Equivalent focal length for MFT lenses

Started Apr 12, 2013 | Discussions thread
KenBalbari Regular Member • Posts: 276
Re: Equivalent focal length for MFT lenses

s_grins wrote:

KenBalbari wrote:

rrr_hhh wrote:

As for the rest, I hate these equivalence debates and won't go further. You have been caught of guard stating that the F stands for focal length while it isn't and you are now trying to rationalize this, using the term aperture in a way most photographers won't use it, unless they are into optics and lens design. Just admit you have goofed with that minor thing,  like I admitted myself above.

But all I was saying is that the f in f/6.7 stands for focal length.  That is correct.

Ken, please stop it.You're doing a great disservice to those whom you wnt to support.

F/5.7 is not a focal lens, it is aperture.

Nobody here thinks that aperture is a diameter of the opening in iris (please wikipedia this word for yourself- iris).

Stop Ballsh^tting and begin to learn things you do not know.

Again - aperture is F-stop, not a diameter. This hole will be 2 times less in diameter on M43 lens, than on FF lens to keep F-stop aka aperture the same

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"1 : an opening or open space : hole b : the diameter of the stop in an optical system that determines the diameter of the bundle of rays traversing the instrument c : the diameter of the objective lens or mirror of a telescope"

"1. an opening, as a hole, slit, crack, gap, etc. 2. Also called aperture stop.  Optics. an opening, usually circular, that limits the quantity of light that can enter an optical instrument."

"In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane"

"1 the hole in a camera that lets light in 2. Formal a small narrow hole"

"a small and often narrow opening, especially one that allows light into a camera"

  1. An opening; an open space; a gap, cleft, or chasm; a passage perforated; a hole; as, an aperture in a wall.An aperture between the mountains. --Gilpin.The back aperture of the nostrils. --Owen.
  2. (optics) Something which restricts the diameter of the light path through one plane in an optical system.
  3. (astronomy, photography) The diameter of the aperture (in the sense above) which restricts the width of the light path through the whole system. For a telescope, this is the diameter of the objective lens. e.g. a telescope may have a 100 cm aperture."

"aperture (plural apertures)

  • an opening, hole, or gap
  • a space through which light passes in an optical or photographic instrument, especially the variable opening by which light enters a camera"

noun"Definition of aperture

"An aperture is an opening, usually a small one. “If you can thread the silk through that aperture and pull it out the other side, we can knot it and create a loop.”

The most common place you’ll find aperture is when you’re talking about cameras or photography. In that case, an aperture refers specifically to the hole or opening in the lens that lets light through, which you can adjust (with the f-stop) to let in more or less light, resulting in a shallow or deep range of focus" "1. An opening, such as a hole, gap, or slit. 2.  a. A usually adjustable opening in an optical instrument, such as a camera or telescope, that limits the amount of light passing through a lens or onto a mirror. b. The diameter of such an opening, often expressed as an f-number. c. The diameter of the objective of a telescope."

And finally:


"Aperture refers to the size of the opening in the lens that determines the amount of light falling onto the film or sensor. The size of the opening is controlled by an adjustable diaphragm of overlapping blades similar to the pupils of our eyes. Aperture affects exposure and depth of field.

Just like successive shutterspeeds, successive apertures halve the amount of incoming light. To achieve this, the diaphragm reduces the aperture diameterby a factor 1.4(square root of 2) so that the aperture surface is halved each successive step as shown on this diagram.

Because of basic optical principles, the absolute aperture sizes and diameters depend on the focal length. For instance, a 25mm aperture diameter on a 100mm lens has the same effect as a 50mm aperture diameter on a 200mm lens."

Look, I'm relatively new to this forum, and if the culture here for some reason is to refer to the aperture as an iris, and the f-stop as an aperture, I'm sure I can adjust if it will help keep the peace.  But in the rest of the English speaking world, the aperture is the actual hole, and in photography it often means the diameter of the hole ("aperture diameter" on a site like this should frankly be considered redundant and unneccesary).  And the F-stop is a specification of the aperture relative to the focal length.

And what's this "whom you want to support"?  Why would I want to support anyone?

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