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Re: Angle of view instead of focal length

 
 
Rob
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      10-03-2012
On 3/10/2012 7:36 AM, Alfred Molon wrote:
> Given the wide variety of sensor sizes, wouldn't it be better if the
> EXIF of a photo contained also the angle of view information? The focal
> length of the lens is not really that important, actually it is quite
> irrelevant.
>



I have never though in angle of view with my DX format Nikons always in
focal length.

I'm aware of the angles of my 16mm and 20mm lenses that's all, but if
you ask, I could not tell you, what the angles were for the rest of my
lenses.

It would be a stupid idea to know what the angle of view was for a 300mm
or 500 mm lens. How would you replicate back to what lens you used.

Things are in mm not angles.
 
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Whisky-dave
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      10-03-2012
On Wednesday, October 3, 2012 2:53:10 AM UTC+1, Rob wrote:
> On 3/10/2012 7:36 AM, Alfred Molon wrote:
>
> > Given the wide variety of sensor sizes, wouldn't it be better if the

>
> > EXIF of a photo contained also the angle of view information? The focal

>
> > length of the lens is not really that important, actually it is quite

>
> > irrelevant.

>
> >

>
>
>
>
>
> I have never though in angle of view with my DX format Nikons always in
>
> focal length.


That's the culture, I used to think of film speeds in ISO terms as I borought CT18 & CT21 film from agfa.

For years even in the UK our focal lenghs were in mm but before 1971 ???????

Why in the USA do you use mm when everythig else is imperial ?
I'd have thought a 'standard' lens in the US would have a focal lenght of 2 inches NOT 50mmm


>
> I'm aware of the angles of my 16mm and 20mm lenses that's all, but if
>
> you ask, I could not tell you, what the angles were for the rest of my
>
> lenses.


I'm not sure I'd find it more difficult to remmember 76 & 60 over 16 & 20
same number of digits .

>
>
>
> It would be a stupid idea to know what the angle of view was for a 300mm
>
> or 500 mm lens. How would you replicate back to what lens you used.


well I know the sun and moon are about 1/2 degree .

How one would work out what lens to use when photographing a pair of royal tits at a distance I'm not sure.....


>
> Things are in mm not angles.


They are just engraving on the lens barrel, you could replace those with almost anything, mm inches, feet, even furlongs or micro-furlongs, it's just a refernce point.
But if you knew the tits we X disatnce apart and the distance from them to the camera you can calculate the angle needed to fill the frame, but hwo would you know which lens to choose ?

Of if someone said to you I want a picture of this bill board and it's 15ft across but there's a fence so you can't get closer than 100 metres to it
, if you could only take one lens (not a zoom) what would you choose ?

You;d also have to change the lens depending on sensor size but if you knew the angle of view then you'll be able to choose the correct lens.



 
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Rob
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      10-14-2012
On 14/10/2012 10:50 AM, rwalker wrote:
> On Wed, 3 Oct 2012 04:31:45 -0700 (PDT), Whisky-dave
> <(E-Mail Removed)> wrote:
>
>> That's the culture, I used to think of film speeds in ISO terms as I borought CT18 & CT21 film from agfa.
>>
>> For years even in the UK our focal lenghs were in mm but before 1971 ???????
>>
>> Why in the USA do you use mm when everythig else is imperial ?
>> I'd have thought a 'standard' lens in the US would have a focal lenght of 2 inches NOT 50mmm

>
>
> Because we don't use imperial for everything. We use an odd mix.
> Perscription drugs, soft drinks, wine and liquour are all sold in
> metric units. Lenses are measured in mm. Distances are miles,
> weights for most things are in lbs. and ounces, but again for
> perscription drugs and other materials, weights are metric. Nuts and
> bolts are as likely to be measured in mm. as in inches. Automobile
> engine displacement in all modern engines are measured in liters.
>


And you sell petrol in real gallons. and not imperial gallons.
 
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Rob
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      10-14-2012
On 14/10/2012 7:02 PM, Eric Stevens wrote:
> On Sun, 14 Oct 2012 16:00:26 +1100, Rob <(E-Mail Removed)> wrote:
>
>> On 14/10/2012 10:50 AM, rwalker wrote:
>>> On Wed, 3 Oct 2012 04:31:45 -0700 (PDT), Whisky-dave
>>> <(E-Mail Removed)> wrote:
>>>
>>>> That's the culture, I used to think of film speeds in ISO terms as I borought CT18 & CT21 film from agfa.
>>>>
>>>> For years even in the UK our focal lenghs were in mm but before 1971 ???????
>>>>
>>>> Why in the USA do you use mm when everythig else is imperial ?
>>>> I'd have thought a 'standard' lens in the US would have a focal lenght of 2 inches NOT 50mmm
>>>
>>>
>>> Because we don't use imperial for everything. We use an odd mix.
>>> Perscription drugs, soft drinks, wine and liquour are all sold in
>>> metric units. Lenses are measured in mm. Distances are miles,
>>> weights for most things are in lbs. and ounces, but again for
>>> perscription drugs and other materials, weights are metric. Nuts and
>>> bolts are as likely to be measured in mm. as in inches. Automobile
>>> engine displacement in all modern engines are measured in liters.
>>>

>>
>> And you sell petrol in real gallons. and not imperial gallons.

