ISO:

The ISO setting corresponds to the ISO or ASA "Film Speed" ratings of camera film.  Since digital cameras use no film, the ISO setting is only an analogy.  A lower ISO number means the sensor has less light sensitivity and less noise and a higher ISO number means more light sensitivity but more noise just like it did when using high speed film back in the 20th century.

It's best to use the lowest ISO setting possible.  If you can't get enough light on the subject by other means you can increase the ISO setting but higher ISO images are often MUCH noisier.  See the following examples:

ISO WAY too high causing lots of image noise (and over exposure):

     http://www.jacksondigital.com/Files/Photos/High_ISO.jpg 

ISO set lower resulting in less image noise (and better exposure):

     http://www.jacksondigital.com/Files/Photos/Low_ISO.jpg 

Zoom:

Use the zoom lens control to get good composition of the image.  Since there's some variation in speed on any ride you need to leave some room for the subject's position to vary a little bit so don't zoom in too tight.  Some cameras (e.g., the Canon PowerShot G10) provide software control of the lens, however many cameras require that you manually adjust the zoom lens.

Focus:

Focus almost always needs to be adjusted after the zoom setting is changed.  If your camera has a software controllable lens, ensure that Thrill-Capture's Focus Lock checkbox is checked, then click on the Focus Lock button to lock the focus on the camera's current field of view.  Many cameras require manual adjustment of focus.
 

Shutter Speed:

The parameter that is most constrained by the real world behavior of the subject is the shutter speed.  Shutter speed is how long the shutter stays open to expose the image sensor to the image.  On a moving attraction you WILL get motion blur if your shutter speed is set too low regardless of whether your camera has a mechanical or an electronic shutter.  If your shutter speed was set to 1/2 second, for example, you would clearly expect the ride to move in that half second so you would expect the image to be a streak in the direction the ride is traveling.

So how do you tell motion blur from being out of focus?  With motion blur the moving subject is not sharp but stationary objects near the subject ARE sharp.  See the following examples.

Motion blur due to slow shutter speed:

     http://www.jacksondigital.com/Files/Photos/Motion_blur_illustration.jpg 

The same image with a faster shutter speed eliminates motion blur:

     http://www.jacksondigital.com/Files/Photos/No_Motion_blur_illustration.jpg 

Iris:

The lens iris mechanism controls the amount of light that's allowed to pass through the lens.  Iris settings are expressed in F Stops ranging from about F1.8 (lots of light admitted) to F22 (a tightly closed aperture).  The following program illustrates the relationship between the F Stop settings available on a digital camera lens and the geometry of the iris.  It IS a program so your anti-virus software might object to downloading it and you WILL have to have the Dot Net framework installed (probably Dot Net 4.0) to run the program.

          http://www.jacksondigital.com/Files/Installs/Lens_Iris_Demo2.zip 

As you can see, at F1.8 the aperture is open very wide so more light is allowed through the lens than at F22.0 where it's almost closed.  So why not always set the lens to the lowest F Stop setting so you always get the most light?

The wider open the iris, the more constrained the focus of the lens.  At F1.8 you've got a very narrow region that's in focus.  That region of good focus is called the depth of field.  When you close the iris more, the depth of field increases.  So focusing is much simpler and more versatile at F22.0 than at F1.8.  If you WANT the background behind the subject to be blurry for aesthetic reasons you might want to use a fairly wide open iris, but for ride photography you will usually want the entire image to be as sharp as possible.  So use the highest F Stop setting you can.

Summary:

So start off by setting the ISO to the lowest possible setting.  This would be ISO 100 on most cameras.

Then compose the image by adjusting the zoom settings.

Then focus on the subject by ensuring that the Focus Lock check box is checked, then click on the Focus Lock button to lock the focus down (or manually adjust the focus on a manual lens).

Then set the shutter speed to a reasonably fast setting (1/1000) and see if you have any motion blur.  If you still have motion blur you'll have to use a faster shutter speed.  If you have no motion blur you might be able to use a slower shutter speed which will also brighten up the image.

Adjust the iris to obtain proper exposure.  Since the sharpest images are obtained with higher F Stop settings you will usually want an F Stop of F5.6 or higher.

If the images are too bright and you're already at F22.0 you can darken the images a bit by increasing the shutter speed to a higher setting than is necessary to eliminate motion blur.  For example if 1/1000 of a second completely eliminates motion blur but your images are still too bright at an F Stop of F22.0 you could increase the shutter speed to 1/2000 to make the images a bit darker.

If the images are too dark you can open up the iris (lower F Stop setting) or increase the ISO setting.  But lower F Stop settings mean a shorter depth of field and higher ISO settings mean more noise.  So lower F Stop settings and/or higher ISO settings should only be used to brighten up a dark image after you've tried to increase the amount of light on the subject.

With almost any camera lens you WILL need to reset the focus any time you change either the zoom or iris settings.  This is because changing either of those parameters affects the optics of the lens and therefore the focus changes as well.  So once you've got the zoom and iris settings where you want them you should click on the Focus Lock button to make sure the camera is properly focused with the current lens settings or manually adjust the focus on a manual lens.