It will be quite a bit more than a couple of thousandths smaller when you take into account the tube thickness and any retaining rings. I would imagine the 1" Ultradot has an unobstructed objective lens diameter of 21-22mm. I am just hoping someone who owns one can measure and let me know.
I put the caliper to my 1" UD and the lens measures about .84" + or - at the front retaining ring. Why do you ask?
Thanks, Rod. I was asking because I currently use a red dot sight that has a 22mm objective lens, and I was trying to make some comparisons to the FOV of my sight vs. a 1" or 30mm Ultradot. I know the FOV is more complicated than the objective size, but I still wanted to know.