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Samsung GX20 Digital SLR Review

Matt Grayson takes a look at the Samsung GX20 flagship DSLR from the largest electronics company in the world.

|  Samsung GX20 in Digital SLRs
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Working in collaboration with Pentax, Samsung have developed a camera that's essentially a K20D clone.

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Samsung GX20: Specification

  • Resolution: 14.6Mp
  • Sensor size: 23.4x15.5mm
  • Sensor type: CMOS
  • Image size: 4672x3104
  • Focus system: TTL phase-matching
  • Focus points: 11
  • Lens mount: Pentax KAF2 bayonet
  • File type: JPEG, RAW
  • Sensitivity: ISO100-6400
  • Storage: SD, SDHC
  • Focus types: Single, continuous, manual
  • Metering system: TTL open-aperture 16-segment
  • Metering types: Multi, centre-weighted, spot
  • Exposure compensation: +/-3EV in 1/2 step increments, +/-2EV in 1/3step increments
  • Shutter speed: 30sec-1/4000sec, bulb
  • Frames per second: 3fps maximum
  • Flash: Built-in, hotshoe
  • Flash metering: P-TTL
  • Flash sync speed: 1/180sec
  • Image stabilisation: Yes maximum 4EV
  • Integrated cleaning: Yes
  • Live view: Yes
  • Viewfinder: Optical, 95% field of view
  • Monitor: Low-temperature TFT colour LCD monitor, 2.7in
  • Buffer depth: 21 RAW, 35 JPEG
  • Interface: USB2.0
  • Power: Li-Ion battery
  • Size: 142mmx101mmx71.5mm
  • Weight: 727g (body only)

Priced at £629 body only, the Pentax K20D is cheaper at £578 body only. They share the same 14.6Mp CMOS sensor, have image stabilisation in camera and a 2.7in screen.

The Nikon D90 at £594 body only has a 12.3Mp CMOS, a 3in LCD screen but image stabilisation is lens based on the Nikon system.

Samsung GX20: Features
From a distance the GX20 and K20D look identical and it's not until you get in close that you see the subtle differences that set them apart. Most of the differences are purely cosmetic such as the different shaped buttons and mildly different body styling. The GX20 has a slightly boxier approach to its design but that's not to say it's undesirable.

Samsung GX20
The focus switch is located where the left hand lies with a quick to RAW button just above.
Samsung GX20
The LCD on the top plate shows all relevant information.
Samsung GX20
The command dial sits a little higher due to the metering switch below.

Because of the partnership with Pentax in the design stage, the lens mount is Pentax KAF which means a whole new dimension of lenses is opened up to the GX20 owner. Even old manual Pentax lenses will fit albeit with no metering or autofocus. On the left side of the barrel is the lens release while on the opposite side is the AF switch from manual to single AF and continuous AF then above that is the RAW button. This is a quick access button to start shooting in RAW and pressing it again will take you back to JPEG. The GX20 only offers DNG RAW format while the Pentax K20D has an additional PEF RAW format.

The top plate holds the usual command dial on the left shoulder which houses features such as Program, Av (aperture-priority), Tv (shutter-priority) and Manual but also has an additional Sv (sensitivity-priority) mode which allows you to adjust the ISO rating while the camera controls the aperture and shutter speed. There's also a TAv mode which will allow you to select the shutter and aperture while the camera changes the ISO to keep the picture exposed correctly. The dial also has a bulb setting for ultra long exposures as well as auto, custom and flash sync.

Below the dial is a switch for changing the metering options from centre-weighted, multi or spot. A Pentax dedicated hotshoe sits over the prism in it's usual place with the built-in flash drooped over the lens barrel and on the right shoulder is the LCD information screen with the green button and shutter release in front. This green button is an override for if you're in aperture, shutter-priority or manual modes and pressing this button flicks the camera into program allowing the camera to take control. The camera will then correct the exposure and when you release the button you're back in the previous mode.

