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Lightroom SQLITE Database Structure

Bill Plunkett

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This question is a little out of the ordinary stuff but I have a particular need for the answer. I am both a photographer and a programmer and write code to manage my photography business. I have reversed engineered the SQLite table (i.e. the Lightroom Catalog) but have one thing I can not figure out. In the AgHarvestedExifMetadata the shutterSpeed column has a figure of 8.321928 for a shutter speed of 1/320 and 5.906891 for a speed of 1/60.

Does anyone possibly know what these numbers mean?

thanks,
 
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2 to the power 8.9321928 = 320
2 to the power 5.906891 = 60
It's the number of stops faster than a shutter speed of 1 second. I have no clue why.
 

Bill Plunkett

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2 to the power 8.9321928 = 320
2 to the power 5.906891 = 60
It's the number of stops faster than a shutter speed of 1 second. I have no clue why.

WOW, thanks Hal. I guess it's back to logarithms... thanks again Hal
 
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2 to the power 8.9321928 = 320
2 to the power 5.906891 = 60
It's the number of stops faster than a shutter speed of 1 second. I have no clue why.
I would suppose the fact the a computer only works with binary numbers (0 & 1) has something to do with it Good sleuthing!
 
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As a programmer myself, this is the kind of thing I was thinking about. Nice shot Hal but about the why of it... no clue either :whistling:

My guess is that it may optimize the calculations time for some adjustments in the develop module. Again, just a guess.
 

Bill Plunkett

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This is a response I got on the Xojo forums:

• Their algorithm uses 2^x so it makes sense to store its value
• By contrast with a division (1/320 or whatever), 2^x will not become 0 or infinity just because of a bad value floating around
 
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I would suppose the fact the a computer only works with binary numbers (0 & 1) has something to do with it Good sleuthing!
A stop is 2x the light.

An f-stop number is 1.414 * the prior stop, which is the square root of two, since lens surface area varies by the square of the radius, so to get twice the area (light) you get 1.414 times the opening.

And ISO's vary by 2x each stop also.

And from a point source light falls off by the square of the distance.

The number 2, its square root and square, appear everywhere in photography. It's really kind of elegant.
 

Bill Plunkett

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A stop is 2x the light.

An f-stop number is 1.414 * the prior stop, which is the square root of two, since lens surface area varies by the square of the radius, so to get twice the area (light) you get 1.414 times the opening.

And ISO's vary by 2x each stop also.

And from a point source light falls off by the square of the distance.

The number 2, its square root and square, appear everywhere in photography. It's really kind of elegant.


But why is all this incumbent on storing what shutter speed an image was shot at in the Lightroom Catalog. It's just a freaking reference for how the image was shot. I minored in Math at college and took 2 physics courses so I get the all this but my question is why does it matter in how the shutter speed is stored in the catalog.
 
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But why is all this incumbent on storing what shutter speed an image was shot at in the Lightroom Catalog. It's just a freaking reference for how the image was shot. I minored in Math at college and took 2 physics courses so I get the all this but my question is why does it matter in how the shutter speed is stored in the catalog.
Somewhere in the decision process there was a geeky computer nerd that made the decision to store the shutter speed as a power of the binary value. I'm sure with your background in math and physic, you have met one or more of these people.
 
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Somewhere in the decision process there was a geeky computer nerd that made the decision to store the shutter speed as a power of the binary value. I'm sure with your background in math and physic, you have met one or more of these people.
Exactly, the same reason that while in college I occasionally encountered, buried in code, some constant expressed in Furlongs per Fortnight. You have moved from the realm of physics, databases and math to that of psychology. Some would say abnormal psychology, but I also started in physics and math so to me abnormal psychology is more about why people think they can answer the "why" of people with science. o_O
 

LRList001

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Furlongs per Fortnight is the standard unit of measure we Brits use to remind our American friends that we speak a different language.
 
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Furlongs per Fortnight is the standard unit of measure we Brits use to remind our American friends that we speak a different language.
And the more common "chips". Serves you right if you come over here and get Crisps with your fish. ;)

I used to think you spoke English then a buddy tried to explain Cockney Rhyming Slang, that weights are in Stone and money in pounds, and I finally started to understand why I never understood Alice in Wonderland -- lack of LSD.
 

LRList001

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And it took me a long time to understand the Cat in the Hat. That last Zed. Aha, its a Zee.
 

LRList001

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I used to think you spoke English then a buddy tried to explain Cockney Rhyming Slang, that weights are in Stone and money in pounds, and I finally started to understand why I never understood Alice in Wonderland -- lack of LSD.
I forgot to say that LSD means Pounds, Shillings and Pence - British currency before decimalisation in 1971. Just to keep the confusion levels high.

From Wikipedia (Pound sterling - Wikipedia):
"These units were abbreviated to 'd' from denarius for penny; 's' from solidus for shilling; and 'L' (subsequently £) from Libra or Livre for the pound."
 
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I forgot to say that LSD means Pounds, Shillings and Pence - British currency before decimalisation in 1971. Just to keep the confusion levels high.

From Wikipedia (Pound sterling - Wikipedia):
"These units were abbreviated to 'd' from denarius for penny; 's' from solidus for shilling; and 'L' (subsequently £) from Libra or Livre for the pound."
LSD explains a lot of british television at the time. ;)

I still miss Emma Peele.
 

PhilBurton

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Furlongs per Fortnight is the standard unit of measure we Brits use to remind our American friends that we speak a different language.
How about a measure of length called "smoot," as in "The Harvard (or MIT) Bridge connecting Boston and Cambridge is 364.4 smoots in length."

I am not making this up.
 
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