Equivalent focal length for MFT lenses

Started Apr 12, 2013 | Discussions thread
GeorgianBay1939
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Vocabulary
In reply to KenBalbari, Apr 15, 2013

If I cause concern by changing to subject to Vocabulary in both this and my reply to DM I apologize, for I am a newbie in these affairs.

I would suggest that you check out my post (above) to DM as some of it applies to this discussion.

KenBalbari wrote:

GeorgianBay1939 wrote:

GOLLYWOP'S ARTICLE  is a good start to help new photographers get a clear understanding of Exposure Vs Brightening.  Unfortunately many folks still believe in the Exposure Triangle and the software houses will continue to mislabel their sliders.

I really don't mind that, honestly.  Of course, traditionally, one referred to the exposure of the film.  And if you changed to a film of different sensitivity, you had to change the exposure.

But traditionally, you had to physically change the film to change sensitivity.  Now that this is a parameter that is easily adjusted in camera, why not consider it part of what determines exposure?

Of course, this changes the meaning of "exposure", to where we are now talking about the "exposure" of an image, not a film.  And this is somewhat divorced from the original meaning, which was how much the film was "exposed" to light. And maybe it would be better to talk instead of image "brightness".  Or to have those software sliders go in the other direction (meaning you can't change the exposure, but you can tell the software how much it was over or under exposed; so as you lower it, the image gets brighter).

Very backwards, because it prolongs the confusion caused by the initial error in terminology.

Instead change the titles of the Exposure slider to Brightening.  Keep them organized as in LR4 (instead of LR3) as they now, at least, relate to the histogram (and (somewhat) to the tone curve)

But meanings of words do change over time, when there are practical reasons.  And I don't mind people talking about exposure of an image, as long as it is clear what we are talking about.  We all the time rountinely say whether an image is "over-exposed" or "under-exposed" when we are really talking about the brightness of the image.

The relative brightness of an image can be DUE to over exposure or under exposure when the image was captured by the sensor.  When it was EXPOSED!

When I first learned some physics, a half a century ago I learned what EXPOSURE meant:

"In photography, exposure is the amount of light allowed to fall on each area unit of a photographic medium (photographic film or image sensor) during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value (EV) and scene luminance in a specified region."

Simple!  When one uses the word as defined above in a discussion about ETTR (or loading the sensor, in my head) the discussion proceeds normally into a proper understanding of s/n, adu, noise reduction, ISO-invariant sensors etc.

However, last fall, when I ventured into RAW shooting, using RAW processing etc, I was terribly waylaid by writers who had simply extrapolated their "understanding" of "exposure" to ETTR with lots of noise and incorrect conclusions.

Simple case of a huge unnecessary learning obstacle probably caused by blind obedience to Bryan Peterson (Who does get it right in his very first paragraph!)  If we are going to include ISO in "exposure" then we need an Exposure RECTANGLE to include the most important variable, Scene Luminance (or Illuminance if measured by a meter).

So this is a simple plea to clean up our vocabulary, at least here.  That way, at least, we, (the proud owners of cameras that are easy to carry, have good EVFs, have good IQ and are fun to use,) can demonstrate that we know what we are talking about.

All good stuff, eh?


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