This review is exactly what it says – impressions. If you are looking for a full technical review documenting every aspect of the camera and detailing each and every button and setting, I would point you to either of the following two excellent sites which specialise in this approach to reviewing cameras:
www.steves-digicams.com
or
www.dpreview.com
My preference, by contrast is to report and comment upon the impressions I have gained from using the camera in the field - on this occasion over the last 12 months.

The 5D was introduced and became available during October/November 2005. I managed to hold out until February 2006, until I could resist no longer and finally took the plunge and acquired one. To provide a little background, I had been shooting about 50% film and 50% digital up to this point. I had approached digital cautiously, purchasing a consumer orientated 300D SLR to initially test the water and see if digital suited me. For me, the 300D worked in certain circumstances, but was not capable of fully usurping my film based (mostly Velvia) photography. I quickly found digital workflow to be immensely convenient – a vast improvement over scanning negatives and transparencies for digital darkroom processing. You will gather from this that the digital darkroom had already replaced a traditional wet darkroom many years earlier. Nonetheless the 300D wasn’t sufficient for me to abandon film completely and in fact I never intended it to. Being a lightweight consumer model it lacked features and robustness, but remained an excellent test-bed for me to trial the digital medium. Since acquiring the 5D my film use quickly diminished to close to zero, despite this I still retain my film bodies, but they are no longer in my kit bag.

The 5D is a 12.8 mega pixel, full frame DSLR, with a market place price of between £1550 - £1700 depending upon how much you shop around and the level of official Canon rebates being offered. The big difference with this camera is the inclusion of full frame sensor at this price point. In fact the only other full frame DSLR available now is the (Canon) 1Ds MkII.

With the 5D, Canon has pitched the camera between the 20/30D and the pro 1Ds. It seems slightly tougher and more robust in use than the 20D, albeit slightly less so than the 1Ds. Price wise it fits comfortably in this slot; being of higher spec that Canon’s prosumer models, but with a specification that differs from that of Canon’s pro 1Ds. Most obvious amongst these, the 5D does not have a weather sealed body, but unless you really punish the camera much like a photojournalist might, this is unlikely to be a real issue. My passion is landscape photography and as a consequence I often find myself in wet or dusty locations. I have never had a camera expire on me whilst out in a rainstorm waiting for the light to come right.

The 5D has no pop-up flash, but I don't find this particularly unusual on this level of camera. I rarely use flash and for my photography tend to rely on cranking up the ISO setting. What I do find unusual is that Canon has included a direct print button on the body of the camera. This is a confused addition – why anyone buying this level of camera would want this “feature” is beyond me. This feature, I can see might be useful for direct printing of “snaps” from a digital compact and I suppose at a stretch from also consumer DSLR’s, however I find it completely out of place on a pro/prosumer camera. What was Canon thinking? Better to remove the button as clutter or better still utilise it for a camera function that would get regular use on this level of camera.

One of the biggest delights in using this camera is the beautifully bright viewfinder, after spending time with APS-C size DSLR cameras, this is such a welcome change. Many DSLR users will have forgotten how bright their film SLR viewfinders were. The 5D is able to offer this thanks due to its larger mirror and prism and this of course explains why the 5D has no built in flash. Canon has sensibly left built in flash to its consumer and prosumer models.

User controls will fall easily to hand to users of Canon’s other prosumer models. The controls are very similar and so are fairly familiar. Canon has introduced a custom setting on the setting dial which allows a custom set up to be configured and then selected at a turn of the dial. This is very handy for predefining a particular camera configuration, allowing the camera to be instantly set up without having to work through the various menus each time. In particular, I use this custom setting for configuring the camera quickly with aperture priority, one-shot AF, continuous drive etc and especially mirror lock up, which is buried deep in the custom function settings menus and a real pain to set. Including mirror lock up as part of my custom setting overcomes this problem and allows me to establish a “default” shooting set-up for my landscape work. Depth of Field program has gone from the setting dial, I won't miss this much, but have got used to having it available and consequently I have used it on occasions.

Being a landscape photographer, frame rate isn't that important to me. The 5D offers 3 fps, this isn't the quickest but is generally sufficient and with the camera's large buffer (17 RAW or approx 60 jpegs images) it strikes a pretty effective balance. Once or twice a year I visit an airshow and I have found that the large image buffer is more important than the pure frame rate when capturing fast jets. Put simply on one such visit last year the large buffer of the 5D outstriped the image capture ability of any other camera being used by friends and colleagues with me.

