ISO number using professional Digital SLR

I've got a great experience in 35mm film cameras and now I plan to

get a digital SLR. I have a question about the results by using

diferents ISO numbers.

 

 

Using film, diferent films with diferent ISO numbers give us diferent

graniny results due the diferent type of emulsion.

 

 

In digital, the results by changing the ISO number on the camera

dont't look too diferent for me. Sometimes I don't see any diference

beetween a ISO 100 image and an ISO 800 image. They appear the same.

 

So, if a scene doens't have sufficient light to shoot f:8/1:60 in ISO

100 mode, why not changing the ISO number otherwise the time and

aperture without sacrificing the image?

<< They appear the same. >>

 

On the screen? In the final print? At 100% magnification?

 

All the tests I've seen on dpreview, even with the very best Digital SLRs, show a difference.

Tom,

 

Try this: Underexpose a couple shots by one and a half stops, one at ISO 100, and one at ISO 800. Now, using your editing or RAW conversion software, adjust exposure or levels so that the histogram looks correct. You should notice a pretty pronounced difference in noise between the two, especially in the lower tones.

 

Even correctly exposed, you should notice a difference in the images when viewed at actual size (i.e. 3026 x 2048 pixels). The higher ISO should exhibit greater noise which will be most apparent in areas of shadow and in solid color areas.

 

Of course, many digital SLR's are so good that noise does not become noticeable until ISO 800 and does not become a problem until ISO 3200. You can even "push" digital SLR's to even higher ISO's by underexposing and then "pushing" the images in post-production. This does produce images with a great deal of noise but, IMO, the result is generally more useable than what can be achieved by pushing fast film and can allow you to produce images in near dark conditions.

Hi Tom, Different DSLRs handle noise differently - some better, some worse. One thing that may account for what you've seen (no difference between ISO 100 and ISO 800) could be the use of a product like NeatImage or Noise Ninja - both of which do a tremendous job in removing digital noise. I've owned a Canon 10D for well over a year and thought it did great with noise. I just bought a 20D today and it's even better with at least a one stop improvement; i.e. ISO 1600 on the 20D looks much like ISO 800 on the 10D. Good luck!

A camera like the 20D will have less noise than the equivalent film of the same ISO. However small (and it gets samller with every new Canon model) the difference is there but, as you point out, not as great as in film. Therefore, yes you can change ISO more freely is a shot requires it.

Tom,

<p>Like the others have pointed out, the higher you set the ISO, the more noise (which looks a little bit like film grain, but not exactly the same) you will see in the images.

<p>The good performance of DSLRs in low light with regard to noise is one of the reasons I bought a 10D a year ago. I've tried using ISO 800 and 1600 colour film, but the results were not so good - there was a lot of grain and besides that, in situations with artificial light, the colours turn orange.

<p>With a DSLR like the 10D, ISO 800 and 1600 do give you some noise, but most of the time not so much that it becomes a real problem. I also use <a href="http://www.neatimage.com">Neat Image</a>, which works amazingly well to remove the noise, while retaining the detail in the image. Also, with a DSLR it's easy to change the white balance so that the colours look good when photographing in artificial light.

Another thing: The noise in images you see on the Internet is not so apparent, because these images are sized down a lot. If you look at images at the original size (for example, 3072 x 2048 from the 10D) or on a larger print, the noise is much more clearly visible.

ISO 800 is very useable with a DSLR, and I've shot 1600 in candlelit halls a few times with a 50mm 1.8 with fairly good results. The noise is most noticeable in the shadows, but properly exposed subjects will hardly have any.

 

I haven't tried it yet, but shooting in the cold is suppose to help with the noise.

You might want to read this article by Roger N Clark on <a href="http://www.clarkvision.com/imagedetail/digital.signal.to.noise/">Signal-to-noise of Digital Cameras</a> (http://www.clarkvision.com/imagedetail/digital.signal.to.noise/).