Canon Powershot A570is Review - and CHDK
If this review reads a LOT like my review of the Canon A720is it's because the two cameras differ only in a few minor details (basically lens, zoom range and pixel count). You might wonder why I'm reviewing the A570is now (April 2009) when it's been discontinued for a while and "replaced" by the A590is and more recently the A1000is. There are three reasons! (1) I just bought one - which leads to (2) They are available (refurbished) from Adorama for under $75 and (3) CHDK compatibility. If you don't know what CHDK is, you will by the time you finish this review...it's basically a firmware update which can add a large number of features to the A570is (and many other Canon Powershot digicams). It's an unofficial "hack", not supported or sanctioned by Canon - but it works!
Here are a few features of the A570is
- Manual exposure mode
- Av exposure mode
- Tv exposure mode
- Manual focus mode
- Manual flash power control (3 steps)
- Exposure compensation +/- 2 stops in 1/3 stop steps
- Flash exposure control +/2 2 stops in 1/3 stop steps
- 35-140mm (equiv), 4x zoom lens
- Shutter speeds from 15s to 1/2000s
- 7.1MP CMOS sensor
- Optical stabilization system good for 3 stops increased stability
- ISO settings from 80 to 1600
- Pocketable size
- 640x480 movies at 30fps with sound
- Uses cheap and easy to obtain AAA batteries
- Optical viewfinder
- Price under $75 (refurbished)
Movie Modes
The A570IS also has a set of movie modes. It can record VGA (480x640 resolution) video at 15 or 30 frames/sec for either 1hr or when the file reached 4GB, whichever comes first. In the highest image quality 30fps mode, 4GB gives you just over 30 minutes of recording. At 15fps you can get 1hr of VGA video. The A5700IS is also capable of recording at 240x320 resolution at 15, 30 or 60 frames/sec. There's also a compact mode which records at 160x120 resolution and 15 frames/sec which can make small files suitable for sending via email. Sound (mono) is recorded while shooting movies. Note that the later 590is isn't capable of 640x480 at 30fps. It's maximum frame rate at that resolution is only 20fps which means that movies will show more motion blur.
Image stabilization operates in movie mode, making handheld shots much smoother, however you can't optically zoom the lens while recording (unless you use CHDK...). Digital zooming (up to 4x) is possible, but digital zooming lowers image quality. You can set white balance for movies but AF does not operate (focus is set on the first frame).
IS and ISO - Low Light Shooting
The image stabilization system allows you to shoot in about 3 stop less light than you could without it. At the 35mm lens setting I could get sharp images down to a shutter speed of around 1/4s, while at the 140mm setting I could get sharp images down to about 1/15s. This is remarkably good performance.
Crops at 50%
ISO can be set to 80, 100, 200, 400, 800 and 1600. Above ISO 400 noise becomes pretty noticeable and at ISO 1600 the automatically used noise reduction algorithm reduces image detail significantly as you can see in the set of 50% crops above. Remember that on a typical monitor, these represent small sections of a large print - something like 18" x 12". I've seen other reviews which imply that ISO 1600 is so bad as to be useless, but I think that's too harsh a judgment. I'll admit that if you look at an ISO 1600 shot on a monitor at 50% it looks pretty bad - but that's just about the equivalent to looking at a 12" x 18" print from a distance of 1ft. I took a number of shots at ISO 1600 and made 4x6" prints from them. To me they looked pretty good, in fact probably better than prints I remember having made from ISO 1600 film some years ago. So although ISO 1600 images are noisy and details are soft when compared to shots at ISO 80, they are far from useless as long as you stick to small prints.
I wouldn't shoot at ISO 1600 unless I absolutely had to, but at least it's there if you really need it.
