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upgrade from 350D....40D or 50D? (1 Viewer)

Peter Ericsson

Well-known member
I am still very happy with my 350D. Have had no problem whatsoever with it.
Still, the time for an upgrade is at hand. What should I go for? Money is not an issue.

Peter
 
No argument with the Roy and John about the merits of the Mark III, if you incline towards the action side of bird photography, it's the best there is. But that's not your style, Peter, and with a 1D III you don't have nearly the reach you do with a 50D. Shooting the same bird from the same spot, a 50D with a 100-400 resolves more detail than a 1D III with a 500/4, if your focus is perfect and the light is good. If I was to pick the perfect bird camera for you with cost no object, it would be a 1Ds III, but I'd also consider the (as yet untried) D3x and 5D II. All three of these have around the same reach as your 350D and the two very expensive ones have the same sort of handling and auto-focus advantages as a Mark III.

But I doubt that you want to get that carried away with a credit card. Nor are you likely to be considering a change of brands. (If you were, the D300 would also be on your radar.)

So let's return to your original question: 40D or 50D? There is no contest. The 50D is easily superior to the 40D. It resolves significantly more detail and makes your lenses longer, where the 40D produces essentially the same quality you already have with a 350D. The 50D also refines and improves on the various improvements, mostly minor individually but significant n aggregate, that the 30D and 40D brought over the 20D - sensor cleaning, menu rationalisation, Live View, viewfinder, button placement, LCD screen, and so on. For bird work, and if you can afford either one, buying a 40D now that the 50D is available makes no sense at all. 50D all the way.
 
, but I'd also consider the (as yet untried) D3x and 5D II. All three of these have around the same reach as your 350D
.
Surely the 5D II is full frame so what do you mean it has the same reach as a 350D, cannot understand this logic. Or are you talking about the cropability of the 21 mp camera eg. to = the FOV of a 1.6 crop camera the 5D mkII comes back to about 8.2mp by my reckoning but I would hardly call it 'reach'.
 
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which one

I should have been a bit more specific. I meant between the 40D and the 50D.

I have read that some experience more grain with the 50D then the 40D due to so many more pixels. Not sure if this is true or not.

Thank you everyone for your input. Coming the end of the month I should have one or the other.
 
Hi Roy,

Reach is the amount of detail you can resolve from a distant small object (such as a bird). The primary determinant of reach is pixel density. (Assuming, of course, that we hold other factors equal: we use the same lens for example, and shoot under similar lighting conditions.)

To a first approximation, then, reach is directly proportional to pixel density.

Reach has nothing at all to do with crop factor. The crop factor of a camera describes how much of the image collected by the lens you throw away because of having a small sensor. When you put a 400/5.6 lens on a 40D, for example, the sensor can "see" 39% of the light the lens collects and throws away the remaining 61% of the light, which falls outside the boundaries of the 40D's relatively small 337mm2 sensor. Put the same lens on a 5D Mark 1 and none of the light is thrown away.

This is why the full-frame 5D is regarded as an excellent camera for use in situations where heavy cropping is not a requirement: it uses more of the light, and captures it with bigger sensor elements which produce a more accurate, less noisy image. Used for (e.g.) a wedding, you can easily compensate for the wider field of view by using a longer lens. Bigger sensors, in short, are better sensors ..... provided that you are not focal length limited and can easily use a longer lens.

But when you consider the situation of the bird photographer, very often it simply isn't possible to use a longer lens and you have to crop hard before you print. Here we see the 5D Mark 1 at its worst. (Or the Nikon D3 and D700 twins - they are very similar in this regard.)

Imagine a bird that nicely fills the frame on a 350D with a 400/5.6. On a 350D, that gives you 8.2MP worth of usable picture. We threw away 61% of the light the lens gathered, but that doesn't matter - we were going to crop that part out anyway. Now, from the same place, take a picture of the same bird with the same lens, but use a 5D Mark 1. Initially we get to keep all the light (throw nothing away) but then we have to crop the shot back to the area of interest, which leaves us with just 5.0MP worth of picture. We have less reach. (In fact, we claw back a certain amount of our loss because those bigger pixels have less noise and better quality, but we are still well down on the overall result we got with the 350D.

