Canon EOS mag

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New products EOS 6D full-frame DSLR

EOS 6D briefing

Full-frame and APS-C

The transition to digital Some people believe that the Advanced Photo System was introduced to get photographers ready for the transition to digital photography. The first Canon digital single-lens reflex camera was the EOS D30 (see table below). It features a digital sensor with a size of 22.7 x 15.1mm – similar to the APS-C film format (see left). This has the same 3:2 ratio as the 36 x 24mm full-frame format. Inevitably, models with the smaller sensor are now known as APS-C format cameras (see table below for a list of all EOS digital models). A year after the EOS D30, the EOS-1D was introduced. The sensor in this camera measured 28.7 x19.1mm, not too far removed from the original APS-H format, but adjusted to keep the 3:2 ratio. Canon would probably have preferred the EOS-1D to have a full- frame sensor, but larger sensors generate more data, all of which needs processing. Processors at the time were relatively slow and a full-frame format would not have allowed the 8fps continuous shooting provided by the APS-H format and required by the news and sports photographers adopting this camera. The first Canon full-frame digital camera was the EOS-1Ds. The maximum 3fps continuous shooting was adequate for the more sedate studio environment where many of these cameras were used. (It was said that the ‘s’ was short for ‘studio’, though we are not sure that this has ever been confirmed by Canon.) Now that the full-frame EOS-1D X camera and its Dual DIGIC 5+ processors are offering up to 14fps, it is likely that the EOS-1D Mark IV will be the last of the APS-H models.

All you need to know about full-frame and APS-C formats

Full-frame and APS-C formats originated with film cameras. Full-frame is a format of 35mm film. It first appeared in the early 1900s and became

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popular with the launch of the Leica camera in 1925. The frame format is 36 x 24mm (35mm refers to the width of the film). Before digital, most Canon cameras – SLR and compact – used this 35mm format. The term full-frame was coined to differentiate it from the 24 x 18mm half-frame format, which gave twice as many frames as full-frame on the same length of 35mm film. The Canon Demi half-frame camera was introduced in 1963 and was followed by a number of similar models, including the popular Canon Dial 35. Easier loading Some camera owners found it difficult to load 35mm film. The Advanced Photo System (APS) was introduced in 1996 to overcome this problem. There was no need to thread the film manually across to a take-up spool in the camera – the APS camera and cartridge system did this automatically. All the original Canon IXUS models were APS film cameras – the IXUS name is now used for Canon digital compact cameras. There were also two EOS APS cameras – the EOS IX and IX 7. There are three APS frame formats: APS-H – 30.2 x 16.7mm (16:9 ratio) APS-C – 25.1 x 16.7 (3:2 ratio) APS-P – 30.2 x 9.5mm (3:1 ratio) In fact, all the images are captured at the APS-H format, but a camera setting determines the format used for printing.

There is a lot of confusion about crop factors, extended reach and telephoto effects when using lenses on APS-C cameras. First, let’s dispel the myth that the focal length of a lens changes when switched between a full-frame camera and an APS-C camera. It doesn’t. Focal length is a characteristic of the lens and is not affected by the camera. Field-of-view What does change is the field-of-view. Take a look at the image above left, shot with an EF 400mm lens. A full-frame camera captures the full image. An APS-C camera only records a part of the full image (as shown by the white box on the left hand image). There is no change to the image created by the lens – it’s simply that the smaller sensor only captures the central area of the image. The rest of the image falls outside the area of the APS-C sensor. Magnification effect When you come to display the image to fill a computer screen or a print, the result from the full-frame sensor is shown above centre. The result from the APS-C sensor is shown above right and appears to show an increased telephoto effect. In fact, the APS-C image has been enlarged more than the full-frame image to match the display size. It is a magnification effect, not a change of focal length. You could get an identical result by enlarging and cropping the full-frame image. Crop factor A crop factor of 1.6x often talked about with APS-C cameras can be explained like this: If you are using a 50mm lens on an APS-C camera and you want to shoot the same scene with the same field-of-view with a full-frame camera you need a focal length of 50 x 1.6, which is 80mm. But how often do you need this information? Our advice is to put a lens on the camera and get used to the field-of-view it gives. Forget about crop factors. Standard lenses A standard focal length for a camera is usually taken as the diagonal of the image frame. On a full-frame camera this is 43mm. On an APS-C camera it is 26mm. A focal length greater than the standard is telephoto and a focal length less than the standard is wide-angle. This is much more useful than knowing the crop factor.