Optical Viewfinder
Optical viewfinders are becoming increasingly rare on digital cameras, but the A570is has one which zooms with the lens from 35mm to 140mm. It only shows about 80% of the frame and there's no diopter adjustment, but it's perfectly fine for aiming the camera and it can more than double the battery life if you turn off the LCD. Of course you can't really turn off the LCD since you need it to adjust the camera settings, but you don't need it on all the time.An additional advantage of the optical viewfinder is that you can use it even in the brightest sunlight, where it's sometimes tricky to see the LCD image clearly, plus I think you can hold the camera steadier held up against your eye than held out at arms length to view the LCD.
Manual Controls
In general the manual controls are available in what Canon call the "Creative Zone" modes, M (manual), Av (aperture Priority), Tv (Shutter Priority) and P (Program).While the Powershot A570is has a shutter speed range of 15s to 1/2000s, not all speeds are available in all modes. While you can set 15s in both M (Manual) and Tv (Shutter Priority) modes, in Av (Aperture Priority) and P (Program) modes the shutter speed won't go longer than 1s. I've seen similar behavior on other Powershot cameras and I don't really know why there is this limit, but just be aware of it). It's not a problem since if you really want a long shutter speed, just switch to Tv or M.
In manual mode the camera displays the set shutter speed and aperture plus an indicator of exposure from -2 (two stops underexposed) to +2 (two stops overexposed) in 1/3 stop steps. When it displays "0", exposure is correct.
The lens aperture is adjustable in 1/3 stop steps. At 35mm the range is f2.6 to f8 and at 140mm the range is f5.5 to f8. You can't stop down past f8 in any mode. This is because the senor is so small that if you could stop down to a smaller aperture, the image would be significantly softened due to diffraction effects. All small sensor digicams are like this, it's the nature of the beast.
Flash exposure can be set to manual or auto when using Tv, Av and M modes. In auto you can dial in from -2 to +2 stops of flash exposure compensation (in 1/3 stop steps). In manual mode there are three power levels, minimum, middle and maximum. With a fixed flash power output you control flash exposure via the aperture and ISO settings you chose. Using a flash meter I measured the maximum flash output GN as about 16 (ft, ISO 100). In M, Av, Tv and P modes you can manually set the flash to 2nd curtain sync. In manual mode you just get one flash, so you could use it with a traditional optical slave flash. In auto mode the flash emits a metering pre-flash, so you need a digital aware slave which fires only on the main flash, not on the pre-flash.
In manual focus mode you can add a 10x magnifier to the center of the screen to make it easier to judge focus. A scale is displayed (in ft or m), though it's not very exact. It does show you where you are within the focus range though. There are two scales. One runs from 50cm to infinity with marks at 1, 2, 5m and infinity. If you close focus the scale switches to 0 to 50cm with marks at 10, 20 and 50cm.
Autofocus
There are a number of autofocus modes on the A570is. You can let the camera select from 9 AF zones which cover the whole image (AiAF mode). You can select the center focus zone only. You can select the center focus zone, but move it to any position in the image (Flexizone) and/or you can make it smaller so you can focus on a smaller area of the subject. There's also a Face Detect mode which focuses on faces and adjusts exposure and flash for best exposure.
White Balance
The A570is has a full set of white balance mode - Auto, Daylight. Cloudy, Tungsten, Fluorescent, Fluorescent H, Underwater and Custom. In custom mode you can take a shot of a grey card (or a white card) and use that to set a custom white balance for future shots.
Image Zone Modes
The A757is has the usual set of Canon fully auto modes which they call the "Image Zone" modes - Portrait, Landscape, Special Scene (Night Scene, Foliage, Snow, Beach, Fireworks, Aquarium, Underwater), Indoor, Kids & Pets, Night Snapshot, Stitch Assist and Movie. In each one the camera chooses the settings which it thinks are best. Some can be changed, though most are fixed. For example, in most of the program modes you can change the drive from single frame to continuous shooting or delay timer and you can set the image resolution and quality, but you can't change the metering pattern, flash exposure compensation, white balance, saturation, sharpness, contrast or ISO setting. The image zone modes are intended mainly for "point and shoot" work, though you can apply exposure compensation in 1/3 stop steps from +2 to -2 stops and turn the flash on and off as well as turning on and off features such as Image Stabilization and Face Detection.
