20D vs 5D - which is better value for money for landscape photography?

5D for landscapes hands down.

You won't have to buy EFS or third party lenses that will be useless when you eventually go full frame and at the prices 5d's go for at the moment it's a much better value than a 20D.

I started on a 20D and it was a breakthrough camera but the 5D should be a no brainer.

Hi Bruce,
correct me if I am wrong, but the article I have posted clearly shows the FF sensor is having worst focal lenght ratio compared to smaller sensor, so actually the 5D full frame should be worst for landscape? Clearly the 5D FF will be better for portrait, but my question is for landscape...Also comparing 250 to 2500 dollars is no brainer for me either.

The 5D is around $1200 used (give or take a few hundred); you've stated the new price. The 5D is the better camera for landscapes, as Bruce said. It's one of the best values (IQ vs. cost) in Canon's lineup.

It's complicated when you talk about "value." At $200 or so for a used 20D, it's tough to dismiss. Of course the 5D will yield much better IQ, but at a much higher price....

What Bruce said. The 5D hands down.

I don't know what you mean by a full frame sensor having a worse focal length ratio.

The smaller the sensor, the greater the depth of field for a given aperture. That is true. Close down a stop with the full frame, and the depth of field is the same. The larger the sensor is, the more you can close down before diffraction rears its head. You cannot resolve more with a smaller sensor.

The smaller the sensor, the greater the enlargement needed for the final print. No matter what you do with the smaller sensor, you cannot change this.

For landscapes, I'd choose a larger sensor everytime.

Eric

The 20D (and the 30D, for that matter) has an 8MP sensor. It is an APS-C sized sensor, which means that all of your lenses are longer, in effect, than they would be on a 35mm sensor like the 5D. This means to get wide, wide-angle vistas, you may want to get an ultra-wide (say 10-22mm or so) lens, which even used will probably cost you in US$, between $300-600.
In the USA, I bought a like-new 5D (mk1) for less than US$1500, but British prices are always a mystery to us over here. Of course, to get the equivalent of the ultrawide on the 20D, here you'd need a 16mm or so, and those aren't cheap either. (the cheaper 17 to 18mm zooms are all EF-S and will work only on the APS-C cameras).
Actually, the 24-105mm IS L lens is not a bad deal with a 5D and you might find them together with a used 24-105 going for perhaps $800 (they are much sought after). There was a time when landscape photographers would have died for as wide a lens as 24mm, so it would serve for landscape. Either the 20D (and its kin) or the 5D mk 1 will do landscapes that are technically capable of large print size. I have printed 13x19 inch prints from a 20D and they are fine.

I have and still use a 20D, and I find it more than adequate, and I also have a bunch EF-S lenses like a Sigma 10-20 and the EF-S 17-85 that I like, and they will not fit on my 5D, of course. I am a big fan of the APS-C format, and would not have bought a 5D if it weren't for some Nikkor legacy lenses that I have that need the full sensor to "do their stuff". It's also a new toy, but I have to confess that even though it's only 12MP, I like the "richness" of the pictures taken with the 5D and the 24-105mm lens.
A 20D (and consider a used 30D which has some minor upgrades) are a very good buy at current prices. A 40D is a serious upgrade, not a minor one, and if you can stretch to that, you'd have a heck of a camera.
If it were just a matter of money, with such a broad gap, maybe the 20D is the way to go. It's not so much money that you will consider it wasted if you later decide to go to a 35mm-sensor camera. Any camera in your hand is a lot better than one sitting on a shelf in a shop somewhere.

If your only criterion is "value" - by which I assume you mean price for a camera that can make landscape photographs - I suppose the cheapest cropped sensor body holds greater "value."

Actually, if that is your main criterion I recommend - in all seriousness since I used to use one - the Digital Rebel XT. For landscape work it will produce photographic results that are equal to those from the 20D in every way. The sensors are essentially the same and the functional differences between the 20D and the XT are largely irrelevant to landscape photography.

These cameras can do a fine job if you plan to print up to, say, 12 x 18 inches - though you can go a bit larger if you use excellent lenses and technique. I have sold prints from my old XT at up to 16 x 24" sizes.

(That said, I switched from cropped sensor DSLR bodies to full frame when the 5D came out and I currently use that body and a 5DII. There are definite advantages to using the larger format for landscape work.)

Dan

Hi Eric,
still not clear for me why you should choose FF sensor, the smaller sensor have much higher pixel density (2nd article) so the images should be more sharp? Combining this with the Depth of Field advantage (1st article above) will make the smaller sensor a winner for landscape where sharp and depth of field are more important.
About print size the 2nd articles says: "Thus, even though the bigger file size of the ... would be considered to give a potential for larger prints, the lower sharpness outside the image centre conflicts with this. We might end up with the paradoxical situation in which both systems can deliver prints up to the same size in practice."

I would follow G Dan Mitchell's advice and get the Rebel XT. A great camera, I still have it.

Pair it with a Canon 10-22mm and you're all set.