Units and measurements in photography


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sweat100

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#1
There are some terms where many people talk about but it still puzzles me. Tried doing a serach but cant gether much info. Would like to ask people in CS for help.

Many people talk amout our noraml film camera as 35mm film camera. Why is it 35mm? Where did they get this measurement from? What i know the size of a negative frame is 36mm x 24mm. So 35mm is from?
Why are those normal roll films called 135? Is there any particular reason?

Now about MF. I understand there is 120 and 220 films. 120 have the paper backing while 220 doesnt have. But how did the 2 numbers come about? Is it possible to find 220 films in SG? Can all MF cameras use 220 films?

Now about photo sizes. What does the suffix "R" stands for? Many people know 4R is 4" x 6". how big exactly is 1 "R"? Does "R" measures area or length?
 

Ian

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Feb 20, 2002
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#3
sweat100 said:
Now about photo sizes. What does the suffix "R" stands for? Many people know 4R is 4" x 6". how big exactly is 1 "R"? Does "R" measures area or length?
The use of the so called R print size series seems to have originated and is limited to South East Asia, in particular Singapore and Malaysia. I've been trying to pin down for over 5 years exactly where it originated and all I've been able to come up with so far is that it's likely a reference to the old Fuji or Kodak cut strip paper sizes for their minilab printers. Perhaps a local Fuji Minilab owner can supply more details.

The only internationally accepted photo size measurements are given in either millimeters, centimeters or inches, for example, 8x10" or 10"x8" (20x25cm), 5x7" (12.5x18cm) etc. As you can see from the examples above that I've given there are two ways to express a print size, and it varies from country to country.

The ONLY paper series designators that use an Alpha (letter) comonent that are internationally accepted are the DIN paper sizes eg the A and B range, eg: A4, B6, A3, A0 etc.

There is an international consortium of major photographics paper manufacturers who are trying to develop genuine international standards for photographic paper sizing, naming conventions and grading, the last I heard they were still in the very early stages of the process though.
 

catchlights

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#4
sweat100 said:
..................
Now about photo sizes. What does the suffix "R" stands for? Many people know 4R is 4" x 6". how big exactly is 1 "R"? Does "R" measures area or length?
I remember in early days some labs offer 3S, 5S, the S here is referring to Square, so I believe that R is refer to Rectangular, like 5R (5”[FONT=Times New Roman, serif]×[/FONT]7”), now if the S is in front of a digit, eg S8R, S10R, is referring to Super, so S8R also call Super 8R.
 

Snoweagle

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#5
sweat100 said:
There are some terms where many people talk about but it still puzzles me. Tried doing a serach but cant gether much info. Would like to ask people in CS for help.

Many people talk amout our noraml film camera as 35mm film camera. Why is it 35mm? Where did they get this measurement from? What i know the size of a negative frame is 36mm x 24mm. So 35mm is from?
Why are those normal roll films called 135? Is there any particular reason?

Now about MF. I understand there is 120 and 220 films. 120 have the paper backing while 220 doesnt have. But how did the 2 numbers come about? Is it possible to find 220 films in SG? Can all MF cameras use 220 films?

Now about photo sizes. What does the suffix "R" stands for? Many people know 4R is 4" x 6". how big exactly is 1 "R"? Does "R" measures area or length?
35mm is measured DIAGONALLY from one corner to the other. Just like LCDs.
 

catchlights

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#6
Snoweagle said:
35mm is measured DIAGONALLY from one corner to the other. Just like LCDs.
Izit?
I never hear of this before, anyway I measured the DIAGONAL already (the diagonal of 24mm×35mm), is about 42mm.

But the width of the 35mm film is indeed 35mm.
 

LittleWolf

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Jan 23, 2005
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#7
Ian said:
The use of the so called R print size series seems to have originated and is limited to South East Asia, in particular Singapore and Malaysia.
I've encountered the R designations in the US. Maybe the disease is spreading. I still don't see what was wrong with simply specifying the linear dimensions of the image.
 

Snoweagle

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#8
catchlights said:
Izit?
I never hear of this before, anyway I measured the DIAGONAL already (the diagonal of 24mm×35mm), is about 42mm.

But the width of the 35mm film is indeed 35mm.
Oh...then maybe it's the width lor :bsmilie:
 

LucidaM

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Apr 30, 2005
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#9
Ian said:
The use of the so called R print size series seems to have originated and is limited to South East Asia, in particular Singapore and Malaysia.
Don't they use R in Perth? In Thailand they use R too.
 

catchlights

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#10
btw,


(weight of format)² + (length of format)² = (focal length of Standard lens)²


eg. (24mm)² +(36mm)² = (43.27mm)² , so we use 50mm as normal lens for 35mm format.
 

Snoweagle

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#11
catchlights said:
btw,


(weight of format)² + (length of format)² = (focal length of Standard lens)²


eg. (24mm)² +(36mm)² = (43.27mm)² , so we use 50mm as normal lens for 35mm format.
Got such logic??
 

doug3fflux

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Feb 21, 2005
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#13
cant u see its not a LOGIC, its a freaking FORMULA. so you should say,

Got such formula??
 

catchlights

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#14
Snoweagle said:
Got such logic??
Yes, there is.

check this out.

just in case you are too lazy to click the link and read it, I extract it for you,

In still photography, a normal lens is a lens whose focal length is roughly equivalent to the diagonal of the image projected within the camera. This roughly approximates the perceived field of view of the human eye.
................................

For a 35 mm camera with a diagonal of 43 mm, the most commonly used normal lens is 50 mm, but focal lengths between about 40 and 58 mm are also considered normal.

The 50 mm focal length was chosen by Oscar Barnack, the creator of the Leica camera, as a compromise between the theoretical value and good sharpness, as lens technology at the time was such that slightly longer focal lengths were able to achieve optimum sharpness.
btw, I not sure where were you, maybe not yet start learning swimming, during the time that I'm more serious about learning photography.
 

Snoweagle

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#16
Del_CtrlnoAlt said:
u like very rude to show disrespect to the MASTER lor... :nono:
Pls lor...in my eyes there's no master or what lor...the way u put it, it's u who's rude. :thumbsd:
 

catchlights

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#17
doug3fflux said:
*all .........................*

Please don't do this, there many far more senior, knowledgeable and respectable photographers then me in this forum, in front of them I'm just like a “half filled bucket”.
 

sweat100

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#19
As what catchlights have mentioned, the diagonal of the film format can be calculated by Pythagoras theorem width^2 + length^2 = diagonal ^2

As for the R i think it might be rectangle. But then how big exactly 1 rectangle? I tried to cut the 4 rectangles up for a 4R but they dont match proportionally to all the various R sizes.
 

Snoweagle

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#20
madmacs said:
that formula you should have learnt in school leh...length of hypotenus (how you spell this freaking thing?).
haha...that formula i know but dunno this has something to do with the formula.
 

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