Dynamic Range -- what it is, what it's good for, and how much you 'need'

Started Oct 17, 2011 | Discussions thread
boggis the cat
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Strawman tactics don't work
In reply to Rikke Rask, Oct 23, 2011

Rikke Rask wrote:

boggis the cat wrote:

(With supporting strawman arguments from Rikke Rask.)

How much more milk is 2.2 liters compared to 2 liters? 10% or 21%?
How many times more light will f/2.2 let through compared to f/2? 10% or 21%?

Ignoring your third attempt at a strawman -- to get back to the original dispute over where FourThirds is positioned compared to other sensor sizes:
http://forums.dpreview.com/forums/read.asp?forum=1022&message=39650611

In the case of FourThirds compared to APS-C we get:

  • FT is 0.5 (1/2) "stop" less efficient than Canon APS-C (1.6x)

  • FT is 0.67 (2/3) "stop" less efficient than APS-C (1.5x)

  • FT is 1.88 "stops" less efficient than 135 ("Full Frame").

And:

The correct measures are:

  • From 24 × 36 to 15.8 × 23.6 is about 1.2 "stops"

  • From 15.8 × 23.6 to (13 × 17.3) × 1.04 is 0.67 "stops".

Adding Canon APS-C:

  • From 24 × 36 to 14.8 × 22.2 is 1.4 "stops"

  • From 14.8 × 22.2 to (13 × 17.3) × 1.04 is 0.49 "stops".

If you have 1.2 litres of water (or anything else) you have nearly double 0.67 litres. An exposure increase of 1.2 stops is nearly double an exposure increase of 0.67 stop.

Or, APS-C (1.5×) is twice as close to FourThirds in efficiency as it is to 135. APS-C (1.6×) -- at 1.4 and 0.49 "stops" -- is three times closer to FT as it is to 135.

Your proposition:

For people not hung up on insignificant decimals it is roughly midway between FT and FF, roughly a stop from each.

http://forums.dpreview.com/forums/read.asp?forum=1022&message=39618215

It's quite simple:

Neither APS-C variant is a "stop" less efficient than 135, and neither is a "stop" more efficient than FourThirds.

Your claim that this is even "roughly" the case is demonstrably false. Why not accept that all of the APS-C variants and FT are "roughly" the same in efficiency compared to 135, if accuracy is unimportant? They are all much closer together in sensor size than they are to 135.

Your attempted diversion into confusing linear and exponential measures, and introducing uncertainty into the theory, serve to demonstrate that you understand this perfectly well (and can't assail the math) so you are choosing to try to introduce confusion -- the normal course of action taken by the "educators" that plague OSTF when their assertions unravel.

I'll reiterate what you've been told over and over -- you have zero credibility precisely because of this sort of tactic. The same applies to Joe.

Keep posting your strawman arguments, and I'll keep posting the facts. Reality wins out over not only flawed theory, but also over total BS.

In case you missed it:

  • FT is 0.5 (1/2) "stop" less efficient than Canon APS-C (1.6x)

  • FT is 0.67 (2/3) "stop" less efficient than APS-C (1.5x).

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