Okay Vladimir, I performed the experiment you suggested. I set up my ED-80 with a temperature probe inside the dewshield, as close to the objective as I was willing to go without risking scratching it (I estimate about 1/4" from the objective). The inside temperature is measured at the probe, the outside temperature at the metal fins at the bottom of the display. The top number is the inside temp, the bottom number is the outside temp. Note that at the beginning (inside my heated house, with everything at equilibrium) the temperature inside is showing slightly higher than outside. I can think of no reason for this, and the difference may indicate the limit of sensitivity of the instrument. Here is a picture of the setup:
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