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Equivalence theory

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Jonas A-R View Drop Down
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Topic: Equivalence theory
    Posted: 04 January 2019 at 05:46
Nice paper on equivalence

Equivalence theory for cross-format photographic image quality comparisons

D. Andrew Rowlands
Optical Engineering, 57(11), 110801 (2018).
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sybersitizen View Drop Down
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 04 January 2019 at 07:13
Just a basic paragraph or two about equivalence is enough to irritate some people. I wonder what'll happen if they see that!
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Post Options Post Options   Quote SnowFella Quote  Post ReplyReply Direct Link To This Post Posted: 04 January 2019 at 07:16
Can't wait for someone to post that over at DP Review...be popcorn time for sure!
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 04 January 2019 at 07:31
I never got why people can be upset by such a simple concept.

I like the term equivalence ratio used here as an alternative to “crop factor”.
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Post Options Post Options   Quote owenn01 Quote  Post ReplyReply Direct Link To This Post Posted: 04 January 2019 at 09:24
Originally posted by SnowFella SnowFella wrote:

Can't wait for someone to post that over at DP Review...be popcorn time for sure!


Go on - just Do It!
My Mantra: "Comment on other's work as you would wish to have yours commented upon". Go on - it's fun!
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Jonas A-R View Drop Down
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 04 January 2019 at 09:55
Originally posted by owenn01 owenn01 wrote:

Originally posted by SnowFella SnowFella wrote:

Can't wait for someone to post that over at DP Review...be popcorn time for sure!


Go on - just Do It!


I’ve done it :)
Although it was in the photographic science and technology forum where I would be surprised to see any controversy. It is not exactly new stuff
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Post Options Post Options   Quote SnowFella Quote  Post ReplyReply Direct Link To This Post Posted: 04 January 2019 at 10:16
Originally posted by Jonas A-R Jonas A-R wrote:



I’ve done it :)
Although it was in the photographic science and technology forum where I would be surprised to see any controversy. It is not exactly new stuff


Aww..should of parked it in the Open or Beginner forum's for max effect....quite similar to what happens if someone asks about HSS. Que a leaf vs focal plane shutter argument in 2 seconds!
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Post Options Post Options   Quote QuietOC Quote  Post ReplyReply Direct Link To This Post Posted: 04 January 2019 at 14:02
Originally posted by Jonas A-R Jonas A-R wrote:


I like the term equivalence ratio used here as an alternative to “crop factor”.

Using diagonal measures to compare varied aspect ratios doesn't work. The area is what is important--the square root of the area is the correct number to use.

I am surprised equivalence deserves a paper. It seems more worthy of a YouTube video like another one I recently watched about scaling which started with throwing a mouse, a dog, and an elephant off a skyscaper.

Edited by QuietOC - 04 January 2019 at 14:14
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Jonas A-R View Drop Down
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 04 January 2019 at 14:32
Originally posted by QuietOC QuietOC wrote:

Originally posted by Jonas A-R Jonas A-R wrote:


I like the term equivalence ratio used here as an alternative to “crop factor”.

Using diagonal measures to compare varied aspect ratios doesn't work. The area is what is important--the square root of the area is the correct number to use.


That is acknowledged in the paper. I think it is ok to use either the diagonal, the height or the width depending on the purpose of the comparison although I realize it will not be accurate in terms of total light.
One could also decide upfront which image aspect ratio will be used for display and compute the required crop of either sensor.
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Post Options Post Options   Quote SnowFella Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2019 at 03:59
Hmm...reading that thread over at DP Review even in the Science & Technology section it ended up popcorn worthy. With people even emailing the site to have it taken down as it just isn't scientific enough.
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Jonas A-R View Drop Down
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2019 at 05:13
Indeed, rather entertaining although you will notice that it is not the typical equivalence denial weirdness, but rather a discussion about whether it should have been published at all as you point out.
The author could perhaps have been more clear that nothing original was presented, but he does open the paper by stating that the theory is commonly used, and in the section where equivalent photos are defined he appropriately cites Joseph James.
It is also listed as a tutorial, not a research paper.
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Post Options Post Options   Quote addy landzaat Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2019 at 06:31
Hmmm, this thread is disappointing. When equivalence is off topic you guys keep going on about it and here, in a dedicated thread, nothing. Just a popcorn worthy thread on dpreview

Anyway, it is a good thing there is a dedicated equivalence discussion in a non-equivalence thread, I can point you here
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Jonas A-R View Drop Down
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Post Options Post Options   Quote Jonas A-R Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2019 at 07:49
Originally posted by addy landzaat addy landzaat wrote:

Hmmm, this thread is disappointing. When equivalence is off topic you guys keep going on about it and here, in a dedicated thread, nothing. Just a popcorn worthy thread on dpreview


Well, so far nobody has said that equivalence is a hoax and the earth is flat. Maybe you wish to start the entertainment?

Originally posted by addy landzaat addy landzaat wrote:

Anyway, it is a good thing there is a dedicated equivalence discussion in a non-equivalence thread, I can point you here


Please do   
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Post Options Post Options   Quote eldonito Quote  Post ReplyReply Direct Link To This Post Posted: 08 January 2019 at 10:20
This is fantastic. Thank you for sharing!
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