Metering
Three metering patterns are available. Evaluative metering takes data from multiple zones. Centerweighted metering takes an average reading weighted for the center region of the image. Spot metering can be set either to take a reading from the center of the frame, or it can be set to take a reading from the AF zone when you have Flexizone AF mode selected (see "Autofocus" section above for Flexizone).
Image Data Display
Prior to shooting the screen displays the shooting mode, ISO setting, shutter speed, aperture, exposure compensation, focusing mode and image stabilization indicator. The above image shows the camera was in Program mode, set to ISO 1600, image stabilization was active and the camera was in macro focusing mode.
Memory Cards and Data Storage
The A570is uses Secure Digital (SD) memory. SD cards are limited to 2GB, but the A570is can also handle the higher capacity SDHC cards. No memory card is supplied with the refurbished camera so make sure you buy a card when you buy the camera. You can also use MMC (MultiMediaCard) cards, though I don't know why you would.Images are stored as JPEG files at one of three different compression levels. The lower the compression the larger the files, but the higher the image quality. The A570is cannot store images in RAW format (in common with most other current Canon digicams)- though again CHDK can enable a RAW capture option.
Power
Like all "A" series Canon Powershots, the A570is is powered by AA cells. In this case just two of them. Canon say that you should get about 140 shots from a pair of alkaline AA cells with 50% flash usage and the LCD on. With the LCD off this goes up to 400 shots. Using rechargable 2500mAh NiMH cells you should get around 400 shots with the LCD on or 900 with it off. Though Canon don't specify what to expect from Lithium AA cells, I suspect you might get almost double the numbers for NiMH. This is pretty respectable performance. The advantage of using AA cells is that if you do run out of power unexpectedly, you can find alkaline AA cells in almost any general store in any part of the world.The A570is doesn't display a battery level indicator until the voltage drops to the point where it warns you to change the batteries. You do get a little time after the warning, but not all that much, so it would be advisable to carry a spare set of batteries with you. CHDK can add a battery level indicator.
Tripod Socket
A minor point, but the tripod socket is located on the left hand side of the camera base, not on the optical axis of the lens. Technically this means that if you use the camera on a tripod and take a series of images to stitch together, you're not rotating about the right axis. Even with the mount in line with the lens, you're still not quite at the right point, but you are closer. In practice this probably isn't going to be a big problem, but it's something to be aware of.The only advantage of having the tripod socket close to the left edge of the camera is that it means you can change the batteries and memory card without having to remove the camera from the tripod, since the battery and memory card door is over on the right side.
Size
The Powershot A570is measures 90 x 64 x 43mm (3.5 x 2.5 x 1.7in). This makes it larger than the smallest digital cameras such as the SD800 IS, which measures 89.5 x 58.0 x 25.1mm (3.52 x 2.28 x 0.99 in.) or the DS200/300 which measure 86 x 54 x 21 mm (3.4 x 2.1 x 0.8 in), but the A570is is still pretty small. The biggest difference is in the thickness of the camera. The A570is has a small "grip" where the two AA batteries fit and this makes the maximum thickness greater. However this grip section makes it MUCH easier to shoot one handed since it allows you to get a firm hold on the camera. You can easily slip the A570is into a jacket pocket and it even fits in the pocket of my jeans without too much trouble. It won't fit in a shirt pocket though, whereas a truly tiny camera like the SD200/300 will. The SD series cameras, while small, don't have the extensive manual control features of the A series cameras, so you have to chose between size and flexibility.
Conclusions
The Powershot A570is is a remarkably capable camera with extensive manual options. There's very little you can't do in the way of manual control as long as you select the correct mode. You have full control over shutter speed, focus, aperture, flash power and operation, metering, AF zones, image sharpness/contrast/saturation, drive mode, image stabilization and just about every other feature the camera offers. Of course you can also operate the camera in fully automatic mode if you wish. The lens quality is good and the zoom range is useful. There can be a little purple fringing of very bright areas, but it's not excessive and it's something seen in just about all cameras of this type. The image stabilization system is very effective. Focus and exposure are consistently good. Extreme highlights occasionally blow out, but that's indicated on the histogram display and is easily corrected by shooting again with a little negative exposure compensation. For the price (under $75 from Adorama) I think it's quite a bargain and even if you already have a DSLR it's a very good and very flexible backup digicam, small enough to carry when the DSLR outfit is just too big.
