Is there such thing as a universal brightness measurement?

[desertrattm2r12]

To Joe -- it means you probably ain't no expert on this. Sorry.

 

[Ysarex]

To Joe -- it means you probably ain't no expert on this. Sorry.

I see. Well the two times that I have taken the stand to testify in the role of an expert witness the court accepted my credentials as appropriate and the testimony I gave as accurate. Probably has something to do with the many decades that I've born the title Professor. In one case I was not only called upon to testify but to also render service -- a demonstration to substantiate my testimony. So, at least before the law, I most certainly am an expert on this. Just sayin'.

Joe

 

[desertrattm2r12]

I did say probably, just sayin'. I think you mean "borne," Professor. Watcha doing since that Gilligan thing? Just askin'.

 

[petrochemist]

The real quote is "the law is a ass, a idiot." (Charles Dickens -- they didn't use "an" in his day.) Whut it means is legally those spouting off on this forum about this who ain't trained in optics is on fuzzy grounds.

The original source of the quote doesn't change the truth of it.
Fortunately the forum isn't a court and you do not need to be an expert certified or otherwise to post. the opinions of complete newbies are allowed, as well as their questions...
Many photographers will be able to explain potential optical causes of a fuzzy image, out of focus, diffraction, chromatic aberration, spherical aberration, lens elements out of alignment... and add a few other not caused by optics: camera shake, subject movement, low sensor resolution, post processing. It may even be that an experienced photographer would immediately spot the optical cause of something such as flare that someone trained in optics would understand but have to think to explain.
Most of the infra-red photographs 'showing' paranormal activity seem to be down to hot-spots. Something that anyone reasonably experienced in proper infra-red photography is likely to be aware of, someone trained in optics but not fully aware of the lens coatings etc. may struggle to explain the cause.

Optics is NOT photography, it may be relevant in many cases, but doesn't cover the chemical processes of film photography or the electronic processes of digital photography. Even where optics are responsible proper analysis may rely on intricate knowledge of the system used.

 

[desertrattm2r12]

Talk a lot, maybe you will convince yourself. My point is pretty simple, one should not think any old squeaky voice on the Internet necessarily comes from an expert. That includes moi. Can you handle that? I noticed the Perfesser said he was an expert witness. But about whut? Greco-Roman wrestling or sand fleas in Florida?

 

[petrochemist]

I wouldn't dream of expecting all answers of a forum to be from experts! Some who think they know everything make significant errors on basics, it's the nature of the internet. However not having 'expert witness' status legally does not make peoples knowledge irrelevant either.

Personally I've never been called upon as an expert witness in legal cases, but I'm listed by name in the rules of at least one national motorsport championship as a 'judge of fact' in my field of expertise, making my opinion on infringement the only one that matter's when it comes to guilty or not (several others just list the company I work for). I'm not responsible for the penalty applied in cases where the defendant is guilty, but give have often given guidance on how far out the competitor was. On one occasion my evidence meant someone had to go to Germany to reclaim a trophy.

 

[andytakeone]

Take a good look at the X-system I mentioned above as the easiest framework to learn actual scene types and the right general exposure settings.

There are basically 13 different exposure values needed, ranging from a bright sunlighted beach, to birthday candles on a cake.

Look at Fred Parker's Ultimate Exposure system, Ultimate Exposure Computer and transpose its EV value system and make it into the X-system. You can easily learn the 12, or 13 common exposure settings. I gave you the first nine exposure setting for the none most common daylight lighting scenarios from full sun down to indoor sports events.

Starlighted landscape shots at Plus-21 X and Moonlighted landscapes at Plus-20 X are about the darkest exposure setting most people will ever encounter.

I'm not really sure that a 12-step range of exposures is really "wildly guessing". You probably alreqdy have memorized frameworks with more that 12 items...the NBA teams, the NFL teams, the McDonald's menu,your favorite TV shows and nights and network channels, the Taco Bell menu, the shelving system at your local grocery, you favorite iPhone MP3 playlists, etc..

There's an old joke: "What is the right exposure for Tri-X?"

"Whaddaya 'mean "the" right exposure for Tri-X? There's TWO right exposures for Tri-X....f/5.6 at 1/250, and f/2.8 at 1/30!"

I see, will do. Thanks.