Live-view was introduced for the first time on the K20D and the GX20 shares this feature. It's also accessed in the same way, by flicking the depth of field preview which brings the screen into life. It's worth mentioning that I had to set the camera up to perform live-view by going into the menu system. The AF button on the back will still force the focusing but, like the K20D, the camera has to drop the mirror therefore technically coming out of live view to enable it to focus.

Samsung are part of the collective that put image stabilisation in camera. This means that the sensor is moved in the opposite direction from the shake ensuring that the image stays sharp on the sensor. Sony use Minolta's method of fixing actuators to the sensor to shift it in the opposing direction while Samsung use centre plate positioning which makes the corrective moves.

Dust removal is also on the same par as the K20D with anti-dust coating on the low pass filter and sensor shake technology. It also has the Dust Alert feature which will take an exposure on the sensor and display the location of any dust meaning you can see if a sensor shake is necessary. It also stores the display image into a folder on your memory card.

At the time of release, the GX20 shared the highest resolution in it's class but natural progression of technology has now outshone this innovation. However, Samsung are still very proud of the small gap between the microlenses on photosites which, they say, are smaller than other gapped microlenses.

In my opinion, the menu isn't the most appealing I've come across. It's a relatively easy one to use with only a few meanings that you may not have heard of such as e-dials, which are the finger and thumb wheels that you use to adjust the shutter and aperture but they can also be designated other tasks. E-dials may be a term that you've heard a lot and have no problem with but in my experience, if I've not heard of it, then 1000 other people haven't either. The layout is the problem as I think it's a bit too cluttered. The controls can take some getting used to such as pressing right to enter the folder of options from the tabs down the left side and you also press right to enter an option but you can't press left to get back out.

The e-dials (I'm learning) will tab down the folders but not the individual options within certain folders. You have to press down on the navigation pad to do that which can be tedious.

Blessedly, there is a function button to the bottom right of the screen which displays an icon of quick access options by pressing the relevant button on the navigation pad. The drive, white balance, flash functions and sensitivity can all be changed here.

One other feature worthy of a mention is Micro AF adjustment. It's a feature recently trumpeted by Sony on the new A900 and is also available on the GX20. It means any old lenses you fit where you're unsure of the focusing performance, the GX20 will allow you to calibrate it saving you time and money in sending it away. It also remembers the lens that you've corrected and applies the same correction when you next fit it to the camera. The technique is to take several photographs of a subject with fore, middle and background detail, focus on the middle ground and check it on a computer to see if it's focusing behind or in front of the subject. You can then adjust it in the menu and retake the same shot repeating the process until the lens is sharp.

Samsung GX20
The ports for remote release and mains adaptor have a protective silicon seal inside the door (the light grey strip). Interestingly, the sync socket isn't protected.

Samsung GX20: Build and handling
It's a sturdy camera and at over 700g has some weight behind it. Dials are firm and buttons need a good press to make sure they work. They aren't particularly unresponsive but a light tippy tap doesn't wash with the GX20 and it ignores such requests. Both the memory card door and battery bay door have twisting key type unlocking switches to open them. This is to aid you in opening and closing due to the silicon trim on the inside that helps with the weatherproofing that the GX20 sports.

It has 72 seals in total to stop moisture getting into the precious electronics. Of course even with this protection, I still wouldn't recommend sitting on the front row at Sea World to get a decent picture of Shamu. It can cope with light rain, mist and drizzle but not from a continuous soaking from a performing killer whale.

Because of its size and weight, I find it particularly pleasing to hold but those of you with small hands may find it difficult to reach the controls.

Using the built-in flash is done by pressing the button on the left side of the pentaprism which will activate the mechanical control for release. It's not a bad flash with a guide number of 13 at ISO100, a 28mm wide angle coverage and 1/180sec synchronisation. You can also sync it to rear curtain flash and it has a recharging time of 3.6sec which is a bit slow compared to other cameras in this class.

