the film would be disadvantaged by going through the scanning process.
The fact that the author mentions nothing of this (I couldn't even find a reference to where the film data came from) makes it difficult to agree with his conclusions based soley on his evidence, even if my gut feeling is that they are probably pretty accurate.

I see it as being much the same as comparing film to digital by printing out the digital images first... in this case the film is being shown at its best, but the digital prints are at the mercy of whatever they are printed on.

Its always going to be tough comparing apples to oranges I guess

What do you think? Or am I just being pedantic?

[Toad]

I think you are right - even the top professional scanners are essentially converting the film images to digital at whatever the resolution of the scanner is. My own experience is that there is always a perceptible loss of quality when any medium is converted to another - if the quality of the original is X - then the conversion can never be greater than X and is generally a measurable margin less than X.

[shuttertalk]

Hm... good point, Kombi/T..

I suppose it would be relevant to people who scan slides in as part of their workflow...

[Don Schaeffer]

Film grain = virtue: stress on the film which equals hard work and reality pressure.

Digital noise = vice: distortion because of crappy camera or bad picture taking or too much post procesing.

[EnglishBob]

Interesting time to bring this up, I spent 4 hours sunday scanning my first roll of slides into the computer using a friends very high quality slide scanner... 4000 DPI..... the pictures come out the equivalents of around a 16mp camera. I am undecided on whch is better quality, my digital or the scanned slides. It is very close.

[shuttertalk]

Hm... interesting Craig. Maybe post some 100% crops so we can compare?


Good point Don, regarding the grain vs noise. Sort of like what Adrian was saying - apples vs oranges.


However, the other obvious point is that if you take the results at face value, then the digital user would have a significant advantage over film in terms of flexibility in low light situations.

[Slej's Left-Hand Hammer]

I don't mind a little "noise" if it looks like grain ...

For general shooting, I'm leaving my 10D at ISO 200 instead of 100, because I get the benefit of an extra stop's worth of speed with only a modest amount of luma noise (grainy appearance) and virtually no chroma noise (those spotchy magenta and green blobs.)

And Capture One does a great job at noise removal during RAW conversion so I'm not bothering with any additional noise reduction.

Regarding the original topic, I saw an article recently (Digital Photo Pro magazine, I believe) which suggested that some pros who shoot a 1D MkII are actually adding grain to their images in post processing to make them look more "filmlike", because the shots are otherwise too smooth. Not sure I believe it, but that's what the article said ...

[shuttertalk]

What's with the guest appearances?

Regarding the original topic, I saw an article recently (Digital Photo Pro magazine, I believe) which suggested that some pros who shoot a 1D MkII are actually adding grain to their images in post processing to make them look more "filmlike", because the shots are otherwise too smooth.

Now that's taking a step backwards isn't it? It's almost like desaturating colour photos just to make them look like old b/w photos... oh wait...

[EnglishBob]

Here's a couple of examples, one digital one scan, no processing done and 100%. Both are pretty soft I have no in camera sharpening set on the rebel.





So which is slide and which is scan? (cheating will only cheat yourself.....)

[Kombisaurus]

I'll say the top one is film, bottom one is digital Craig... definately. (and I didn't cheat)

I totally believe that many people add noise to digital images, and I have done it myself on many occassions - sometimes I've even removed noise from an image and then added my own noise over it!

But "noise ain't noise" so to speak.. just as Don mentioned that film grain is an endearing quality while digital noise is bad, so to film grain usually doesn't look the same as digital noise.
Slej cleverly seperated luma noise from chroma noise... and IMHO I think chroma noise is the ugliest thing ever.. but luma noise *can* add character to a shot I think.

Apart from there being lots of different noise algorithms available (and semi-random textures that can give similar effects), adding noise can be an effective way to mask other defects with an image such as posterisation or imperfect surfaces that should appear smooth... the brain knows the noise isn't part of the image and so tends to remove all imperfections from the image when processing it.

Its funny, as noise was my biggest annoyance with my Oly c750 and I used to take almost all my images at ISO 50.. and only now I'm just starting to relax with the 350D and not be afraid to use ISO 200 or even <gasp> 400 or 800. I refuse to use 1600 unless it is an absolute emergency however... but I still end up with too many blurry shots at ISO 100 because I'm too scared to crank it up.

[EnglishBob]

Looking at those pictures now... 100% with no sharpening does not look good! The slides look wonderful when projected, as do the digital images when on screen and printed after sharpening etc... The film in question by the way was Velvia 50 slide film. THe colors came out so good from that roll that I am almost sad I have 30 rolls of Sensia 100 in the fridge.

[shuttertalk]

Hard to say coz they're not the same "size" - but I'll say film top, digital bottom.

So which one's which?

[EnglishBob]

Yup, film is top. They aren't the best examples to compare, they were both shot on the same 2 days but the sky was very cloudy with the light changing constantly and never at it's best. One minute harsh sunlight, the next patchy light and then total shadow.

[Toad]

Darn - I didn't get a chance to vote - I would have said film on top because of the better handling of highlights on the girls' cheeks.