Teardown: Airis Photostar N702D 3.2MP Digital Camera

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People often donate old and unwanted gear to me, in the hopes that I have some use for it, or I can have some use for it – whether that means taking it apart, or writing a blog about it. Many of these items do end up sitting around until I get some down-time to go and examine them. This weekend, I came across this very neat point and shoot camera in a velcro case … what would this mysterious camera be?

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As it turns out, it’s an Airis Photostar N702D. A “what?” you might ask. I had exactly the same thought. Searching online yielded few results, although it seems that AIRIS was born from Infinity Systems in 1998, a predominantly Spanish company without any real noteworthy products. Interestingly, a datasheet still seems to exist, and the driver downloads seem to be alive as well. According to this, it seems to be a 2032 x 1520 pixel native sensor (~3MP), with an interpolated 6.3MP mode, and has an internal 16Mb memory with support for up to 512Mb MMC/SD card expansion with a JPEG and AVI (MPEG-1) video mode.

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I think it was immediately apparent upon taking it out of the casing, that it was one of those cameras that people who don’t know about digital cameras end up buying. You know, the cheap, very lightweight, very plasticky cameras with no brand name and interpolated pixels that always end up a disappointment. Lets face it – no camera that’s been anything decent offers an interpolated mode. Maybe this is something that’s not even good enough for the “Pro Photographer, Cheap Camera” antics of DigitalRev.

But regardless, it didn’t seem to be the worst “toy camera” I’ve come across. It seems to have a Xenon flash, and a slide over lens cover. It seems to have a red LED, but I think it’s fixed focus, so it’s probably more a self-timer indicator …

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The rear has a very generic “Digital Camera” branding, a limited set of buttons, an LED and an LCD display. At least it has an LCD display – some of the toy-grade cameras don’t let you review or see what it’s capturing and just rely on a viewfinder. There’s also a two position switch for Landscape and Macro. A swivel eye is provided for the wrist-strap, although given how much this camera’s probably worth, it’s probably not worth having a strap on it.

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The top proudly proclaims its 3.2 megapixel designation, and has a power and shutter button. The shutter button is a one-stage clicky button, thus implying no focus on this camera. Results will be shocking, for sure. That being said, since most basic level phones now ship with a better sensor than this, I’m doing the world a favour by getting rid of it. The camera taking pictures of this camera has over 7.5 times the number of pixels.

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The underside has a SD card slot trap door exposed to the outside – no flaps to undo before swapping cards. It accepts two AAA batteries for power, which is quite convenient. It also has a tripod mount socket.

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The only means of connectivity? Mini-USB-B connector. It’s not that old if it has one of these!

Testing it Out

Having a little time on my hands, I decided to give it one last run before I “sacrificed” it in the name of science garbage. Interestingly, the camera seemed to work perfectly fine, although the LCD screen was so grainy as to be hard to read. Taking photos was possible indoors, as long as the flash was on and the distance to your subject is decent. The quality, however, was very jagged and noisy, with colour cast due to a bad automatic white balance. It might be okay for web, but it was very much prone to shutter shake blurring. In all, it’s worse than many tablet cameras I’ve tried.

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The photos taken have an EXIF data as follows:

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It seems that the EXIF model of 3MP-9CA is used by several other models (such as the Premier DS3088S, DS3090S, Mirage Steel 3.0), which look very similar. As a result, it’s easy to conclude this is a “generic” camera. It claims to use an exposure time of 1/8th of a second, which is pretty strange for a shot taken with the xenon flash – maybe it hasn’t got a decent synchronization mechanism. It also claims an aperture of f/2.8, although it doesn’t actually have a diaphragm I can see. It claimed to be shot at ISO 100, but how much of this is true? I don’t know. Interestingly, this is one camera that has no date and time capabilities, and in the recorded files on the card, it also doesn’t have any date and time recorded, coming up blank.

Putting it Out of its Misery

The world doesn’t need this camera, so I have taken it for dissection and disposal. To start off, I’ve gone around the whole unit undoing every Philips #0 screw I could find. This eventually let me separate the halves.

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The top half doesn’t really have much – a cut-out for the lens, a window for the xenon flash, a light-pipe for the self timer LED, a trap door for the SD card slot, a tripod socket and a spring-loaded door slider mechanism fill most of the front. The molding also has features for the buzzer, USB port cap and battery separators.

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The other half is more interesting. The battery holder can be seen to be a module mounted onto the board. The top panel where the power and shutter buttons resides also is a Xenon flash board with a large flash capacitor. The buzzer can be seen stuck to the SD slot, which itself hovers over some DRAM. The camera lens can be seen to the right, with the external landscape-macro switch actually rotating the lens, which is pushed down by two springy bits of metal. This is a very “manual” focus system with only two settings! There is a piece of copper tape to ground the mini-USB-B port, possibly due to the high levels of EMI that the flash circuit might generate.

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20150808-1902-8867Removing the whole board from the case allows us to look at the rear – nothing special with buttons that push against surface-mounted buttons on the main PCB. The rear LCD module seems to be a self-contained, fully shielded unit, connected by flat flexible ribbon cable.

