SURVEY - Do FT / mFT users know the difference from "full frame"? Replies wanted!!

Started Apr 26, 2013 | Discussions thread
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Great Bustard Forum Pro • Posts: 36,630

Mr.NoFlash wrote:

Great Bustard wrote:


As a corollary, "equivalent lenses" are lenses that produce equivalent images on their respective formats, which means they will have the same AOV and the same aperture diameter.  ........

Thus, 25mm f/1.4 on mFT (4/3) and 31mm f/1.8 on 1.6x result in the same AOV and DOF for a given perspective (subject-camera distance).  If we also include the same shutter speed, the same total amount of light will be projected on the sensor for each system.  If the sensors are equally efficient, this will result in the same total noise.  If the mFT (4/3) lens is twice as sharp as the FF lens, and the 1.6x lens is 1.6x as sharp as the FF lens, the sensors have the same pixel count and AA filter, then all will capture the same detail.

Please rethink the effect of IBIS ( in body  image stabilisation ) on the shutter speed if the camera is held by the same hands.  assume a factor of perhaps 2 on average ( if the target does not move, its a factor of ca 3, if the target moves or a tripod is used, perhaps a factor of ca 1 - 1.5, i assume both cases happen roughly equally often ). Please include  in body  image stabilisation  into your theory or rename your theory to Dof-equivalence. Remember that no canon 50mm lens has image stabilisation.

...a huge fan of IS, but it's only relevant for static scenes, or scenes where motin blur is desireable.  That said:

Note the "danger" in comparing partially equivalent situations -- the lower shutter speed used to maintain the lower ISO will not always be feasible due to motion blur and/or camera shake, and is especially important to consider in lower light situations.  Regardless, being able to "safely" use a lower shutter speed with a larger sensor system is still a common scenario.  Of course, this can go in the opposite direction when one system has in-camera IS and/or in-lens IS that the other system does not, and motion blur is not a factor:

  • 5DII at 50mm, f/5.6, 1/50, ISO 1600
  • D300 at 33mm, f/3.5, 1/50, ISO 640
  • 7D at 31mm, f/3.5, 1/50, ISO 640
  • E30 at 25mm, f/2.8, 1/13, ISO 100

In this scenario, we are assuming a static scene and that the 5DII, D300, and 50D are not using IS lenses, whereas the E30 has sensor IS, and can thus use a much lower shutter speed and ISO to obtain a cleaner image at the desired DOF / sharpness.

In short, maybe you should read what I've written before telling me what to "rethink".

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