Pentax 645D Canon EOS 1Ds Mark III Comparison Digital SLR Review

Handling and Features
Performance
Verdict
Specifications

Gary Wolstenholme compares the Pentax 645D and Canon EOS 1Ds Mark III to see whether there really is much difference between a flagship full frame DSLR and this Medium Format offering from Pentax.

Thinking back to when the first 35mm full frame DSLRs were released, I remember much internet discussion about how those new cameras were the closest digital thing to the quality of medium format. Obviously the march of technology is never ending and these full frame cameras now sport sensors capable of recording in excess of 20Mp, when back in 2004 a Phase One P20+ digital back was only capable of recording 16Mp.

Aside from the resolution recorded, there are other notable differences between the two formats. As medium format sensors are larger than the 35mm imaging area, there should be fewer issues with diffraction at smaller apertures, and less depth of field at wider apertures, due to the longer focal length lenses to give an equivalent angle of view. Another notable difference is the cost. Currently the 40Mp Pentax 645D is a bit of a trailblazer as far as price is concerned as it is available for around £10,200 with the 55mm kit lens, or for around £9200 as a body only. To put this into perspective a Phase One IQ140 40 megapixel digital back costs an eye-watering £18,000 before you've even bought a camera to attach it to. So, Pentax must be onto a winner here? Their 645D promises the benefits of medium format at a relatively affordable price.

Now to the crux of this article. If you're in the market for the best camera money can buy, you've probably been considering a full frame pro DSLR such as Canon's flagship EOS 1Ds Mark III or Nikon's D3s. But now Pentax have added to your dilemma by launching the 645D - a medium format camera with an even bigger and potentially higher quality sensor. In this review we've put the Canon EOS 1Ds Mark III in a head to head test with the Pentax 645D to see if a full frame DSLR can deliver images of similar quality to a medium format camera in a bid to help you make the right choice.

Pentax 645D Vs. Canon EOS 1Ds Mark III: Handling and Features
Judging purely on appearance, you'd be forgiven for thinking we are comparing apples with oranges in this article, and in some respects, you'd be correct. The medium format Pentax is a noticeably larger camera than the Canon, especially when the 55mm kit lens is attached. The larger size makes the 645D feel slightly like a Duplo version of a DSLR, due to its large grip and oversized controls. This is a positive thing though, as I soon felt very comfortable controlling the camera and dare say it would make photographing while wearing gloves less of a chore too. Weighing in at 1480g for the body, it isn't that heavy though and should be quite comfortable to carry around in a suitable camera bag. The body claims to be weather resistant, and rubber seals can be found around the memory card and battery doors to keep any moisture out.

Within the 645D is a 40Mp Kodak CCD sensor, which is 44 x 33mm in size and what is interesting about this sensor is there is no low pass filter instilled in front of it. Low pass filters are normally fitted to digital sensors to reduce the chances of moire patterns spoiling images containing fine detail. The unfortunate consequence of having one of these filters present is that they tend to soften images, so images straight from the 645D should require less sharpening in post production.

The size of the sensor isn't truly 645 format, but is slightly smaller, so just as with crop sensor 35mm digital DSLRs, there is a crop factor to consider when choosing lenses for the 645D. When comparing the sensor to the full 645 format frame size, there is a crop factor of roughly 1.3x. This means the supplied 55mm kit lens provides a field of view equivalent to a 70mm lens on a full sized 645 frame. When comparing the 645D to 35mm, then the crop factor is roughly 0.8x, which means this 55mm lens provides the same angle of view as a 44mm lens on a 35mm camera.

Keeping in line with their other products, Pentax have opted for SDHC memory cards in a dual slot configuration. Personally I find this a little odd, firstly that SDXC card are not supported, as this camera could really make use of the extra capacity and read/write speed, and secondly that they chose SD over Compactflash. UDMA Compactflash cards are generally faster and available in larger capacities than supported by SDHC, so to me they would be the natural choice. With a camera this size, it’s not like the slightly larger Compactflash cards are going to cause a crisis when it comes to packing your gear.

Autofocus is provided by an 11 area SAFOX IX+ autofocus sensor which is relatively small compared to the imaging area and so all the focusing points are bunched up near the centre of the frame, which leads to plenty of focusing and recomposing if you require your subject further than a little off-centre. Continuous shooting is possible at a rather sedentary 1.1 frames per second, which may be a little slow for those wishing to capture action.

