Sensor format and lens performance: Replies to bobn2 and Jim Stirling Locked

Started Nov 24, 2013 | Discussions thread
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Anders W Forum Pro • Posts: 21,468
Sensor format and lens performance: Replies to bobn2 and Jim Stirling

This thread expired before I had the opportunity to respond to some allegations made by bobn2 and Jim Stirling. Consequently, I do so here instead, in this post to Bob, and in the one that follows, to Jim.

bobn2 wrote:

I know several scientists with a propensity to cherry pick data.

I don't. I do know of academics with that propensity though. But these are not worthy of being called scientists and are mostly people I know of rather than know.

Anders, both with Jack and with me, you're standing on your dignity, rather than arguing the case.

In precisely what regard am I "standing on my dignity"? By explaining to Jack why I found his unsubstantiated contention about cherry-picking insulting? Or by telling you that your attempt to write off my objections as a matter of psychological hang-ups was no better? For obvious reasons, neither response of mine is an attempt to "stand on my dignity". I simply explained why these two unsubstantiated contentions of yours (one sentence in each case) were not worthy of a substantive response.

If you have any further examples, where, in my exchange with Jack and you, you consider me having "stood on my dignity" rather than argued the case, please specify them carefully, along with a link to the relevant source post, so that everyone can readily see for themselves whether you are right or not.

Jack is right, look at the available data and the best FT or mFT lenses rarely if ever match the best FF lenses for lp/ph.

Specifically what data would you point to in support of that sweeping generalization?

Certainly, every one of those sources can be argued against for one reason or another, because none of them has a completely sound or worked out testing methodology.

The fact that every source of data has shortcomings doesn't mean that they are equally bad for a specific purpose (in this case comparisons of lens performance across sensor sizes). In line with good scientific practice, better data should be preferred to worse data.

As for my discussion with you, all I ever said is that there is no evidence to support the proposition that the 12-40 is the sharpest zoom yet, and indeed there is evidence that suggests that other zooms are sharper, yet you argued post after post arguing, for what position, I'm no longer sure -

If you have trouble understanding what my contentions and arguments are, that's really not my problem. As everyone can see for themselves, they have been clearly stated all along. If anything remains unclear, I am of course willing to help you out to the best of my ability. But where we left off, i.e., here

there were no questions of yours that I had failed to address.

then there again retired 'insulted'.

As everyone can see for themselves, I didn't "retire" from the substantive discussion. Jack did. And judging by your lack of response to the post I link to above while you still had the opportunity to respond to it, you did as well.

I would contend in both cases your methodology is less to cherry pick data but to selectively discount data that doesn't fit your proposition.

Specifically which valid and invonvenient evidence have I discounted?

When I discount data, I do so on methodological grounds and spell out what those grounds are. For example, in my discussion with you about DxO's P-MPix, I made it perfectly clear for what reasons I found it appropriate to discount them. Again, see the post you never responded to for examples:

Again, choosing between data sources on methodological grounds is in line with good scientific practice and should not be confused with cherry-picking or discounting data on the ground that they don't fit one's proposition.

Sure, none of it is perfect, but a picture still begins to emerge through the noise.

See my question above about the evidence you wish to refer to in support of your generalization about lens performance.

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