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Pentax and Sony DSLR Face-Off

Pentax and Sony DSLR Face-Off

Two entry-level DSLRs go head to head! the Pentax offers video and a new sensor while the Sony provides excellent Live View and a tilting LCD. Fight!

CMOS Sensor

It’s the big difference between the K-m and the K-x – the move from a 10 MP CCD to a 12 MP CMOS sensor, both from Sony. It seems like a small change, but it completely changes the camera.

Highly praised in its day, the aging CCD sensor is now showing its age. Quality drops above ISO 1600 and it’s not capable of continuous imaging, meaning no possibility of Live View (the Alpha 330 "cheats" by using a second sensor for that).

The CMOS used in the K-x is similar to the one in the D300 and Alpha 700, introduced in 2007. Highly appreciated from its introduction for its efficiency in continuous imaging (making Live View possible, but also bursts of up to 8 fps on the D300), it made its mark above all for its sensitivity, the like of which had never been seen at the time on a "small" APS sensor. The sensor in the K-x even puts the high-end K-7 to shame!

A year after Pentax released its highly rated K-m, there is a new entry-level DSLR with the K-x. The two cameras are very similar, with the exception of one major change. The old 10 Megapixel CCD sensor is out, and a new 12 Megapixel CMOS sensor is in. So what we expect is a comfortable, pleasant-to-use little SLR with improved sensitivity. Let’s see if that’s what we get!


The K-x uses the same shell as the K-m. We notice only two changes – the delete button has been moved to make way for the Live View button; and the '?' button has been replaced by the “green” button Pentax likes so much. So the K-m’s guide is gone, but the interface is still exemplary, with quick access to the most common settings and well-designed menus. The construction is still just as light, the display remains at 230,000 pixels, but the handling qualities are amazingly good for a body this size thanks to the deep handgrip.

On the negative side, despite the return of 11-point autofocus as used on the K200D and previous models, there’s still no display of the focusing points in the viewfinder. So in multi-zone, it’s impossible to know what’s being focused on, and – as with the K-m – we advise you to use the center AF point only.

Certain kitschy details are also annoying, like the chrome strip around the top of the body and the extremely aggressive power indicator (fortunately, a custom function lets you turn it off). Finally, while we appreciate the discretion in the K-7’s shutter, the K-x fails in that department, with the shutter making an unpleasant clacking noise.


Among DSLRs, the K-x is up there with the best of the moment. Start-up is instantaneous, focusing is fast (but noisy with the kit 18-55 mm DA L lens), and so is image saving... provided you don’t enable the optical correction functions, which cause a delay of approximately three seconds when saving files! But since the same corrections exist in photo-retouching software, it may be better to leave them up to the computer. Burst mode is fairly fast, at 4.5 frames per second for nine JPEG images – an excellent result for an entry-level camera.

In Live View, as on nearly all SLRs (Sony being the exception), it’s much slower. Focusing is far from having the response of a micro four-thirds, and in practice the mode is unusable on moving subjects.

Kit Lens: 18-55 mm, f/3.5-5.6 DA L
Image Stabilization
Sensor Shift
Internal/External Memory
Sensitivity (ISO Range)
200-6400 (extension: 100-12800)
Video Format
Power Supply
4 AA batteries
4.8”x3.6”x2.7”/20.5 oz. loaded

Image quality

The K-x is the first Pentax to use the excellent 12 MP CMOS sensor from Sony —undoubtedly a sign of chillier relations with Samsung, who had supplied the sensors for the K200D and K-7. So we expected spectacular progress. And we were not disappointed!

Up to ISO 1600, results were impeccable. At 3200 ISO, noise is visible in shadows, but it’s well contained and not a problem. Only at 6400 ISO does the quality really drop off, with noise visible on a 13x18 cm print. Those results compare with the Nikon D5000, the current benchmark for cameras using APS sensors, and will come as a real shock to anyone who’s tested Pentax products in the last two years.

