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Canon Introduces PowerShot G12


Canon Introduces PowerShot G12

Canon has announced the latest addition to its popular point-and-shoot PowerShot line - the G12.

This model is a replacement for its predecessor, the PowerShot G11, which we highly rated when we reviewed it last year. The new model offers a number of enhancements such as 720p 24fps video capture, Canon’s HS System, enabling higher ISO shooting, and Hybrid IS, which Canon claims increases the effectiveness of the optical Image Stabilizer when shooting macro subjects.

Canon has again fitted a 10-megapixel CCD in combination with Digic 4 processing. Standard ISO settings go up to 3,200, and can even be extended up to 12,800 for very low-light situations. The lens is 28mm wide, with a 5x zoom range and shots can be viewed on the 2.8in variable angle LCD display at the rear.

Images can be captured as up to 4.2 shots per second and it can capture in JPG or RAW formats. A High Dynamic Range feature has been added, which takes three different exposures of an image and combines them in the camera to create the optimal image.

All told it looks likely to be another hit for Canon. The PowerShot G12 will be available from October 2010 and will have a RRP of £539.

Go to comments

Mike B

September 14, 2010, 5:11 pm

Since the Canon is more expensive than the new Nikon P7000 which has a better zoom lens looks like few will be sold!


September 14, 2010, 5:57 pm

It looks nice but it has tough competition these days from the new mirrorless interchangeable lens cameras.

This camera has crop factor about 4.5, which makes it a 28-140mm, f/12.6-20 equivalent. The equivalent f/ number of course being extremely low in comparison to DSLRs or the new breed of compact interchangeable lens cameras.

iain coghill

September 14, 2010, 8:08 pm

@CSMR What do you mean by equivalent f/No? Do you mean in terms of minimum depth of field? I expect for most shooters using a compact a larger DoF is probably deemed desirable, especially considering the current fashion for over-saturated everything-in-focus images (eeugh!).


September 14, 2010, 9:02 pm

A decent camera no doubt , but it is looking a little dated compared to the competition . I cannot think of a reason for anyone to buy it over the G11 , Which can be had for less money right now .

Martin Daler

September 14, 2010, 9:45 pm

I think you will find "crop factor" (i.e. the size of the sensor) has no bearing on the f-stop (aperture) values, just like it has no bearing on the focal length of the lens. And why would it? The lens doesn't "know" how large a sensor it projects its image onto. The only thing it affects is the angle of view - the more you crop from the periphery of the view the narrower it becomes, but the brightness of the remaining central part of the image is unaffected by having the periphery cropped away. If it says f2.8 on the lens, then that is what it is.

Looks like a great camera. It looks like Canon's copy of Nikon's copy of the previous Canon...


September 15, 2010, 5:00 am

Of course the focal length and f/number, as stated, are 6.1mm f/2.8 to 30.5mm f/4.5.

These terms have come to be useful to photographers for determining field of view and the physical aperture (the size of the actual opening), which determines given the field of view the amount of light taken in per second and the depth of field. However these are only determined given the sensor size. The same camera placement with the same focal length and f/stop will give different images on different sensor sizes.

For that reason, "equivalent" focal lengths and f/stops can be used to specify these optical properties of a lens/sensor combination.

When I said the camera is 28-140mm, f/12.6-20 equivalent, I meant that the key optical properties (field of view, rate of light intake, depth of field) are the same as that of a 28-140mm, f/12.6-20 lens on a 35mm camera.

NB for the same image, don't fix the same ISO, you need the same equivalent ISO for the images to be actually the same. A crop factor c camera at focal length x, f-stop f/y and ISO z is equivalent to a 35mm camera with focal length c*x, f-stop f/(c*y), and ISO (c^2)z.


September 15, 2010, 5:27 am

@CSMR: You say...

"When I said the camera is 28-140mm, f/12.6-20 equivalent, I meant that the key optical properties (field of view, rate of light intake, depth of field) are the same as that of a 28-140mm, f/12.6-20 lens on a 35mm camera."

You may be right with regard depth of field but surely, as other commenters have pointed out, the rate of light intake is unaffected. That is, the total rate of light intake may be lower due to small size of the lens but the light per unit area of sensor will be identical, which is what matters with regards low light shooting.