Does this mean smaller sensors are better for bird photography? Absolutely not! Reach has got nothing at all to do with sensor size. It's all about pixel density: the number of pixels containing information about the bird. The 5D Mark 1 is a poor choice as a birding camera not because it has a large sensor - that is irrelevant as we crop away most of it anyway - it's a poor choice because it has low pixel density.

Now, let's try the same shot with a 5D Mark II. Once again we use the same lens and the same bird (by now we have nailed it to the perch, all in the name of scientific objectivity). Once again we crop away the part of the picture that does not contain any information about the bird, and we wind up with 8.2MP worth of useful information ...... exactly the same as if we had shot with the 350D. (Or with a 20D or a 30D, all three share an almost identical sensor.)

(Actually, if we want to nit-pick, it isn't exactly the same, the 5D II has marginally more detail: it returns 8,213,400 pixels where the 350D returns 8,185,344 pixels - but that's a difference too small to bother about.)

So far as reach is concerned, pixel density is the name of the game. The 50D is the current champion with 44,605 pixels per mm2; next comes the 450D with 36,049 px/mm2; the 40D, 400D, and 1000D with 29,860 px/mm2; the 1Ds III and the 5D II have 24,336 px/mm2; the 20D, 30D, and 350D all have 24,253 px/mm2, and the 1D III has 19,178 px/mm2.

Now, let's consider the secondary factors. I said earlier on that pixel density is the primary determinant of reach, but there are other factors. For example, under identical conditions (same lens and same long-suffering bird as before) a 20D will resolve detail about as well as a 40D - although it has fewer pixels, each one works more effectively. (I'm not sure why, but careful comparison between my two 20Ds and my two 40Ds confirms this: there is nothing to chose in the overall result. I suspect that the 40D went a fraction beyond what was sensibly possible so far as sensor design went at that time, where the 20D/350D/30D sensor did, and still does, punch harder than its weight.) Similarly, the 1D III, despite having significantly lower pixel density than a 20D or 40D, produces almost the same amount of detail, and does it with better colour and contrast.

A year or two ago, we all though that pixel density had reached its limit. Because the 40D was unable to improve on the 20D/30D despite having more pixels, we all thought that 25,000-30,000 odd px/mm2 was the limit. Beyond that, we thought, we were into a game of diminishing returns.

Then the 36,000 px/mm2 450D came along and made everybody wonder, and now the 44,600 px/mm2 50D has decisively demonstrated that it can return more detail per mm2 than any previous SLR. Clearly, the sensor manufacturers have learned another trick or two. This leaves the 50D as the current "reach champion". I haven't used one but I imagine that the 450D comes next, and on the face of things we have an 8-way tie for third place: 350D, 20D, 30D, 40D, 400D, 100D, 5D II, 1Ds III. All eight are around the 25-30,000 px/mm2 mark. You could argue that the 10MP 40D, 400D and 1000D are in front, but many observers (I count myself amongst them) do not think there is any genuine difference in reach between (e.g.) a 20D and a 40D. Or you could throw another, as yet unmentioned but very, very important variable into the mix: focus accuracy. Of those eight just mentioned, the 1Ds III has by far the best autofocus system, and a perfectly focused 24,000px/mm2 shot will beat a slightly blurry 29,000px/mm2 shot every time. A 1Ds III, in other words, has a better chance of producing an acceptably sharp image of a distant bird than a 40D, or indeed a 350D. And that - producing an acceptably sharp image of a distant bird - is what reach is.

As a footnote, I think it's this last reason that keeps my 1D III in service as my front-line birding camera. In theory and in formal testing it resolves no more detail than my 20D or 40Ds, and it certainly resolves less than the 50D does - but in real-life conditions, the 1D III focuses faster and gets an accurate focus more often, so I mostly go to it as my first choice. Sometimes, however, I resort to the 50D for extra reach, especially when I have a static subject with good contrast for it to "grip" on.
 
