Abstract: Canon EOS 5D or EOS 20D - which one to choose?

Photography - Canon EOS, digital, nature, Canon EOS 20D

Canon EOS 5D

EOS 5D or EOS 20D or...

Canon EOS 5D or EOS 20D - which one to choose?

With the announcement of the new Canon EOS 5D, Canon users have a new option when choosing a DSLR. Buyers will need to consider such factors as cost, sensor size, frame rate, storage capacity  and other camera features to decide which fits their needs, but for most people I think that cost and sensor size will be the dominant factors, followed perhaps by frame rate and image buffer size.


You can get a new EOS 20D for under $1350 if you shop around ,and you can now find used or even refurbished ones for quite a bit less. The 5D will start selling in mid-October at $3300. The price may well come down after a few months but my guess is that it will probably stay over $3000 for most of it's lifetime, so the price difference will be around $2000. That's not insignificant by any means. Cost will be a factor for most people who are looking at either a 20D or a 5D and is obviously strongly on the side of the EOS 20D.

NOTE: As of 12/17/05 you can get a Canon EOS 5D for under $2950 through Amazon.com

Sensor Size

The EOS 5D is full frame, as is the EOS 1Ds MkII, the EOS 1D MkII N has a 1.3x "crop factor" and the EOS 20D and 350D  have a 1.6x "crop factor". What do these mean? Well below is a table which gives the sensor size, resolution (in pixels)  the size of each pixel (in microns) and the PPI (Pixels Per Inch) that you would get if you printed an 18" x 12" image. Larger pixels typically mean lower noise, all else (sensor design, electronics etc.) being equal.

Sensor size (mm) Resolution (pixels) Pixel size (microns*) Crop Factor PPI for 12" x 18" print
EOS 350D 22.2 x 14.8 3456 x 2304 6.4 1.6x 192
EOS 20D 22.5 x15 3504 x 2336 6.4 1.6x 195
EOS 5D 35.8 x 23.9 4368 x 2912 8.2 1x 243
EOS 1D Mk II N 28.7 x 19.1 3520 x 2336 8.2 1.3x 195
EOS 1Ds Mk II 36 x 24 4992 x 3328 7.2 1x 277
* 1 micron is one millionth of a meter or 1/1000 mm

As you can see, the EOS 20D and EOS 350D have the smallest pixels (6.4 microns square), the EOS 5D and ID MK II N have the largest (8.2 microns square)  with the EOS 1Ds MkII  in between (7.2 microns square). If you print an image taken by each sensor at full frame the shot from the 1Ds will give you the highest resolution (277ppi), the 5D comes next (243ppi) and the 1D MkII N, 20D and 350D are all very similar at 195ppi (192ppi for the 350D, but that's a negligible difference). The higher the PPI, the better the image quality, especially for very large prints. Once you drop much below 200 ppi, you'll start to notice the drop in quality.

The crop factor is the effective focal length "multiplier", i.e. it give you the focal length of a lens which would have the same field of view when mounted on a full frame 35mm film (or digital) camera. So for example if you have a 100mm lens and you mount it on a camera with 1 1.6x crop factor, you get the same field of view as you would with a 160mm lens mounted on a full frame 35mm camera (like any film camera, the 1Ds Mk II or the EOS 5D).

Now this isn't a problem for most focal lengths. These days it's just a matter of zooming. So if you want the same field of view as a 160mm lens when shooting with your EOS 20D, you just zoom your 70-200/4L lens to 100mm. The opposite works too. If you have an EOS 5D and you want the same field of view as you get with your 70-200/4L lens set to 100mm on your EOS 20D, you just zoom out to 160mm and voila!, you have it. So most of the time you can simply compensate for the crop factor by zooming or (somewhat less conveniently) using a different lens.

