The alignment of a scope is only one of the more common causes of eye fatigue for scope users.
Parfocality is the ability of a scope to be focused at high magnification and maintain focus all the way to low magnification in both eyes. If a scope is not adjusted and setup properly it may not have parfocality which will cause eye strain for the users. Absolute Clarity corrects this problem as part of its Preventative Maintenance Service.
A lack of regular and proper maintenance is the only cause of the most difficult problem of all. The problem is internal contamination of the optics. The internal lubricants aromatic components evaporate after as few as 2 to 5 years and begin the internal contamination process. Once a film of sticky contamination has coated the internal optics dirt can stick to the film making the images dull and hazy. You may notice that the zoom knob is hard to turn or the optics may chatter when zooming up or down. If you look backwards through the scope (up through the bottom lens) and slowly turn the zoom knob, you will be able to see the dirt on every optical surface in the system. (This will not work on infinite focus optical systems such as collimators, telescopes, long range binoculars or Theodolite.)
ACC is a microscope sales, microscope service and microscope repair company. We offer high quality stereo microscopes and high power flat field microscopes, comparator service, Gemological microscopes, video measurement systems, optical calibration, microscope service, NIST traceable optical calibrations, 20.5mm eye loupes, halogen lighting and bulbs. Take a look at our impartial list of stereo microscopes to buy and avoid.