The 18-55 mm DA L is an adequate kit lens, with good performance at the center and some loss of sharpness in the angles. It will be acceptable in many situations, but the most demanding users will want to replace it with a more high-end lens.


The K-x’s video mode has at least one advantage: It exists. Such is not the case with the Canon Rebel XS, Nikon D3000, or the Sony Alpha 550. However it’s still in the embryonic stage, since the autofocus is still too slow in live preview. In fact it’s disabled during recording, leaving you with manual focusing with lenses that allow focus touch-up, that is, which is not true of the kit 18-55 mm DA L. There’s simply no focusing at all, unless you switch to MF using the focus mode lever at the left of the lens mount.

So we won’t complain about the poor-quality monophonic sound recording or the use of the Mjpeg codec, which produces overly large video files.

You turn the camcorder on by pressing the Power button, which automatically opens the lens shutter, which covers a 10x optical zoom that starts at a focal length of 43mm – a bit narrow. We would have hoped for a slightly wider angle, even if the Sony HDR-CX520 does no better.

Pentax K-x
  • Clean and simple design
  • Sensitivity
  • Remote flash function
  • Comfortable viewfinder
  • Built-in stabilization
  • No focus point display in viewfinder
  • Slow Live View
  • Embryonic video mode
  • Noisy shutter, focusing

The Pentax K-x is an ambitious new entry-level SLR. While the video function won’t appeal to anyone in their right mind, it’s a very pleasant camera to use and the image quality easily equals, and sometimes beats cameras costing twice as much.

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  • 0 Hide
    Anonymous , December 8, 2009 6:08 AM
    K-x Pentax undoubtedly produce a remarkable/clear picture up to its boundary , say:ISO 2500 and using RAW can give fairly printable at 3200-6400 ISO, While most photographers on their right mind mostly uses up to the limit of ASA/ISO 100-400 by using a powerful flashgun leaving high iso stupidly silent. To be Fair by no means, Enthusiast have different perspective on taking a picture and that where K-x pentax come along specially for a budgetarian. ((Wealthy idividual just hire photographer thru phone, and sleep, no worry ))So its always the money that talks and often an object in buying a DSLR.
    And for the video thing, you need to know your gadget well and you objectives to be able to produce a good video out of K-x, If you're just a push button user ? why not call photographer/videographer who knows what to do ? IMHO

  • 0 Hide
    Anonymous , December 9, 2009 6:25 AM
    One of the little mentioned facts about the built in HDR function of the A500 and A550 is that, if you set the camera to 1 stop HDR, feel free to shoot at 3200 and 6400 all day: the HDR mode acts as a quick image stack, allowing much cleaner, sharper High ISO imaging simply due to the HDR processing. A little added DR, a lot less noise = killer images in low light.

    Also, don't forget you can do the HDR mode in black and white... allowing zones of gray to be visible in rich tones across the image that would also be otherwise unheard of. The HDR in black and white is one of THE reasons to own this camera, IMO.

    Also I note that you undersold the fact that the Steadyshot Inside on the A500/A550 is far more accomplished than any other internal IS system to date and is easily as good as any optical system in the market, no matter the competition.

    We are currently showing 30x40 images from the A550 HDR that are simply stunning. The great thing is that the HDR is a jpeg file, so no one can accuse us of mucking with RAW in order to get a better looking image. No, the A500 and A550 are simply capable of direct to print images that are impossible for other brands to shoot. HDR makes this so.

    The K-x is a nice camera, I wholeheartedly agree, but it's not exactly cutting edge, save for the video which, as you mentioned, is still in its first phases. The progressive CMOS in the A550 alone allows for speed unheard of in this class of camera, let alone 5 fps with af live view on, with a proper HD screen, no less. The A550 also adds wireless ttl flash to the mix, along with a proper spot meter to boot, sharing these features with the A500.

    Sony's getting serious. People will have some eyebrows raised, I suspect, come later this coming year.
  • 0 Hide
    Anonymous , December 10, 2009 2:49 PM
    Thanks for the reviews! I didn't know Tom's did more than computer stuff (basically my homepage years ago when I was building computers).

