small aperture test
in [Digital Cameras]
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From: Bob Larter is Lionel Lauer - Look it up. on 6 Nov 2009 22:14 On Sat, 07 Nov 2009 13:50:31 +1000, Bob Larter <bobbylarter(a)gmail.com> wrote: >Outing Trolls is FUN! wrote: >> On Fri, 06 Nov 2009 09:50:52 +0100, Ofnuts <o.f.n.u.t.s(a)la.poste.net> >> wrote: >> >>> Trolls is FUN! wrote: >>>> On 06 Nov 2009 07:28:51 GMT, rfischer(a)sonic.net (Ray Fischer) wrote: >>> <snip prespoterous claims> >>> >>>> YOUR LOSS! >>>> >>>> And a huge loss for everyone. Caused by trolls like you. Now everyone has >>>> to do the searching for that software based only on a vague description. >>>> Good luck finding my most favorite and vastly configurable one as described >>>> above, I've not seen it on the net for about two years. You useless trolls >>>> taught me well. NEVER share the most important bits of information as long >>>> as a news-group is being overrun and taken over by a pack of useless and >>>> pathetic trolls. The trolls will only use that information to be better at >>>> pretending to be photographers with the next newbies who can't immediately >>>> see the trolls for what they truly are. >>> I don't believe this stuff exists. Prove me wrong! >> >> I suppose I could upload two sample images, one without and one with a >> depth-map catadioptric-lens annulus bokeh applied to it, > >Oh, I doubt that. Bob Larter's legal name: Lionel Lauer Home news-group, an actual group in the "troll-tracker" hierarchy: alt.kook.lionel-lauer (established on, or before, 2004) Registered Description: "the 'owner of several troll domains' needs a group where he'll stay on topic." <http://groups.google.com/groups/search?hl=en&num=10&as_ugroup=alt.kook.lionel-lauer> "Results 1 - 10 of about 2,170 for group:alt.kook.lionel-lauer."
From: Bob Larter is Lionel Lauer - Look it up. on 6 Nov 2009 22:15 On Sat, 07 Nov 2009 13:48:28 +1000, Bob Larter <bobbylarter(a)gmail.com> wrote: >Outing Trolls is FUN! wrote: >> On Fri, 06 Nov 2009 11:56:53 +1000, Bob Larter <bobbylarter(a)gmail.com> >> wrote: >> >>> John Navas wrote: >>>> On Thu, 05 Nov 2009 23:39:40 +1000, Bob Larter <bobbylarter(a)gmail.com> >>>> wrote in <4af2c78c$1(a)dnews.tpgi.com.au>: >>>> >>>>> The 50mm/F1.8II is a surprisingly good lens for the money. I've taken a >>>>> lot of excellent shots with mine, so please don't sell it short! >>>>> I've since 'upgraded' to a 50mm/F1.4, but it's not as much of an >>>>> improvement as you might expect from the price difference. >>>> What you get for the money with the f/1.4 over the f/1.8 is speed, >>>> not IQ. >>> The f1.4 also has more aperture blades, so the bokeh is a bit nicer as well. >> >> Post-processing plugins with depth-map masks afford an infinite number of >> aperture blades for bokeh, > >Um, no, it doesn't. > >> as well as even emulating catadioptric lens >> systems no matter what camera took the image, and more. > >Why the hell would anyone in their right mind want to emulate the >doughnut-shaped bokeh you get with a cat lens? Bob Larter's legal name: Lionel Lauer Home news-group, an actual group in the "troll-tracker" hierarchy: alt.kook.lionel-lauer (established on, or before, 2004) Registered Description: "the 'owner of several troll domains' needs a group where he'll stay on topic." <http://groups.google.com/groups/search?hl=en&num=10&as_ugroup=alt.kook.lionel-lauer> "Results 1 - 10 of about 2,170 for group:alt.kook.lionel-lauer."
