Porro prism spotting scopes
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— the presence of a Porro-type prism (more precisely, several such prisms — they are rarely used one at a time) is almost guaranteed to mean that the tube has an eyepiece that is offset or bent relative to the longitudinal axis of the body (see "Location of the eyepiece"). If we compare this option with Roof prisms, then its advantages are an extensive field of view and a large image depth, the disadvantage is some bulkiness of the case due to the increased dimensions in height.