small aperture test
in [Digital Cameras]
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From: Ray Fischer on 7 Nov 2009 13:28 Chris Malcolm <cam(a)holyrood.ed.ac.uk> wrote: >Educationg Trolls Is An Endless Task <etiaet(a)somewhere.net> wrote: >> Pushing a broom and emptying waste-baskets in a publisher's collating >> department could also be construed as "working alongside .... (authors)". >> If I was forced to assume your trolls' comment above was conveying your >> truth, from the vast amount of misinformation you spew that would be my >> guess of how you came to believe what you believe. > >Your research skills are pathetic. It's ridiculously easy to discover >my academic affilation and status. Don't argue with it. It doesn't care about the truth. It will keep lying and keep arguing as long as you keep responding to what it writes. -- Ray Fischer rfischer(a)sonic.net
From: Educationg Trolls Is An Endless Task on 7 Nov 2009 13:46 On 7 Nov 2009 16:32:35 GMT, Chris Malcolm <cam(a)holyrood.ed.ac.uk> wrote: >Educationg Trolls Is An Endless Task <etiaet(a)somewhere.net> wrote: > >> Pushing a broom and emptying waste-baskets in a publisher's collating >> department could also be construed as "working alongside .... (authors)". >> If I was forced to assume your trolls' comment above was conveying your >> truth, from the vast amount of misinformation you spew that would be my >> guess of how you came to believe what you believe. > >Your research skills are pathetic. It's ridiculously easy to discover >my academic affilation and status. > Why on earth do you think anyone would be interested enough in you to do something as hugely pointless a waste of time as that? Your words here speak for themselves. You're an idiot. A semi-educated idiot. The world is crawling with them. Some of the most stupid people I have ever met in life even had PhD and Dr prefacing their names. >> exponentially proportional to size. There is no law on which area of that >> lens may have the greatest error. > >Let's get down to specifics and try to avoid confusing the issue with >a smokescreen of rare exceptions. No smokescreen at all. Poor lens figuring is DIRECTLY RELATED to why you CANNOT MEASURE the amount of diffraction, especially when stopped down. If you cannot obtain the sharpest image at full aperture, then that means YOUR OPTICS ARE NOT DIFFRACTION-LIMITED. Therefore, stopping down that lens is NO GUARANTEE that the softness you are observing is in any way related to diffraction. Are you this pathetically stupid that you can't grasp something so simple? > Let's take one of the largest and >simplest kinds of lens aberration -- chromatic aberration. > >Do you really seriously claim that what you wrote above usually >applies to chromatic aberration in DSLR camera lenses? > Ahhh.... the bleats of a pure troll. Red-herring CA bullshit smokescreens that have has nothing to do with the diffraction problems being discussed. >>>2. Lens diffraction errors vary with aperture. > >> Wrong. It varies with distance of aperture edge to imaging plane. > >Of course it does! But do you not realise that there is no >contradiction between that fact and the fact that the proportion of >diffraction error in an image formed by a given camera lens at a given >image distance increases with aperture? This will be the last time I tell you this. If the optics are not of diffraction-limited quality, then your optics CANNOT create diffraction artifacts to even measure it or detect it. You only asked that I disagree with ONE of your points and prove it. ALL THREE were wrong. I suggest you pay for some courses on these areas of study instead of trying to manipulate someone far more intelligent than you into educating you for free. Go away useless troll. I'm done with you.
