EOS 5D and 24-105 f4L IS USM
EOS 20D and 17-85 f4-5.6 IS USM
PART 5 - Handling
Effectively the designs of the 5D and 20D are identical, so there is not much to be said about this topic, however there are some subtle differences.
Weight and build quality
My no-expense spared high-tech laboratory measuring equipment (kitchen scales) tell me that the EOS 5D with 24-105L lens weighs 1606g. The EOS 20D with 17-85 lens weighs in at 1266g. Both are quite bulky in their way, but the 5D is significantly bulkier. The lens is sufficiently longer and end-heavy that it makes the camera/lens combination droop on the strap compared to the lighter 20D and 17-85. It might have been more appropriate for the strap on the 5D to be attached to the body nearer the shutter button rather than at the back of the camera, to avoid "droop".
The 24-105L lens feels like a proper "L" lens, made out of metal and glass. By comparison the 17-85 is a "consumer" lens and feels a bit rattly, plasticky and insubstantial.
Build quality of the 5D seems identical to the 20D, ie both feel solid and substantial.
There are reports that the 5D has a "brighter" viewfinder than the 20D. This is not really true. It is bigger (effectively twice the size, as is the sensor) but no brighter. It is like comparing a 30 inch monitor to a 20 inch monitor. The 30 inch is just bigger, not brighter. The 5D viewfinder is similar to that on film cameras such as the EOS 100. By comparison the 20D viewfinder is like looking down a tunnel. The viewfinder info LCD seems massive because the viewfinder itself is so small. It is also "grainy" looking through the 20D viewfinder compared to the default 5D one. Interchangeable screens are available for the 5D. There is the standard one, one with grid lines on it, and one which is darker and grainer but is supposed to be more precise to improve manual focus accuracy.
In some ways the "tunnel" effect viewfinder on the 20D can aid composition - you are always aware of the framing as the border is clearly visible. By comparison the 5D viewfinder fills your entire field of vision, so you are much less aware of the edges. The viewfinders are different, and each has its own strengths, but I much prefer the one on the 5D. Just like upgrading to a larger monitor, it gives you a bigger and better, clearer, view on the world.
I have not set out to test the nuances of the autofocus performance, but the EOS 5D appears identical to the 20D in this respect. They are both very good.
One of the advantages of the EOS 20D over the 5D is that it can shoot 5 frames per second. The disadvantage, which I imagine may be linked to this, is that the shutter is loud. The EOS 5D only does 3 frames per second, like the EOS 10D, and like the 10D it is much quieter than the 20D. Comparing the 5D to my EOS 100, the shutters sound remarkably similar. The 5D even makes a whining sound a lot like film being wound on! I suspect that in making the 20D mirror return fast enough to achieve 5FPS, Canon reduced the damping and caused the "slapping" sound. In practice, the noise of the 20D can distract subjects and attract attention. I think the 5D is a significant step up in this respect.
Whilst on safari in South Africa I made some use of the "sub-machine gun" shutter on the 20D. I soon realised that this just resulted in an unmanageable number of nearly identical shots, and that restraint, concentration and timing were more likely to result in excellent results. After a couple of frustrating evenings of editing on the Epson P2000, I calmed down and held back from machine-gunning. In conclusion, for me the 5 frames per second feature of the 20D is something I can happily live without. Your mileage may vary.
I have been asked whether the 5D suffers from "shutter lag". It doesn't. Much is written about cameras on the internet by people who have never actually used one but have poured over the technical specifications trying to pick holes. I haven't read the tech specs myself, preferring to find out the important things empirically. It may be that some of the technical specifications differ by a few milliseconds from the 20D or other cameras, but in practice I can tell you that there is no shutter lag. The camera fires exactly when you press the shutter.
Built in Flash
The 20D has a built in flash but the 5D doesn't. This is not a huge loss as the 20D built in flash is pretty pathetic, but sometimes a pathetic flash is better than nothing at all. My elderly EOS 100 has a substantial built in flash, and if this could be done 10 years ago on a full-frame camera I don't accept claims that Canon "couldn't fit" a flash on the 5D. Deleting the flash is purely a marketing decision. Fortunately the 5D works well in low light, and shots lit by flash usually suck quite badly anyway, so no great loss.
The screen on the 5D is about twice the size of that on the 20D, which is clearly an improvement. As far as LCD screen quality goes, it's not the worst and it's not the best.
One of the annoying things about the 20D is that once it goes to sleep (power saving mode), you need to half-press the shutter button to wake it up again. The 5D wakes up on pressing any of a number of buttons, such as the menu button or the button to illuminate the top LCD. I much prefer this.
There is a new button for printing directly to a Canon printer. This is utterly pointless on a camera of this nature. Hopefully firmware updates will come out to allow photographers to customise this button to do something useful.
Shooting in Raw+large JPEG mode (which I would recommend for a number of reasons), the 5D will take approximately 45 shots on a 1Gb compactflash card, compared with 77 on the 20D. In both cases this is better than 36 exposures on a film, but I think my next compactflash card will be a 2GB one for 90 images.
The ability to show RGB histograms on the "info" screen on the 5D is useful, as it gives a more accurate representation of the exposure and enables you to re-take the shot if one of the channels has "clipped" (ie over-exposed).
The 5D will shoot at 50ASA (when enabled through a custom function). The 20D's slowest film speed is 100ASA. I would have thought the difficult thing for manufacturers was to make the sensor more sensitive to light, and that to reduce gain would be simple. Why not, therefore, have 25, 12, 6 and 3 ASA settings as well as 50? Perhaps this could even be done with just a firmware change? I would find this extremely useful when using the image stabilised lens to create shots with an element of movement in them. As it is, to achieve sufficiently long shutter speeds to cause movement blur in daylight requires the use of minimum aperture, and even that is often not enough. Neutral density filters can be used to work around this problem, but the 5D's 50 ASA setting is a step in the right direction.
Slightly strangely, when I used a compactflash card which I had been using in the 20D in the 5D, it carried on with the continuous numbering from the 20D. This may be useful for some, but as I was shooting with both cameras simultaneoulsy it was highly confusing! Fortunately there is an option to reset the counter to zero.
One bizarre change is that the remote release socket on the 5D is the opposite way around to that on the 20D, meaning that on my cheap "compatible" cable release, the cable points forward towards the lens rather than backwards towards the photographer. Also it didn't fit the 5D (although it fits the 20D perfectly) until I shaved a bit off with a knife. Cheers, Canon. I spend another £3000 on your stuff and you redesign it to penalise me for saving £20 on a cable release!
EOS 5D and 20D together
I feel these two would work together really well as a team. Having attempted to use two-camera systems in the past, I am convinced that you should only ever use two identical camera bodies or at least two bodies with identical user interfaces. As the 5D and 20D are so similar, they compliment each other brilliantly. A lot of photographers carry two bodies, one with a wideangle zoom and one with a telephoto zoom. With full frame and 12.8 megapixels the 5D would make the perfect wideangle body, whereas with its 1.6x crop-factor and 5 frames per second the 20D would be ideal for telephoto. If I could afford it I would keep the 20D as a backup body.