I have read that some experience more grain with the 50D then the 40D due to so many more pixels. Not sure if this is true or not.

If you compare correctly - i.e., compare finished images - not true. 50D wins comfortably. If you do silly things like compare 100% crops, you may well get this result, but it's meaningless. You need to compare two things by reproducing them the same way, at the same size. If you do this, the 50D is well in front.
 
Hi Roy,

Reach is the amount of detail you can resolve from a distant small object (such as a bird). The primary determinant of reach is pixel density. (Assuming, of course, that we hold other factors equal: we use the same lens for example, and shoot under similar lighting conditions.)

To a first approximation, then, reach is directly proportional to pixel density.

Reach has nothing at all to do with crop factor. The crop factor of a camera describes how much of the image collected by the lens you throw away because of having a small sensor. When you put a 400/5.6 lens on a 40D, for example, the sensor can "see" 39% of the light the lens collects and throws away the remaining 61% of the light, which falls outside the boundaries of the 40D's relatively small 337mm2 sensor. Put the same lens on a 5D Mark 1 and none of the light is thrown away.

This is why the full-frame 5D is regarded as an excellent camera for use in situations where heavy cropping is not a requirement: it uses more of the light, and captures it with bigger sensor elements which produce a more accurate, less noisy image. Used for (e.g.) a wedding, you can easily compensate for the wider field of view by using a longer lens. Bigger sensors, in short, are better sensors ..... provided that you are not focal length limited and can easily use a longer lens.

But when you consider the situation of the bird photographer, very often it simply isn't possible to use a longer lens and you have to crop hard before you print. Here we see the 5D Mark 1 at its worst. (Or the Nikon D3 and D700 twins - they are very similar in this regard.)

Imagine a bird that nicely fills the frame on a 350D with a 400/5.6. On a 350D, that gives you 8.2MP worth of usable picture. We threw away 61% of the light the lens gathered, but that doesn't matter - we were going to crop that part out anyway. Now, from the same place, take a picture of the same bird with the same lens, but use a 5D Mark 1. Initially we get to keep all the light (throw nothing away) but then we have to crop the shot back to the area of interest, which leaves us with just 5.0MP worth of picture. We have less reach. (In fact, we claw back a certain amount of our loss because those bigger pixels have less noise and better quality, but we are still well down on the overall result we got with the 350D.

Does this mean smaller sensors are better for bird photography? Absolutely not! Reach has got nothing at all to do with sensor size. It's all about pixel density: the number of pixels containing information about the bird. The 5D Mark 1 is a poor choice as a birding camera not because it has a large sensor - that is irrelevant as we crop away most of it anyway - it's a poor choice because it has low pixel density.

Now, let's try the same shot with a 5D Mark II. Once again we use the same lens and the same bird (by now we have nailed it to the perch, all in the name of scientific objectivity). Once again we crop away the part of the picture that does not contain any information about the bird, and we wind up with 8.2MP worth of useful information ...... exactly the same as if we had shot with the 350D. (Or with a 20D or a 30D, all three share an almost identical sensor.)

(Actually, if we want to nit-pick, it isn't exactly the same, the 5D II has marginally more detail: it returns 8,213,400 pixels where the 350D returns 8,185,344 pixels - but that's a difference too small to bother about.)

So far as reach is concerned, pixel density is the name of the game. The 50D is the current champion with 44,605 pixels per mm2; next comes the 450D with 36,049 px/mm2; the 40D, 400D, and 1000D with 29,860 px/mm2; the 1Ds III and the 5D II have 24,336 px/mm2; the 20D, 30D, and 350D all have 24,253 px/mm2, and the 1D III has 19,178 px/mm2.