Pentax 645D key features: Click on the thumbnails for a high resolution image.
Due to the large sensor, mirror and lens the 645D is a noticeably larger camera than the Canon.		The 3inch screen positively tiny relative to the size of the camera. A second large LCD information display is located on top.
The Pentax 645AF2 lens mount is backward compatible with all Pentax 645 lenses, right back to manual focus optics from the 1980s.		I find the choice of twin SD slots over Compactflash support slightly bizarre, although this is in keeping with other Pentax cameras.

Despite the relatively compact dimensions of the Canon 1Ds, it still weighs 1210g, which is only just over 200g lighter than the Pentax 645D. This is mainly due to the extra-rugged build, as it is designed to be carted about and deliver images, rain or shine. As a result of the more compact size, the buttons used to access menus and other features, such as exposure modes are much smaller and packed more tightly together. Still they are arranged in a way so that commonly used functions are incredibly easy to access with either finger or thumb.

A 36 x 24mm 21Mp CMOS sensor takes care of recording images and unlike the Pentax a low pass filter is permanently attached to reduce the chances of moire spoiling images containing fine details. Once the data is captured it is processed by two DIGIC III processing chips, to help speed image capture. As the sensor is the exact same size as the 35mm film imaging area, there is no crop factor to worry about, so a 50mm lens gives exactly the field of view you'd expect.

Dual memory cards are also provided on the 1Ds, but instead of providing two SD slots, a Compactflash slot is provided along side one for SDHC cards. This will allow you to take advantage of the latest and fastest UDMA cards available which should reduce the amount of time taken to clear the shooting buffer, leading to fewer lock ups when shooting fast action.

The 1Ds sports an autofocus sensor with 19 cross-type focus sensors, capable of detecting both horizontal and vertical contrast and with extra sensitivity for low light shooting. 26 assist points that are not user selectable also help with focus tracking, which should improve the camera's performance when focusing on moving subjects. The layout of the focus points is spread more evenly across the frame than on the Pentax, allowing for easier focusing when composing off-centre. Continuous shooting at speeds up to five frames per second is possible, making this high resolution camera suitable for sports and action as well as for use in a studio.

Canon EOS 1Ds Mark III: Click on the thumbnails for a high resolution image.
Although the Canon is much more compact, it isn't that much lighter due to the extremely rugged design.		The familiar Canon 1D series design places all controls within easy reach.
Canon's extensive range of EF autofocus lenses are all compatible with this camera.		Two memory card slots are provided, one for Compactflash and one for SD cards.

Viewfinder
Both camera's viewfinders are impressively bright, clear and large with exposure information clearly displayed below the image area. My personal favourite is the Pentax 645D's finder, which is ever so slightly larger and a little easier to use when wearing spectacles. I also find the Pentax screen much easier to confirm focus on as focused areas really stand out against out of focus regions.

Pentax 645D		Canon EOS 1Ds Mark III
The 645D's finder is bright, clear and makes it very easy to confirm focus.		The Canon's viewfinder is also impressive, but I found it a little more difficult to use when wearing spectacles.

As far as handling and features are concerned, the Canon EOS 1Ds Mark III just edges ahead for me, due to its support of faster UDMA Compactflash cards, compact dimensions and extensive range of lenses supported.

Pentax 645D Vs. Canon EOS 1Ds Mark III: Performance
Both cameras were put through there paces in a variety of conditions and all images were taken in RAW + JPEG for comparison.

Exposure
The 645D's 77 zone metering system seems to have been tuned to retain highlight detail at all costs and in a range of different conditions positive exposure compensation is necessary to produce a balanced exposure. Conversely, Canon's 63 zone metering system is very reliable and difficult to fool in a wide range of contrasty conditions. Exposures are well-balanced with plenty of detail in both the highlights and the shadows.

The 1Ds also has a wider range of shutter speeds available, with it covering a range from 1/8000sec to 30 seconds in automatic exposure modes, whereas the shutter on the Pentax maxed out at 1/4000sec. Both cameras have a bulb exposure capability for those times where 30 seconds just isn't long enough.

When using flash with either camera, again the Canon is more flexible, having a maximum flash sync speed of 1/250sec, which is one stop faster than the 1/125sec of the Pentax. The ISO range available is also greater on the Canon, with a sensitivity range of IS50 - 3200 available with expansion enabled. The 645D loses a stop at either end, even with expansion enabled as it covers a range of ISO100 - 1600.

