ISO Settings

[samdring]

Read here somewhere (methinks twas Bob Gross) that settings should be ISO 100 (Bright); 200 Cloudy Bright; 400 Cloudy Grey through to indoor settings etc.

Question is whether such settings are solely cos of need to improve AV range or whether such increases in ISO will inherently improve shot regardless of AV.

Hope that's not too stupid a question!

[defordphoto]

General rule is to shoot the lowest ISO you can no matter where you are. Of course, rules are made to be broken...Grain is fun sometimes.

And no, that's not a stupid question. :)

[DAMphyne]

ISO value is the controlling factor when determining F-stop and shutter speed.
If you set your Apeture at a specific F-stop, and use AV, then you can control the shutter speed with the ISO.
Higher ISO value= faster shutter speed.
This also works in reverse if using TV

[Dans_D60]

As mentioned in other threads, ISO (formally ASA) is a measure of sensitivity to light. Film or digital sensors act somewhat the same with regards to light sensitivity. The higher ISO number the more sensitive the sensor is to light. Higher ISO settings allow you to capture the same image but with less light hitting the sensor. This is important with action or low light photography. Attempting to capture a race car with a decent depth-of-field may require a shutter speed of 1/2000 at f8 or even faster. Very little light is hitting the sensor so you will need to dial up the ISO accordingly. Attempting to capture snapshots at dusk or on a cloudy day may also require higher ISO speeds because of the reduced light conditions.

But these higher ISO speeds come with a price. Noise (or grain with film). The higher you dial up the ISO speeds the more electrical noise is produced by the sensor. Noise will appear as “specks” on your images. Also every place a noise pixel materializes means the real data is missing.

It is a balance and photographers have been dealing with light sensitivity issues for over 100 years. Sometime you may want a “grainy” look. I can remember back in my school days some 30 years ago we “pushed” ASA 400 film to ASA 1600 in the development process. Extreme grain images but it was the look we wanted. On the contrary my preferred portrait film was rated at ASA (ISO) 25 that allowed 8X10 prints from 35mm film with practically no grain.

Hope this helps.
Dan
http://www.pettusphoto.com

[robertwgross]

samdring wrote:
Read here somewhere (methinks twas Bob Gross) that settings should be ISO 100 (Bright); 200 Cloudy Bright; 400 Cloudy Grey through to indoor settings etc.

Question is whether such settings are solely cos of need to improve AV range or whether such increases in ISO will inherently improve shot regardless of AV.

Hope that's not too stupid a question!

I think that was my statement of a good place to begin. Later, when you have a good feel for what is going on, you can set up your own guidelines.

To avoid the most color noise, try to keep the ISO setting low, like 100. On a bright sunny day, you can set ISO 100, and still have a suitable range of aperture or shutter settings to do almost whatever normal shots you need to do. As the available light gets dimmer, the suitable range will force you into wide-open apertures or else ultra-slow shutters, and those bring DOF problems or movement-blur problems. That forces you to increase ISO. If you were shooting sports action during daylight hours, you might accept a little color noise in return for pushing the shutter speed faster, so you set the ISO higher. If you were shooting sports action during night hours with only field lighting, you might accept a lot of color noise in return for pushing the aperture wide open, so you might set the ISO almost to its highest.

Besides, if you get a super shot with high ISO, and you see some color noise, you can always process that out using a program such as Neat Image. That has saved me more than once when I had to go to very high ISO settings.

---Bob Gross---

[design crusader]

ISO... ISO...

The previous "rule of thumb" posts are excellent and accurate. Also, like some of the other replies stated, it is entirely subjective to the content of the photo. It could be daylight and you shoot ISO 100 with a fast shutter, cloudy and you can shoot ISO 100 with a slower shutter speed, or you can shoot night shots with ISO 100 with a very slow, long shutter speed -- just realize that with longer shutter speeds you need to have a steady camera (i.e. tripod) and preferrably a stationary subject that won't blur from motion (unless this is the effect that you are going for).

Experiment with what you want to do, that is what is so great about digital, experimentation costs nothing but time. You will begin to get a feel for the "sweet" f stop numbers of your lens and better shutter speeds while hand holding your camera (125 or 180).

Look at some of the photo examples that others post to the site, and look at the lenses, f stops, shutter speeds and ISO settings that they used to capture their moments in time. Then, use this to try it out on your own.

The better you get, the more of your own personal creativity you can begin to interject into your shots, it stops becoming so technical and begins to become more intuitive.

[defordphoto]

design crusader wrote:
The better you get, the more of your own personal creativity you can begin to interject into your shots, it stops becoming so technical and begins to become more intuitive.


Wow. That is so very well said.

[CyberDyneSystems]

In addition to what has allready been said,. I wanted to address this specific part of youre question

samdring wrote:

Question is whether such settings are solely cos of need to improve AV range or whether such increases in ISO will inherently improve shot regardless of AV.




The answer is most definatley NO :)

Increasing ISO will add noise to your image. So it is usually best to work with as low an ISO setting as you can get away with. (granted the 10D has remarkably high quality high SO images)

It all has to do with the shutter speed you need.

The time to bump up the ISO is when you can't get a fast enough shutter speed to get an image.

For landscape shots and still lifes this is hardly ever a concern so you will 9 out of 10 times be better off at the lowest ISO setting to keep noise down.


:)

[Jesper]

Dans_d60 wrote:
As mentioned in other threads, ISO (formally ASA)...

"Formally ASA" ?? Did you mean "formerly" (as in: "previously")?

ASA = American Standards Association
ISO = International Standards Organisation

It used to be called "ASA" before it became a standard of the ISO.