FoV instead of mm

On 31/05/2019 17.14, Alan Browne wrote:
On 2019-05-31 06:17, Whisky-dave wrote:
On Thursday, 30 May 2019 20:23:05 UTC+1, Alan BrowneÂ* wrote:
On 2019-05-30 08:58, Whisky-dave wrote:

True and in this digital age why do we still use 1/x for exposure
times why say 1/250th second when you can say 4 milliseconds or 4ms ?

Reciprocity.

what has that got to do with it.

Do you have a single notion of how exposure works considering depth of
field?

Do you mean perhaps that DOF doubles or halves as exposure doubles or
halves?

Why would DOF not work if we use ms?

Where is the reciprocity?

Please illustrate. :-)


--
Cheers, Carlos.

On 5/31/2019 11:47 AM, Whisky-dave wrote:
On Friday, 31 May 2019 15:27:25 UTC+1, Ron C wrote:
On 5/31/2019 8:47 AM, Whisky-dave wrote:
On Friday, 31 May 2019 11:45:36 UTC+1, David Taylor wrote:



Would you quote horizontal, vertical or diagonal FoV?

a good point and with fish-eye lenses do fish actually have tthe sort of FoV
that we accosiate with a fish eye lens, it seems odd that they'd have that sort of vision.

OK, I had to look it up. Seems the term was coined based on a phenomenon
called Snell's window :
[snippet from wiki]
"Under ideal conditions, an observer looking up at the water surface
from underneath sees a perfectly circular image of the entire
above-water hemisphere—from horizon to horizon."

But fish don;t have a great need to look up, they tend to look forward .
The angler fish might do so and it also has to account for the distotion of refraction.
I'd like to know what fish see in their world as far a angle of view.

OK, another article on fish vision suggests that a lot of fish have
vision that's quite similar to that of terrestrial animals. What surprised
me is that most fish have color vision. I'm not sure what evolutionary
advantage that gave/gives them.
--
==
Later...
Ron C
--

On 5/31/2019 10:07 PM, Ron C wrote:
On 5/31/2019 11:47 AM, Whisky-dave wrote:
On Friday, 31 May 2019 15:27:25 UTC+1, Ron C* wrote:
On 5/31/2019 8:47 AM, Whisky-dave wrote:
On Friday, 31 May 2019 11:45:36 UTC+1, David Taylor* wrote:



Would you quote horizontal, vertical or diagonal FoV?

a good point and with fish-eye lenses do fish actually have tthe
sort of FoV
that we accosiate with a fish eye lens, it seems odd that they'd
have that sort of vision.

OK, I had to look it up. Seems the term was coined based on a phenomenon
called Snell's window :
[snippet from wiki]
"Under ideal conditions, an observer looking up at the water surface
from underneath sees a perfectly circular image of the entire
above-water hemisphere—from horizon to horizon."

But fish don;t have a great need to look up, they tend to look forward .
* The angler fish might do so and it also has to account for the
distotion of refraction.
* I'd like to know what fish see in their world as far a angle of view.

OK, another article on fish vision suggests that a lot of fish have
vision that's quite similar to that of terrestrial animals. What surprised
me is that most fish have color vision. I'm not sure what evolutionary
advantage that gave/gives them.
PS:
I believe you're thinking of the archer fish rather than angler fish.
--
==
Later...
Ron C
--

On 2019-05-31 15:39, Carlos E.R. wrote:
On 31/05/2019 17.14, Alan Browne wrote:
On 2019-05-31 06:17, Whisky-dave wrote:
On Thursday, 30 May 2019 20:23:05 UTC+1, Alan BrowneÂ* wrote:
On 2019-05-30 08:58, Whisky-dave wrote:

True and in this digital age why do we still use 1/x for exposure
times why say 1/250th second when you can say 4 milliseconds or 4ms ?

Reciprocity.

what has that got to do with it.

Do you have a single notion of how exposure works considering depth of
field?

Do you mean perhaps that DOF doubles or halves as exposure doubles or
halves?

Yes. That is what reciprocity means. Thus, more natural to use than ms.

f/2.8 to f/4
1/250 to 1/125.
4ms to 8ms.

The latter, proportional to aperture stops, seems clunky to me.