Removing the unit from the rear shell by prying on the tabs reveals that the unit originates from AUOptronics, a fairly decent major manufacturer of LCD panels. That’s a surprise to me.

Removing a few labels from the rear of the board, we can now see exactly what the camera is made of:

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The camera itself is labelled as DS3088S 9CA37, so it’s likely that this is the original branding. The camera is built around the SQ916B-L, a 3MP CMOS DSC Processor from a Taiwanese company called Service & Quality – which I have never heard of. The processor seems to be date coded with Week 31 of 2006. There are two types of flash on the board, the MX 29LV040CTC-70G is likely to be a parallel flash containing the firmware for the unit, whereas the Hynix HY27USQ8281A forms the 16Mb on-board flash for capturing files without a memory card inserted. The buttons can be seen to be flat surface mount pieces of pressed metal – not highly durable units at all.

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Trying to get this camera apart is now going to turn destructive, as the top board with the flash is soldered via a right angle 10-way board-to-board connector. I get out my pair of side-cutters and cut that, all the while, unscrewing different screws to try and release even more bits and pieces.

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Here, we can see the flash capacitor, from PCF (a no-name), rated at 85uF 300v – a little low on the voltage rating in my opinion.

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Here, we can see how the flash unit was formed – there is a flash tube slotted into the plastic retainer and held in place by a silicone band with two rings in it. Each end of the flash tube is connected to a wire (red, black) with the metal reflector inside the plastic retainer soldered to a trigger wire (green), which is used to set off the discharge.

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20150808-1912-8874Moving our attention to the lens assembly itself, it also holds another interesting surprise. The movement of the outside switch pushes on an arm, which rotates the lens along threads to cause the distance to the sensor to change, thus focusing the camera. This isn’t the only thing that happens though, as there is a protruding cam which pushes on a microswitch just underneath, which might change the camera’s behaviour (e.g. reduced flash power output to prevent overexposure). I didn’t expect that.

Removing the two screws holding the springy metal loosens the whole lens assembly.

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It is interesting to note that the lens is actually made of glass. Many cheaper cameras use plastic lenses which make for even softer images. The black screw-down plastic frame system seems to be a favourite amongst cheap web-cams and is easy to take apart. It’s not very mechanically sturdy either. There is no intervening optics in play – i.e. there is no adjustable aperture, thus this is a fixed aperture system. However, when tilted, the lens did have one interesting feature …

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… as it seems to be coated with something on the rear. I suspect this may be an infrared-cut coating, to try and improve the quality of the images by reducing “haze”. I suppose this means that the camera wasn’t made with the least care possible, although its performance is hardly noteworthy.

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With the frame removed around the sensor, we can see the sensor chip surface-mounted to the PCB. Sadly, there isn’t that much more we can do to tear it apart, as we’ve just about seen all there is to see, but the sensor is always a beautiful chip to look at closely.

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The sensor seems to be built on a ceramic chip, with gold wire bonds to the pads. Only a sensor gives you the chance to admire the delicate work involved in making the connections to a piece of etched circuitry.

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Some pads had three wires connected in parallel (likely for power), others had two, while most had one.

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The nice purple-grey colour of the ceramic former, contrasting with the yellow in the gold makes for a vibrant component when backed on a green PCB. It’s almost artsy. So, what sort of sensor is it? *gets out the hot air gun*

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Ta da! It’s an Omnivision OV3620, 3.2MP CMOS CameraChip with OmniPixel technology, made in Week 26 of 2006 (about 9 years ago). It has a native 2048 x 1536 resolution with 10-bits A/D. I suspect some of the pixels are not active, hence the datasheet claims 2032 x 1520 pixel resolution of the output. It also claims a 46dB signal to noise ratio (so, about 200:1), and a dynamic range of 60dB. As a result, really, the output is just under 8-bits (256 values). The pixel size is 3.18um, which is relatively large compared to the 1um pixels of most phone sensors today, but I suspect the sensor and processing technology have advanced so much that it completely masks the difference.

Conclusion

I don’t really think it needs to be said, but those cheap, lightweight, no-brand cameras you can buy from variety shops and other “homewares” stores are often pure generic junk. They are priced cheaply, often promise a lot of megapixels, but just never deliver on visual quality.

Good images are more than just the sensor of course, and so it’s likely such generic solutions are let down by poor optics (i.e. fixed focus with small aperture, plastic lenses, crude slow-autofocus), poor construction (focal plane alignment is poor), poor sensors (below claimed resolution using interpolation, low dynamic range causing washed out colour, high noise) and poor processors (shutter lag, slow capture, limited video recording quality). There are often other nasty things as well, which you don’t realize until you examine the images closely on a computer. After all, some of them are merely glorified webcams.

Unfortunately, it’s often people who don’t know anything about cameras that “fall” for these pieces of junk. If anyone around you ever considers buying this … do them a favour and tell them otherwise! Luckily, now that most phones have decent cameras on them, it’s no longer as big of an issue today as it was five to ten years ago.

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
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