ISO

[rksmith51]

I think we would generally agree that the lower end of the ISO range will give less grain in the image. I was wondering if there is any speed that combined with the best ISO setting gives a better image. What I mean is, do you get a better image with say , ISO 200 at 1 1/30sec or is it better with ISO 200 at 1/1000 sec. 

what do ya think guys.

[spinner]

I've always operated on the preposition that it was aperture setting, generally specific to the glass you were using that improved or degraded image and that speed related to the ISO as a determined by the available light and the type of shot.

[Malcolm1938]

As my kit lenses perform best at f6.3 to f8 I try to keep my shutter speed within the range 1/60 to 1/1000 at f8 using ISO 100, I only change the ISO setting if there is not other way of staying within my choosen setting range.

Using ISO 200 at 1/30 at say f8 will give a great result if that is the correct exposure and a lousy one if it is not the correct exposure.

Dont worry about ISO settings - getting the exposure right is much more important

Malcolm

[picsfor]

I think ISO is the one measure of digital cameras that seems to be evolving with the technology.

MY 30D had a top ISO of 3200 - and this was really pushing the boundaries. MY 5DMkII has a top ISO 25600 and yet, when set at ISO 3200, it will produce pictures with far less "grain" then my 30D could ever hope to achieve.

As sensor technology improves then so will the "grain" derived from various ISO settings.

Of course, the truth is, digital cameras don't produce "grain" like film. They produce digital signal noise which is a product of the sensor not being able to clearly identify the colours satisfactorily.
So i refer to my opening statement and say that each kit set up has its "sweet spot" that gives the "cleanest image" (the one with the least amount of noise).

[Hinfrance]

What you want then is Pentax's TaV mode - you set the aperture and shutter you want, the camera sets a stepless ISO to match

[Oldboy]

I usually try to keep my ISO at 200 and just change the speed and aperture to achieve that, but it depends on the light and what I'm shooting. Like picsfor my D3 will go upto ISO 25,600, but I have it locked down to 6,400. Nikon cameras give better results at ISO 200, but with the D3s it would be hard to see this at ISO 6,400 in the printed image.  

[rksmith51]

What you want then is Pentax's TaV mode - you set the aperture and shutter you want, the camera sets a stepless ISO to match

Hi H, I use Nikon's auto ISO when shooting sport, it sounds like a similar mode, I set the f stop and speed and the camera varies the ISO within the range I set.

What I was trying to find out was if anyone had noticed that the sensor will deliver a sweeter image with more light ( a shorter exposure ) or less light, I know we get lots of noise with long exposure and that's why we use various methods of long exposure noise reduction, but is there a point higher than ISO 200 that is less noisey. Most of my shots this week were between ISO 4000 - ISO 10,000 all usable, they are posted on my flickr pages for the players to download.

The reason I'm investigating this is that I don't have a long enough lens for some of the sport so have to crop in PP to get the image I want, so the continuing quest for lowest noise to produce the cleanest crops .

PS, I just found I can use PS bridge as a filter to quickly sort images into ISO \ speed groups and compare them.

[SimonW]

Maybe this will help answer your question (or raise more controversy).

With my 8 year old 4 megapixel Canon, not surprisingly I can see noise in the dark areas of a photo taken in low light. What's interesting is that I can't really see much difference between the photos taken at ISO 400 and those taken under the same conditions at ISO 50 with a correspondingly longer exposure time.

Simon

[Hinfrance]

What I've noticed is that the amount of available light affects the outcome - if a scene is dim then there will be more noise at all ISO settings.

I guess Bob that to use auto ISO you have to set the aperture and shutter in manual mode? My Pentax bodies also have auto ISO that you can cap and collar, but I think that works in ISO steps, rather than completely stepless as in TaV mode.

[spinner]

Well if it's digital noise that's the issue, it's almost entirely down to the iso, I can't think of any reason why speed would effect it other than how much light gets in and that's a variable you can't fix.

[Hinfrance]

Spin, do you remember reciprocity failure? I wonder if a similar thing happens with sensors.

[spinner]

Well since the various camera's have an ISO limit there must be something of a similar nature occurring. The difference appears to be the ability of the digital sensor designers to overcome the limitations with design change.

[Oldboy]

Spin, do you remember reciprocity failure? I wonder if a similar thing happens with sensors.

Well since the various camera's have an ISO limit there must be something of a similar nature occurring. The difference appears to be the ability of the digital sensor designers to overcome the limitations with design change.

I don't think this applies to sensors in the same way as it did to film emulsion. Noise/grain in sensors is caused by the current powering the sensor, and leads to the generation of random noise which the sensor thinks is a proton hitting the detector. There are two ways around this, one is bigger sensors or reducing the power supplied. Kodak did some tests which showed that by removing the Bayer mask filter would produce less noise, and the colours could be produced by the software in the camera working out the colours by the charge they produce in each site. Of course, there is a limit to the number of micro lenses you can pack onto a chip and this is where quantum effects take over, but we are a long way from that a present for full frame cameras. 

[spinner]

Yes it's an apples to oranges comparison, one is created by a chemical reaction limitation the other by a photo electric one. Or electro mechanical one. But they each, have a limitation similarity, I do think though the digital one can and will be overcome.