# at what point does it make sense to stop obsessing over gear minutia ?

Started 2 months ago | Discussions thread
Re: When you are satisfied with what you have

Lee Jay wrote:

mamallama wrote:

Lee Jay wrote:

mamallama wrote:

Lee Jay wrote:

mamallama wrote:

Lee Jay wrote:

D Cox wrote:

Lee Jay wrote:

Gerry Winterbourne wrote:

TRIODEROB wrote:

in other words how far down the rabbit hole should you chase small improvements in gear.

will it translate to much better images if you get a lens which score 7% more on a optical test ?

I can't think of any meaningful optical test that can give scores in percentage points;

Since MTF is a number from 0 to 1, you can think of it as a percentage if you like.

It isn't a single number, it's a function -- that is, a set of numbers that you can plot on a graph.

Of course, I know that. In fact, it's a complex function and what we call MTF is just the absolute value.

https://en.wikipedia.org/wiki/Optical_transfer_function

But sometimes people say MTF50 (or MTF9 for Rayleigh, for example), for 50%, and they mean at the center at a particular f-stop or diffraction limited.

So now MTF is not a number from 0 to 1. What changed?

Read the above that you quoted and do so with your brain turned on this time.

All I see are conflicting statements by you.

That's because you aren't literate.

Literate? What does it take to understand two simple conflicting sentences??? Your insult is a joke and shows your desperation to deflect.

No, you just don't understand simple language.

Do you care to clarify the conflict? Do you still think MTF is a number from 0 to 1? Or is it a complex function?

I'll explain it to you like you're a 4-year-old.

OTF (Optical Transfer Function) is a complex function.

MTF is the absolute value of OTF, so it's a real function.

However, many people simplify that real function to a single point and describe that single point by a fraction, decimal or percentage. For example:

http://www.normankoren.com/Tutorials/MTF.html

"Perceived image sharpness (as distinguished from traditional lp/mm resolution) is closely related to the spatial frequency where MTF is 50% (0.5)— where contrast has dropped by half."

Just in case you are wondering if he's credible:

https://en.wikipedia.org/wiki/Imatest

"Imatest LLC is a company that produces image quality testing software and offers a range of consulting services. Imatest was founded by photographer/engineer Norman Koren in Boulder, Colorado in 2004 to develop software for testing digital camera image quality."

Got it now?

Your words are just to obfuscate.

So you're going to tell me Norman Koren is wrong by using the statement above?

Those with their brains turned on know that the "F" in MTF stands for function, which is not a number from 0 to 1.

A function can have a value and still be described by the name of the function. This sort of thing is done all the time, and MTF is described as a number commonly.

http://lmgtfy.com/?q=%22MTF50%22

You make a dumb statement and when called on it you go look up something and write a bunch of unrelated words and give some links to obfuscate as you just did.

Well, if my statement was dumb than so was Norman's and the same with all the hundreds of people that show up in the search above.

I think that makes you dumb for not recognizing the obvious, not me.

Sorry, you wasted all that time (4 hours) since my post looking up an article that does not prove your point. There is nothing there that says MTF is a number between 0 and 1. Keep trying. But you are looking for something that does not exist. Google Search is not your friend when looking for something that does not exist.

Yes everybody knows functions will have a particular value (number) at each argument, but a function is not a number. You used the word "is". Do you know the meaning of "is"?

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