Botanical Photography

The Light Meter in simple camera usually has a needle, a bracket and +/- markings. When the needle is in the center of the bracket, all is well and it is time to shoot. If the needle is on the plus side, there is too much light. If it is on the minus side there is not enough light! HINT!!! To get saturaing colors it is best to expose your film slightly underexposed (slightly negative). I always bracket my photos (slightly +, middle & slightly -) if they are important. The position of the needle is dependent on four factors. A] The amount of ambient light B] The ASA rating of the film C] The shutter speed D] The lens aperture (f stop)
To see how this works, Focus on a subject and note the position of the arrow. Rotate the Shutter Speed knob and see how the needle behaves. You could do the same with the ASA settings but this is harder to do.
In most cases you adjust the shutter speed or the lens aperture to get a proper exposure. However, at shutter speeds below 1/60 a blurry image will be produced unless the camera is fastened to a copy stand or tripod. Consequently, you could be limited to exposures of 1/60 sec. or less for field photography. This is impractical! Hence, you will need to alter the lens aperture to allow more light to reach the film.
The camera lens contains an iris diaphragm like the one in the field diaphragm or condenser of your microscopes. There are numbers called f-stops on the camera lens which indicate the diameter of the camera iris. The f-stops on my lenses range from 4-32. (They can range from 1-32) At f- 4 the iris is completely OPEN! (Maximal Aperture) At f- 32 it is narrow! (Minimal Aperture)
f-4 Maximal Aperture	f-32 Minimal Aperture