Meaning of ISO value in digital photography?

On 06/15/2018 07:11 PM, Carlos E.R. wrote:
On 2018-06-15 22:18, Jim-P wrote:
On Thu, 14 Jun 2018 19:47:36 -0700, Savageduck wrote:

On Jun 14, 2018, Ken Hart wrote
(in article ):

On 06/14/2018 08:05 PM, Savageduck wrote:
On Jun 14, 2018, Jim-P wrote
(in article ):



In the film days, we used the "Sunny-16" rule: Set the shutter speed
equal to the ISO (then "ASA"). In bright sunshine, use f/16. Slightly
cloudy- use f/11, open shade- f/8, full shade- f/5.6. This technique
would usually give a good exposure.

Combine that with the "focal length equals shutter speed" rule: The
longer the focal length, the faster the shutter speed to give acceptable
hand-held images. For a 200mm lens, you use a shutter speed of 1/250
second.

Example: 100mm lens calls for 1/100 second minimum. Set the ISO also at
100, and use the "Sunny-16" rule. Then refer to SD's exposure triangle,
three paragraphs down...

Let us start by asking, what camera are you using?

It would still be good to know what camera the OP is using.

I am using a smartphone camera. Although it is not as high quality as a
DSLR the principles should be the same and I am interested in understanding
them before taking my photography further.

The smartphone model is a Moto G5 Plus with a Sony IMX362 Exmor RS camera
module which is also used in the Nokia 7 and Samsung S7 Edge

https://phoneproscons.com/794/moto-g...enfone-3-zoom/

I recall that old Sunny 16 rule and the thing which strikes me most about
it now is how slow the shutter speeds were in the old days. 1/250 was one
of the faster speeds I would use for day to day photography years ago but
my current smartphone often uses speeds of 1/1000 or 1/2000 which is
fantastic because by hand steadiness is not what it used to be.

My old SLR had 1/2000

The mechanics had a trick that allowed high effective shutter speed
while the shutter in fact moved relatively slowly, at 1/60 or
thereabouts. And old trick, actually. It opened a slit on the rectangle,
and the slit travelled the length of the aperture. If the slit was 1/5,
the effective speed was the actual speed multiplied by 5.

That is the standard way a focal plane shutter works (worked) for speeds
typically over 1/60 second. The first curtain would start to open, and
before it was all the way open the second curtain would start to close.
To use electronic flash, you could not sync at a speed where the shutter
was not totally open. Vertical travel focal plane shutters usually
sync'ed at a faster speed because they had less distance to travel.

The shutter tester I use to test my cameras provides a readout of the
shutter speed and each curtain speed. Typically, for my Canon FX
cameras, the curtain speed is in the neighborhood of 12msec. If there a
difference in the speeds of the two curtains, one side of the frame will
be over- or under-exposed.

When you photograph a subject moving across the frame (such as a fast
car), the subject will be either compacted or stretched in length,
depending on direction of travel.

--
Ken Hart