Noise and ISO

[tomlaronge]

I suppose that what I am about to ask is a bit stupid as I realize that there cannot be a generic or simple answer. Nevertheless, I keep reading more noise about noise and noise reduction. I also understand there exists dedicated software designed to stictly reduce image noise.

My goal is to overall take and print high quality photographs and not to be a graphic artist. With this said, at what ISO values in modern, high end SLRs does excess noise become degradingly noticeable?

How much difference in apparent noise-related image degradation typically differs by shooting the same camera in daylight at say ISO = 400 versus ISO = 800? At ISO = 200 vs ISO = 400?

For us beginners, this is truly a potentially critical issue as most affordable modern camera lenses have relatively small maximum apertures. Therefore, stopping image motion is a bit critical, i.e. a dog running, etc. I tried to research this and found discussions of luminance versus ISO at different gray scale valuess. Instead of illuminating me, I simply became more confused and decided to canvas our own internal group of caring experts. Thanks to you all for your enlightenment and opinions and suggestions.
Regards,
Tom

[chas3stix]

Hi,
There are software programs such as "Noise Ninja" that greatly reduce noise effects in digital photos. Noise may vary from camera to camera. One common denominator about noise is high ISO added to long exposure times. With this combination, noise usually shows up in shadow areas. Night scenes are a common site for noise. I hope this helps.
Chas

[TonyW]

I guess as you say there are many factors - sensor type, sensor size, in camera noise reduction firmware and probably a few more. Different ISO's come from upping the signal amplification from the sensor and that's the source of most of the noise. Post processing can help but you can't beat having the camera not create it in the first place. Although generally the more you pay the less noise you get there are differences between cameras costing the same. Best source of comparisons is one of the review sites like dpreview.com. The reviews include comparisons of noise levels at different ISO's both visual and graphical.

Tony

[Byron Gale]

Tom,

I think there are a couple of general rules... the higher the ISO, the more noise you will get... the better a camera is at reducing noise at upper ISO settings, the costlier the camera.

I enjoy reading the practical reviews at sites like http://www.steves-digicams.com or http://www.dpreview.com to see what findings they report with regard to things like noise.

HTH,

Byron

[tomlaronge]

Chas, Tony and Byron,
Thanks much. What you have each said is my experience also.

I have read the reviews of interest about noise, but I do not understand what I am reading. I have no idea of a tolerable noise level. Can you shed any light on this issue?

If I print and include "lightening shadows", does this have the illusion of minimizing noise? What about altering the contrast?

Finally, what is your results with photographing in bright daylight at IS) *00 vs Iso 400?

Thank you again.

Tom

[GaryK]

Tom

I'm not sure if you have ever shot film. The same issues arose then. Faster films ..more grain. (again ... just general rule of thumb)
I took an intro course for my camera (Rebel 300D) a year or so ago, and asked the instructor if the noise was comparable to the grain. I was kind of curious if there was a lot of noise about nothing:D.
He said it was comparable, ISO 400 noise same as ASA 400 grain ..although grain tended to be slightly less annoying because it was all one colour where as the noise tends to be multicoloured thus more noticable.
He was a professional and shot in both formats (not just a spec guy), so I'll give him at least some knowledge. :)
I think part of the problem?? is that you can now change the ISO with the flip of a button, so you can go really fast without having to think about getting very fast film and how much you are going to shoot ..etc., etc.
Heck, it would have been tough to get 800 ASA or faster film without going to a dedicated camera shop.

