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  1. #21

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    Quote Originally Posted by Ian Grant View Post
    Nothing you say falls into line with reality
    That's what you think.
    It is reality. Inescapable law of nature.
    Even Ed's favourite mr. Fresnel knows this.

    Quote Originally Posted by Ian Grant View Post
    and the fact that LF lenses are designed to be used at f22/32 and have excellent resolution across the field.

    Some lens designs don't achieve edge/corner sharpness until f22m andthen how do you explain the outstanding performance of an f5.6 150mm Xenar at f32 & f45, it stops down to f64 ?

    Well, there is excellent and there is excellent.

  2. #22

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    Quote Originally Posted by Ed Sukach View Post
    No, I DON'T "know" this!
    Well, there we are!

    Based on your bragging, you should though.


    Quote Originally Posted by Ian Grant View Post
    Considering where you are starting from (and your attitude)...
    That's perhaps because we cannot all be as learned as you, right?


    Quote Originally Posted by Ian Grant View Post
    Even though I am under NO obligation to instruct you in anything - you will just have to learn for yourself, I will direct you to:

    This from one of the important text books:

    What is Light? By A.C.S. van Heel and C.H.F. Velzel,World University Library - Library of Congress Catalog Card Number: 67-24448

    Page 97, Section 4, Diffraction:
    We can now turn to another facet in the study of light: the diffraction effects, the existence of which has already been mentioned. (See section 2 on the rectilinear propagation of light, and section 18 on the distribution of light at the focal plane of a lens upon reduction of the size of the diaphragm). To explain such phenomena, the great physicist and optician, Augustin Fresnel (1788 - 1827) developed a theory of the propagation of light, with which we begin our discussion.

    Until now we have used as a model for the propagation of light, the theory of Huygens, which we define as follows.
    One can imagine a wave front to originate out of the previous one by supposing each point in the latter to be a secondary source of spherical waves. The envelope of these spherical waves forms the new wave front..."


    **Fascinating**. I will admit to having read this section a number of times, but I finally gained a fairly good "grasp" of what was going on.
    Nice quote.
    But it says absolutely nothing about this matter.
    So not well chosen.

    Quote Originally Posted by Ian Grant View Post
    Polarisation, section 5, was another matter. I passed the "tests" - but I'm still not completely sure...
    Who is?

    Quote Originally Posted by Ian Grant View Post
    Ah! Obviously an infallable way to test a lens, free from subjective judgement and preceptual bias.... NOT!
    Who said anything about an infallible test?

    But you do know (i assume, but tell me if i am wrong) that photography is a visual medium, and that what you see is what you get?
    Good!

    Quote Originally Posted by Ian Grant View Post
    As interesting as that my be ... I doubt that it has anything to do with diffraction. Is the article available on-line ? Or ...?
    Yes.
    It has everything to do with diffraction (you really need to get those books out again)
    And yes, it is available online.


    Quote Originally Posted by Ian Grant View Post
    The last refuge of one insecure in his argument: an "Ad Hominem" attack.
    That's why you started by pointing out your personal qualifications?


    I don't doubt your personal qualifications. So not even an ad hominem.
    But given that your argument is based on authority, it is not possible to dismiss your mistake as such without touching your proffered authority.


    Quote Originally Posted by Ian Grant View Post
    The same source? Zeiss? Now I am really interested!
    You know it is optics 1.0.1.
    So you really should know this, and not find this interesting, but old hat.


    Quote Originally Posted by Ian Grant View Post
    Nice table. Anything to do with diffraction?
    It is about nothing else but diffraction.

    Quote Originally Posted by Ian Grant View Post
    I understand some of the factors that influence lens design... What happened to "diffraction"?
    What are you asking?


    Quote Originally Posted by Ian Grant View Post
    Well, that really says it all. There is only ONE definition recognized as "Circle of Confusion" - an important criteria in lens design.
    Only one? You think so?
    I think 'the place where your head is (was?) spinning' qualifies as a perfectly good definition.

    Now just stop digging.
    Last edited by Q.G.; 08-12-2009 at 06:07 PM. Click to view previous post history.

  3. #23
    richard ide's Avatar
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    Out for lunch and lost his way back!
    Richard

    Why are there no speaker jacks on a stereo camera?

  4. #24
    Ed Sukach's Avatar
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    [QUOTE=Q.G.;844547]
    I]Today’s high quality color films do reach resolutions in the region of 140 line pairs per millimeter with Kodak Ektar 25 leading the field at 200! The full resolution potential of these films cannot be utilized with existing depth-of-field concepts nor f-settings of f/11 and beyond.[/I]
    Carl Zeiss, Camera Lens News, no. 2, Fall 1997.
    I've finally reached the Zeiss website, and D'Ld the .pdf file. I see where you are coming from, but I will submit that you are extrapolating to reach an unwarranted conclusion. Here, Zeiss is commenting on theoretical limits of resolution, tied in some manner, to f/stops. I would really be interested in their methods of determining these approximate limits, but no information is provided.
    According to Zeiss, a resolution of 45 l/mm (one way to look at resolution) is reaced at f/11. The normally accepted design criteria for a 35mm frame is 1/60th mm, so there will be some degradation at an aperture smaller than f/11. Notice that I wrote "some" ... the image will not abruptly disappear into a ball of "fuzz".