From: Educationg Trolls Is An Endless Task on 7 Nov 2009 08:07 On Fri, 06 Nov 2009 15:04:20 -0600, Educationg Trolls Is An Endless Task <etiaet(a)somewhere.net> wrote: >You can display the diffraction of >light with a single knife-edge, no aperture required. Some interesting images found while bored. Referred to as "Grimaldi's Shadows" in days of yore. Circa 17th century. The resident-trolls posting in these news-groups today are 300 to 400 years behind the learning curve. They're not mental-throw-backs to just last century. I'm not at all surprised. Full double-edge razor blade: <http://micro.magnet.fsu.edu/primer/lightandcolor/images/diffractionfigure2.jpg> Internal space in a double-edged razor blade: <http://hyperphysics.phy-astr.gsu.edu/HBASE/PHYOPT/phopic/razcut.jpg> Razor blade corner (oops, no aperture at all): <http://hyperphysics.phy-astr.gsu.edu/HBASE/PHYOPT/phopic/razcor.jpg> Also related to my previous posts: While finding the above, I stumbled upon a fairly good example of optics being given the Ronchi-test where the central portion has the worst figure. <http://www.retrotechnology.com/glass/06mar13_9r.jpg> Stopping down the aperture will cause softening due to figure errors, not diffraction. (For those green to Ronchi-test patterns, here's a quick overview: <http://schmidling.com/etron.gif> TDE=turned down edge)
From: Chris Malcolm on 7 Nov 2009 11:32 Educationg Trolls Is An Endless Task <etiaet(a)somewhere.net> wrote: > On 6 Nov 2009 14:50:57 GMT, Chris Malcolm <cam(a)holyrood.ed.ac.uk> wrote: >>Not at all. I've worked alongside colleagues who've written books on >>the subject. > When a youth was giving himself airs in the Theater and saying, "I am wise, > for I have conversed with many wise men." Epictetus replied, "I too have > conversed with many rich men, yet I am not rich." > You were saying something? LOL! > I'm sure your colleagues, if you indeed ever had any, kept you around as > their little puppy dog that didn't piddle on the carpet too often. Or > conversely, got many laughs out of your incessant piddling habits. As I do > with how often you piddle your nonsense to usenet. > 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. >>The mathematics of the relationship between lens optical >>aberrations and diffraction is simple, uncontroversial, and has long >>been well known. Your position can only logically be maintained if you >>disagree with one of the following propositions: >> >>1. Lens optical errors vary inversely with aperture. > Wrong. The central part of a lens or lenses may have the greatest figure > error. Especially in a complex compound lens where one element or group of > elements may have more imaging weight as aperture is increased or reduced. > However, for a given amount of effort, fabrication and figuring errors are > 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. 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? >>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? Your responses in this thread suggest that you do have access to some reasonably authoritative source of information on the topic, but that you don't really understand what it means. > The > amount of light in the image only reveals or hides the fixed amount of > diffraction created/caused by distance. You can display the diffraction of > light with a single knife-edge, no aperture required. This is why shorter > focal-length lenses have less diffraction problems. This also is why it's > so easy to create truly diffraction-limited optics for P&S cameras due to > the smaller focal-lengths required and smaller optics diameters required > (i.e. for a given effort, a smaller diameter optic is easier to figure > accurately). That's exactly what I thought. You don't really understand this at all. What you say is perfectly true, but if you really understood what you've written you'd realise that it has nothing to do with the change in the relative amount of diffraction in an image formed by a non-diffraction-limited lens at varying apertures. >>3. Lens errors combine at worst multiplicatively. > Wrong. > Grade-School Math 101 You appear to have as little understanding of Maths 101 as Physics 101 or Optics 101. It's a bit pointless citing such elementary sources to someone whose education has gone well past that point. If you want to disagree, then rather than vaguely waving your hand at an unspecified first year undergrafuate textbook, why not try to actually find the relavant page and quote it? I am of course generously assuming that you once did such courses and can still remember what's in the textbooks :-) >>Can you enlighten us as to which of those you disagree with, or >>whether you're using a different mathematical foundation for the >>relationship? > Three strikes, you're outta here TROLL. > Blatantly Obvious 101 That's one course I have no doubt you attended :-) -- Chris Malcolm
From: Educationg Trolls Is An Endless Task on 7 Nov 2009 13:08
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. |