Canon PowerShot A640 Digital Camera Review

|  Canon PowerShot A640 in Compact Cameras
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The flip-out LCD from the Canon G-series has been found safe and well on an A-series compact with 10Mp resolution as Duncan Evans explains.

The PowerShot A-series from Canon had a reputation as the cheap and cheerful, easy to use range of entry-level compacts. Canon has rather thrown that assumption in the bin with their latest two releases, of which the A640 is the 10Mp replacement for the A620.

The front angled view

  • 10.0 Megapixels
  • 4x optical zoom
  • 2.5" vari-angle LCD
  • DIGIC II and iSAPS
  • 21 shooting modes and My Colours
  • High-speed ISO800
  • Safety Zoom & Digital Tele-Converter
  • 1cm macro mode
  • 30fps VGA movies
  • Range of accessories
  • Takes 4 AA batteries
  • USB 2.0 interface

Functionality is the key to the top end of the A-series, eschewing the point and shoot budget simplicity of its origins. For this they are up against cameras like Samsung's 10Mp NV10 and Kodak's 10Mp V1003.

The rear view
Modes and features
Like the A620 before it, the 640 features a flip out and rotating LCD screen, though it's gone up in size from 2” to 2.5”. Using it on an inexpensive range instead of the G-series seems a thoroughly bizarre decision, but anyone on a budget should be well pleased that this has been done. The advantages of an LCD like this cannot be overstated. It even flips completely around so that people can photograph themselves.

The other main feature of the A640 is that the resolution has jumped to 10Mp, which is surely overkill on a camera of this type. Certainly, it means that only around five hi-res, superfine pictures can be stored on the the supplied 32Mb SD card. This is rather tardy, but the good news is that the A640 supports SDHC, which is the high capacity version of the SD card. Pictures are stored as JPEGs, with varying degrees of compression and quality, and also resolutions. There's even a widescreen mode, designed to make pictures compatible with widescreen TVs. Obviously you could just crop any existing image, but this makes composition easier in the first place.

The battery compartment
The zoom is a 4x optical affair, with digital cropping available on top of that. The control for it is a standard rocker switch around the fire button. It's handily placed and easy to use, even if it does go in short steps rather than very smooth increments. The control dial on the top of the camera contains all the usual suspects with P,A,Tv,M, as well as Auto and Custom. Custom is the Auto mode, with a few settings retained for personal preference. After this are the Portrait, Landscape and Nighttime Portrait modes. These have been pulled out from the Scene mode settings, as they are the most commonly used. Smart thinking there from Canon. To round things off, there's a Stitch Assist mode for panoramas and the video mode which offers 640x480 or 320x240 resolutions at 30fps or 15fps. At 640x480 and 30fps a 256Mb SD card can store around 1min 27secs of footage.

On the back of the camera there's an optical viewfinder, which doesn't contain any info or have a dioptre for adjustments, so it's about as basic as it could be, The controls are generally neat and obvious. A slider switches between playback and shooting modes, while a selection button is surrounded by a four-way joypad. Pressing the selection button brings up the common option shooting menu, which contains things like resolution, AWB, colour profiles, metering and the ISO range. This runs through 80, 1000, 200, 400 up to 800. There's also a Hi-ISO mode, activated elsewhere, that only works in program mode. It's fairly obvious why it only goes to ISO800 – 10Mp squeezed into a small sensor will generate plenty of noise at higher ISO levels.

Three of the buttons surrounding the joypad aren't likely to see much use as they cover direct printing, the preferences menu and display options. Also, pressing downwards on the joypad switches between AF, manual focus and the macro mode. This latter item allows focussing as close as just 1cm, which is astonishing. With the rotating screen, the A640 is ideally suited to capturing small objects in awkward places, like insects. Pressing upwards sets the flash options.

The other button is dedicated to exposure compensation which offers +/-2EV, not a huge range, but acceptable for an inexpensive camera. What is nice is that the display changes in real time as this is adjusted so its easy to see the effect and how much you need to bring the sky back in for example. The fact that it can be done in 1/3rd increments make for more precise adjustments.

Autofocus has a couple of interesting options. Either a centre zone can be used, a movable zone, or the nine point AiAF mode. This looks around the nine zones for things to focus on. As this may not be what you want, it's slightly risky, but it does pick up multiple areas and adjusts the focus between them.

The side view
Build and handling
It should come as no surprise to realise that it has a plastic hand grip but a fair portion of the body is pleasing black metal. The grip is very welcome as it allows good control of the camera, though it does feel fairly insubstantial. The LCD doesn't look like it will take much rough treatment, but the display on it is fine, and considering the price point of the camera, it's churlish to complain at all. The controls are all easy to use, and i like the fact that you can use, say exposure compensation, change the focus, and on exit from that option, be left back in exposure compensation to continue making changes until you're done. The menus are simple to navigate, sharing the same system as the G7 and A710, but with just a joypad, rather than a dial which the G7 has in addition, it simplifies the whole process.

