Is added adapter similar to extension tube?

Started 3 months ago | Questions thread
fferreres Veteran Member • Posts: 6,440
Re: Is added adapter similar to extension tube?

grsnovi wrote:

Paraphrasing Wikipedia , I understand that extension tubes:

Contain no optical elements...

and they move the lens farther away from the focal plane results in:
- closer focus,
- greater magnification,
- and greater loss of light.

Lens adapters may unintentionally have an effect similar to an extension tube.

(I had extension tubes for my FTb in 1970).

You can use a macro tube to focus a lens. Or you can use a mount with the wrong distance and focus past infinity or much closer. There’s nothing special about adapting fully manual lenses.

However, many mounts can operate or read info from the lens, either change lens options, instruct focus, change aperture, etc. So an adapter may have more features, and likewise, and extension tube may have more features.

The important thing to know is the lens and the sensor do not care one bit what’s around the optics. The lens always does the same thing (unless with floating parts) regardless of anything else, so at the right distance from the sensor it will always show the same thing regardless of sensor type, maker, or astrological sign of the photographer.

The only thing we need is for a sensor and lens to be the right distance apart, to make the same image. Of course, we need to also prevent light not coming from the lens from going into the sensor.

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