However, where this becomes a problem is at the telephoto end of the shooting range. Sports and Wildlife photographers often use long lenses. Typically you'll see them shooting with 500mm and 600mm lenses, sometimes adding a 1.4x multiplier and sometimes even a 2x. So if you are shooting with a 500mm lens on your EOS 20D and its' barely long enough for your subject and then you switch to an EOS 5D (or 1Ds MkII), you'll need to use an 800mm lens to get the same view - and Canon don't make an 800mm lens and even if they did, you probably couldn't afford it or want to carry it. This is where the crop factor can come into play. Sure you can add a TC, but what if you're already using the TC to get the image you need on the 20D?

Canon EOS 5D or EOS 20D - which one to choose?

Now of course it's a CROP factor, so you can get the same field of view (magnification if you like) by simply cropping down the larger image. However if you do, you throw away pixels. Below is a table of the effective sensor resolution if you crop the EOS DSLRs to an APS-C sized frame (the frame size used in the 20D and 350D).

Size Cropped to APS-C (mm) Resolution (pixels) PPI for a 12" x18" print
EOS 350D 22.2 x 14.8 3456 x 2304 (8MP) 192
EOS 20D 22.5 x 14.8 3520 x 2336 (8.2MP) 195.5
EOS 5D 22.5 x 14.8 2745 x 1830 (5MP) 152.5
EOS 1D MkII N 22.5 x 14.8 2760 x 1840 (5.1MP) 152.5
EOS 1Ds Mk II 22.5 x 14.8 3120 x 2080 (6.5MP) 173

What's clear here is that from a final print resolution perspective, the higher pixel density (smaller pixel size) of the EOS 20D and 350D yields a higher resolution print than you can get from cropping images from the other EOS DSLRs, even the $8000 EOS 1Ds Mk II.

Someone is bound to ask "Would the image on a 20D be better than on a 5D using the same lens plus a TC"? Well, you'd need a 1.6x TC to make the view equal, and they are rare. However a 1.4x TC maintains excellent optical quality and almost gets you the same field of view so only a slight crop of the 5D image would be needed. If you had a 20D and a 500mm lens, a 5D with the same lens plus a 1.4x TC (=700mm) would get you pretty close to the same shot. After cropping to the same view, you'd end up with a 9.8MP image which was 3834 x 2556 pixles. So on this basis I'd say that after cropping to give the same field of view, you'd probably get a slightly better technical quality image from the 5D with a 500mm + 1.4x TC combination than from a 20D with the 500mm lens alone, though only if both the lens and TC were high quality, and I doubt the quality difference would be huge. You have more pixels, but you may have lost a little optical quality by using the TC. Of course you can then say that if you put the 1.4x on the lens with the 20D, you'd need to put a 2x on the lens with the 5D. In that case I suspect that the 20D image might be the better since 2x TCs tend to degrade image quality more. Of course if you're shooting the 20D with the 500 +2x, you've nowhere to go with the 5D (stacking TCs isn't a good idea!).

Remember also that adding TCs might mean loss of AF, especially with cameras which cut off AF past f5.6 (which both the 5D and 20D do). A 500/4.5L won't AF with a Canon EF 1.4x TC for example. A 500/4L and a 600/4L won't AF with a Canon EF 2x TC.

The lesson here is that if you are limited by available focal length (i.e. you're at your upper focal length limit with nowhere else to go) then it may be better to shoot with an EOS 20D (or even a 350D) than to use a larger frame size camera (with lower pixel density) and have to crop the image.

At the other end of the range, i.e. wideangle lenses, frame size becomes important again and you run into limitations which prevent you from just zooming to adjust the field of view. For example, if you are at 16mm on your 16-35 zoom and you are using a full frame camera, you can't then mount the same lens on an EOS 20D and "zoom" back to 10mm to get the same view. You have to use another lens, in this case the Canon EF-S 10-22mm. That's OK, but it's an EF-S lens, so if you have a full frame camera, you can't use the EF-S lens on it. This isn't as big a deal as at the telephoto end of things, because the wider lenses are available and they are light and relatively inexpensive. Carrying an extra 16oz  lens which costs $750 for extra wideangle use isn't as much trouble as carrying a 15lb lens which costs $8000 for telephoto use!

You can go a little wider with a full frame camera since you can use either a 14mm prime or the Sigma 12-24mm zoom, both of which cover full frame. The widest you can go with an APS-C sized sensor is 10mm, which gives you the same field of view as a 16mm lens does on a full frame camera.

