Popcorn was fine up to a certain point... But I have to agree with neuro on this.
We are discussing whether or not there is an IQ difference between sensors of similar resolution but different physical size. All other factors must be equal in testing this, or perceived differences could be due to something other than the physical sensor size.
I will grant that in some situations those other factors may be practically relevant. For example, when the choices were the 5D and 20D there were no good options for UWA on crop. But in judging any of this we must first determine what, if any, sensor differences exist absent all other influences.
Sorry, I'm not seeing a viable suggestion from you. The sensors are different sizes - something must change for the resulting images to be framed the same. The three options are crop the FF image, change the distance to the subject, or change the focal length. The first defeats the purpose, the second changes the perspective of the image. Maybe I should have moved the camera, but arranged for the Museum of Fine Arts building to be moved closer to the foreground? Or maybe I should have chosen perfectly flat subjects like test charts, obviating perspective? Have I missed any options?
Cropping the image and doing side-by-side comparisons definitely isn't the way to go. Assuming that the camera position was not moved and the same lens and focal length were used, you have a 22MP (say the 5D3) at focal length X and an 18MP (i.e. 7D) at focal length 1.6X. So cropping this to produce the same view would mean that your APS-C image has 2.0736 times more pixels than the FF one. You could resample the images but that would give the APS-C image a slight advantage.
Besides, why would you have to deal with the crops? The fact is, the FF cameras out there (on Canon's end at least) have higher resolutions than the APS-C ones. Do our eyes crop the image to equalize the resolutions? Doesn't it make more sense to compare whole images?
Zooming in the lens like neuro makes sense since that at least preserves perspective without biasing the resolution significantly. In fact, if you think about it, some lenses perform poorer on the long end so it can actually be to the FF disadvantage anyway. When you downsample everything to a smaller resolution like neuro did, the difference between 18MP and 22MP should be negligible along with minor fluctuations in lens characteristics (assuming good lenses were used of course). At least that way, there is less bias.
Translation: you can't prove your point with hard evidence, so you're taking your ball and going home.
I was never trying to prove a point with hard evidence. Please go back and reread my initial post, and this time, pay very close attention to the part you ignored in your first response, the part where I stated that my observations were subjective and completely anecdotal. Your treatment of it as if it were hard evidence was your first and biggest mistake, one that essentially renders the rest of the discussion moot.
Hard evidence was never neuro's point from his first post. But if we're discussing hard evidence, shouldn't the methodology at least be properly established?
FWIW, I am a card-carrying 'strict scientist', PhD and a day job in the field
This means nothing at all. All that matters is how a test is performed, and not who performed it. As a "card-carrying 'strict scientist' PhD' you should know and live by this.
What a classic and intriguing case of human bias and emotion in action, and from a "card-carrying 'strict scientist', PhD" no less. This is why I never automatically trust scientists even in their narrow fields of study, but treat their claims with the same critical eye as I would anyone else. No matter what is claimed in training or degrees (pieces of paper with ink), they are still human, and display all the classic flaws of human nature.
Okay... now that really ticked me off. While it is true that everything should be taken with a grain of salt, it is equally as true that scientists do a lot to get their degrees. These are "pieces of paper with ink" but are they inked so easily? Objectivity is one important aspect that is learned as a scientist. You don't publish works that scream out "BIASED". Those things rarely get past peer reviews.
FWIW, I am an academic researcher myself and I deal especially with image processing. And from what I see, neuro's post was anecdotal but technically sound. This would be much easier if there were a good ubiquitous no-reference quality metric but subjective testing is really the only option at this point and there can never really be a perfect "standard" procedure that everyone agrees on.
Personally, I haven't used a FF yet so I can't tell if there is really a difference. I've been using the 60D and I do feel that there's an extra quality that's missing. Maybe its my lenses. Or maybe its the effective DoF. Heck, maybe its even just me! I'll only know for sure when I get my hands on the 5D3 arriving soon.