1. A device used by an observer to estimate the distance between said observer and a designated object designated by said observer, comprising: a planar surface which said observer designates said designated object, said planar surface embossed or marked with reference point markings, said reference point markings including a single main mark, said single main mark optionally located at the mid-point of said planar surface, and a plurality of reference point markings located either on one side or on both sides of said single main mark, wherein each of said plurality of reference point markings includes a corresponding numerical mark associated with each said reference point marking, wherein the distance between each of said plurality of reference point markings and said single main mark has been determined prior to the construction of the device, and a solid housing or grip attached to said planar surface which said observer may use to hold the device during its operation.