5 ms·

Kaufmann's Posographe: a pocketable analog exposure calculator

58 points by polm23 5y ago

elromulous 5y ago
I presumed this somehow summed radiation exposure.
- snypher 5y ago
  Did you read the article?
lmilcin 5y ago
And completely unneeded. Thanks to Ansel Adams we have the Zone System which I use to accurately set up my exposures in manual mode to cover exactly the part of dynamic range of my camera that I want. With some training I can set my exposure to within 1/2 EV within 2-5 seconds (depending on how many parameters I need to change) which means it actually saves me time compared to built in meter.
- heisenzombie 5y ago
  Are you saying you meter by eye? Without using an exposure meter?
  - frostburg 5y ago
    No, you use a spot meter for the zone system, generally.
    - lmilcin 5y ago
      Yes, spot meter. At least until you learn to go without one. The easiest is to use the one you already have in camera (I assume DSLR). Just configure it to be smallest possible spot. Then measure objects depending on which zone you want to place them. This means manipulating camera exposure until the spot meter shows it in the right zone. Unless I have some very specific artistic effect in mind, typically the most important measurement is to measure highlights as overexposing is much more damaging than underexposing on digital camera (which is exactly opposite to film photography).
  - lmilcin 5y ago
    What do you think people were doing before there were exposure meters available or when one was just too expensive for them? For a long time exposure meters were a luxury.
- gerikson 5y ago
  This device pre-dates the Zone system by quite some time.
  - lmilcin 5y ago
    Actually, I could not find a date. Adams was born in 1902 and Kaufmann in 1885. Zone System was "formulated" in 1930 when Kaufmann would have been 45. Kaufmann was said to be quite brilliant at early age and so it is possible or even likely that the device predates Zone System, but not by all that much (probably 2 decades at most).
raymondh 5y ago
It's pretty cool what humans can design. This piece is quaint and charming, but the mechanism is especially clever.
- snypher 5y ago
  I love the implication that even with the correct math you might still need to tweak it to be accurate. Does anyone know where you would get started on making something like this, especially the conversion from a mathematical formula into a linkage system?
  - _Microft 5y ago
    The Oughtred Society might have resources on this on their website: http://www.oughtred.org/ http://www.oughtred.org/

58 points by polm23 5y ago

elromulous 5y ago

I presumed this somehow summed radiation exposure.

snypher 5y ago
Did you read the article?

lmilcin 5y ago

And completely unneeded. Thanks to Ansel Adams we have the Zone System which I use to accurately set up my exposures in manual mode to cover exactly the part of dynamic range of my camera that I want. With some training I can set my exposure to within 1/2 EV within 2-5 seconds (depending on how many parameters I need to change) which means it actually saves me time compared to built in meter.

heisenzombie 5y ago
Are you saying you meter by eye? Without using an exposure meter?
- frostburg 5y ago
  No, you use a spot meter for the zone system, generally.
  - lmilcin 5y ago
    Yes, spot meter. At least until you learn to go without one. The easiest is to use the one you already have in camera (I assume DSLR). Just configure it to be smallest possible spot. Then measure objects depending on which zone you want to place them. This means manipulating camera exposure until the spot meter shows it in the right zone. Unless I have some very specific artistic effect in mind, typically the most important measurement is to measure highlights as overexposing is much more damaging than underexposing on digital camera (which is exactly opposite to film photography).
- lmilcin 5y ago
  What do you think people were doing before there were exposure meters available or when one was just too expensive for them? For a long time exposure meters were a luxury.
gerikson 5y ago
This device pre-dates the Zone system by quite some time.
- lmilcin 5y ago
  Actually, I could not find a date. Adams was born in 1902 and Kaufmann in 1885. Zone System was "formulated" in 1930 when Kaufmann would have been 45. Kaufmann was said to be quite brilliant at early age and so it is possible or even likely that the device predates Zone System, but not by all that much (probably 2 decades at most).

raymondh 5y ago

It's pretty cool what humans can design. This piece is quaint and charming, but the mechanism is especially clever.

snypher 5y ago
I love the implication that even with the correct math you might still need to tweak it to be accurate. Does anyone know where you would get started on making something like this, especially the conversion from a mathematical formula into a linkage system?
- _Microft 5y ago
  The Oughtred Society might have resources on this on their website: http://www.oughtred.org/ http://www.oughtred.org/