Now, let's consider the secondary factors. I said earlier on that pixel density is the primary determinant of reach, but there are other factors. For example, under identical conditions (same lens and same long-suffering bird as before) a 20D will resolve detail about as well as a 40D - although it has fewer pixels, each one works more effectively. (I'm not sure why, but careful comparison between my two 20Ds and my two 40Ds confirms this: there is nothing to chose in the overall result. I suspect that the 40D went a fraction beyond what was sensibly possible so far as sensor design went at that time, where the 20D/350D/30D sensor did, and still does, punch harder than its weight.) Similarly, the 1D III, despite having significantly lower pixel density than a 20D or 40D, produces almost the same amount of detail, and does it with better colour and contrast.

A year or two ago, we all though that pixel density had reached its limit. Because the 40D was unable to improve on the 20D/30D despite having more pixels, we all thought that 25,000-30,000 odd px/mm2 was the limit. Beyond that, we thought, we were into a game of diminishing returns.

Then the 36,000 px/mm2 450D came along and made everybody wonder, and now the 44,600 px/mm2 50D has decisively demonstrated that it can return more detail per mm2 than any previous SLR. Clearly, the sensor manufacturers have learned another trick or two. This leaves the 50D as the current "reach champion". I haven't used one but I imagine that the 450D comes next, and on the face of things we have an 8-way tie for third place: 350D, 20D, 30D, 40D, 400D, 100D, 5D II, 1Ds III. All eight are around the 25-30,000 px/mm2 mark. You could argue that the 10MP 40D, 400D and 1000D are in front, but many observers (I count myself amongst them) do not think there is any genuine difference in reach between (e.g.) a 20D and a 40D. Or you could throw another, as yet unmentioned but very, very important variable into the mix: focus accuracy. Of those eight just mentioned, the 1Ds III has by far the best autofocus system, and a perfectly focused 24,000px/mm2 shot will beat a slightly blurry 29,000px/mm2 shot every time. A 1Ds III, in other words, has a better chance of producing an acceptably sharp image of a distant bird than a 40D, or indeed a 350D. And that - producing an acceptably sharp image of a distant bird - is what reach is.

As a footnote, I think it's this last reason that keeps my 1D III in service as my front-line birding camera. In theory and in formal testing it resolves no more detail than my 20D or 40Ds, and it certainly resolves less than the 50D does - but in real-life conditions, the 1D III focuses faster and gets an accurate focus more often, so I mostly go to it as my first choice. Sometimes, however, I resort to the 50D for extra reach, especially when I have a static subject with good contrast for it to "grip" on.
All very interesting 'Tannin', thanks for that.
I am a heavy cropper owing to the fact That I cannot get near to most of my targets (I refuse to crawl around in the mud or wait in a hide for hours to do so). I do not do a lot of printing so most of my shots are for web use only. I have had a 350D 30D and 40D and as far as being able to crop heavily and get a decent image the 40D wins hands down IMO. It is because of the big difference I have found between the 30D and 40D that makes me interested in the 50D as a means of cropping even harder.
I must say that some of the examples of heavy cropping from the 50D have been a bit disappointing to me because of the seemingly extra noise in a heavy crop (to me 100% crops are not meaningless).

I am very seriously considering a 500mm f4 lens instead of my current 400mm as a means of getting more 'reach' with my 40D.
Would you say I am better off sticking with the 400 and upgrading to a 50D? If so that would be great as I could save myself over £3k.
 
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I should have been a bit more specific. I meant between the 40D and the 50D.

I have read that some experience more grain with the 50D then the 40D due to so many more pixels. Not sure if this is true or not.

Thank you everyone for your input. Coming the end of the month I should have one or the other.

Peter,
I have both the 40D and 50D, both the cameras are a good upgrade from the 350D, I suggest you go for the 50D, due to the 1 to 1.5 stop advantage on noise level against the 40D. I know the shooting conditions you are facing since both you and me are shooting in the same region.
However, if money is no object than go for the Mk3. It beats the 50D hands down. I use the Mk3 as my primary and my 40D as secondary until I got hold of the 50D. The AF tracking of the Mk3 is definitely better than the 50D it is useful for BIF and the AF is faster and AF at f/8.0 will not be a problem with the Mk3.
 