From: Frank on 7 Nov 2009 15:21 I found a site w/ ISO 12233 photos. You can see how various lenses perform. http://www.the-digital-picture.com Look at this and shut up. On Sat, 07 Nov 2009 12:08:41 -0600, Educationg Trolls Is An Endless Task <etiaet(a)somewhere.net> wrote: >On 7 Nov 2009 16:32:35 GMT, Chris Malcolm <cam(a)holyrood.ed.ac.uk> wrote: > >>Educationg Trolls Is An Endless Task <etiaet(a)somewhere.net> wrote: >> >>> Pushing a broom and emptying waste-baskets in a publisher's collating >>> department could also be construed as "working alongside .... (authors)". >>> If I was forced to assume your trolls' comment above was conveying your >>> truth, from the vast amount of misinformation you spew that would be my >>> guess of how you came to believe what you believe. >> >>Your research skills are pathetic. It's ridiculously easy to discover >>my academic affilation and status. >> > >Why on earth do you think anyone would be interested enough in you to do >something as hugely pointless a waste of time as that? Your words here >speak for themselves. You're an idiot. A semi-educated idiot. The world is >crawling with them. Some of the most stupid people I have ever met in life >even had PhD and Dr prefacing their names. > > >>> exponentially proportional to size. There is no law on which area of that >>> lens may have the greatest error. >> >>Let's get down to specifics and try to avoid confusing the issue with >>a smokescreen of rare exceptions. > >No smokescreen at all. Poor lens figuring is DIRECTLY RELATED to why you >CANNOT MEASURE the amount of diffraction, especially when stopped down. If >you cannot obtain the sharpest image at full aperture, then that means YOUR >OPTICS ARE NOT DIFFRACTION-LIMITED. Therefore, stopping down that lens is >NO GUARANTEE that the softness you are observing is in any way related to >diffraction. Are you this pathetically stupid that you can't grasp >something so simple? > > >> Let's take one of the largest and >>simplest kinds of lens aberration -- chromatic aberration. >> >>Do you really seriously claim that what you wrote above usually >>applies to chromatic aberration in DSLR camera lenses? >> > >Ahhh.... the bleats of a pure troll. Red-herring CA bullshit smokescreens >that have has nothing to do with the diffraction problems being discussed. > > >>>>2. Lens diffraction errors vary with aperture. >> >>> Wrong. It varies with distance of aperture edge to imaging plane. >> >>Of course it does! But do you not realise that there is no >>contradiction between that fact and the fact that the proportion of >>diffraction error in an image formed by a given camera lens at a given >>image distance increases with aperture? > >This will be the last time I tell you this. If the optics are not of >diffraction-limited quality, then your optics CANNOT create diffraction >artifacts to even measure it or detect it. > >You only asked that I disagree with three of your points. ALL THREE were >wrong. > >I suggest you pay for some courses on these areas of study instead of >trying to manipulate someone far more intelligent than you into educating >you for free. > >Go away useless troll. I'm done with you. > >
From: Educationg Trolls Is An Endless Task on 7 Nov 2009 15:36 On Sat, 07 Nov 2009 12:21:45 -0800, Frank(a)Zappa.com wrote: >I found a site w/ ISO 12233 photos. You can see how various lenses perform. > >http://www.the-digital-picture.com > >Look at this and shut up. One minor problem, that won't help at all with individual lenses. Ever hear of "The Lemon Law" concerning cars? Lens figures between any two lenses of the same model number can differ wildly. This is why pros will take home 4 or more lenses of the same model number to pick out one that might be better. (For the same reason that pros that shoot with P&S cameras will do the same, not only for the lens, but for the sensor installed, no two being alike in noise performance for the same camera model.) The surest and simplest way for the novice to find out if their lens is NOT of diffraction-limited quality is if the details become softer at widest apertures. If that is true, then all tests for diffraction problems at any f-stop become pointless. Diffraction artifacts only reveal themselves with diffraction-limited quality optics. That is why they call it that. The image resolution is now only limited by the physics of light and diffraction itself because the lens figures are that precise.
From: tony cooper on 7 Nov 2009 16:28
On Sat, 07 Nov 2009 14:36:18 -0600, Educationg Trolls Is An Endless Task <etiaet(a)somewhere.net> wrote: >For the same reason that pros that shoot with P&S cameras will do the same, not only for the lens, but >for the sensor installed, no two being alike in noise performance for the same camera model. A pro using a P&S. That's like Hermann Maier using barrel staves as skis. -- Tony Cooper - Orlando, Florida |