Pentax 645D		Canon EOS 1Ds Mark III
The Pentax has been fooled slightly by this predominantly bright scene, exposing a little too dark for my taste.		The Canon's 63 zone metering system has done a good job, creating a balanced and faithful exposure.
+1.7 EV compensation was needed to prevent this statue becoming a silhouette.		Adding the same amount of compensation to the Canon results in a loss of detail in the highlights as the meter coped better initially with the harsh back lighting.
This evenly lit, contrasty subject has resulted in a balanced exposure with +0.3EV exposure compensation.		No exposure compensation was required for a satisfactory exposure with the Canon.
A flash sync speed of 1/125sec may be limiting for those wishing to balance flash with daylight.		A 1/250sec sync speed and a minimum sensitivity of ISO50 allow for greater creativity with flash in bright conditions.

Focusing
When presented with a static subject and using the centre focusing point, both cameras focus fairly quickly and precisely. During use I had no issues with either camera mis-focusing on static objects, even in low light conditions, although the canon does obtain focus noticeably quicker than the 645D.

When confronted with a moving subject, the performance gap between the two cameras is like night and day. When attempting to focus on cars driving around a roundabout at relatively low speed, the Pentax just can't keep up with the motion and consistently focused behind the cars as they approached. This test is a walk in the park for the Canon, which had no problems whatsoever keeping pace with the moving traffic.

Pentax 645D		Canon EOS 1Ds Mark III
The 645D consistently focused behind the moving cars as if it couldn't keep up.		The slow moving traffic posed no issues for the Canon, which delivered sharp shots each and every time.

Time and time again the Canon EOS 1Ds Mark III's exposure system performed in a way that inspired confidence. When you have to make split second decisions to get the image your require, this can make a huge difference. The Pentax required more time and care to be taken due to its tendency to produce incorrect exposures and also due to the slower autofocus performance, so the Canon notches up a win in this section also.

Noise
With both cameras there is no significant noise present until ISO400, although if you examine the image closely a little noise can be seen creeping into the shadows in images taken with the Pentax at this setting.

As the sensitivity is increased then the performance of the cameras starts to diverge slightly as each manufacturer appears to have a different approach to noise reduction. At ISO1600 images for the Pentax retain excellent detail and sharpness, but blotches typical of noise are clear to see on close inspection. Canon's noise reduction system appears to be more aggressive, taming noise levels, but also sacrificing fine detail. The image from the 1Ds at this setting looks softer on close inspection. To be fair on both cameras, images taken at this setting should be perfectly usable and there is little to tell the difference between them.

Of course the Canon allows images to be taken at an expanded sensitivity of ISO3200. Although it's nice to have this setting for when nothing else is possible, levels of chroma noise dominate the image, especially in the shadows and fine details are smudged like a Pointillist painting. I even noticed the odd hot pixel creeping in, which is never a good sign.

If hand-held low light shooting is your area of interest, there are much more capable cameras than either of these, that will produce better results at high ISO sensitivities.

Pentax 645D	Canon EOS 1Ds Mark III
ISO50 not available on the Pentax 645D.
	ISO50
ISO100	ISO100
ISO200	ISO200
ISO400	ISO400
ISO800	ISO800
ISO1600	ISO1600
ISO3200 not available on the Pentax 645D.
	ISO3200

To be fair, there is little difference between the two cameras when looking at noise levels. The Canon earns brownie points for having a wider range of sensitivities available, but the Pentax also earns points for retaining more detail at higher ISO sensitivities, which is why I believe this section is a draw.

Image Quality
Both cameras are more than capable of producing stunning quality images, but each have their own quirks which set them apart. First of all the look of images taken with the Pentax is slightly different to those of the Canon, especially at wider apertures. The larger sensor in the 645D reduces the depth of field for a given aperture value and the 55mm kit lens is capable of rendering backgrounds smoothly, melting away and really emphasising the point of focus. Although shallow depth of field is possible with the Canon, it just doesn't look the same, with the transition from in focus to smooth being slightly more gradual.

As far as dynamic range is concerned, again both cameras perform well, but straight out of the box, the 1Ds produces more contrasty images, which occasionally sacrifice detail in the shadows and highlights. Even so, when inspecting RAW files produced by each camera, the Pentax has the edge when it comes to dynamic range.

