Depth of Field

Depth of Field is the range over which you are able to achieve visual resolution (discrimination).

It is recorded in terms of the nearest and furthest extremes of distance from the surface of your eye to the object observed (e.g., a Depth of Field from 13"-18.5").
It may also be recorded in terms of the difference between these extremes (e.g., a 4" Depth of Field).

Most manufacturers rate their magnification systems for a specific range (e.g., 13"-19.5"). They may call this the "Depth of Field" for the telescope, or they may refer to it as the "Working Distance" for the telescope.

Be aware that regardless of what the manufacturer indicates, you may experience an entirely different Depth of Field based upon your own visual status, age, etc., so it is wise to check each device to determine the actual Depth of Field you experience while you are using that device.

Test your surgical telescopes by looking at a fine grid, or your own fingerprint, to determine its actual Depth of Field.

Your will need an assistant with a measuring tape to measure the near and far extremes at which you can comfortably make clear visual resolution of the image.

You should compare what you have measured as the telescope's Depth of Field to your musculoskeletal Working Distance to determine whether this particular telescope system works for you.

Note: If you have to compromise your Working Distance to meet the limitations of the telescope system, this is not acceptable.

Remember: Depth of Field is a quality of the optical system which you use.

The Depth of Field you experience for each surgical telescope may vary greatly from the range for which the manufacturer rates it, depending upon your own visual prescription and other factors.

If you have comments or suggestions,

lrucker@interchange.ubc.ca

This page created with Netscape Navigator Gold