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Meaning of ISO value in digital photography?



 
 
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  #21  
Old June 16th 18, 12:11 AM posted to rec.photo.digital
Carlos E.R.
external usenet poster
 
Posts: 278
Default Meaning of ISO value in digital photography?

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.

--
Cheers, Carlos.
  #22  
Old June 16th 18, 12:39 AM posted to rec.photo.digital
Savageduck[_3_]
external usenet poster
 
Posts: 16,487
Default Meaning of ISO value in digital photography?

On Jun 15, 2018, Carlos E.R. wrote
(in article ):

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 ):



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...r-camera-same-
amazing-sensor-as-in-xplay-6-and-zenfone-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 rolling shutter effect which has returned with the advent of the
electronic shutter found in smartphones, digital video cameras, and many
mirrorless cameras. With some of the advantages of the electronic shutter,
rolling shutter effect can produce some unwanted effects with high speed
shots of moving subjects. For example athletes can be given elongated and
spindlely legs, wheels can be made oval, not round, propellor and rotor
blades can be unrealistically distorted.

https://en.wikipedia.org/wiki/Rolling_shutter

--

Regards,
Savageduck

  #23  
Old June 16th 18, 12:49 AM posted to rec.photo.digital
Jim-P
external usenet poster
 
Posts: 34
Default Meaning of ISO value in digital photography?

On Fri, 15 Jun 2018 13:46:46 -0700, Savageduck wrote:

On Jun 15, 2018, Jim-P wrote
(in article ):

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 ):

On Thu, 14 Jun 2018 14:26:40 -0400, PeterN wrote:

On 6/14/2018 1:48 PM, Jim-P wrote:
In film cameras, ISO referrs to the sensitivity to light of the
emulsion.
Manufacturers formulate different film emulsions with different
sensitivites tarding increased grain with increased ISO speed.

In a digital camera, presumably the sensor does not adjust itself to
have
greater sensitivity. Or does it?

So what is happening in a digital camera when I choose a greater ISO
setting? Is more amplification being used?

I tried to understand this page but it got far too technical....

https://photography.tutsplus.com/art...echnical-explo
ration--photo-11963

I am going to try to give you a simplified, non-technical explanation.
As with most generalities it is not 100% technically accurate, but
should serve as a guideline.
ISO is a measurement of the light sensitivity of the sensor. Digital ISO
is adjustable in many cameras. And yes, it is a matter of adjusting the
amplification. If you are using a wider lens opening, and slower shutter
speed, you will be able to use a lower ISO.
Digital noise is one of the undesired artifacts in the image. Higher ISO
will result in more digital noise, and lessor image quality. Many of the
newer high quality sensors are designed to work at a higher ISO, with
less noticeable noise, and reduction in image quality.
There are some of us here who do not object to noise, while others have
serious objections. The point at which noise becomes objectionable often
comes down to a matter of taste and personal preferences.

Thanks. This makes me wonder what ISO I should set, if I don't leave it
on
auto.

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...y-imx362-rear-
camera-same-amazing-sensor-as-in-xplay-6-and-zenfone-3-zoom/


There is nothing wrong in using a smartphone camera. However, you are going
to have limitations which you will not find in modern DSLR, or mirrorless
digital cameras (MILC). Even with third party photo apps for your smartphone
you are going to have limitations of physical sensor size, and adjustability
of the exposure triangle.

The next question is; are you intending to add a modern digital camera to
your current photography kit?


I need to work out how to get the best from my smartphone first.

I'm new to smartphones but they take surprisingly good pictures which are
almost as good as my point and shoot. They are aso very forgiving and
don't need lots of setting up.

I wonder what the cost is for a point and shoot giving pictures a notch
above a smartphone.
  #24  
Old June 16th 18, 01:17 AM posted to rec.photo.digital
nospam
external usenet poster
 
Posts: 24,165
Default Meaning of ISO value in digital photography?

In article , Carlos E.R.
wrote:

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's not a trick, but how focal plane shutters work.

the speed at which the slit is the same size or larger than the film
frame in the dimension the shutter is traveling is the flash sync
speed, typically in the 1/60-1/250 range.

as always, there are exceptions. some digital slrs have a focal plane
shutter that can sync at any shutter speed.
  #25  
Old June 16th 18, 01:34 AM posted to rec.photo.digital
Savageduck[_3_]
external usenet poster
 
Posts: 16,487
Default Meaning of ISO value in digital photography?

On Jun 15, 2018, Jim-P wrote
(in article ):

On Fri, 15 Jun 2018 13:46:46 -0700, Savageduck wrote:

On Jun 15, 2018, Jim-P wrote
(in article ):

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 ):

On Thu, 14 Jun 2018 14:26:40 -0400, PeterN wrote:

On 6/14/2018 1:48 PM, Jim-P wrote:
In film cameras, ISO referrs to the sensitivity to light of the
emulsion.
Manufacturers formulate different film emulsions with different
sensitivites tarding increased grain with increased ISO speed.

