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Thread: Sensor Aspect Ratio

  1. #1
    dje's Avatar
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    Sensor Aspect Ratio

    As far as I'm aware, most if not all DSLR's use a sensor with an aspect ratio of 3:2 whereas compact cameras and most Compact System Cameras use a sensor with an aspect ratio of 4:3. Presumably the aspect ratio of 3:2 is a carryover from the days of 35mm film. However why is 4:3 used for the compacts ?

    A couple of contributing factors I've read about are

    • Until 16:9 widescreen came along, 4:3 was the stanard AR for TV and monitors
    • A 4:3 AR is more economical because it is "squarer" and hence for a given pixel pitch and total pixel count, the diagonal of the sensor is smaller. This makes lens design more economical and keeps the marketing peple happy with a nice large pixel count.


    But maybe there are other factors ? I've seen some people advocating square sensors but I can't see that being accepted in consumer cameras. Any thoughts ?

    Dave

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    Re: Sensor Aspect Ratio

    Learn something new every day! I was going to post this link:

    http://en.wikipedia.org/wiki/Aspect_...ll_photography

    and discovered that I had never realized Canons' APS-H sensor is a native 16:9 à la HD-TV!

  3. #3
    dje's Avatar
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    Re: Sensor Aspect Ratio

    Quote Originally Posted by xpatUSA View Post
    Learn something new every day! I was going to post this link:

    http://en.wikipedia.org/wiki/Aspect_...ll_photography

    and discovered that I had never realized Canons' APS-H sensor is a native 16:9 à la HD-TV!
    That's quite a comprehensive article Ted. Haven't seen it before. Must read it in detail.

    Dave

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    William W's Avatar
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    Re: Sensor Aspect Ratio

    Quote Originally Posted by dje View Post
    . . . other factors ? . . . Any thoughts ?
    The two types of cameras evolved from different rationale:

    Digital SLR cameras have an obvious and also STRONG heritage derived from ‘Miniature 135 Format' Single Lens Reflex Cameras. As well as not wanting to alienate the consumer, there would be practical aspects warranting keeping the same aspect ratio as the DSLR Camera series were developed.

    However, the majority of other ‘digital cameras’ , i.e. all ‘consumer ‘digital cameras OTHER THAN DSLR’s, evolved and were designed to match the mainstream COMPUTER SCREEN aspect ratios of that time: VGA, SVGA, XGA and UXGA, such being an Aspect Ratio4:3.

    ***

    Quote Originally Posted by xpatUSA View Post
    I had never realized Canons' APS-H sensor is a native 16:9 à la HD-TV!
    The Canon EOS 1D MkIV sensor size is approx: 27.9mm x 18.6 mm, which is actually 3:2

    The ‘APS-H’ in this instance refers to Canon Inc.'s internal nomenclature and NOT the (original) film size or the aspect ratio, 16:9.


    This point is (correctly) mentioned previously, in the web page cited:

    “Canon actually developed two standards, APS-C and a slightly larger area APS-H (not to be confused with the APS-H film format) . . .”

    Wikipedia , op. cit.

    WW

  5. #5
    dje's Avatar
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    Re: Sensor Aspect Ratio

    Quote Originally Posted by William W View Post

    Digital SLR cameras have an obvious and also STRONG heritage derived from ‘Miniature 135 Format' Single Lens Reflex Cameras. As well as not wanting to alienate the consumer, there would be practical aspects warranting keeping the same aspect ratio as the DSLR Camera series were developed.
    Yes Bill I can imagine these arguments would have been quite compelling.

    Dave

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    Re: Sensor Aspect Ratio

    Dave it is something I do not understand either. I would think all ratios should be adapted to the size of standard printing paper. OOPS what is standard? Think there lies the problem - is there a standard?
    If all the world used A4 size paper as a standard it would make sense to have all displays adapted to that ratio. Printing paper, TV screens, Computer screens, Camera sensors, etc.

    Why is the whole world not using metric instead of imperial? Is metric not easier and makes more sense? Why use miles while kilometers are so much easier?

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    Re: Sensor Aspect Ratio

    Quote Originally Posted by AB26 View Post
    Dave it is something I do not understand either. I would think all ratios should be adapted to the size of standard printing paper. OOPS what is standard? Think there lies the problem - is there a standard?
    Just look at any decent print shop offerings... From what I remember from my darkroom days, the most common formats were 10x15 (2:3), 18:24(3:4), 30x40(3:4), 50x60 (5:6) (sizes in cm).
    And those ratios and sizes are still common...

