Extreme macro

Started 2 months ago | Questions thread
jimhughes
jimhughes Senior Member • Posts: 1,319
Re: Definitions

Leonard Migliore wrote:

jimhughes wrote:

D Cox wrote:

jimhughes wrote:

Filters and extension tubes don't increase "magnification" - they just reduce the minimum focus distance. 2 macro lenses of the same focal length might have different minimum focus distances, so the subject will fill different amounts of the frame.

They certainly do increase magnification. Using either a close-up lens, an extension tube or a bellows will give a bigger image of the object on the sensor. You will probably need to re-focus.

The image on the sensor doesn't get bigger unless you move closer.

Well, if you put an extension tube or a close-up lens on a camera lens, you have to move closer to be in focus. That's the whole point of those devices. Note that if you move closer to an object than the lens's minimum focus distance, the magnification will increase. It just won't be in focus.

Magnification has a specific definition in optics. It's the ratio of the image size to the object size. Period. Please do not redefine it.

I agree to the extent that another term for "reproduction ratio" is "photographic magnification".

Adding a so-called closeup filter does not in itself increase this, as one can see by experiment. It does allow you to increase it by further reducing the distance to the subject and re-focusing.

Here's how Nikon puts it:

https://imaging.nikon.com/lineup/dslr/basics/19/04.htm

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