So the bottom line here is

  • If you're an ultratelephoto fan and tend to shoot all your zoom lenses at maximum extension as well as hauling around the longest telephoto lens that you can afford and carry, then you may well be better off buying an EOS 20D than an EOS 5D - at least you'd have an extra $2000 to put towards those big lenses!
  • If you're a midrange shooter with a good selection of lenses so you have all your focal length needs covered, you'll get higher technical quality images from an EOS 5D than an EOS 20D. If you make your living from photography, perhaps selling stock or doing editorial work, the full frame EOS 5D could well be worth the higher cost.
  • If you're a dedicated wideangle shooter who can never get a wide enough lens and can't live without the coverage of a circular fisheye lens, then the 5D might make you happier than the 20D.

Frame Rate and Buffer Size

Frame rate and buffer size are two of the more important differences between EOS DSLRs. None are exactly slow, since they will all do at least 3 frames per second and unless you are an action shooter, that's probably all you'll ever need or want.

  Max. frame rate Typical # of JPEG Images Typical # of Raw Images
EOS 350D 3 fps 14 5
EOS 20D 5 fps 23 6
EOS 5D 3 fps 60 17
EOS 1Ds Mk II 4 fps 32 11
EOS 1D Mk II N 8.5 fps 48 22

Though the  20D has a higher frame rate and the 5D has a larger buffer, I doubt that either will be a deciding factor for most people in choosing between these cameras. Few people need to shoot faster than 3 fps and few need more than a 23 image buffer. If you shoot RAW a lot through, the buffer size on the 5D is almost 3x as large as on the 20D (17 vs. 6).

Other 5D/20D Differences

  • Built in flash - The 20D has one, the 5D doesn't. While not the best choice for flash work, a built in flash is always with you and so can, at times, be useful.
  • Flash sync - The 20D is 1/250th, the 5D is 1/200th. Not really enough of a difference to worry about.
  • Spot meter - The 5D has one (3.5%), the 20D doesn't - the best it has is a 9% partial metering "fat spot".
  • ISO - the 5D has ISO adjustable in 1/3 stop steps, the 20D has ISO adjustable in 1 stop steps. The 5D also has an ISO 50 setting, though like the other 1D series cameras, ISO 100 is probably higher quality than ISO 50 and isn't intended for normal use.
  • LCD monitor - the 5D has a larger LCD then the 20D (2.5" vs. 1.8") which may make reviewing images easier.
  • AF - the 5D has a newly developed 9-point auto focus system features 6 additional invisible Assist AF points located inside the spot-metering circle.

There's a copy of the Canon Press Release and the full specifications of the 5D on the Canon EOS 5D preview page

Which One

Tough choice. The price difference is $2000 which isn't insignificant! Though the 5D is a breakthrough in pricing for a full frame camera, it's still out of the reach of many photographers at $3300. For those doing studio work or landscape and editorial shooting, the 5D will be a great camera and I'm sure it will sell very well indeed. For anyone shooting a lot of action, the slightly more expensive ($3999) EOS 1D MkII N, with it's 8.5fps frame rate and 48/22 JPEG/RAW buffer will still probably be the camera of choice. For penurious amateur wildlife shooters who never have a lens long enough to capture their subjects, the 20D probably remains the camera of choice due to its higher pixel density and significantly lower price. The 1Ds Mk II will still command the attention of those wealthy enough to buy it and who need the durability of a fully weather sealed camera with the ultimate in full frame image quality. However I'd guess that the 5D might well eat into 1Ds MkII sales as the $4700 price difference is more than a lot of people will be able to justify.

