If you would like to post, you'll need to register. Note that if you have a BCG store account, you'll need a new, separate account here (we keep the two sites separate for security purposes).
In the old times we used to think that a film of 400 ASA was two times as sensible as one of 200 ASA (ISO)
In the old times we used to think that a film of 400 ASA was two times as sensible as one of 200 ASA (ISO)
I continued "thinking" of this kind of sensitivity without giving much thought to what is really happening in the camera. For taking photographs, I think that the result is the same
Makes my life easier
Easy answer is forget the why (ignore the math) and simply remember that when it comes to F stops, small number equals big hole/more light (and shallower depth of field).
Of course you're right. I only wanted to stress that some kind of knowledge is unnecessary in the practice, perhaps even confusing, depending on your purpose
www.cambridgeincolour.com
Of course you're right. I only wanted to stress that some kind of knowledge is unnecessary in the practice, perhaps even confusing, depending on your purpose
I for example understand the mechanics of a car. My wife doesn't.
Still, she's the better driver
Of course you're right. I only wanted to stress that some kind of knowledge is unnecessary in the practice, perhaps even confusing, depending on your purpose
I for example understand the mechanics of a car. My wife doesn't.
Still, she's the better driver
![backcountrygallery.com](https://backcountrygallery.com/backcountry-gallery-stop-struggling-with-shadows-recovery/\"/apple-touch-icon.png\"){kind=icon}
backcountrygallery.com
![backcountrygallery.com](https://backcountrygallery.com/amazing-high-iso-the-end-of-fast-glass/\"/apple-touch-icon.png\"){kind=icon}
backcountrygallery.com
Ages ago I wondered the same aperture question. I found the answer then and have never considered it again in, oh, 45 years.
... and physics, too. Otherwise, aperture would be meaningless to photographers.
ok thanks
thanks for your kinds informationUnderstanding Camera Lenses
Scroll down to graphic under 'INFLUENCE OF LENS APERTURE OR F-NUMBER' showing how the area of the aperture changes by a proportional amount (eg 2x or 4x more / less light). Changing the aperture by 1 f-stop doubles/halves light transmitted through the lens - by the same amount - whether the lens is a Ultra-wide or a Telephoto.
For the respective lens, the settings for the aperture blades are calibrated to this scale that uses set values of the ratio of aperture to focal-length.... The table lower down compares how much light is transmitted by maximum apertures ie faster vs slower lenses. We exploit these interrelated standard setting to control illumination off any scene in the well known Exposure Triangle. Thus, thanks be to these fixed ratios [called f-stops] we have a comparable index of how much light is reaching the sensor independent of differences in the focal length of lenses etc
The corollary is Shutter speed is adjusted by halving/increasing the light illuminating the sensor ie 1/500 > 1/1000 halves the light, or one can change aperture from f2 > f2.8 to half the light to keep the shutter set at 1/500. In summary, this method is essential to compare, replicate and report how much light was controlled by the lens (and/or shutter and sensor) using a standardized scale.
Note, to be more pedantic 1 Stop is universally referred to as 1 EV, Exposure Value, where the EV reading can be changed using either set increments of Aperture or Shutter Speed or ISO. Typically an EV is compared at a designated ISO for different combo's of aperture/shutter settings - and knowing Absolute EV is useful for comparing Equivalent settings if using a light-meter eg EV 0.0 is defined as f/1.0 and 1 second at ISO100, with Equivalent settings of f1.4 and 2sec, or f2 and 4sec etc. Without getting too much deeper into exposure and different imaging devices, we can also compare the Dynamic Range of a sensor using EV or f-Stops as a standard of their overall performance range: https://www.cambridgeincolour.com/tutorials/dynamic-range.htm
Here's a more detailed explanation why all this matters especially for movies, and also the underlying mathematics: https://www.scantips.com/lights/evchart.html
And an easy back-envelope method to remember the F-stop scale -
It's the other way round in my house!Of course you're right. I only wanted to stress that some kind of knowledge is unnecessary in the practice, perhaps even confusing, depending on your purpose
I for example understand the mechanics of a car. My wife doesn't.
Still, she's the better driver
This is actually a tricky subject. It turns out the ISO standard for digital cameras (12232:2019) does not even mention sensors at all. It's all about the "sensitivity" of the camera as a whole, where the camera is treated as a black box--internals irrelevant--that takes in a measured amount of light and outputs a final digital photographic image (JPG, TIFF, HEIC, etc, but not raw, because raw files are not final images).
I used to run a metrology lab in a major appliance manufacturing facility. When we were gearing up for ISO 90001 certification, I knew an engineer who wasn’t fond of the endeavor. He would say that it would allow you to make a life preserver out of concrete... but it would be in spec.
Well, to quibble a little bit: the ISO standard is related to final camera image output, regardless of specific image format. It does not specifically require JPG for measuring ISO. You just can’t use the camera’s raw output to measure ISO because raw is not an image format. Raw requires further processing to turn into an image.