>
> I have a number of containers calibrated in real gallons. For some
> reason I'm always short-changed when I buy from someone who uses US
> gallons.
>



Correct but they did change the size of the gallon because they could
not reduce the tax. that was after the English invaded the US.
 
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Grimly Curmudgeon
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      10-14-2012
On Sun, 14 Oct 2012 16:00:26 +1100, Rob <(E-Mail Removed)> wrote:

>And you sell petrol in real gallons. and not imperial gallons.


What, them ****y little American gallons?
 
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James Silverton
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      10-14-2012
On 10/14/2012 4:10 PM, Savageduck wrote:
> On 2012-10-14 12:57:51 -0700, Eric Stevens <(E-Mail Removed)> said:
>
>> On Sun, 14 Oct 2012 22:34:45 +1100, Rob <(E-Mail Removed)> wrote:
>>
>>> On 14/10/2012 7:02 PM, Eric Stevens wrote:
>>>> On Sun, 14 Oct 2012 16:00:26 +1100, Rob <(E-Mail Removed)> wrote:
>>>>
>>>>> On 14/10/2012 10:50 AM, rwalker wrote:
>>>>>> On Wed, 3 Oct 2012 04:31:45 -0700 (PDT), Whisky-dave
>>>>>> <(E-Mail Removed)> wrote:
>>>>>>
>>>>>>> That's the culture, I used to think of film speeds in ISO terms
>>>>>>> as I borought CT18 & CT21 film from agfa.
>>>>>>>
>>>>>>> For years even in the UK our focal lenghs were in mm but before
>>>>>>> 1971 ???????
>>>>>>>
>>>>>>> Why in the USA do you use mm when everythig else is imperial ?
>>>>>>> I'd have thought a 'standard' lens in the US would have a focal
>>>>>>> lenght of 2 inches NOT 50mmm
>>>>>>
>>>>>>
>>>>>> Because we don't use imperial for everything. We use an odd mix.
>>>>>> Perscription drugs, soft drinks, wine and liquour are all sold in
>>>>>> metric units. Lenses are measured in mm. Distances are miles,
>>>>>> weights for most things are in lbs. and ounces, but again for
>>>>>> perscription drugs and other materials, weights are metric. Nuts and
>>>>>> bolts are as likely to be measured in mm. as in inches. Automobile
>>>>>> engine displacement in all modern engines are measured in liters.
>>>>>>
>>>>>
>>>>> And you sell petrol in real gallons. and not imperial gallons.
>>>>
>>>> I have a number of containers calibrated in real gallons. For some
>>>> reason I'm always short-changed when I buy from someone who uses US
>>>> gallons.
>>>>
>>>
>>>
>>> Correct but they did change the size of the gallon because they could
>>> not reduce the tax. that was after the English invaded the US.

>>
>> I think there was an element of rationalisation. An Imperial gallon of
>> fresh water weighs 10 lbs which makes 1 Imperial pint weigh 1.25 lbs.
>> A US gallon weighs 8 lbs which makes 1 US pint weigh 1 lb.

>
> Not if you use fluid ounces. 16 fluid ounces = 1 US pint; 1 US Gallon =
> 128 fluid ounces, and 1 Imp. Gallon = 153.72159 fluid ounces.
>

Surely, that's obfuscation since fluid ounces are defined differently.
One fluid ounce (US) is 29.5737 cubic centimeters
One fluid ounce (British) is 28.4130 cc
Eight pints make a gallon in both US and British measure but a pint (US)
is 16 fluid ounces (US) and a British pint is 20 fl. oz (British)

Thus we have 1 US gallon is 3,785.4336 cc and 1 British gallon is
4,546.08 cc.
--
Jim Silverton (Potomac, MD)

