An improvement upon telemicroscopic loupes of the type which are adjustably mounted to an eyeglass frame, headmount or through-lens designs. The preferred embodiment includes a cap including an optical element to adjust for the working distance of a loupe. The cap may be frictionally fit onto the loupe or threadably attached to the loupe body. According to an alternative embodiment, one or more eyepiece components may be used alone or in combination with the end cap for adjusting prescription and/or working distance.