Interesting experiences there, Roy. "Interesting" because my experimentation with a very similar pair of cameras leads to a very different conclusion!

I had two 20Ds, which were pretty much indistinguishable quality-wise. Naturally, I had a favourite one out of the two, but I don't try to fool myself that the older one was in fact any better than the newer one. I still have and use the older one, on its second shutter now and (usually) demoted to wide-angle landscape duties - mostly because it hasn't got a self-cleaning sensor and I tend to leave either the 10-22 or hte Tokina 10-17 fish on it all day. I sold the other 20D.

I have also owned a 400D and two 40Ds. Nothing to choose between these three either, except that I missed the back control wheel on the 400D and believe that it got exposures wrong more often than the 20Ds and 40Ds. But assuming correct exposure, it was much of a muchness detail-wise with the 40Ds. I gave the 400D to a family member and still have both 40Ds, though I'll give the older one to a different family member soon. (For no reason at all, I like the newer 40D better than the other one. In reality, I'm sure that they are exactly the same. But sometimes I pretend that the newer one takes better pictures. Well, right now it does because the older one needs a service, but usually they are the same.)

Anyway, that gives me 5 cameras in the Canon 8 and 10MP families, and I have never been able to make any real or meaningful distinctions between them. Even when I shot some pretty careful formal tests a while back, there was nothing in it. Maybe marginally more detail in the 40D shots - and I do mean marginal - but more pleasing colour and contrast in the 20D shots. Bottom line: the only things I miss about my 40Ds when I'm using the 20D are: (1) raw buffer, (2) faster shot review to check exposure when you chimp, (3) ISO in the viewfinder, (4) sensor cleaning, and (5) pre-programmed user modes. Want ISO 100, mirror lock-up, f/11, and 2 second delay for tripod landscapes? Turn the 40D to USER 1, take the shot. Want to go back to standard hand-held general settings? Return to Av mode on the dial and it remembers my ISO 200, single shot, whatever else I want. It's a great feature!

But IQ-wise? I'd just as soon use the 20D.

I look pretty carefully at my shots and have no reason not to believe that you do the same. So why do we come up with such different answers?

(I'll turn to your question in another post.)
 
I am very seriously considering a 500mm f4 lens instead of my current 400mm as a means of getting more 'reach' with my 40D.
Would you say I am better off sticking with the 400 and upgrading to a 50D? If so that would be great as I could save myself over £3k.

Very, very different things!

You don't actually gain all that much extra reach with a 500/4 as compared with a 400. A bit, yes, but nowhere near enough to justify the expense (huge) or the weight (massive). Of course, you can add a 1.4 converter for 700mm f/5.6, and that becomes significant, but look at it this way: you will get more detail with a 50D & 400mm than you get with a 40D and 500mm.

But the 500/4 isn't really about extra reach. Most of the time, the reach you gain is lost before you get it because you simply can't move as quietly and unobtrusively with the big white as you can with a 100-400 or any other 400/5.6-clas lens. It's big, it's heavy, and you can't hold it up for long so you wave it around a lot and, in the end, you don't get as close to the bird.

What you do gain, above all else, is that vital extra stop. The difference between having f/4 available and being limited to f/5.6 is massive and a lot of the advantage applies even if you are shooting at f/8. With an f/4 lens your camera AF system (any camera) is faster and more accurate, and this really does make a big difference. With an f/4 lens, your ISO 800 shots are taken at ISO 400, and your ISO 1600 shots at ISO 800 - and your can't-take-any-shots-it's-too-dark shots becoume tough but do-able.

Perhaps a good way of putting it overall is to say that with a 500/4 every hour you spend walking around looking for birds and trying to get into position for a shot is pretty damn painful, and every moment when you actually have a bird in frame and are ready to take pictures in unalloyed joy.