Not much more to add, the others have seemed to cover all the factors

[GaryK]

Tom

I would hazard a guess that daylight ... 400 ISO ...full sized sensor would yield negligable noise.
I would almost say that most DSLRs would work well at those settings, full sized sensor or not.
Of course there are exceptions, and some people are pickier than others but my feelings anyway.:)

[tomlaronge]

Gary,
Thanks for sharing. I have shot film in still picture mode from 8mm through 8" X 10" for literally 49 years. I know of what you shared. What you stated, that I did not know is the comparison of grain at ISO 400 in both film and digital modes.
Gary, when I shot film, both professionally and as an amateur, I almost never shot at ISO higher than 100. I also shot film at ISO 10 when I needed super-fine grain.
With this said, I have shot a few hundred digital photos at ISO 400 and blown these up tp 11 in X 14 in. equivalent or larger with very acceptable results. I would like to try shooting at ISO 800 as I could get the motion freezing effects desired plus the desired depth-of-field. I guess this will be true "PSE", i.e. Photograph Subjects Experimentally!
Tom

[GaryK]

Tom

The grain comparison was the instructors feeling on it. I was like you and was really trying to figure out how bad noise was/is.
I happen to give the nod to digital. :rolleyes:
I have a few pictures (400 asa 35 mm) I took over 20 years ago and I found when I blew them up to 11x14 the grain was very noticable.
I will admit, I knew little back then (which is more than now :D) so there could be more factors to the negative and resultant enlargement than film speed.
There was also some advancements made to film since those days, so my comparison might be out of date.

I also am not slighting non DSLRs, a lot of those are very good. It is just my only experiance with those is of the very low end and just not fair to compare.

[chas3stix]

Tom,
The noise produced by digital sensors comes from the electronics heating up. In low light situations the sensor's amplifiers are working like mad....thus heat is produced and the result is noise in the photo. As camera manufacturers get better at electronic amplification noise will cease to be an issue. No free lunch here...you only get what you pay for.
Chas

[tomlaronge]

Once again, thanks Gary and Chas.
Chas, what you wrote about temperature and amplification makes all the sense in the world. I appreciate the learning you have given to me.

Gary, film and digital are quite complex as quality is impacted. I only know enough about digital to be dangerous. However,the grain in film is rather markedly affected by the type of film, its age, the storage temperature, the ISO, whether this is negative film or positive film, whether this is color film or Black & white film, the time between exposure and development, the specific developer, development temperature, differential temperature among all wet processing steps, the strength and nature of the stop bath, the time in the stop bath, the type of fixer and the time in the fixer, the length of washing time, the temperature of drying and I feel certasin that i left out a few dependent variables including those not mentioned that apply to color by virtue of the processing differences in bleaching and multiple film layers, etc., etc. etc. So, the bottom line is get the best image recorded and print with the fewest number of steps in the darkroom or with the computer. This is just the ancient KISS Principle all over again.
Tom

[GaryK]

Tom

Thanks, the 11x17s I were referring to were done waaaayyyy back not long after the pictures were taken. Not a big deal about the grain.. the negs are probably not in that good of a condition nowadays anyway. I was just using that as a comparison.

As Chas metioned the noise from a digital is caused by the sensor heating up and some say there is some cross talk between the ccds (they are just packed so close together). I'm no Electrical Engineer but anything seem feasible.

That is why a 6 mp small sensor tends to show more noise than a 6 mp larger one, particularily in lower light.

Once again .. just sort of general assumptions your mileage may vary, and you can get very good, and you can get not so good, at both ends of the sensor range.

[chas3stix]

Tom,

gary was dead-on about the parallels between film and digital. It all boils down to this....get the exposure right from the start....in the camera. Moose Peterson
lives by those words. And it sure as heck works for him!
Chas

[GaryK]

But ..But....Chaaaaassss

If we did it right the first time .. what would we have to be creative with?:D:D

[tomlaronge]

Thanks you all! I guess some of my not so good exposures make me an equal expert at attempting crativity and a failure at the same. Oh well, maybe there is hope.

Tom

[GaryK]

Tom

We all have different aspirations.
I am very happy to make nice photos, but I am just as happy to make a nice creation from photos that I have taken.

[chas3stix]

Gary,
Isn't a proper exposure what we're striving for? Be it during capture or post capture?....:D
Chas