In article , Eric Miller
writes
Kennedy McEwen wrote:

If it is just about the math then you need to quantify the lens
quality contribution as well

No, the question posed in the original post had nothing to do with that.

I suggest you read what you wrote in your question again and, in future
ask what you mean or mean what you ask! You specifically refer to
resolution and that is a lot more than just pixel density!

- your math is less than half the story, dealing only with pixel
geometry.

That would actually be the whole story, since the original question
strictly concerned the pixels.

No, you stated: "if there is a way to think of resolution as effective
focal length versus the 10D".

Pixels are only one component of resolution: optics contribute
significantly and, in this particular case, dominate.

Others have tried to explain this to you in the thread, but it is
clearly making your "head hurt too much"!

To include the lens contribution you need to use significantly more
complex math, convolving pixel geometry with lens aberration geometry,
or a completely different type of math using pixel MTF and lens MTF to
scale resolved spatial resolutions at equal contrast. That is what
the discussion on the LL site is trying to explain.

Pertinence to this thread?

If you have to ask that question then the answer is clearly beyond you,
but it is pertinent on at least three counts:
1. It is the full answer to your question, which you clearly seem unable
to understand. Even perfect optics have a finite resolution, and when
the sensor resolution approaches that, which is certainly the case in
the 7D, that needs to be included in any scaling comparison, as
explained in the LL article. The optical resolution is limited in terms
of the minimum blur spot, while the sensor is limited in resolution by
the pixel area. The cameras limits are determined by convolution of
optical blur spot and pixel area. Convolution is a fairly complicated
mathematical procedure and it is simpler to represent these parameters
in terms of MTF curves simplifying the calculation of the camera
resolution as it is just the product of the MTFs. The effective focal
length scaling, in terms of reach, is simply then the ratio of the
spatial resolutions at which the limiting contrast is achieved. That is
the COMPLETE answer to your question. Whether you understand it or not,
pixel scaling is only part of the issue and, in the case of comparing
anything to the high pixel density of the 7D, will yield highly
optimistic scaling on its own.

2. It has already been linked to in this thread, but obviously ignored
by you. I suggest you read it again and make some effort to understand
it before claiming it is irrelevant, since optics dominate the question
you have asked, NOT pixels.

3. Others who read this thread in future, which will be archived
forever, may be less mentally challenged than you and be looking for a
more complete answer, not a simple pixel scaling answer which is trivial
to calculate but optimistic at best and wrong in general.
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)