For those of you wanting to refine your image processing (something we all need), this new tutorial by Michael Reichemann and Jeff Schewe is the best $40 you will ever spend. Eight hours and 29 lessons. The only problem is that for me anyway the download time is about four times longer than the lessons (slow DSL out here in the mountains).
Tim, thanks for the link, I downloaded their tutorial on printing and it was excellent!
Posted by Tim Buchanan on April 18, 2008 at 11:27 AM
I'm about 6 hours into viewing it. Great stuff so far (and even a few tips that were unfamiliar). The interviews snippets from Thomas Knoll (the guy that wrote ACR) are pretty interesting too.
Definitely worth 40 bucks. But I was just a bit surprised to hear Jeff Schewe refer to degrees kelvin in the white balance part. I thought everybody knew that since 1968 there have been no degrees kelvin as with the Fahrenheit and Celsius scales - only kelvin...
I guess I don't understand - I've never heard anything from anyone but degrees kelvin - how else would you say it? And if everyone is still using "degrees" I guess that means it is indeed still the norm - that is only logical. Of course, just like the way the forest fire service is burning down our forests in Arkansas right now I guess not everything our government does is logical! We as individuals can only hope to continue to do as many logical things as possible, so I think I'll stick with degrees kelvin until there is another reason to do otherwise. Spock
I'm sure most photography circles still use degrees, but in the scientific world it has been that way for quite some time. Here's an excerpt from the Wikipedia:
Until the 13th General Conference on Weights and Measures (CGPM) in 1967-1968, the unit kelvin was called a "degree", the same as with the other temperature scales at the time. It was distinguished from the other scales with either the adjective suffix "Kelvin" ("degree Kelvin") or with "absolute" ("degree absolute") and its symbol was °K. Note that the latter (degree absolute), which was the unit’s official name from 1948 until 1954, was rather ambiguous since it could also be interpreted as referring to the Rankine scale. Before the 13th CGPM, the plural forms were "degrees Kelvin" or "degrees absolute". The 13th CGPM changed the name to simply "kelvin" (symbol K). The omission of "degree" indicates that it is not relative to an arbitrary reference point such as the Celsius and Fahrenheit scales, but rather an absolute unit of measure which can be manipulated algebraically (e.g. multiply by 2 to indicate twice the amount of heat).
The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures (CGPM, never GCWM). It is one of the three organizations established to maintain the International System of Units (SI) under the terms of the Convention du Mètre (Metre Convention) of 1875. It meets in Paris every four to six years. The CGPM represents 51 member states and 25 further associate members.
I think in a room of photographers, nobody would probably notice if someone used "degrees kelvin" . Photographers are not generally considered scientists - we're artists. But I'm sure a room full of engineers, chemists, and physicists would be quick to correct if one were to express temperature that way. Most of the United States has long been behind the rest of the world when it comes to measurement units. We still like to use feet, inches, gallons, miles, and some still use degrees kelvin. Scientists and engineers are an exception. Most professional scientific journals switched over to metric (SI) years ago.
Here's the wiki site for those inquiring minds that want to know. There's even a short discussion on color temperature.
Oh, OK - the same folks who converted us to metric! That went over pretty well too! Sounds like in the real world of color photography the term degrees continues to be the norm so no reason to do otherwise. Thank goodness - I thought I had missed something...
Posted by Tim Buchanan on April 22, 2008 at 5:12 PM
What? You mean 4 °F isn't twice as warm as 2 °F?
One nit I had was with Reichmann's description of smart RAW objects (I'm not sure he's used them very often). He seemed to imply that a link exists back to the original RAW file, which is not the case - it's an embedded copy.
Discussion
8 repliesLuminous Landscape Guide to Camera Raw
Until the 13th General Conference on Weights and Measures (CGPM) in 1967-1968, the unit kelvin was called a "degree", the same as with the other temperature scales at the time. It was distinguished from the other scales with either the adjective suffix "Kelvin" ("degree Kelvin") or with "absolute" ("degree absolute") and its symbol was °K. Note that the latter (degree absolute), which was the unit’s official name from 1948 until 1954, was rather ambiguous since it could also be interpreted as referring to the Rankine scale. Before the 13th CGPM, the plural forms were "degrees Kelvin" or "degrees absolute". The 13th CGPM changed the name to simply "kelvin" (symbol K). The omission of "degree" indicates that it is not relative to an arbitrary reference point such as the Celsius and Fahrenheit scales, but rather an absolute unit of measure which can be manipulated algebraically (e.g. multiply by 2 to indicate twice the amount of heat).
The General Conference on Weights and Measures is the English name of the Conférence générale des poids et mesures (CGPM, never GCWM). It is one of the three organizations established to maintain the International System of Units (SI) under the terms of the Convention du Mètre (Metre Convention) of 1875. It meets in Paris every four to six years. The CGPM represents 51 member states and 25 further associate members.
I think in a room of photographers, nobody would probably notice if someone used "degrees kelvin" . Photographers are not generally considered scientists - we're artists. But I'm sure a room full of engineers, chemists, and physicists would be quick to correct if one were to express temperature that way. Most of the United States has long been behind the rest of the world when it comes to measurement units. We still like to use feet, inches, gallons, miles, and some still use degrees kelvin. Scientists and engineers are an exception. Most professional scientific journals switched over to metric (SI) years ago.
Here's the wiki site for those inquiring minds that want to know. There's even a short discussion on color temperature.
One nit I had was with Reichmann's description of smart RAW objects (I'm not sure he's used them very often). He seemed to imply that a link exists back to the original RAW file, which is not the case - it's an embedded copy.