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Subject distance does vary the amount of light in accordance with the inverse square law.

If you increase the subject distance by 2x it becomes 1/2 the size LxW at the image plane... .5L x .5W is .25 the area, and 1/4 the amount of light... or factor 2 square inversed (the ISL formula).

So the exposure, light per area, doesn't change; but the total light from the source does... This is the same thing as looking at situation 1 from the perspective of the apple... the brightness of the bulb doesn't change, but the amount (intensity) of light at the apple does.

This is also the same thing that happens when you zoom in/out on a subject with a constant aperture zoom lens. And it is why larger sensors tend to perform better in low light; because they actually receive more light (subject is larger on larger sensor for same composition).

Subject distance does vary the amount of light in accordance with the inverse square law.

If you increase the subject distance by 2x it becomes 1/2 the size LxW at the image plane... .5L x .5W is .25 the area, and 1/4 the amount of light... or factor 2 square inversed (the ISL formula). I.e. a smaller area at the same brightness IS less light.

So the exposure, light per area, doesn't change; but the total light from the source does... This is the same thing as looking at situation 1 from the perspective of the apple... the brightness of the bulb doesn't change, but the amount (intensity) of light at the apple does.

This is also the same thing that happens when you zoom in/out on a subject with a constant aperture zoom lens. And it is why larger sensors tend to perform better in low light; because they actually receive more light (subject is larger on larger sensor for same composition).

Subject distance does vary the amount of light in accordance with the inverse square law.

If you increase the subject distance by 2x it becomes 1/2 the size LxW at the image plane... .5L x .5W is .25 the area, and 1/4 the amount of light... or factor 2 square inversed (the ISL formula).

So the exposure, light per area, doesn't change; but the total light from the source does...

This is also the same thing that happens when you zoom in/out on a subject with a constant aperture zoom lens. And it is why larger sensors tend to perform better in low light; because they actually receive more light (subject is larger on larger sensor for same composition).

Subject distance does vary the amount of light in accordance with the inverse square law.

If you increase the subject distance by 2x it becomes 1/2 the size LxW at the image plane... .5L x .5W is .25 the area, and 1/4 the amount of light... or factor 2 square inversed (the ISL formula).

So the exposure, light per area, doesn't change; but the total light from the source does... This is the same thing as looking at situation 1 from the perspective of the apple... the brightness of the bulb doesn't change, but the amount (intensity) of light at the apple does.

This is also the same thing that happens when you zoom in/out on a subject with a constant aperture zoom lens. And it is why larger sensors tend to perform better in low light; because they actually receive more light (subject is larger on larger sensor for same composition).

Subject distance does vary the exposure in accordance with the inverse square law... just not quite as you are thinking.

If you increase the subject distance by 2x it becomes 1/2 the size LxW at the image plane... .5L x .5W is .25 the area, and 1/4 the amount of light... or factor 2 square inversed (the ISL formula).

So the exposure, light per area, doesn't change; but the total light from the source does...

This is also the same thing that happens when you zoom in/out on a subject with a constant aperture zoom lens. And it is why larger sensors tend to perform better in low light; because they actually receive more light (subject is larger on larger sensor for same composition).

Subject distance does vary the amount of light in accordance with the inverse square law.

If you increase the subject distance by 2x it becomes 1/2 the size LxW at the image plane... .5L x .5W is .25 the area, and 1/4 the amount of light... or factor 2 square inversed (the ISL formula).

So the exposure, light per area, doesn't change; but the total light from the source does...

This is also the same thing that happens when you zoom in/out on a subject with a constant aperture zoom lens. And it is why larger sensors tend to perform better in low light; because they actually receive more light (subject is larger on larger sensor for same composition).