Each camera reproduces colours differently, with the Canon favouring punchy, vibrant colours, which are especially suited to being reproduced straight from the camera. Colours are generally more subdued from the Pentax, lending images from this camera to a little post-production work to achieve the desired effect. Images from the Canon also tend to have a slight warmth to them, which really suits portraits, whereas portraits taken with the Pentax often show slightly magenta skin tones.

Pentax 645D		Canon EOS 1Ds Mark III
Very shallow depth of field is possible as shown in this image taken at f/2.8.		Although the depth of field is still shallow, the Canon doesn't quite produce the same look as the Pentax.
Images display excellent dynamic range and detail.		The Canon tends to favour more contrast, but highlights can occasionally be clipped as a result.
Skin tones have a slight magenta cast in this sunlit portrait.		More warmth is present in the skin tones in the image from the Canon.
Colours straight from the camera tend to be quite subdued, but there are plenty of options to change this if required.		The Canon produces images with punchier colours straight out of the box.

Although the colour saturation tends to be lower when using the standard settings with the Pentax, I personally prefer the look achieved with the larger sensor. Images really seem to jump out of the page, with impressive clarity and dynamic range. Due this this, Pentax wins this section, not there's anything wrong with the images produced by the Canon, I just feel the images from the Pentax are generally of higher quality.

Sharpness and Detail
Earlier in the review I mentioned the lack of a low pass filter in front of the Pentax 645D's sensor and how that may affect sharpness. Both the JPEG straight from the camera and the image processed from RAW have an astounding level of detail and crisp clearly delineated edges. Every fine detail has been rendered superbly and luckily there are no moire patterns creeping in, even in the finer woven cloth.

The image produced by the Canon is also very sharp and clearly detailed, but on close inspection the difference the low pass filter makes can be seen in areas of the watch and the finer woven fabric, where the Canon looks ever so slightly softer, especially in the JPEG image.

Pentax 645D	Canon EOS 1Ds Mark III
JPEG	JPEG
RAW	RAW

The following series of images shows the effect diffraction caused by the lens has on detail. Softening due to diffraction can be seen especially clearly in areas of fine detail, such as tree branches, or on some of the fine concrete work on the block of flats in the distance.

The Canon starts to show signs of softening due to diffraction at f/16 and the effect is quite noticeable at f/22. The larger sensor of the Pentax appears to gain at least an extra stop before diffraction starts to affect image detail with only a slight hint of softening showing at f/22. This can be especially useful when longer exposures are required.

Pentax 645D	Canon EOS 1Ds Mark III
f/8	f/8
f/11	f/11
f/16	f/16
f/22	f/22

This is another strong area for the Pentax 645D. On close inspection, the images from the 645D are sharper and contain a noticeable amount of extra detail over the Canon, which will allow for greater cropping or enlargement of images. The fact the larger sensor allows the lens to be stopped down further, with less impact on sharpness due to diffraction also so for me, the Pentax is a clear winner here.

White Balance
To test the white balance capabilities of each camera shots were taken under incandescent lighting indoors as this is one of the most common scenarios for causing colour casts in images.

When using the auto white balance setting the Pentax delivers the most accurate correction of the amber cast, leaving just enough warmth behind so that it doesn't kill the atmosphere. The image produced by the Canon using this setting has a strong amber cast. Unfortunately the 1Ds doesn't seem to fair much better when shooting in the preset incandescent setting either. The amber cast remains, but with an added hint of magenta. Again with the preset the Pentax appears to perform better, although the warmth has been replaced by a feint green cast.

Both cameras do a grand job of reproducing colours accurately when the white balance is preset from a neutral surface.

Pentax 645D	Canon EOS 1Ds Mark III
Auto White Balance.	Auto White Balance.
Tungsten Preset.	Tungsten Preset.
Custom Preset.	Custom Preset.

Pentax 645D Vs. Canon EOS 1Ds Mark III: Verdict
Each of these two cameras are excellent at what they do best. For example, the 1Ds Mark III is a more flexible tool, capable of holding its own when high levels of detail are needed, but without sacrificing aspects for handling such as the compact 35mm form factor, impressive autofocus and high speed continuous shooting.

The areas in which the Canon excels were never going to be the strongest areas of performance for the Pentax 645D. What it lacks in speed it makes up for in sharpness, resolution and other image quality factors, such as white balance performance and dynamic range.