    The A550 is nice, but leaves some more important (to me) things that the K-x has while costing twice as much...

    dim viewfinder, build quality, no mirror lockup. Also, this is the first I've heard that the IS system is better than Pentax or Olympus. Do you have any links?

    Not all pro's will never use high ISO - many times it is impossible to have an external flash stand in the right spot or a ceiling to bounce off of.

    Btw, dyna, your point of HDR being a jpeg and not mucking around in RAW is the opposite of what I've typically seen. When images are saved in JPEG, being much smaller, the camera's processing includes only what it wants (I see this as mucking around with data), while RAW is supposed to include everything untouched.

    Your point about HDR (or RAW works pretty well too) is spot on - B&W should always be shot in RAW (greyscale mix capability, simply more luminosity levels stored 65,536 vs 256...) or HDR.

    Anyways, the A550's 7-fps no-automation feature is a great one that I wish more cameras had.

    As for the K-x, I wouldn't advise only to use center-AF point. Select AF point works just as well (and is actually my favorite mode on cameras with LED indicators when shooting anything, including sports), and you can have a button set to center-AF and easily change the AF point to a known location without removing your eye from the VF. 11-point and 5-point AF is what is much less useful on the K-x - agreed there.

    As for MJPEG, it is indeed much bigger, but that data allows more post-processing abilities and quality than other more compressed codecs - a fair compromise for me.

    I am not sure what this part is for:
    You turn the camcorder on by pressing the Power button, which automatically opens the lens shutter, which covers a 10x optical zoom that starts at a focal length of 43mm – a bit narrow. We would have hoped for a slightly wider angle, even if the Sony HDR-CX520 does no better.

    You can choose whatever focal length that the lens offers with video - the kit lens lets you choose 18-55mm or 28-82.5mm 35mm equivalent. The coolest part is the macro video capabilities you can create, allowing videos like this:

    I agree about LiveView being slow focusing on the K-x - exactly why I use phase-detect AF in Live View - downside is you don't get to see the image while its focusing (not a big deal), but also you get the mirror slaps (can be bad). With the new firmware 1.01, I find contrast-detect AF is faster as it doesn't hunt to the extremes nearly as much.
  • 0 Hide
    juu , December 10, 2009 7:17 PM
    The Sony is 1.5 times more expensive!!! How can you rate them both equally?

    I think the Pentax K-x wins hands down.
  • -1 Hide
    TunaSoda , December 13, 2009 1:27 PM
  • 0 Hide
    Anonymous , December 15, 2009 10:57 AM
    The video review doesn't seem very fair at all. First off, the only other DSLRs that shoot video in the price range of the k-x is the Rebel T1i and the D90 (both of them being fairly more expensive than the k-x), and neither of them have auto focus while shooting. In fact, there are no DSLR's that can auto focus while shooting video at the moment.

    The tone of the review makes it sound like these HDSLR's need to operate like a camcorder. That's like comparing a point and shoot with a DSLR. It's exactly what they're NOT suppose to be, for they serve completely different purposes.
  • 0 Hide
    oneguy , December 15, 2009 6:10 PM
    Sony A500 is closer to Kx price ($699 right now on amazon). A500 has everything that is in A550 (except 7fps, 920K LCD, and A550 has larger buffer).

    A550 is a little behind than Kx/D90/D5000 in high ISO performance but that’s probably due to jpeg output. Perhaps Sony will issue a firmware update for jpegs. On Dxomark, A550 sensor scores over 800 points in low-light ISO category (higher than D300s/A700), so the new 14 MP sensor has more potential than the current jpeg output shows.

    By the way, Nikon D5000 also has video, and is cheaper than D90 (close to Kx price).
  • 0 Hide
    oneguy , December 15, 2009 6:41 PM
    You need to fix Specifications section of this article (for A550). It's appear to be that of Kx
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