    If all the world used A4 size paper as a standard it would make sense to have all displays adapted to that ratio. Printing paper, TV screens, Computer screens, Camera sensors, etc.
    A4 might be a handy size for printing, but cinema has been using various wide-screen ratios a long tile now (as they are better adapted to human vision?). And there are other
    paper formats that are just as 'standard' as A4, but less easy for industrial use.

    Why is the whole world not using metric instead of imperial? Is metric not easier and makes more sense? Why use miles while kilometers are so much easier?
    Because kilometers are a new-fangled notion that are difficult to learn? And they were invented by (*shudder*) the French...
    And the metric system is dangerous: see http://en.wikipedia.org/wiki/Mars_Climate_Orbiter. I mean, if they
    just had stuck to good old pound-seconds ...

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    xpatUSA's Avatar
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    Re: Sensor Aspect Ratio

    Quote Originally Posted by revi View Post
    And the metric system is dangerous: see http://en.wikipedia.org/wiki/Mars_Climate_Orbiter. I mean, if they just had stuck to good old pound-seconds ...
    . . . and that airliner that got re-fueled with pounds, not kg.

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    Moderator GrumpyDiver's Avatar
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    Re: Sensor Aspect Ratio

    Quote Originally Posted by xpatUSA View Post
    . . . and that airliner that got re-fueled with pounds, not kg.
    Ah yes, the "Gimli Glider"; a.k.a. Air Canada flight 143....

    http://en.wikipedia.org/wiki/Gimli_Glider

    I was going to comment that here in the Americas paper sizes for photography and paper sizes for normal use did not match up until the digital age. In spite of us Canadians going metric in the 1970s, photo papers stubbornly stuck to their roots. Not only do we not use the metric sizes, we had different sizes of paper, measured of course in inches. Paper for office use was generally 8-1/2" x 11" a "legal" size of 8-1/2" x 14". If you got into engineering paper drawings were eventually codified into ANSI standards or architectural drawings that have their own Arch standards.

    Back in the darkroom days, common paper sizes were 3-1/2" x 5", 5" x 7", 8" x 10", 11" x 14" and 16" x 20". Kodak (US) and Ilford (UK) historically turned out those sizes and even the Germans (Agfa) produced their lovely Brovira and Agfacolor papers to these standards. Even today, these common photo paper sizes are still used in the off-the-shelf picture frames.

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    Re: Sensor Aspect Ratio

    Quote Originally Posted by revi View Post
    Because kilometers are a new-fangled notion that are difficult to learn? And they were invented by (*shudder*) the French...
    And the metric system is dangerous: see http://en.wikipedia.org/wiki/Mars_Climate_Orbiter. I mean, if they
    just had stuck to good old pound-seconds ...
    Remco, metric is easy once you master the 10x table. 10x10=100, 100x10=1000, 1000x10=10000, 10000x10=100000 and I did not even need a calculator to do that. Simply makes more sense.

    An interesting article. Perhaps the big mistake was software developers suffering from Dunning/Kruger effect. While everyone else was working in metric they stuck to imperial. More proof of the need to standarise.

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    rpcrowe's Avatar
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    Re: Sensor Aspect Ratio

    Andre wrote, "Why is the whole world not using metric instead of imperial? Is metric not easier and makes more sense? Why use miles while kilometers are so much easier?"

    That is a good question...

    We inherited our measuring system from the English who have discarded the system and gone over to metric.

    I have heard that American students are at a one-year disadvantage against the world's other students when studying mathematics because our students are chained to this antiquated and inefficient system.

    I am sure that the switch to metric caused some problems in the U.K. and other Commonwealth nations that made the switch and that the switch cost quite a bit of money. However, I would expect that most of the people in the Commonwealth have adjusted to the metric system over time and now most (if not all) measuring devices, road signs, etc. are in metric...

    I am a little surprised that the U.K. did not change over to a decimal monetary system when they went metric for their measurements.

    Although metric measurements are easier, I don't expect Americans to switch over to that system any time in the near future.

    Actually, there are a lot of other complicated ways to measure such as: a person's weight in "stones" (is that still used) and I know that horses heights are measured in "hands"...

    I really wish we had changed to the metric system; although as an old man, I would probably continue to convert metric values into those with which I am used to working!