Above left to right These photographs show that an APS-C image is simply a cropped full-frame image. There is no change of focal length. See the main text on this page for more details.

Lenses and full-format cameras EF lenses are ideal with full-frame cameras, in that you are using the maximum coverage of the lens. However, there is a downside. Some older EF lenses were designed for film cameras and their performance with full-frame digital cameras is less than perfect – especially at the corners. To get the best from your digital EOS you need to use the more recent EF lenses – these have been optimised for digital cameras. We will not cover the technical side here, but it has to do with the angles at which rays of light hit the sensor. If you were using EOS film cameras before moving on to digital, one advantage of a full-frame camera is that the coverage of EF lenses is unchanged. Lenses and APS-C cameras EF lenses can be used on APS-C cameras, though with the cropping effect shown above. This can be useful for older lenses as the reduced edge performance is cropped. The downside is that you lose wide-angle coverage. The ultra- wide EF 14mm lens gives a field-of-view similar to that of a 22mm lens used on a full-frame camera. The EF-S 10-22mm lens has been introduced to restore the balance. A 10mm focal length on an APS-C camera gives the same field-of- view as a 16mm lens on a full-frame camera. EF-S lenses are generally smaller and lighter than EF equivalents, but the image they produce only covers an APS-C sensor, not the larger full-frame sensor. EF-S lenses will only fit APS-C cameras (excluding the early D30, D60 and 10D models). If you have an APS-C camera, but think you might move on to a full-frame camera in the future, it is worth staying with EF lenses. The higher-quality L-series lenses are only available in EF mounts. EF lenses fit full-frame and APS-C cameras. Format choice Full-frame cameras give the best of both worlds – wide- angle coverage and the option to enlarge part of the image for a closer view of the subject. However, full-frame cameras are more expensive than APS-C cameras. In terms of image quality, you can get great results from both types – the format used will not be obvious in the photographs.

The difference in price Full-frame digital cameras are more expensive than their APS-C counterparts in part because the sensors cost a lot more to manufacture. Sensors are not produced individually, but on a large circular ‘wafer’ which is then cut into rectangles of the required size. You can get many more APS-C sensors from the wafer than full-frame sensors. The cost of the full-frame sensor is a lot more than double that of the APS-C sensor.

Below This chart shows the introductory date and format of every EOS digital camera (except the new EOS M, which needs its own category). The EOS 7D* refers to the EOS 7D with firmware update 2.0 (see page 66). Although not a new camera, the updated EOS 7D offers a range of new features. You can see that the new EOS 6D starts a new category.

YEAR

APS-C FORMAT

APS-H

FULL FRAME

ENTRY LEVEL

MID-RANGE FLAGSHIP

ENTRY LEVEL MID-RANGE

FLAGSHIP

2000

EOS D30

2001

EOS-1D

2002

EOS D60

EOS-1Ds

2003

EOS 300D EOS 10D

2004

EOS 20D

EOS-1D Mark II

EOS-1Ds Mark II

2005

EOS 350D

EOS-1D Mark II N

EOS 5D

2006

EOS 400D EOS 30D

2007

EOS 40D

EOS-1D Mark III

EOS-1Ds Mark III

2008 EOS 1000D EOS 450D EOS 50D

EOS 5D Mark II

2009

EOS 500D

EOS 7D EOS-1D Mark IV

2010

EOS 550D EOS 60D

2011 EOS 1100D EOS 600D 2012 EOS 650D

EOS 7D*

EOS 5D Mark III

EOS-1D X

EOS 6D

16 Reproduced from EOS magazine October-December 2012

Reproduced from EOS magazine October-December 2012 17