# Thread: Units and measurements in photography

1. ## Re: Units and measurements in photography

Originally Posted by sweat100
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.
I believe the R is just simply means rectangle, not S or Square.

But, for what I know, for 16"×20", 8"×10", 4"×5" all are 4:5 ratio, and you can cut
4 pieces of 4"×5" out of one pieces of 8"×10"
4 pieces of 8"×10" out of one pieces of 16"×20"

and 4R is 2:3 ratio, same as S8R (8"×12"), S10R (10"×15"), 12"×18"

3R is 3.5:5 ratio, very close to 5R (4.9:7) but is half size of 5R

6R is 6:8 ratio, also call 645 format.

so the R do not really inter related here, unlike the A (A0, A1, A2, A3 etc)

2. ## Re: Units and measurements in photography

All this while I tot R was refering to some darkroom magnification ratio or setting... tink I'm misled liao

3. ## Re: Units and measurements in photography

Originally Posted by LucidaM
Don't they use R in Perth? In Thailand they use R too.
I've never encountered R measurements at any Prolab outside of SE Asia, that includes the whole of Australia, Europe, South America and the USA, though as littlewolf said it is rarely used in the USA.

4. ## Re: Units and measurements in photography

Originally Posted by catchlights
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”×7”), now if the S is in front of a digit, eg S8R, S10R, is referring to Super, so S8R also call Super 8R.
A horrible thought just crossed my mind, one that goes back to my first travels in SE Asia as a kid in the mid 60s. The use of S for square and R for rectangular and a number could just have started off as a simple way of specifiying a print size in the same way that many restaraunts did and still do put a number next to the display item of the meal.

5. ## Re: Units and measurements in photography

Originally Posted by catchlights
I believe the R is just simply means rectangle, not S or Square.

But, for what I know, for 16"×20", 8"×10", 4"×5" all are 4:5 ratio, and you can cut
4 pieces of 4"×5" out of one pieces of 8"×10"
4 pieces of 8"×10" out of one pieces of 16"×20"

and 4R is 2:3 ratio, same as S8R (8"×12"), S10R (10"×15"), 12"×18"

3R is 3.5:5 ratio, very close to 5R (4.9:7) but is half size of 5R

6R is 6:8 ratio, also call 645 format.

so the R do not really inter related here, unlike the A (A0, A1, A2, A3 etc)
Nice idea in theory, the only drawback is that most labs use roll paper that is slightly oversize and only trim the ends when printing.

6. ## Re: Units and measurements in photography

Originally Posted by Ian
Nice idea in theory, the only drawback is that most labs use roll paper that is slightly oversize and only trim the ends when printing.
This part is I refering to sheet size, when I still do b/w work,
But, for what I know, for 16"×20", 8"×10", 4"×5" all are 4:5 ratio, and you can cut
4 pieces of 4"×5" out of one pieces of 8"×10"
4 pieces of 8"×10" out of one pieces of 16"×20"
And yes, mini labs are using roll paper, they tell me that mostly using 5" paper (for 3R and 5R), 6" paper (for 4R and and 6R), 10" paper (for 8R, 10R and 10RW), 12" (for S8R and 12"×18"), hope I remember correctly.

7. ## Re: Units and measurements in photography

Originally Posted by Ian
A horrible thought just crossed my mind, one that goes back to my first travels in SE Asia as a kid in the mid 60s. The use of S for square and R for rectangular and a number could just have started off as a simple way of specifiying a print size in the same way that many restaraunts did and still do put a number next to the display item of the meal.
well, looks like it is the idea behind, should ask this to Kodak Labs.

8. ## Re: Units and measurements in photography

Originally Posted by Ian
I've never encountered R measurements at any Prolab outside of SE Asia, that includes the whole of Australia, Europe, South America and the USA, though as littlewolf said it is rarely used in the USA.
most Prolab don't speacially do machin print, all they use sheet paper, and they call 3½"×5" instead of 3R, 5"×7" instead of 5R..etc, and all are call "custom prints", allow cropping, burn in and dodging, these are the thing that can't do it on machine print (mini Lab), so basically the "R" or "S" are also refering print sizes use on machine print (mini Lab).

9. ## Re: Units and measurements in photography

Wah...becoming so technical here

10. ## Re: Units and measurements in photography

aint it all about the tech details.

11. ## Re: Units and measurements in photography

Originally Posted by catchlights
most Prolab don't speacially do machin print, all they use sheet paper, and they call 3½"×5" instead of 3R, 5"×7" instead of 5R..etc, and all are call "custom prints", allow cropping, burn in and dodging, these are the thing that can't do it on machine print (mini Lab), so basically the "R" or "S" are also refering print sizes use on machine print (mini Lab).
Most genuine pro labs I've dealt with world wide (and that is an awful lot) offer both machine prints (standard prints, roll paper) and custom prints (often called "commercial prints" hand done on sheet paper). The main difference with the pro lab machine prints is the pro labs use top end machinery and very experienced operators and fully adhere to the daily testing and calibration of their printers, unlike most minilab operators.

12. ## Re: Units and measurements in photography

Yes, here not all pro lab offer machine print and "commercial prints" together, even not much pro labs in S'pore nowadays.

13. ## Re: Units and measurements in photography

Originally Posted by catchlights
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.
dun mind if i ask? is it weight or is it width? if it is weight, what does it mean?

14. ## Re: Units and measurements in photography

Originally Posted by zoossh
dun mind if i ask? is it weight or is it width? if it is weight, what does it mean?
ooppsss, typo error, is (width of format)² + (length of format)² = (focal length of Standard lens)²

15. ## Re: Units and measurements in photography

that formula you should have learnt in school leh...length of hypotenus (how you spell this freaking thing?).
hypotenusa...

16. ## Re: Units and measurements in photography

Originally Posted by catchlights
ooppsss, typo error, is (width of format)² + (length of format)² = (focal length of Standard lens)²
Phytagoras triangle??

17. ## Re: Units and measurements in photography

More like Pythagoras Theorem LOL

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