In a digital camera, presumably the sensor does not adjust itself to
have
greater sensitivity. Or does it?

So what is happening in a digital camera when I choose a greater ISO
setting? Is more amplification being used?

I tried to understand this page but it got far too technical....

https://photography.tutsplus.com/art...-technical-exp
lo
ration--photo-11963

I am going to try to give you a simplified, non-technical explanation.
As with most generalities it is not 100% technically accurate, but
should serve as a guideline.
ISO is a measurement of the light sensitivity of the sensor. Digital
ISO
is adjustable in many cameras. And yes, it is a matter of adjusting
the
amplification. If you are using a wider lens opening, and slower
shutter
speed, you will be able to use a lower ISO.
Digital noise is one of the undesired artifacts in the image. Higher
ISO
will result in more digital noise, and lessor image quality. Many of
the
newer high quality sensors are designed to work at a higher ISO, with
less noticeable noise, and reduction in image quality.
There are some of us here who do not object to noise, while others
have
serious objections. The point at which noise becomes objectionable
often
comes down to a matter of taste and personal preferences.

Thanks. This makes me wonder what ISO I should set, if I don't leave it
on
auto.

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...y-imx362-rear-
camera-same-amazing-sensor-as-in-xplay-6-and-zenfone-3-zoom/


There is nothing wrong in using a smartphone camera. However, you are going
to have limitations which you will not find in modern DSLR, or mirrorless
digital cameras (MILC). Even with third party photo apps for your smartphone
you are going to have limitations of physical sensor size, and adjustability
of the exposure triangle.

The next question is; are you intending to add a modern digital camera to
your current photography kit?


I need to work out how to get the best from my smartphone first.

I'm new to smartphones but they take surprisingly good pictures which are
almost as good as my point and shoot. They are aso very forgiving and
don't need lots of setting up.


If it meets your needs there is little point looking for something else, but
if you want more you should consider something other than a compact/P&S
camera.

I wonder what the cost is for a point and shoot giving pictures a notch
above a smartphone.


There are some excellent compact, or P&S cameras from most of the
manufacturers such as Canon, Nikon, Panasonic, Sony, etc, prices, and
performance vary. The big issue with the P&S cameras is, they are being
killed off by smartphones. The big advantage to a dedicated camera rather
than a phone camera is ergonomics. No matter how much one might argue, a
smartphone is awkward to use as a camera due to its unavoidable phone shape.

Personally, if one is only considering a compact/P&S camera as an upgrade
from a smartphone, consider what you are going to be doing with your
photography, it might be better to stick with the smartphone. Otherwise, I
would suggest moving to a mirrorless camera with, or without interchangeable
lenses. They can be more expensive than a smartphone, but your photographic
experience will be more enjoyable.

I an unabashed fan of the Fujifilm mirrorless cameras, and for somebody
wanting something reminiscent of the analog days, a great fixed focal length
camera is the Fujifilm X100F.

https://www.dpreview.com/reviews/fujifilm-x100f

https://www.techradar.com/reviews/fujifilm-x100f-review

I currently own several Fujifilm bodies and a bag full of lenses.

https://www.dropbox.com/s/5yeyllbh2jd8g0a/IMG_2527e.jpg

To get some idea of what is out there in the compact camera range check out
dpreview:

https://www.dpreview.com

--

Regards,
Savageduck

  #26  
Old June 16th 18, 02:18 AM posted to rec.photo.digital
Carlos E.R.
external usenet poster
 
Posts: 278
Default Meaning of ISO value in digital photography?

On 2018-06-16 02:17, nospam wrote:
In article , Carlos E.R.
wrote:

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's not a trick, but how focal plane shutters work.


I have seen it in solid metal non focal plane shutters. Actually a part
of the mirror assembly.


the speed at which the slit is the same size or larger than the film
frame in the dimension the shutter is traveling is the flash sync
speed, typically in the 1/60-1/250 range.


Yes..

as always, there are exceptions. some digital slrs have a focal plane
shutter that can sync at any shutter speed.



--
Cheers, Carlos.
  #27  
Old June 16th 18, 02:26 AM posted to rec.photo.digital
Carlos E.R.
external usenet poster
 
Posts: 278
Default Meaning of ISO value in digital photography?

On 2018-06-16 01:49, Jim-P wrote:
On Fri, 15 Jun 2018 13:46:46 -0700, Savageduck wrote:

On Jun 15, 2018, Jim-P wrote
(in article ):

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 ):



....

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...y-imx362-rear-
camera-same-amazing-sensor-as-in-xplay-6-and-zenfone-3-zoom/


There is nothing wrong in using a smartphone camera. However, you are going
to have limitations which you will not find in modern DSLR, or mirrorless
digital cameras (MILC). Even with third party photo apps for your smartphone
you are going to have limitations of physical sensor size, and adjustability
of the exposure triangle.

