Macro Photography: Sensor Size / Aspect Ratio

Flashback (AR -Macro Nov. 3rd, 2007) :

Real macro photography is where you are working around 1:1 ratio and closer thereby giving an image on film that is equal in size or larger than the subject being photographed. The range from life size on film (1:1) up to ten times (10:1 , or even bigger) enlargement on film is be the strict definition of macro photography.

Most lenses are not capable of getting you a clear macro shot because they are not able to get close enough to the subject. Zoom lenses ( on point and shoot cameras) are usually equipped with a “macro” setting where they may get close enough to get a 1:4 ratio ( that means the image on film is 1/4 the size of the subject) If your shot is crisp and clear you might be able to crop the subject , but I have to point out that when shooting at anything less than 1:1 ratio (e.g. 1:4) we are no longer talking macro.

When I say film, I mean the actual negative NOT the result you see on a print. So if you use a 35mm film, the subject should not be bigger than 35mm so it fits with a 1:1 ratio aspect on that negative. Same goes for sensor, it depends on how big your sensor is, the subject should not be bigger than the sensor. And no what you see on your computer screen has nothing to do with it either, of course the picture on the computer is way bigger then life size.

Point and Shoot cameras usually have a "macro" setting where the zoom lens may get close enough to give maybe 1:4 ratio (image on film/sensor is 1/4 the size of the subject). Any normal 4"x6" print made from that negative will make a picture of the subject about life size due to the approximately 4x enlargement needed to make the print. But if it was a small flower/bug it still will be a small flower/bug on the print. But please keep in mind that all this ratio aspect talk has nothing to do with the print or what you see on your computer screen. This is very important for you to understand. Macro photography is a technique where you need some expensive equipment and there is no BUT about this. No offense to any point and shoot camera people but you need to understand that real macro just isn’t done with such cameras.
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Now, what is the size of 35mm film or my digital sensor ?

The diagram below illustrates the relative size of several standard sensor sizes on the market today. Most digital SLR's have either a 1.5X or 1.6X crop factor, compared to 35 mm film, although some high-end models actually have a digital sensor which has the same area as 35 mm. Sensor size labels given in inches do not reflect the actual diagonal size, but instead reflect the approximate diameter of the "imaging circle" (not fully utilized). Nevertheless, this number is in the specifications of most compact cameras.



A fucking car (not even a light of a car) , a Christmas tree, the Himalaya or a Cheeseburger ... Do NOT fit on any of these sensors !!!

Sensor of a standard DSLR:



example Sensor of most Compact Cameras:




Sensor Size by Bob Atkins :

Sensor Size

The size of the digital sensor element (which is equivalent to the size of the negative for film cameras) is pretty small in all consumer digicams - typically around the size of a fingernail (and a small fingernail at that!). As I said above, a 35mm film frame is 24mm high by 36mm wide but most digital cameras use sensors very much smaller than this. Here are some typical digicam sensor sizes. The "name" of the sensor is based on specification for old TV tubes used in the 1950s. Nobody is quite sure why it's being used for modern digital sensors since the "sizes" don't really relate in any consistent way to the actual physical size of the sensor. However these names are widely used, so it's best to know what they are. They are often listed in digital camera spec sheets.





Most of the current small 5MP digital cameras use 1/1.8" sensors which are about 7mm x 5mm. They have an area 25x smaller than 35mm film and about 9.5x smaller than a small sensor digital SLR like the Canon EOS 10D. You might wonder why sensor size matters and that's a pretty complex issue. The bottom line is that, for a given pixel count, the larger the sensor (and hence the larger the area of the individual pixels) the better the image quality and the lower the noise level. While large sensor cameras like the EOS 10D can operate at the equivalent of ISO 3200 (though the image does get noisy), many consumer digicams with small sensors cannot operate above ISO 400 before the noise becomes excessive. Size also matters because images made on small sensors have to be enlarged to a greater extent to make a given print size. This means that any lens defects are enlarged more, so small sensor cameras demand high quality lenses - and that's not always something you get in a relatively inexpensive camera. Whatever way you look at it larger sensors and larger pixles yield better quality images.

Another factor in quality here is that small sensors tend to be of a different type than large sensors. Small sensors, and the sensors used on all consumer digital cameras, use a scheme which can read the data from the sensor in real time using a scheme called "interline transfer" and the CCD electronics control exposure rather than a mechanical shutter. Large sensors used on more expensive Digital SLRs are often of a different design known as full frame - which doesn't refer to their size, but their design - and which require the use of a mechanical shutter. They don't read out and the display the data in real time, only after the exposure so they can't give real time LCD displays or record video. The advantage of this scheme is that the whole pixel area can be used to capture light while interline transfer CCDs use part of each pixels to store charge. Since smaller pixel areas generate more noise and interline transfer CCDs are not only smaller to start with but use some of their pixel area for charge storage, their noise level is significantly higher. So the smaller interline transfer sensors in consumer digital cameras yield lower quality images than those used in higher end DSLRs, they can do more "tricks" like recording video clips and giving a live image display on their LCD screen. The lack of a mechanical shutter also makes the cameras cheaper and simplifies construction.

Small sensors mean that short focal length lenses are needed to give the same field of view as cameras using larger sensors or 35mm film. So, for example, a typical consumer digicam may need a 7mm lens to give the same view as you would get using a 35mm focal length lens on a 35mm camera. This has consequences on depth of field and means that most consumer digicams have a vary large depth of field. Great if you want everything in focus, not so great if you want a blurred background.


Thank you for your time and for reading this !

_{I hope the images show right for you, I use a 1680x1050 display, so I apologize if on smaller displays the CSS goes kaput}

Do you know what macro photography is ? Can you tell what is macro and what is not ?

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