CHDK
I'm not sure what CHDK stands for, but some have speculated "Canon Hacking Development Kit". Whatever it stands for, it's firmware which can be loaded into compatible Canon Powershot cameras and which adds a large number of new features. Just a few of these features include (from the CHDK Wiki):- RAW - CHDK can record raw files, giving you access to every bit of data the sensor saw, without compression or processing. Raw files can be manipulated on the camera, or processed on your PC. CHDK also has experimental support for the open DNG raw standard.
- Override Camera parameters - Exposures from 64s to 1/60.000s with flash sync. Full manual or priority control over exposure, aperture, ISO and focus.
- Bracketing - Bracketing is supported for exposure, aperture, ISO, and even focus.
- Video Overrides - Control the quality or bitrate of video, or change it on the fly. Add optical zoom while shooting video.
- Scripting - Control CHDK and camera features using ubasic and Lua scripts. Enables time lapse, motion detection, advanced bracketing, and much more. Many user-written scripts are available on the forum and wiki.
- Motion detection - Trigger exposure in response to motion, fast enough to catch lightning.
- Battery Level - Readout of remaining battery power in %.
- Edge overlay - Detect the edges in a scene, and display them later. Ideal for timelapses, stop-motion, stereography and much more.
- Live Histogram - CHDK includes a customizable, live histogram display, like those typically found on more expensive cameras.
- Zebra-Mode - Displays under and overexposure areas live on the screen.
- GRIDS - Create custom grids and display whichever one suits your shooting conditions.
- Multi-Lingual Interface - CHDK supports about 22 languages, and adding more languages is simple.
- DOF Calculator - Display detailed DOF information on the screen.
- Customizable OSD - Improved display of battery status, free space, camera parameters, and much more. Fully customizable with an on-screen editor.
- Filebrowser - Manage files without a PC.
- Textreader - Display text files on your camera.
- Games - Play Reversi, Sokoban, Mastermind or 4-in-a-Row on your camera.
- USB remote - Simple DIY remote allows you to control your camera remotely.
- Benchmark - Compare the performance of your SD cards.
- User Menu - Edit your own customizable User-Menu for fast access to often used features.
Since there are whole websites dedicated to CHDK, I won't go into any more details here, except to say that the A570is (with firmware v1.00e or 1.01a) is fully supported. The refurbished A570is I purchased from Adorama came with Canon firmware v1.01a. The CHDK firmware update for 1.01a I downloaded from http://mighty-hoernsche.de/" worked just fine. The firmware loads on top of the camera's firmware from the memory card. It doesn't overwrite the original firmware and if you don't have CHDK on the memory card the camera just uses the standard Canon firmware when it boots up.
Where to Buy
The A570is is hard to find new at a decent price, but as of April 2009, Adorama have a Canon refurbished A570is for $74.95 which seems like a pretty fair deal (I bought one so it must be!). It doesn't come with a memory card, so if you don't have any SD or SDHC cards you'll want to get one with the camera. I"ve tried 2GB, 4GB and 8GB cards and they all seemed to work just fine. An 8GB card will give you about 1hr video recording time (in two takes since the maximum file size allowed by the operating system is 4GB). I've tried both class 4 and class 6 cards and didn't see any real difference (class 6 cards are faster than class 4 cards in theory, but in practice write speeds may be limited by the camera). Here's a good deal on an 8GB class 6 card:
Kingston also have a nice card reader. Older card readers and PCs which support SD cards may not work with SDHC (high capacity cards over 2GB). This card reader adds SDHC support and plugs into a USB port.