Comparison of EOS 5D and EOS 20D Specifications

The areas shaded in pink show where one camera seems to have an advantage over the other

Sensor Size and Type 35.8 x 23.9 mm CMOS 22.5 x 15.0 mm CMOS
Pixels 12.8 million 8.2 million
"Crop Factor" 1x 1.6x
Image sizes (L/M/S) 4368 x 2912
3168 x 2112
2496 x 1664
3504 x 2336
2544 x 1696
1728 x 1152
Lens Mount Canon EF lens mount ( EF-S lenses NOT supported) Canon EF lens mount (EF and EF-S lenses supported)
Auto focus 9-point TTL plus 6 "invisible assist AF points" within the spot metering circle 9-point TTL

AF range -0.5 to 18 EV -0.5 to 18 EV
AF assist No (external flash with AF assist required) Yes
Continuous speed 3 fps 5 fps
Buffer Size 60 / 17 - JPEG / RAW 23 / 6 - JPEG / RAW
Metering modes Evaluative 35 zone
Partial (8%)
Spot (3.5%)
Center-weighted average
Evaluative 35 zone
Partial (9%)
Center-weighted average
Metering Range 1.0 to 20 EV 1.0 to 20 EV
ISO range ISO 100 - 1600 plus 50 and 3200 via CF ISO 100 - 1600 plus 3200 via CF
ISO steps 1/3 EV steps 1 EV steps
Image parameters "Picture Style"
User 1
User 2
User 3
Parameter 1
Parameter 2
User 1
User 2
User 3
Custom image parameters Sharpness: 0 to 7
Contrast: -4 to +4
Saturation: -4 to +4
Color tone: -4 to +4
B&W filter: N, Ye, Or, R, G
B&W tone: N, S, B, P, G
Sharpness: -2 to +2
Contrast: -2 to +2
Saturation: -2 to +2
Color tone: -2 to +2
B&W filter: N, Ye, Or, R, G
B&W tone: N, S, B, P, G
Viewfinder 96% frame coverage
0.71x magnification
Focusing screen can be changed
95% frame coverage
0.9x magnification
LCD monitor 2.5" TFT LCD
230,000 pixels
1.8" TFT LCD
118,000 pixels
Histogram Luminance and RGB Luminance only
Flash sync 1/200 sec 1/250 sec
Built-in flash None GN 13/43 (m/ft at ISO 100)
Shooting modes Auto
Program AE (P)
Shutter priority AE (Tv)
Aperture priority AE (Av)
Manual (M)
Program AE (P)
Shutter priority AE (Tv)
Aperture priority AE (Av)
Manual (M)
Auto depth-of-field
Night portrait
Flash off
Folder selection Yes No
File size display on playback Yes No
Playback jump 10 images
100 images
By date
By folder
10 images
Custom functions 21 with 57 settings 18 with 50 settings
Vertical grip BG-E4 BG-E2
Weight 810 g (1.8 lb)
895 g (2.0 lb) with battery
685 g (1.5 lb)
770 g (1.7 lb) with battery
Dimensions 152 x 113 x 75 mm
(6.0 x 4.4 x 2.9 in)
144 x 106 x 72 mm
(5.6 x 4.2 x 2.8 in)
Price (est. street) $3300 $1350

What would I do?

I think right now if I was a typical serious amateur shooter getting into the Canon EOS system and I had $3300 to spend on photography, I'd be inclined to go for an EOS 20D, an EF-S 10-22, an EF-S 17-85IS and an EF 70-200/4L. The total cost would be around the same as the 5D body alone ($3300) or maybe $100 or so less. The EOS 20D gives excellent image quality up to 11x14 and maybe even 16x20 and, in reality, that's as big as most people ever go.

If you're a pro, then a EOS 5D makes sense in some situations. Some stock agencies require submissions be at least 12MP (native, not upsized) and so a 20D just won't cut it. If you're selling large prints then the full frame 12.8MP EOS 5D may give you an edge, as well as allowing you to maintain quality even if some cropping is required.

Personally, I'm still waiting for that 24MP full frame sensor DSLR at $1200. I think I'll be waiting for quiet a long time though...check back sometime around 2010...

See also:

Where to buy?

I've been buying photo gear through Amazon.com for the last couple of years. Their prices are as low as, sometimes lower than, the photo discount stores, plus they often offer free shipping and on many items they have a generous 30 day return policy. I've found their customer service dept to be helpful too.


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