Samsung GX20: Performance
The more I use the GX20, I get unhappier with its performance. Images continually come out looking soft and the colours produced on the colour chart are laughable.

Blue is darker than acceptable, primary green is muted while red looks off colour. The skin tone tile (next to brown) is pink and the only thing I'm happy with is the blacks, whites and greys.

Samsung GX20
Colours are off with primaries being the worst culprits. I like the mono tones but that's about it.
Samsung GX20
Images are coming out darker than I expect meaning I have to over compensate. Fringing is evident on the contrast areas and despite f/22, there's some decent detail in the foreground.

Using a DSLR in the test images is great because I don't have to stick it in landscape or portrait mode and let the camera do it all for me. I can override the system and take control which is why the landscape image has an aperture of f/22. Of course it means the image will be softer and I accept it on this picture. Despite the day being brighter than recent forecasts would lead me to believe, I had to push the sensitivity to ISO400 to get a steady shot.

I had the standard kit lens fitted and this has left fringing on the edge of the white bar leading into the canal lock.

Samsung GX20
The normal portrait has produced a good skin tone despite the colour chart result. There's a fair amount of detail in the hair but the lack of fill-in has left deep shadows.
Samsung GX20
There's something about Nikita. The flash has changed the tone of the image cooling it down. Catchlights are added nicely and a lot of the shadow has been removed but some still remains. To be fair it was windy.

Even though the colour chart skin tone tile was a horrible colour, the portrait image has given a nice result. The skin tone is smooth and there's a fair amount of detail. Using flash has retained a good skin tone while adding catchlights to the eyes. The shadow on the wall is minimal but the shadow in the hair on the left side of the head remains and I would like to see that illuminated to some degree.

Samsung GX20
Although I used an aperture of f/5.6, the depth of field in this shot is very narrow.
Samsung GX20
Dust Alert will display an image of the sensor illustrating the location of dust. In this case, after three shakes, it's all fallen to the bottom.

I shot a shallow depth of field image in JPEG and RAW to see if the detail of the focal plane is recorded any better in RAW. I used the quick RAW button which focuses when it switches over but I focused again anyway. The JPEG looks a lot sharper although suffers from noise more. The RAW file appears to have a misty look to it.

You can look at the RAW file here: Samsung GX20 RAW image comparison.

The same dust removal and dust alert system is used on the GX20 that we saw on the K20D and it works by scanning the sensor for dust particles. It then displays on the screen the location of any dust it has found while saving that display into a folder on your memory card called Dust. This process allows you to see whether the sensor needs shaking or if it needs a deeper clean.

With a maximum continuous performance of 3fps, the GX20 is strictly middle of the road. For the enthusiast that the camera is aimed at, the speed should be ample. It's not UDMA enabled so will only benefit marginally from those types of cards. You'll be able to get 38 JPEG images or 16 RAW at the full 3fps or you can opt for the slightly slower 2.3fps. This won't affect the number of RAW images but you can shoot as many JPEG's as your card can cope with.

Samsung GX20: Focus and metering
Mentioned earlier was the focus switch found on the front of the camera which will flick between singlefocus, continuous (the motor constantly works to keep the subject in focus once lock is found) and manual. One thing I like about manual focus that the GX20 has is that when you twist the focus ring and the image is sharp, the AF will still beep when it's in focus.

You can also change the "Catch in Focus" so that the camera won't take pictures if the manual focusing isn't sharp. This is good if you're trying manual focus for the first time or if you don't trust your eyes.

Some of you may inwardly groan at the thought of the camera still taking control but you could say the tripod takes control if you want to level your photos. Think of it as an aid to getting sharp images because that's what it's all about.

In live view, the focusing can be activated by pressing the AF button on the rear of the camera. The mirror has to drop down for it to work so is a bit slower than some other systems but it means it's accurate.