Even though it does seem like apples have been compared to oranges, the differences between the two cameras, especially when it comes to some aspects of image quality, are not as different as night and day and many aspects such as noise performance are very close indeed.

At the end of the day, your particular specialism will dictate which camera is best for you. If you find yourself comparing these two, then it will come down to how much you are likely to be shooting in situations where you are not in control of your subject, the lighting and of time and the variety of different shooting scenarios you'll find yourself in. If you often deal with surprises, erratic subjects etc., then the Canon is a clear winner for you.

If however, you know what you like and tend to stick to it, and what you like is shooting landscapes, portraits under controlled conditions such as in a studio or disciplines like product photography, then the Pentax may be a compelling choice, if you can afford it.

If I had to judge the cameras on image quality alone then the Pentax would be a clear winner. Unfortunately life isn't that straightforward, and as the Canon excels in some areas and the Pentax is superior in others I find it impossible to choose a clear winner in this comparison. Your choice will depend on what you shoot, at the end of the day.

Pentax 645D Vs. Canon EOS 1Ds Mark III: Pros

Pentax 645D Superb sharpness and resolution Excellent dynamic range Good handling Weather Sealing Good white balance performance Lowest price medium format digital currently available Compatible with Pentax 645 lenses

Canon EOS 1Ds Mark III Excellent build quality Superb autofocus High speed continuous shooting Decent sharpness and resolution Vibrant contrasty images Good colours straight from the camera 1/250sec flash sync speed

Pentax 645D Vs. Canon EOS 1Ds Mark III: Cons

Pentax 645D Meter often underexposes Slow continuous autofocus 1/125 flash sync speed

Canon EOS 1Ds Mark III Softening at higher ISOs Poor white balance performance Viewfinder a little difficult to use when wearing glasses

	Pentax 645D	Canon EOS 1Ds Mark III
FEATURES
HANDLING
PERFORMANCE
VALUE FOR MONEY
OVERALL

It's a draw!

Pentax 645D Vs. Canon EOS 1Ds Mark III: Specifications

	Pentax 645D	Canon EOS 1Ds Mark III
Price	£9,200.00	£5,100.00
Contact	www.pentax.co.uk	www.canon.co.uk
Lens mount	Pentax 645AF2	Canon EF mount
Resolution	40Mp	21.1Mp
Sensor size	Meduim Format 44x33mm	Full Frame 35mm - 36x24mm
Sensor type	CCD	CMOS
Max. Image size	7264 x 5440	5616 x 3744
Aspect ratio	4:3	3:2
Crop factor	1.3x	N/A
Viewfinder	Trapezoid prism finder - 98% coverage	Pentaprism – 100% coverage
Focusing system	SAFOX IX+ 11 point AF	TTL-AREA-SIR with a CMOS sensor 19 cross-type AF points (plus 26 Assist AF points)
Focus types	Continuous, Single Shot, Manual Focus	One Shot, AI Servo, Manual Focus
File types	JPEG, RAW	JPEG, RAW, sRAW
ISO sensitivity	ISO100 - 1600	ISO50 - 3200 with expansion
Metering system	77 segment metering	TTL full aperture metering with 63 zone SPC
Metering types	Multi Segment, Centre Weighted, Spot	Evaluative, Partial, Spot, Centre-weighted
Exposure compensation	+/- 5EV	+/- 3EV
Shutter speed range	1/4000 – 30seconds + Bulb	1/8000 – 30seconds + Bulb
Continuous shooting	Max. 1.1fps	Max 5fps
Image stabilisation	No	No
Movie mode	No	No
Monitor	3inch LCD	3inch LCD
Media type	SD, SDHC	SD, SDHC, Compactflash
Live View	Yes	Yes
Interface	USB, HDMI	USB
Power	Li-Ion Rechargeable Battery	Li-Ion Rechargeable Battery
Size (wxdxl)	117 x 156 x 119mm	156 x 159.6 x 79.9mm
Weight (with battery)	1480g	1210g

The Pentax 645D costs around £9200 for the body only and is available from Warehouse Express here:

The Pentax 645D Body only

The Pentax 645D costs around £10200 with the 55mm f/2.8 lens and is available from Warehouse Express here:

Pentax 645D and 55mm f/2.8 lens

The Canon EOS 1Ds Mark III costs around £5100 for the body only and is available from Warehouse Express here:

Canon EOS 1Ds Mark III Body only