I've posted a number of times here to say how impressed I am with the 50D, and I am. But neverteless, the difference between a 50D and a 40D (or a 50D and a 350D) is one only of degree. Stepping up to a 500/4 is a difference of kind.

Sooner or later, if you are keen, you will get a 500/4 (or something else in that general class). It will last you for many years, much longer than any camera. You might as well do it now while you are still young enough and strong enough to carry the damn thing for a few more years!
 
comparing

If you compare correctly - i.e., compare finished images - not true. 50D wins comfortably. If you do silly things like compare 100% crops, you may well get this result, but it's meaningless. You need to compare two things by reproducing them the same way, at the same size. If you do this, the 50D is well in front.

I am not sure I understand. Forgive me for being a bit slow.

Taking an image with the same lens using both the 40D and the 50D. Cropping it and resizing it to let's say 800 x 600. Which camera produces least noise?
I almost always have to crop pretty heavily.

By the way, I borrowed a 500mm F4.0 and a 300mm F2.8 with 1.4 TC a few days back. The 300 was much to my likening. Here is a sample shot
http://www.pbase.com/peterericsson/image/106712499
The 500 was too cumbersome to log around in hilly terrain. More for stationary photography I suppose.

Now there is a used 300 in the local store going at 3500$US...........hmm.....

I also borrowed a 40D and must say I enjoyed having a full grip, big screen, 6fps and the wheel control....
 
You might as well do it now while you are still young enough and strong enough to carry the damn thing for a few more years!
Best compliment I have had for a time - I pick up my OAP in 6 weeks time ;)

I have obvious concerns about the weight of the 500 but the way I look at it is :
a) I can afford it
b) As you say, I might not be able to manage it in a few years time so for me it is now or never.

I have also considered the 300mm f2.8 but would need to use a 1.4 tc at least and maybe a 2x to gain any real reach advantage of my 400 f5.6 Not sure that it would give consistent results with a 2x.
I know it would give me 420 at f4 with a 1.4tc but the extra light/stop is no big deal for me as I am a 'fine weather shooter'.
 
I am not sure I understand. Forgive me for being a bit slow.

Taking an image with the same lens using both the 40D and the 50D. Cropping it and resizing it to let's say 800 x 600. Which camera produces least noise?
I almost always have to crop pretty heavily.

.
If I was in your position Peter and it was a straight choice between the 40D and 50D I would definitely go with the 50D ( I was unsure that you meant this from your original post)

Upgrading from the 40D to the 50D is less clear cut IMO. I share your concerns about noise levels when cropping heavily. I can only go by samples I have seen of heavy crops where there appears to be more noise from the 50D than the 40D. And yet some people claim the 50D has a 1 to 1 1/2 stop advantage in the noise stakes. All very confusing :eek!:

I looks obvious that 'Tannin' is not a heavy cropper like us so when he talks of the finished image he is talking about different things. Indeed he indicates that things like 100% crops are silly but I use near 100% crop frequently. I guess we all have different needs.
 
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different experiences

If I was in your position Peter and it was a straight choice between the 40D and 50D I would definitely go with the 50D ( I was unsure that you meant this from your original post)

Upgrading from the 40D to the 50D is less clear cut IMO. I share your concerns about noise levels when cropping heavily. I can only go by samples I have seen of heavy crops where there appears to be more noise from the 50D than the 40D. And yet some people claim the 50D has a 1 to 1 1/2 stop advantage in the noise stakes. All very confusing :eek!:

I looks obvious that 'Tannin' is not a heavy cropper like us so when he talks of the finished image he is talking about different things. Indeed he indicates that things like 100% crops are silly but I use near 100% crop frequently. I guess we all have different needs.

Yes, I have a friend who has both the 50 and the 40D. He definitely prefers the 40D still. Talks about the 50D being better in good light but producing more noise when cropped. I don't understand all the technical points. For me what counts is the end result and in my case that is webpostings.

PS> by the way, I produced a desktop calendar of Birds of Thaland for 2009.. it came out very nice as a high end product....has sold very well....all for charity...
 