Focus points can be selected using the ring around the D-pad on the rear unde the AF button. You have the choice of spot AF, selectable point allowing you to choose the point to focus on or wide AF which uses any of the points available on the camera.

The GX20 offers three metering modes which can be accessed by flicking the switch under the main command dial on the left shoulder. Multi segment metering will split the image into 16 parts, meter each one and determine the correct overall exposure from the result. Centre-weighted takes a reading over the whole general area with emphasis directed to the centre of the frame while spot metering takes a reading from around 2-3% of the centre of the frame

Metering appears to be slightly off and throughout thetest I had top continuously raise the ISO or boost exposure compensation. Sometimes by anything up to a stop.

Exposure can be assisted with a number of features on the Samsung GX20 such as bracketing which is in the top right corner on the rear of the camera or by exposure compensation which also doubles up as the LCD illumination button.

Samsung GX20: Noise test
Clarity, noise control and colour are very good at the lowest ISO rating and although at full size a slight increase in degradation can be seen at each step, it doesn't get particularly unpleasant until ISO800 where colour spots start to appear.

Even at ISO3200 there's detail in the petals although the grey card is turning into a kaleidoscope. I think only really ISO6400 has lost all favour with purple noise creeping in on the petal, loss of detail and definition on it's way out.

Still, viewing any of the images at 25% gives a decent amount of detail. If the GX20 has a decent modern noise control fitted it could be pushedup to 12,800 and still give OK results.

The RAW versions of ISO100 and ISO6400 can be downloaded by following the links below:
Samsung GX20 ISO100 RAW file.
Samsung GX20 ISO6400 RAW file.

Samsung GX20
The ISO100 test.
Samsung GX20
The ISO200 test.
Samsung GX20
The ISO400 test.
Samsung GX20
The ISO800 test.
Samsung GX20
The ISO1600 test.
Samsung GX20
The ISO3200 test.
Samsung GX20
The ISO6400 test.
Samsung GX20
The ISO100/6400 RAW comparison.

DxOMark provides objective, independent, RAW-based image quality performance data for lenses and digital cameras to help you select the best equipment to meet your photographic needs.

Visit the DxOMark website for tests performed on the Samsung GX20.

Samsung GX20: Verdict
I was surprised by the pictures taken with the GX20 as most of them came out underexposed meaning I had to compensate.

I like the compatability of Pentax lenses as well as the availablility of Schneider lenses. Fringing is visible on the standard kit lens so upgrading your glass will be a priority.

Despite all my negativity, it isn't a bad camera to use or look at. The menu isn't easy to use but I've seen worse and picture quality is good but not the best. In essence, the GX20 is a camera that sits slap bang in the middle of the road.

Disabled Photographers Society
Alan Kelly is partially sighted and said that the Samsung, like the Pentax K-m has a nice screen with good contrast on the lettering which is easier to see. He said: "Contrast is better than brightness for partial sight as it's easier to pick up."

Samsung GX20: Plus points
Compatible with Pentax lenses
Good noise control
Good portrait results
Nice build quality
Camera based image stabiliser
Dust alert feature

Samsung GX20: Minus points
Colour rendition is off
Underexposing on 75% of shots
Two extra options on the dial are taking the fun away





The Samsung GX20 costs £629 body only and is available from Warehouse Express here: Samsung GX20.


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Photographs taken using the Samsung GX20

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Monecel 12 5 United Kingdom
21 Jan 2009 12:41AM
I Have Pentax K20 .not as good as my old Panasonic FZ20. Claude
Jure 11 14 Slovenia
8 Oct 2009 6:33PM
I have GX20 for more than 1 year.
No problems - for me the perfect camera. I used it also at havy rain with no umbrella - teh result: perfect night-rain photos.

As I see the test photographers have problem with WB (not only here & not only by Samsung, Panasonic, Pentax!), so they do not get natural colours - especialy the colour of grass on the sun. At first I've had the same problem, but now when I am used at it - the colours are just normal.

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