Flash options
The A640 can be connected to the Canon high power flash unit HF-DC1, or it can use the built in unit. This isn't very powerful having a range of just 4.2m at ISO100, but it does offer a red-eye reduction mode, and can be tailored to use as fill-flash, making portraits easier to produce.

The shooting speed is fairly ordinary, but then that isn't important in a camera in this market. What is important is that it starts up quickly, and is ready to shoot in around three seconds. The aperture range is f/2.8-f/8, which is fairly standard, and while the top shutter speed of 1/2500th isn't particularly fast, at the other end, being able to shoot an exposure up to 15secs is a real advantage for long exposures.

What really matters is that the menu system and the controls are all logically laid out and easy to access and use. With the flip-out LCD it's easy to compose shots in awkward places.

When shooting landscapes there's reasonable depth of field, but it's no surprise to find that with 10Mp shoe-horned into such a small space, noise and image artefacts are common in darker, shadow areas, or in the backgrounds, even at ISO80. The quality isn't bad as such, and won't be readily visible unless printing at higher than A4. When the ISO range is ramped up to 800 then colour noise is readily apparent, and quite bitty to the extent that it would make a portrait picture unpalatable. It's still acceptable for certain types of picture, particularly monochrome ones though.

Other picture flaws include the fairly inevitable colour fringing on white sky days. To be fair, there isn't a compact that doesn't produce this, and its no worse than anything else. What is good is that even on standard settings, there's strong colour saturation on grey and dull days that would usually kill an exterior photo.

Speaking of bad conditions, the camera coped well under dreary, drizzle-filled skies, being able to focus quickly and accurately. The metering systems of zone, centre weighted and spot all work well, and reflect what they are reading, in real time on the LCD. Zone systems invariably fail under bright skies, which is where the exposure compensation system came in very useful.

The landscape test
This isn't bad as there is little colour fringing, except for a red glow on the white stanchions on the right side of the canal. The image does have a bitty-feel to at close up, and the grass in the mid-distance has been rendered rather mushily. An exposure compensation of -1 2/3rds EV was required to retain the sky.
Field test of a church
Exposure compensation was used to stop the sky turning completely white. While the wide angle end of the lens causes the building to bend, never mind have converging verticals. The sharpness is good and the colour and detail in the brickwork of the 10th century church tower is worth noting.

The colour chart
The significant element here is that the primary red is much brighter than it should be, which has resulted in the light skin colour turning out more pink. Cyan is lighter as well, resulting in the blue-green mixture having a bias towards cyan. Orange and yellow are both a lot flatter and weaker. This isn't a particularly good result.
The portrait test
The standard AP mode shot for the portrait gives a detailed picture, though the skin tones are patchy in the shadow areas.
The blue cast comes from the AWB setting itself to counter the interior lights and not the exterior daylight.

Seeing the camera cope with bright light
While being packed full of detail, this boatyard shot on a very grey day is also quite bitty, with the grasses at the front of the picture being fairly poorly rendered.
The macro gets in close, down to 1cm
The macro function allows focussing down to an incredible 1cm. This macro shot is from further away but captures the detail in sharp focus.

Noise tests
The ISO80 picture is nice and clean, with lots of detail and no noise, but it starts to appear at just ISO100, thought it's minimal. At ISO200 the noise is apparent, but not significant, whereas at ISO400 it's larger still but perfectly acceptable and fit to use. There's a sudden and dramatic change in the ISO800 picture with the orange colour shifting towards red and the colour noise a lot more noticeable.

ISO80 test
ISO80 test
ISO100 test
ISO100 test

ISO200 test
ISO200 test
ISO400 text
ISO400 test

ISO800 test
ISO800 test

For a budget range camera to have a selection of full-feature camera modes, a flip-out LCD and a 10Mp resolution is something of a surprise. The A640 is a willing, lightweight and convenient little camera that can taken anywhere and used without drawing much attention to the photographer. The 10Mp is overkill and the result of packing those pixels in is that images are noisy, but fortunately, not to a significant degree at ISO 100.

What the A640 does do well is portraits, with nicely filled-out flash and is good in general use. It's also brilliant for macro work with a focus capability of just 1cm. The fact that you can also do 640X480, 30fps video and implement various colour profiles gives the camera real versatility. As with others in this and the G-series there are options to add wide angle and telephoto convertors as the metal ring on the front of the camera unscrews.

The image quality might not be flawless, but considering the functionality on offer its scarcely problematic. For a budget range camera that has a street price of around £250, it's like finding that your Toyota Yaris has a V6, 2.5litre engine under the hood.

The Powershot A640 from the front
Plus points:
10Mp resolution
2.5” LCD
Good controls
Lots of colour modes
4x optical zoom
1cm macro mode

Negative points:
Only sRGB
Not great range of exposure compensation
Not a fast shooter
Images noisy





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