The next question is; are you intending to add a modern digital camera to
your current photography kit?


I need to work out how to get the best from my smartphone first.

I'm new to smartphones but they take surprisingly good pictures which are
almost as good as my point and shoot. They are aso very forgiving and
don't need lots of setting up.

I wonder what the cost is for a point and shoot giving pictures a notch
above a smartphone.


They start at about 75 euros, and I see models up to 400. Wait, I see
one for 1100.

IMO, it is easier to get reasonably good optics when lenses are bigger,
not cramped in 5 mm. On the other hand, I've seen better software on a
phone than a camera of the same manufacturer. At least apparently. I
mean, more features.

You can have a compact of 150€ with optical zoom. I don't see a phone of
that price having optical zoom.

--
Cheers, Carlos.
  #28  
Old June 16th 18, 07:37 AM posted to rec.photo.digital
Savageduck[_3_]
external usenet poster
 
Posts: 16,487
Default Meaning of ISO value in digital photography?

On Jun 15, 2018, Carlos E.R. wrote
(in article ):

On 2018-06-16 01:49, Jim-P wrote:
On Fri, 15 Jun 2018 13:46:46 -0700, Savageduck wrote:

On Jun 15, 2018, Jim-P wrote
(in article ):

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 ):


...

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...y-imx362-rear-
camera-same-amazing-sensor-as-in-xplay-6-and-zenfone-3-zoom/

There is nothing wrong in using a smartphone camera. However, you are going
to have limitations which you will not find in modern DSLR, or mirrorless
digital cameras (MILC). Even with third party photo apps for your
smartphone you are going to have limitations of physical sensor size, and
adjustability of the exposure triangle.

The next question is; are you intending to add a modern digital camera to
your current photography kit?


I need to work out how to get the best from my smartphone first.

I'm new to smartphones but they take surprisingly good pictures which are
almost as good as my point and shoot. They are aso very forgiving and
don't need lots of setting up.

I wonder what the cost is for a point and shoot giving pictures a notch
above a smartphone.


They start at about 75 euros, and I see models up to 400. Wait, I see
one for 1100.

IMO, it is easier to get reasonably good optics when lenses are bigger,
not cramped in 5 mm. On the other hand, I've seen better software on a
phone than a camera of the same manufacturer. At least apparently. I
mean, more features.

You can have a compact of 150€ with optical zoom. I don't see a phone of
that price having optical zoom.


I don’t see a phone of any price having optical zoom. My iPhone 8+
certainly doesn’t have it, but it does have a twin lens set up which makes
for some interesting portrait, and lighting features.

--

Regards,
Savageduck

  #29  
Old June 16th 18, 11:45 AM posted to rec.photo.digital
nospam
external usenet poster
 
Posts: 24,165
Default Meaning of ISO value in digital photography?

In article .com,
Savageduck wrote:


I don¹t see a phone of any price having optical zoom. My iPhone 8+
certainly doesn¹t have it, but it does have a twin lens set up which makes
for some interesting portrait, and lighting features.


apple calls it optical zoom and the results are noticeably better than
digital zoom with just one lens.

nevertheless, there have been true optical zooms on phones, and not
surprisingly, did not sell well.

https://www.samsung.com/uk/smartphon.../SM-C1150ZKABT
U/

https://images.samsung.com/is/image/...laxy-k-zoom-c1
15--45680117?$FB_TYPE_C_JPG$
  #30  
Old June 16th 18, 04:33 PM posted to rec.photo.digital
Alan Browne[_2_]
external usenet poster
 
Posts: 696
Default Meaning of ISO value in digital photography?

On 2018-06-14 13:48, Jim-P wrote:
In film cameras, ISO referrs to the sensitivity to light of the emulsion.
Manufacturers formulate different film emulsions with different
sensitivites tarding increased grain with increased ISO speed.

In a digital camera, presumably the sensor does not adjust itself to have
greater sensitivity. Or does it?

So what is happening in a digital camera when I choose a greater ISO
setting? Is more amplification being used?


Typically two stages:

0: the natural ISO of the sensor (whatever value it is - somewhere in
the 100 - 800 range).

1: Analog gain (possibly negative) applied at the time the image is
"read off" of the sensor. This will go up to some limit, eg: ISO 2000
(depending on the model it will be more or less). Noise is amplified
with signal. Analog and/or digital noise filtering may be applied.

2: Digital gain applied to the data after it is read off, before it is
stored on the data card. This has no limit at all except of course
contribution to noise, especially quantization noise. Digital noise
filtering may (and likely is) applied.

--
"2/3 of Donald Trump's wives were immigrants. Proof that we
need immigrants to do jobs that most Americans wouldn't do."
- unknown protester
 




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