Angle of View

[BUGSBUNNYBOSS]

Though it is not related to this discussion, I'd like to clarify a terminology here. The ["] symbol in divisors 2/3",1/1.7"1/2.3"...what does it indicate? It cannot be inches! because 2/(3inch)=is 0.02mm. But the area of 2/3" sensor is 58.1 sq.mm. I was just curious about it. and is there any particular reason why the sensor sizes are cut down (eg. from 36*24 mm to 23.7*15.7mm and so on.) the way they have been?

Book a conference room with a whiteboard and some dry-erase markers and we could probably knock this out in half an hour.

Was that a joke?

[BUGSBUNNYBOSS]

Ooops, I forgot the question on illumination.

Look at the sensor size comparison again and consider that if the lens is not designed to cover the sensor but has a larger angle of view than necessary then some of the light is falling off the edges. That is lost illumination. The right lens will put as much light as possible directly on the sensor.

So the min. illumination, represent the lost light by the sensor from the lens?

[Saorsa]

Part of it. There is the FOV in front of the lens and then there is the projected image. Most lenses are designed for a particular format so there is very little spill. The f or T stop of the lens also makes a difference in the illumination delivered to the sensor.

It's even more complicated than that. The sensor has to be able to discriminate between frequencies well enough to show some separation. That's one reason most thermal imaging systems seem fuzzy. They aren't seeing the limits of the objects, they are seeing temperatures. Stand a naked person in from of a panel heated to 98.6F and it would be ambiguous. You can seem some parts because of temperature differences. For example a cold nose and/or ears and your brain fills in the gaps.