For moving objects shutter speeds not slower than on hundredth of a second should be used. Shutter and f-stop combination will depend upon lighting conditions; dusk, cloudy day, bright sunlight, ect. If your camera does not require such settings, just take pictures.
Do not move camera during exposure.
Take several pictures of the object; as many as you can. If you can, include some ground in the picture of the UFO.
If the object appears to be close to you, a few hundred feet or closer, try to change your location on the ground so that each picture, or few pictures are taken from a different place. A change in position of 40 or 60 feet is good. (This establishes what is known as a base line and is helpful in technical analysis of your photography.) If the object appears to be far away, a mile or so, remain about where you are and continue taking pictures. A small movement here will not help. However, if you can get in a car and drive 1/2 to a mile or so and take another series of pictures this will help.
After pictures of UFO have been taken, remain where you are: now, slowly turning 360 degrees take overlapping, eye level photography as you turn around. By this technique the surrounding countryside will be photographed. This photography is very valuable for the analysis of the UFO you have just photographed.
Your original negative is of value. Be sure it is processed with care.
IF you can, have another negative made from the original.
Any reproductions you have made for technical study and analysis should be made from the original negative and should be printed to show all the picture including the border and even the sprocket holes, if your film has them.
Using the freedom of information act in the U.S. we were able to obtain many documents from different branches of the Government and the military. Some of these declassifed files show interesting facts and research about aliens, flying saucers, and UFOs.