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James Silverton
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      10-14-2012
On 10/14/2012 4:51 PM, James Silverton wrote:
> On 10/14/2012 4:10 PM, Savageduck wrote:
>> On 2012-10-14 12:57:51 -0700, Eric Stevens <(E-Mail Removed)> said:
>>
>>> On Sun, 14 Oct 2012 22:34:45 +1100, Rob <(E-Mail Removed)> wrote:
>>>
>>>> On 14/10/2012 7:02 PM, Eric Stevens wrote:
>>>>> On Sun, 14 Oct 2012 16:00:26 +1100, Rob <(E-Mail Removed)> wrote:
>>>>>
>>>>>> On 14/10/2012 10:50 AM, rwalker wrote:
>>>>>>> On Wed, 3 Oct 2012 04:31:45 -0700 (PDT), Whisky-dave
>>>>>>> <(E-Mail Removed)> wrote:
>>>>>>>
>>>>>>>> That's the culture, I used to think of film speeds in ISO terms
>>>>>>>> as I borought CT18 & CT21 film from agfa.
>>>>>>>>
>>>>>>>> For years even in the UK our focal lenghs were in mm but before
>>>>>>>> 1971 ???????
>>>>>>>>
>>>>>>>> Why in the USA do you use mm when everythig else is imperial ?
>>>>>>>> I'd have thought a 'standard' lens in the US would have a focal
>>>>>>>> lenght of 2 inches NOT 50mmm
>>>>>>>
>>>>>>>
>>>>>>> Because we don't use imperial for everything. We use an odd mix.
>>>>>>> Perscription drugs, soft drinks, wine and liquour are all sold in
>>>>>>> metric units. Lenses are measured in mm. Distances are miles,
>>>>>>> weights for most things are in lbs. and ounces, but again for
>>>>>>> perscription drugs and other materials, weights are metric. Nuts
>>>>>>> and
>>>>>>> bolts are as likely to be measured in mm. as in inches. Automobile
>>>>>>> engine displacement in all modern engines are measured in liters.
>>>>>>>
>>>>>>
>>>>>> And you sell petrol in real gallons. and not imperial gallons.
>>>>>
>>>>> I have a number of containers calibrated in real gallons. For some
>>>>> reason I'm always short-changed when I buy from someone who uses US
>>>>> gallons.
>>>>>
>>>>
>>>>
>>>> Correct but they did change the size of the gallon because they could
>>>> not reduce the tax. that was after the English invaded the US.
>>>
>>> I think there was an element of rationalisation. An Imperial gallon of
>>> fresh water weighs 10 lbs which makes 1 Imperial pint weigh 1.25 lbs.
>>> A US gallon weighs 8 lbs which makes 1 US pint weigh 1 lb.

>>
>> Not if you use fluid ounces. 16 fluid ounces = 1 US pint; 1 US Gallon =
>> 128 fluid ounces, and 1 Imp. Gallon = 153.72159 fluid ounces.
>>

> Surely, that's obfuscation since fluid ounces are defined differently.
> One fluid ounce (US) is 29.5737 cubic centimeters
> One fluid ounce (British) is 28.4130 cc
> Eight pints make a gallon in both US and British measure but a pint (US)
> is 16 fluid ounces (US) and a British pint is 20 fl. oz (British)
>
> Thus we have 1 US gallon is 3,785.4336 cc and 1 British gallon is
> 4,546.08 cc.

Can I just add a very important statistic, a standard beer bottle (12
oz) contains 354.88 cc in the US and the British are cheated at 340.96
cc, tho' for a pint of beer (unusual in the US), Americans get 473.18 cc
and British get 568.26 cc.

--
Jim Silverton (Potomac, MD)

Extraneous "not" in Reply To.
 
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Huuter
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      10-14-2012
On 2012.10.14 17:55 , Alfred Molon wrote:
> In article <k5f8j8$dje$(E-Mail Removed)>, James Silverton says...
>> Thus we have 1 US gallon is 3,785.4336 cc and 1 British gallon is
>> 4,546.08 cc.

>
> Interesting. How much is a gallon of gasoline in the USA right now?


Recently over $5 in some areas (notably CA which has two major
refineries in major repair state and the rest in transition to "winter"
blend.)

 
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James Silverton
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      10-15-2012
On 10/14/2012 5:55 PM, Alfred Molon wrote:
> In article <k5f8j8$dje$(E-Mail Removed)>, James Silverton says...
>> Thus we have 1 US gallon is 3,785.4336 cc and 1 British gallon is
>> 4,546.08 cc.

>
> Interesting. How much is a gallon of gasoline in the USA right now?
>

Pushing $4 for regular at the moment.

--
Jim Silverton (Potomac, MD)

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James Silverton
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      10-15-2012
On 10/14/2012 6:44 PM, Alan Browne wrote:
> On 2012.10.14 16:51 , James Silverton wrote:
>
>> Thus we have 1 US gallon is 3,785.4336 cc and 1 British gallon is
>> 4,546.08 cc.

>
> "cc" is not used to describe liquid measure. Use "ml" (millilitres").
>
> And for the volumes and accuracies you're using, one would use litres.
>
> And it's not a "British" gallon, but an "Imperial" gallon.
>
> eg: 4.54608 litres/Imp. Gal.
>

Pedantic, any base unit will do for the comparisons even if the ml is
normal in scientific use. What Empire, who uses British gallons these
days except the British?

--
Jim Silverton (Potomac, MD)

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