September 15, 2010, 5:59 pm

No, neither point is right. Two equivalent camera/lens combinations, and assume same sensitivity and resolution, same shutter speed:

A: crop factor c camera at focal length x, f-stop f/y and ISO z

B: 35mm camera with focal length c*x, f-stop f/(c*y), and ISO (c^2)z

The same amount of light will be let in by both. This is the important factor.

Simplifying by thinking in terms of pixels, if the images have the same number of pixels, each pixel will receive the same number of photons. This is the important equivalence.

The light per unit area of sensor is greater on A. But this is of no fundamental importance to the photographer. Although he might have to know it because typically photographers deal with the less convenient set of variables (ISO f/stop, focal length) rather than their equivalent counterparts. And light density is important for ISO.

iain coghill

September 15, 2010, 10:28 pm

@CSMR: I think you are confused, or at least needlessly confusing.

If, on a bright sunny day, set at ISO 100, shutter speed 1/100th second and aperture at f16 (this is the venerable "sunny 16" rule used by generations of photographers to estimate exposure) I will get the equivalent exposure regardless of whether I am shooting with a 50mm lens on the latest full-frame DSLR, a 350mm lens on a 10"x8" sheet film camera from the 1940s or indeed the Canon PowerShot G12 from this article. This is the very basis of exposure calculation and has no need of the notion of "equivalent" f-stops. Indeed measuring apertures using f-stops is already a "relative" measure rather than an absolute one designed to make life simple.

Martin Daler

September 15, 2010, 11:42 pm

f-stop is focal length (the real one) divided by aperture (i.e. effective diameter of pupil). So longer focal length lenses need bigger apertures to achieve the same f-stop, which is why a 300mm f2.8 is a humungous lens with a massive front element, but a 6.1mm lens (as here) can achieve f-2.8 with a far smaller piece of glass. You do not need to know the size of the sensor to calculate the f-stop, it does not enter the equation.

On a full frame sensor a 6.1mm focal length would yield a very wide field of view. The only difference with the smaller sensor is that someone took some scissors to the picture capturing surface and snipped away the outside edges, thereby narrowing down the field of view. You could achieve exactly the same result by taking your scissors to a photo taken by a full frame camera, and cutting off that part of the photo captured by the outer reaches of the sensor. Neither action would have any impact on the brightness of the image, as expected.

Confusion arises only because focal length has become a proxy for angle of view, which varies according to both focal length and sensor area. Even in the says of film it was confusing with several different sizes of film. Now it is just hopeless.


September 16, 2010, 1:46 am

@CSMR: You say neither point is right but don't make it clear which points you're referring to then just throw random equations around. Really not helpful.

Getting to the crux of things though, what were you actually trying to say in your original post? By what criteria is the lens on this camera equivalent to f/12.6-20?


September 16, 2010, 1:55 am

@Martin Daler: Precisely! What we need is a number to capture field of view, and another to capture effective aperture. Unfortunately such is the dominance of focal length and f-stop, saying "a 60degrees wide lens with a 40mm opening" doesn't convey much to a working photographer. Most are stuck with a confusing combination of sensor, focal length, f-stop and ISO to work this out. Using "equivalent" numbers means you can use just "equivalent focal length", "equivalent f-stop", and "equivalent ISO", 3 numbers instead of 4. But it's a compromise which doesn't respect the technical meanings of f-stop etc..

@iain coghill: Not confusing, it converts everything to 3 numbers instead of 4, so makes things as simple as if everyone were using 35mm sensors.

You can still use the exact same rule when using equivalent numbers (every rule that works can be used with them since it can be used with 35mm sensors and everything that is true of a lens on 35mm is true of a lens with some other sensor with equivalent numbers).

The advantage that equivalent numbers is that they tell you the field of view and depth of field, and also that equivalent ISO will give an indication of noise characteristics more than actual ISO, when comparing across sensor sizes.

You can do some things with rules using non-equivalent numbers (e.g. set exposure as you say) but you can but every rule applies also to equivalent numbers and many rules become simple (by removing sensor size as a variable).


September 16, 2010, 2:01 am

@Ed: your points 1.a) "total rate of light intake may be lower" (not correct, between lens/sensor combinations with same equivalent numbers the total light intake is the same) and 1.b) "the light per unit area of sensor will be identical (not true, it is lower on the larger sensor) and 2. "light per unit area... is what matters with regards low light shooting".

These are wrong as I explained.