    Here is a paraphrased conversation I had with another American...

    Me... "I think that the U.S. should change to metric measurement."
    Friend... "Why the heck should we do that?"
    Me... "How many feet are there in a mile?"
    Friend... "How should I know?"
    Me... "You just made my point!"

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    Re: Sensor Aspect Ratio

    I've been raised on metric... Born and raised in the Netherlands, now living in France, both of which have
    abandoned inches, feet etc. a long time ago. It was actually quite a shock to see pounds, ounces, miles etc.
    in everyday use during a (1-year) stay in Scotland... I was trying to be a bit 'tongue in cheek' above, seems
    to have misfired

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    Moderator GrumpyDiver's Avatar
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    Re: Sensor Aspect Ratio

    Quote Originally Posted by rpcrowe View Post
    I am a little surprised that the U.K. did not change over to a decimal monetary system when they went metric for their measurements.
    Richard; you've got to get out a bit more often. The UK switched over to decimal money in 1971. Pounds and pence.

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    dje's Avatar
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    Re: Sensor Aspect Ratio

    Gee I don't know, I go to bed and wake up to all this hilarity ! You've all put in your two bob's worth, or two cents worth as the case may be and gone the extra mile, or kilometer, to ponder the imponderable question of standardisation. One last question - why has it always been called 35mm film ? (as distinct from 1 1/2 in) . Are togs smarter than your average bear ?

    Dave

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    Moderator GrumpyDiver's Avatar
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    Re: Sensor Aspect Ratio

    Quote Originally Posted by dje View Post
    Gee I don't know, I go to bed and wake up to all this hilarity ! You've all put in your two bob's worth, or two cents worth as the case may be and gone the extra mile, or kilometer, to ponder the imponderable question of standardisation. One last question - why has it always been called 35mm film ? (as distinct from 1 1/2 in) . Are togs smarter than your average bear ?

    Dave

    Because it is 35mm wide... Technically 34.98 ±0.03 mm

  16. #16
    dje's Avatar
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    Re: Sensor Aspect Ratio

    Quote Originally Posted by GrumpyDiver View Post
    Because it is 35mm wide... Technically 34.98 ±0.03 mm
    Or 1.377in

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    Re: Sensor Aspect Ratio

    I don't know the why, but the correct size in inches is 1 3/8, not 1 1/2.

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    Re: Sensor Aspect Ratio

    I just want to add to your confusion and say that A4 is an ISO size. It may be measured in mm (ie the metic system) but it is not necessarily part of the metric system. Different countries use the metric system but had different standard paper sizes. You can get the gist of it here: http://en.wikipedia.org/wiki/Paper_size

    And if you think that is confusing, how many folk know how long a metre is (ie what is the standard that it is based on)?
    http://physics.nist.gov/cuu/Units/meter.html
    Last edited by FootLoose; 1st February 2013 at 11:46 PM. Reason: typo

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    Re: Sensor Aspect Ratio

    The meter (metre) used to be a chunk of metal in Paris, but it's probably something much more absurd now, like wavelengths of a phaser set to stun, especially as the original chunk of metal was a bit inaccurate, IIRC. (I resisted the temptation to visit the nist.gov site, honest :-)

    Did I do good?

    Years ago, my GF used to pour scorn on people who wrote 1/10" circuit board pitches as 2.54mm much as we, in our turn, would question the sanity of a 1.968503973" focal length prime lens.

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    Re: Sensor Aspect Ratio

    I love this thread.

    In terms of scientific measurements then I agree that metric is easier to deal with but it is very hard to visualise in the real world.

    If someone told me something was two feet long I'd be able to visualise it in my mind - its easy - its about two feet, but if they said it was 61cm I wouldn't have a clue - its a meaningless number. Feet and inches go way, way back to Egyptian and similar times something like 3000BC and have evolved through the Greeks and Romans who then spread them round their empires. They are organic being based on bits of the body and as I said above they are easy to visualise. I was educated in metric but still use imperial measurements for many day-to-day things. I know the morning wander I do down through the village, along the coast and back up past the windmill is about two miles. Not too far but a recognisable distance and one that I have no wish to convert into Km.

    Money I'll agree is better in a decimalised system. It doesn't need to be visualised so being based on 10/100 units makes sense. Money is a concept, it doesn't exist in any real form so you don't need to think about its size or weight.

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