--
"Even with the brain dead, the pig's heart keeps on beating...
sort of like ... pick a Kardashian."
-Anthony Bourdain, Parts Unknown

On 6/1/2019 12:44 AM, RichA wrote:
On Friday, 31 May 2019 22:07:41 UTC-4, Ron C wrote:
On 5/31/2019 11:47 AM, Whisky-dave wrote:
On Friday, 31 May 2019 15:27:25 UTC+1, Ron C wrote:
On 5/31/2019 8:47 AM, Whisky-dave wrote:
On Friday, 31 May 2019 11:45:36 UTC+1, David Taylor wrote:



Would you quote horizontal, vertical or diagonal FoV?

a good point and with fish-eye lenses do fish actually have tthe sort of FoV
that we accosiate with a fish eye lens, it seems odd that they'd have that sort of vision.

OK, I had to look it up. Seems the term was coined based on a phenomenon
called Snell's window :
[snippet from wiki]
"Under ideal conditions, an observer looking up at the water surface
from underneath sees a perfectly circular image of the entire
above-water hemisphere—from horizon to horizon."

But fish don;t have a great need to look up, they tend to look forward .
The angler fish might do so and it also has to account for the distotion of refraction.
I'd like to know what fish see in their world as far a angle of view.

OK, another article on fish vision suggests that a lot of fish have
vision that's quite similar to that of terrestrial animals. What surprised
me is that most fish have color vision. I'm not sure what evolutionary
advantage that gave/gives them.
--
==
Later...
Ron C
--

Same reason so many fish are brightly coloured, defenses and venom toxicity. Seeing it is heeding a warning.

Hmm, seems I've spent too much time diving in the north east [USA] where
all the fish seem to be various shades of (dull) gray.
--
==
Later...
Ron C
--

On 01/06/2019 17.34, Alan Browne wrote:
On 2019-05-31 15:39, Carlos E.R. wrote:
On 31/05/2019 17.14, Alan Browne wrote:
On 2019-05-31 06:17, Whisky-dave wrote:
On Thursday, 30 May 2019 20:23:05 UTC+1, Alan BrowneÂ* wrote:
On 2019-05-30 08:58, Whisky-dave wrote:

True and in this digital age why do we still use 1/x for exposure
times why say 1/250th second when you can say 4 milliseconds or 4ms ?

Reciprocity.

what has that got to do with it.

Do you have a single notion of how exposure works considering depth of
field?

Do you mean perhaps that DOF doubles or halves as exposure doubles or
halves?

Yes.Â* That is what reciprocity means.Â* Thus, more natural to use than ms.

f/2.8 to f/4
1/250 to 1/125.
4ms to 8ms.

The latter, proportional to aperture stops, seems clunky to me.

But diafragm numbers are clunky, they are not "reciprocal". But still I
do not see the relation to depth of field in exact meters.


--
Cheers, Carlos.

On 2019-06-01 13:40, Carlos E.R. wrote:
On 01/06/2019 17.34, Alan Browne wrote:
On 2019-05-31 15:39, Carlos E.R. wrote:
On 31/05/2019 17.14, Alan Browne wrote:
On 2019-05-31 06:17, Whisky-dave wrote:
On Thursday, 30 May 2019 20:23:05 UTC+1, Alan BrowneÂ* wrote:
On 2019-05-30 08:58, Whisky-dave wrote:

True and in this digital age why do we still use 1/x for exposure
times why say 1/250th second when you can say 4 milliseconds or 4ms ?

Reciprocity.

what has that got to do with it.

Do you have a single notion of how exposure works considering depth of
field?

Do you mean perhaps that DOF doubles or halves as exposure doubles or
halves?

Yes.Â* That is what reciprocity means.Â* Thus, more natural to use than ms.

f/2.8 to f/4
1/250 to 1/125.
4ms to 8ms.

The latter, proportional to aperture stops, seems clunky to me.

But diafragm numbers are clunky, they are not "reciprocal". But still I
do not see the relation to depth of field in exact meters.

But - so what? It's a ratio and you may recall that's important wrt to
exposure. Imagine trying to calculate it for different FL's... on that
note, the use of fractions of seconds (1/125) is also a good reminder
for the hand holding rule of thumb (yes, I know that's not as relevant
these days...).

As to DoF in "exact" meters that's irrelevant for at least 2 reasons
that come to mind:

1. Technical. Most DoF calculations (including the gradations on
lenses) are for a certain print size and for someone looking at that
print from a normal distance. 8x10 inches comes to mind. Said lens
gradations assume a specific film size and print size, IOW.

