Digital Reciprocity Failure Charts
Jan 18, 2019 14:36:12 #
Oh the days of those old mechanical calculators. In the early 1970s, in college, we had a room full of those including the Monroe units which looked like big typewriters. The digits appeared on the slide and, given these units were 1960s tech, the did fairly well. Dividing was interesting though. Dividing by zero was just so cool. The unit would spin, sputter and purr, and slowly the digit 9 would appear in every window until the last 9 and then everything would STOP. The fix? Unplug the calculator, do some kind of manual reset, plug it in again and then get back to work. Note that pocket calculator was just coming out and they had some all electronic units as well. Hard to believe that the fantastic HP-80 and HP-35 came out as just about the same time. These were WAY ahead of everything else out there. Divide by zero? You just get a flashing 0.00 in the display. Ditto for any illegal math operation, like the ARCSINE of 2. Hit CLX or CLEAR and move on.
Jan 18, 2019 14:44:10 #
Mathematics aside, since I made the transition to digital photography, I have not seen the classic gremlins caused by reciprocity law failure that sometimes occurred with film; extreme under exposure, having to exponentially extend long exposures, color crossover, underexposure due to extremely short flas durations. Film data used to include reciprocity factors. With color transparency films in large format, what with multiple filter (filter factors), bellows extensions and long exposure or multiple "pops" sometimes reciprocity failure was a nightmare. Ain't seen any of that in a long time! If anything a few bracketed exposures cover any possibilities. Don't need a chart!
Now let me get my calculator out and make sure it has a "ZERO" button!
Now let me get my calculator out and make sure it has a "ZERO" button!
Jan 18, 2019 15:00:50 #
nadelewitz wrote:
Research this yourself.
Key word in the OP, then reaffirmed later, was SATIRICAL - as in satire.
Jan 18, 2019 15:25:24 #
Jan 18, 2019 16:12:26 #
Shutterbug57 wrote:
Key word in the OP, then reaffirmed later, was SATIRICAL - as in satire.
And, because this WHOLE thread is a put-on, perhaps, that explains why there's NO "Return to Digest" Link!!!
Jan 18, 2019 16:24:50 #
Jan 18, 2019 17:18:13 #
St.Mary's wrote:
Pie are round, cake are square
I beg your pardon? … I think you'll find cakes come in all shapes and sizes …
But, pi - is only a letter in the Greek alphabet, and a thing in algebra, too …
Whichever, pies are usually round, but PI is used to measure the circumference …
Now, where on earth is that "return to digest" hyperlink?
Maybe, it got swallowed up in a SQUARE pi, huh?
Jan 18, 2019 17:48:54 #
BartHx wrote:
In high school, (when we were still using slide ru... (show quote)
We had Fridens, and they must have been a bit different than Marchants. When you hit both division keys without a number entered, they would just go into a mechanical loop. The solution was always to just unplug them, and they'd reset on their own.
My Dietzgen slide rule has a leather case, and it's constructed of bamboo. I still get it out occasionally to see if I can still estimate past the indexes.
As an aside, the Texas Instrument SR10 came out in 1972. In January 1973 the book store sold them for $150, or so. They were a life saver in Bus. Stats. By the start of classes in September, they were going for $10 on sale.
Jan 18, 2019 18:52:15 #
TheShoe
Loc: Lacey, WA
jerryc41 wrote:
Well, you're almost right. Digital works with 1s and 0s. Dividing by 1 would get you what you started with. What you must do is divide by zero! As any good mathematician knows, there is something magical about dividing by zero.
Of course, but you have to deal with first order transcendental numbers.
Jan 18, 2019 23:08:07 #
nadelewitz wrote:
Funny, I was researching this subject just the oth... (show quote)
You may have noticed I (for one) was implying I knew that at the outset of this thread.
Jan 18, 2019 23:13:30 #
BartHx wrote:
In high school, (when we were still using slide ru... (show quote)
Now I know why the teachers would not let the students touch the mechanical calculating machines. Division by 0 in FORTRAN caused issues too. I bought my first electronic calculator, a HP45 in 1974. Wow, was it expensive.
Jan 19, 2019 01:40:14 #
In answer the OPs original question about digital reciprocity, It is a moot point.
Digital storage holds so many photos you just shoot and erase until you get it right.
I shot the Northern lights in Iceland at I time when they just look like a grey cloud to the naked eye. I started at ISO 800 for 10 seconds and only captured the grey cloud the eye sees.
A fellow shooter was shooting ISO 1600 for 20 seconds with a fast lens so I shot ISO 3200 for 30 seconds with a 2 second delay to steady the camera and the eerie green glow was all over the sky in the view finder. Since my camera has a bulb setting I am only limited by how long I want to wait for an exposer.
Take your best guess then quadruple the exposure (roughly 4 stops) until you can hone in on the settings you like.
Digital storage holds so many photos you just shoot and erase until you get it right.
I shot the Northern lights in Iceland at I time when they just look like a grey cloud to the naked eye. I started at ISO 800 for 10 seconds and only captured the grey cloud the eye sees.
A fellow shooter was shooting ISO 1600 for 20 seconds with a fast lens so I shot ISO 3200 for 30 seconds with a 2 second delay to steady the camera and the eerie green glow was all over the sky in the view finder. Since my camera has a bulb setting I am only limited by how long I want to wait for an exposer.
Take your best guess then quadruple the exposure (roughly 4 stops) until you can hone in on the settings you like.
Jan 19, 2019 08:27:44 #
St.Mary's wrote:
Pie are round, cake are square
Wrong!
π² = 9.86960440109
https://www.youtube.com/watch?v=QPRAylPAgXk (globe cake - aka round cake)
or, see below
Jan 19, 2019 08:50:50 #
larryepage
Loc: North Texas area
In the South, we generally say that pi are round, cornbread are square. There are several counterexamples, though. My wife bakes round cornbread, the raspberry pi controllers that the smart kids use to build robots and such are square or rectangular, and as demonstrated above, cobblers, which really aren't pi's anyway, are most usually square.
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