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

Started Apr 26, 2013 | Discussions thread
Great Bustard
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Re: If you would rename your equivalence to DOF-equivalence
In reply to Mr.NoFlash, Apr 27, 2013

Mr.NoFlash wrote:

Great Bustard wrote:

Jon Stock wrote:

It was beaten to death before Joemama was banned the first time.

The only reason to post in the daily equivalence threads is to push them toward 150 sooner.

Name one famous professional photographer from any time period who specialized in really shallow DOF.

The endless pictures posted of a closeup of a meaningless object (for example - a rusty nail in a plank of wood) with really shallow of field is as gimmicky as neon colored HDR.

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Jon

http://www.josephjamesphotography.com/equivalence/index.htm#quick

  • Equivalence says nothing about shallow DOF being superior to deep DOF, as this is entirely subjective.
  • Equivalence makes no claims whatsoever about which system is superior to another system, especially given that there are so many aspects about systems that Equivalence does not address.

Seems like you missed those parts of the "discussions".

If you would rename your equivalence URL, title and headline to DOF-equivalence, i would less critisize it.

But it's not just DOF.  The same total amount of light will fall on the sensor for Equivalent photos, which will result in the same noise for equally efficient sensors.

As it stands your equivalence theory name implies aperture and sensor size are the only two parameters which defiine that two cameras with lens are equivalent ( plus perhaps focal length ), despite you agreed to my post above that there are much more parameters.

In fact, Equivalence is based on 5 parameters, but additional assumptions, such as noise and detail, can also be figured in:

http://www.josephjamesphotography.com/equivalence/index.htm#equivalence

Equivalent photos are photos of a given scene that share the following five parameters:

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.  For example, 25mm on mFT (4/3) and 31mm on 1.6x areequivalent to 50mm on FF since these focal lengths result in the same AOV on their respective formats.  Furthermore, f/1.4 on mFT (4/3) and f/1.8 on 1.6x areequivalent to f/2.8 on FF since those f-ratios result in the same aperture diameter for the same AOV on their respective formats (25mm / 1.4 = 31mm / 1.8 = 50mm / 2.8 = 18mm).

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.

Of course, sensors are not equally efficient (although often, but not always, close for a given generation).  However, that doesn't stop us from saying that a 50 / 1.4 on a Canon 5D is not equivalent to a 50 / 1.4 on a Nikon D600.  Nor are lenses equally sharp, have the same color, bokeh, or flare characteristics, but this does not stop us from saying that the Canon 50 / 1.4 is equivalent to the Nikon 50 / 1.4G which is equivalent to the Sigma 50 / 1.4.

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