2. Judgement when in the field or studio - photographers usually don't
go about looking for a particular DoF based on exact centimetres or
metres of desired DoF but rather a desired aesthetic. (Exception may be
made where DoF is critical for some particular outcome. See 1. above.).
Experience counts.

--
"Even with the brain dead, the pig's heart keeps on beating...
sort of like ... pick a Kardashian."
-Anthony Bourdain, Parts Unknown

On 2019-06-04 06:01, Whisky-dave wrote:
On Friday, 31 May 2019 17:09:48 UTC+1, Savageduck wrote:
On May 31, 2019, Whisky-dave wrote
(in ):

On Friday, 31 May 2019 16:14:43 UTC+1, Alan Browne wrote:
On 2019-05-31 06:17, Whisky-dave wrote:
On Thursday, 30 May 2019 20:23:05 UTC+1, Alan Browne wrote:
On 2019-05-30 08:58, Whisky-dave wrote:

True and in this digital age why do we still use 1/x for exposure times
why say 1/250th second when you can say 4 milliseconds or 4ms ?

Reciprocity.

what has that got to do with it.

Do you have a single notion of how exposure works considering depth of
field?

Depth of field doesn't alter due to exposure.

Aperture is part of the exposure triangle, and if aperture is adjusted it
will alter the DoF.

It is the aperture that is 'responsible for Dof NOT exposure time.
That's some of the very basics of photography.

You can't change aperture w/o changing exposure time for the same light
and sensitivity (ISO).

So, even more basics of photography - and that is the whole point of
reciprocity.

--
"Even with the brain dead, the pig's heart keeps on beating...
sort of like ... pick a Kardashian."
-Anthony Bourdain, Parts Unknown

In article ,
Whisky-dave wrote:

it offers *no* benefit over what exists now. only disadvantages.

The advantages are more accurate shutter settings.

shutter settings are already accurate, and if the camera is in aperture
priority or program mode, the shutter speed can be anything, such as
1/201 or 1/697th.

How do you set a shutter speed of 1/50th when most camera only allow 1/60 ?
and if they have 1/50 then you can't have 1/60.

that will not make any difference in the result.

not that it matters, since anything less than 1/2 stop off isn't going
to make a difference.

Same difference with film.
and with film you could have 1/3 stop changes.

film speed was actually a guide.

what exists works perfectly fine.

Film also worked perfectly fine.

it did, up until it was replaced by something *much* better.

and having infinitely adjustable settings is alway preferable of so called
digitally fixed setting.

no.

tvs and radios used to have infinitely adjustable tuners, which was
much harder to accurately in a station.

changing shutter speeds to milliseconds is not much better. it's not
better at all. it's worse for all sorts of reasons.

but no you can state.

incomplete sentence.

In article ,
Whisky-dave wrote:

it offers *no* benefit over what exists now. only disadvantages.

The advantages are more accurate shutter settings.

shutter settings are already accurate, and if the camera is in aperture
priority or program mode, the shutter speed can be anything, such as
1/201 or 1/697th.

How do you set a shutter speed of 1/50th when most camera only allow 1/60
?
and if they have 1/50 then you can't have 1/60.

that will not make any difference in the result.

depends what you mean by result doesn't it.

no. 'result' has a clear meaning.

Here in the UK we use 50Hz which mean talking pictures of rotating machines
at 50Hz is totally differnt result to those at 60Hz the result will be
differnt.

nearly everything works perfectly fine with either one without any
issue at all, with synchronous motors being the obvious exception.



not that it matters, since anything less than 1/2 stop off isn't going
to make a difference.

Same difference with film.
and with film you could have 1/3 stop changes.

film speed was actually a guide.

What do you mean by guide, ISO is also a guide.

the photographer can choose to use a different value.

for print film, it was common to double the rated asa/iso, and for
slide film, cut it slightly.

and having infinitely adjustable settings is alway preferable of so called
digitally fixed setting.

no.

Yes.

no

tvs and radios used to have infinitely adjustable tuners, which was
much harder to accurately in a station.

Irrelivant.

nope. it's continuously variable, and actually more relevant than line
frequency.

changing shutter speeds to milliseconds is not much better. it's not
better at all. it's worse for all sorts of reasons.

but no you can state.

incomplete sentence.

None you can state.

no need to state the obvious.