For the same shutter speed and assuming the same efficiency of sensor, a shot with this camera at focal length x, f-stop f/y and ISO z (whatever the stated numbers of x and y) will have the same characteristics as a lens with focal length c*x, f-stop f/(c*y), using ISO (c^2)z, on a 35mm camera. Here c=4.5 the crop factor, x=6.1mm to 30.5mm, y is f/2.8 to f/4.5.


September 16, 2010, 2:36 am

@CSMR: Okay...

1. a) As Martin Daler points out, to achieve the same field of view the front element of a lens for a camera with a larger sensor needs to be bigger for any given fstop than that required for a smaller sensor. Thus the small size of lenses for small cameras. By the very nature of the front lens being bigger it thus lets in more light.

1.b) The exact numbers I haven't worked out but to all intents and purposes the amount of light is the same. Thus why for any given combination of ISO, fstop, and shutter speed you'll get the same brightness of picture.

2. Where do you explain this? It seems pretty clear to me that the amount of light hitting any given area of a sensor is what determines how bright a picture you get. That's just how photons work.


September 16, 2010, 5:38 am

1. You are not comparing lens/sensor combinations that are equivalent. You are comparing lenses that have the same f-stop. I am comparing 2 equivalent lenses. In my original reply to you, look at A and B; they are what I am comparing and saying are equivalent.

2. If you use the equivalent ISO you will get the same brightness of final image. "What matters with regards low light shooting" is not brightness, which is just a matter of the user or the camera selecting the correct ISO or normalizing afterwards, but detecting photons. It's photons received by the whole sensor that matters, not per unit area. The more photons you detect, the more information you have to build up an image with high s/n ratio.

If this is not intuitive, make it more concrete by fixing resolution and thinking in terms of pixels, as I explained above: "Simplifying by thinking in terms of pixels, if the images have the same number of pixels, each pixel will receive the same number of photons."

iain coghill

September 16, 2010, 1:36 pm

@CSMR: Seriously, you need to consult some basic texts on photographic theory. F-stops are themselves the "effective aperture" you seem so keen on. Your derivation of "equivalent aperture" is of no consequence to a photographer wrt exposure. None whatsoever. For a given scene brightness the resultant image values depend on sensor/film sensitivity (usually expressed as ISO, though strictly speaking ISO standard only applies to film), shutter speed and f-stop. Differences in pixel density and the number of photons arriving at an individual pixel are captured in the derivation of the ISO sensitivity value and are of no relevance to photographers, except in the general sens of bigger sensors giving better results. Attempting to relate that in terms of "equivalent aperture" is just perverse as it is a constant for the device setting and is not affected by aperture adjustments.

I am sorry if my tone is beginning to sound a little narked, but really this is not rocket science.


September 16, 2010, 7:15 pm

@CSMR: As iain says, I think you should visit wikipedia or something, you have some fundamental flaws in your knowledge. I shall ask again: going back to your original post, by what criteria is the lens on this camera equivalent to f12.6-20?


September 18, 2010, 5:31 pm

I think after watching what happened to Panasonic FZ40/FZ100 and Fuji HS10, Canon has stuck to G11 as is , not much of an improvement here but at least the image quality will be good.

@CSMR , I think you cannot explain what you are really trying to say or as others have said you are confused or have mixed up data, which made me confuse ..... I suggest you go to Nikon's Lens Simulator site http://imaging.nikon.com/produ...

here you can see the crop factor of DX lenses and can match FX (full frame) cameras and lenses and see what happens to Field of View (FOV) as it moves along in degrees with the focal length from 10mm to 600mm , if you choose a DX lens for a FX camera and DX camera for a FX lens. 50mm FX lens on FX camera FOV = 46-40 degrees , while on a DX lens it becomes 31-30 degrees (more close to subject or zoom factor), so, to use a real 50mm FOV 46-40 on a DX lens it's roughly about 34mm or 33mm. Sensor has nothing to do with this, it will only show what the lens and aperture throws at it whether its small or big , small lenses are calibrated in this way with tiny sensors to capture as much wide or narrow FOV, but the basic principle remains the same , no matter how big , tiny ,long (zoom) or wide they perform. In digital cameras do not confuse yourself with electronics and optics.

BTW , Google some Pro photographer's sites for articles on this , and only Wikipedia is not a reliable source. People like me have edited it ! :-)

Good day.

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