Long Exposure Photography
I have a Nikon d-90 and i typically use a 70-300mm lense. When I shoot long exposure I have a difficult time knowing which settings to use, and when I do it, the entire picture is just white.
What settings should I use and how do I fix this?
Put the camera on a tripod, and select manual exposure. You can experiment.
When are you taking the photos?
In any sort of daylight you won't be able to take any long exposure without using a neutral density filter.
At night you're more likely to underexpose than overexpose.
Here's where you really need to understand what your camera is telling you (& read the manual). The camera does have an exposure meter which will appear as a series of bars with another bar that moves across it. Number 21 in the linked photo showing the D90 viewfinder. When the moving bar is in the middle, that's where the exposure is nominally correct. You adjust aperture, shutter speed and ISO to get it centred. For long exposures you'll want the ISO as low as possible.
The rear panel display also has the exposure readout and the photos in the 2nd link show this, the pale blue image about 1/3 of the way down the page.
When an image is white, it's over exposed. Basically it means you have failed to check the exposure. If you are setting everything manually you will need to check the exposure for every shot. There's no way to tell you the settings to use - it will differ in every single shot according to the lighting conditions at the time.
There are two basic methods of taking photos with long exposures (an easy way, and a harder way):
1. If you want the camera to set the exposure for you, use Shutter Priority Mode (S on a Nikon, or Tv on other cameras) - then dial in your required shutter speed - and the camera will make any adjustments to the aperture to get the correct exposure.
2. Learn to use Manual Mode and the light meter (or exposure meter) in your camera to check the exposure manually. You will need to adjust the Aperture and ISO settings yourself to get the proper exposure. Your camera's user manual will tell you how to operate your camera in manual mode and how to use the light meter.
If you want to find out more about exposure, read this: Understanding Exposure: http://www.cambridgeincolour.com/...posure.htm