Taking an image with the same lens using both the 40D and the 50D. Cropping it and resizing it to let's say 800 x 600. Which camera produces least noise?
Peter, this isn't the question you should be asking.

Suppose you take a shot of a bird that takes up one-fifth the height of your image. On a 40D you could crop that from 2592 pixels high to 600 pixels high and you'd have the bird (518 pixels high) contained in your cropped image.

But on the 50D the bird would take up 3168/5 = 634 pixels. If you cropped that image to 600 pixels high then you'd be cropping part of the bird.

The question you really want answering is -

Taking an image with the same lens using both the 40D and the 50D. Cropping it and resizing it to let's say one-fifth the linear dimensions. Which camera produces least noise?​

And I'd bet money that the answer would be - they're about the same.
 
Sorry Peter, I should have expressed that more clearly.

Take the same picture of the same bird with the same lens (poor little thing must be really wishing we would pull out those nails holding it on the perch by now) with a 40D and a 50D.

I did a fairly lengthy post on exactly this the other day in another place a bit closer to home than here - http://www.ausphotography.net.au/forum/showthread.php?t=20625 - it includes illustrations to make things clearer but I think you have to join up to see them - that's free if you want to. Anyway, I'll try to summarise.

Take those same-lens, same-everything shots and crop out the background, leaving just the bird. Let's say you do a medium-hard crop and wind up with a 4.0MP image from the 40D. The exact same crop will give you 6.0MP with the 50D image.

Now, resize the two images to any size you please - doesn't matter which size, so long as they are the same, and so long as you are not making it so small that you can't see any difference - i.e., don't take them down to the size of a postage stamp or even a postcard. (You can even up-size them if you want to, just so long as you make the final images the same size.)

The 50D image will always win. It probably has slightly more noise per-pixel (though opinions differ on that, some say it doesn't), but it also has a 50% advantage in the number of pixels you started with after cropping and before resizing. The more pixels you have to play with, the less contribution each pixel makes to the final image, and the less noise you end up with. Noise, remember, is random variaton between pixels. When you combine pixels, you reduce the noise. The 50D combines 50% more pixels to make the same (e.g.) 800 x 600 image. For the 40D to match it, it would have to have way less noise per pixel, enough less to outweigh that 33% handicap.

(50%? 33%? Yes, those are the correct figures because 6 milion is 50% more than 4 million, but 4 million is 33% less than 6 million.)

If, on the other hand, you decide to show the whole bird with the 40D image and only part of the bird with the 50D image, then of course you are going to get a different result! This is where these silly "50D has more noise" arguments come from - if you do a 100% crop on both images, you are not[/i] looking at the same thing at all! You are looking at 100% of the bird on the 40D shot, and only 66% of the bird with the 50D shot and your comparison is meaningless.

Roy, we all crop as much as we have to. Some of my published shots are 100% crops - not too many, but a few. I'm not for one moment saying that a 100% crop for artistic reasons is a bad thing (though of course it's better to avoid that if you can). The point here is that if you take the same shot from the same place of the same poor little bird with the same lens, and for artistic reasons you need to take a 100% crop from the 40D image to get your finished image, you will only need to take a 66% crop from the otherwise identical 50D image. Or, if the bird is so small in frame that you need a 100% crop from the 50D, then to print it at the same size from the 40D image you need to take a "150% crop" - i.e., enlarge the 100% 40D crop from (say) 640 x 480 to something like 800 x 600! And the result, of course, will be well below the quality of the 50D result either way.
 
Spot on, Frank.

And I'd bet money that the answer would be - they're about the same.

I'll take that bet ...... but only after we carefully define what we mean by "about".

With the same lens and same everything else - including the same cropping to show the same amount of the bird - images from 20D, 40D, 50D, and 1D III are indeed about the same. None of them are mind-blowingly different from one another. All of them are way better than anything you'd get with a P&S.

But there are differences. How much is "about"?
 
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