One big difference comes with the size of the rear LCD. Canon has increased the LCD size to 2 ½ inches. For reviewing images and changing settings on the camera this is a real advantage. The one drawback with this LCD is that it does suffer from being difficult to read in bright sunlight. In bright sun the LCD needs to be shaded. This is one area that could have need improved as there are better LCD’s available out there, even on compact digitals.

Battery life seems fine – no better and no worse than Canon’s other DSLRs. I am pleased that the 5D continues to use the now very familiar BP – 511A lithium ion rechargeable. To my mind the availability and affordability of this battery is a real plus and allows several to be kept in the kit bag. Although I usually find that a battery lasts a shoot, it's handy to have spares particularly if a long all day shoot is planned or travelling makes it uncertain when the next opportunity to recharge batteries will be possible.

Full frame brings with it a larger brighter viewfinder along with 35mm lenses without the 1.6x cropping factor. Be aware however that full frame is not kind to poor quality lenses. There is nothing new in this, it has just silently been forgotten, with APS-C sized sensor DSLRs utilising only the centre sweet spot of a lens. 35mm film cameras with fine grain film exhibit the same sensitivity to poor quality glass, it's just that with digital it's rather easier to see - thanks to Photoshop “pixel-peeping”. Full frame brings advantages in terms of sensitivity to lens diffraction; allowing a smaller limiting aperture before diffraction starts to affect image sharpness. (For example, for a 10 x 8 print, APS-C sensors have a limiting aperture of about f/16 whereas full frame 35mm is at about f/22). Image noise is excellent and even at higher ISOs is well controlled, this continues Canon’s excellent reputation for low noise and image processing.

Dust on the sensor seems to be more bothersome than with previous Canon DSLRs. Reports on user forums however seem to suggest that this may be caused by flock and chamber coatings initially wearing off as the camera is “run-in” as it does seem to improve with time and settle down. So far all I have found necessary is a Giotto Hurricane Blower to gently puff the sensor with air. Nonetheless, I have invested in a Visible Dust sensor cleaning kit, so that I’m ready if something more stubborn presents itself! All digital cameras with interchangeable lenses suffer from dust to one degree or another and it is certainly not as bad as dust that gathers on film ready to be printed or scanned from, so its not a big deal really.

One year on I still feel that the 5D will be seen as a landmark camera, indeed one year on it still has no effective competition something quite amazing given the fast pace of change in the industry. I remain delighted with it; it being ideally suited to my landscape work. At nearly 13 mega pixels it has enough resolution to reproduce images demanded by most photographers. It is difficult to better the image quality. It is capable of large prints (without extrapolation) up to at least Super A3/A3+ (13" x 19") size. From my comparisons, images have a depth to them when printed large that isn’t readily obtainable from cameras with a 6-8 mega pixel, pixel count. The camera has nothing missing that is of importance and offers full frame quality that until now hasn’t been available at this price point.

For me, as a landscape photographer small APS-C sensors have no advantages, particularly with the emphasis on the wide-angle focal range. For those into action and nature photography where long lenses are the mainstay of the equipment bag, the balance may well be different as the crop factor from small sensors effectively increases the focal length. I remain a traditionalist and therefore my preference is for a 24mm lens to perform as a traditional 24mm. Throughout my years of photography I have become accustomed to how a lens on a traditional 35mm SLR behaves. In my mind 24mm means 24mm and not 38mm as it becomes on a APS-C size sensor. In much the same way as one adopts a mental image as to how long an inch, foot or yard is (mm, cm or metre etc) the same is true when considering the angle of view (focal length) of a lens. I wish to keep to these familiar references and have no wish to adopt a new system, requiring new terms of reference.

Since the early days of 35mm SLRs (arguably dating from the Contax S in 1949) a 35mm lens has produced a consistent image, with the advent of digital no one asked for this relationship to be changed. The camera manufacturers forced cropping factors on us, simply because they had to balance price and manufacturing capability in order to bring digital SLRs to market. Progress marches on and this is no longer a necessity and I for one am delighted that Canon has rolled out full frame sensors beyond its pro flagship 1Ds MkII. This more than anything vindicates my decision to adopt Canon gear some 20 years ago.