    One thing to remember: the "practical limit" of any lens system is not entirely and wholly dependent on "diffraction"... it would be, IF the remaining parameters were all perfect... and the chances of that happening are not great.

    I will ask one favor: Direct me to web site where I can find Zeiss's formula for determining "diffraction limitation". Until I can check that out, I will not continue to discuss their assumptions.

    It is interesting that you consider "Diffraction" as one of the simple. basic phenomena. I think it is one or two notches above "basic".

    BTW... I've been considering the "tone" and syntax of your posts ... in some way, vaguely familiar. Would you happen to be posting from St. Louis, Missouri?

    Seriously, what have you been smoking!?
    Ad hominem, again. You do know ad hominem means, don't you?

    Go back to your books then. I bet you haven't touched them since "many moons" ago.
    I hate to break the news, but, that time span is about 15 minutes.
    I was going to suggest that you look up the formula that describes the relation between f-stop and resolution when posting Zeiss' table when i saw what you wrote here.
    I now strongly urge you to do so!
    Sounds good to me --- WHERE??


    I can. Several
    One is about the thing your head seems to be spinning in right now.
    Hilarious. Indicative of your sharp wit, I suppose.
    Carpe erratum!!

    Ed Sukach, FFP.

  5. #25
    richard ide's Avatar
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    Ed,

    I thought it could be HIM also.
    Richard

    Why are there no speaker jacks on a stereo camera?

  6. #26
    Ian Grant's Avatar
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    Complete rubbish and misquoted

    Complete rubbish, you attribute quotes to me that are most certainly not written or said by me.

    This is ALL I have said:

    Quote Originally Posted by Ian Grant View Post
    Tessar type lenses (135mm and over) only reach optimum performance at f22, that's intrinsic to the design, a modern Xenar 150mm f5.6 has a marked aperture scal to f64 and is still razor sharp at f45.

    I'm not sure where you drag that myth from, both Schneider and Rodenstock manufacture their LF lenses to be used at f22/32 and with longer lenses f45/64.

    Ian
    and

    Quote Originally Posted by Ian Grant View Post
    Nothing you say falls into line with reality and the fact that LF lenses are designed to be used at f22/32 and have excellent resolution across the field.

    Some lens designs don't achieve edge/corner sharpness until f22m andthen how do you explain the outstanding performance of an f5.6 150mm Xenar at f32 & f45, it stops down to f64 ?

    Ian
    So please don't fabricate facts.

    These quotes are what you claim I've written:


    Quote: Originally Posted by Ian Grant
    Considering where you are starting from (and your attitude)...

    That's perhaps because we cannot all be as learned as you, right?


    Quote: Originally Posted by Ian Grant
    Even though I am under NO obligation to instruct you in anything - you will just have to learn for yourself, I will direct you to:

    This from one of the important text books:

    What is Light? By A.C.S. van Heel and C.H.F. Velzel,World University Library - Library of Congress Catalog Card Number: 67-24448

    Page 97, Section 4, Diffraction:
    We can now turn to another facet in the study of light: the diffraction effects, the existence of which has already been mentioned. (See section 2 on the rectilinear propagation of light, and section 18 on the distribution of light at the focal plane of a lens upon reduction of the size of the diaphragm). To explain such phenomena, the great physicist and optician, Augustin Fresnel (1788 - 1827) developed a theory of the propagation of light, with which we begin our discussion.

    Until now we have used as a model for the propagation of light, the theory of Huygens, which we define as follows.
    One can imagine a wave front to originate out of the previous one by supposing each point in the latter to be a secondary source of spherical waves. The envelope of these spherical waves forms the new wave front..."


    **Fascinating**. I will admit to having read this section a number of times, but I finally gained a fairly good "grasp" of what was going on.


    Nice quote.
    But it says absolutely nothing about this matter.
    So not well chosen.

    Quote: Originally Posted by Ian Grant
    Polarisation, section 5, was another matter. I passed the "tests" - but I'm still not completely sure...

    Who is?

    Quote: Originally Posted by Ian Grant
    Ah! Obviously an infallable way to test a lens, free from subjective judgement and preceptual bias.... NOT!

    Who said anything about an infallible test?

    But you do know (i assume, but tell me if i am wrong) that photography is a visual medium, and that what you see is what you get?
    Good!

    Quote: Originally Posted by Ian Grant
    As interesting as that my be ... I doubt that it has anything to do with diffraction. Is the article available on-line ? Or ...?

    Yes.
    It has everything to do with diffraction (you really need to get those books out again)
    And yes, it is available online.


    Quote: Originally Posted by Ian Grant
    The last refuge of one insecure in his argument: an "Ad Hominem" attack.

    That's why you started by pointing out your personal qualifications?

    I don't doubt your personal qualifications. So not even an ad hominem.
    But given that your argument is based on authority, it is not possible to dismiss your mistake as such without touching your proffered authority.


    Quote:
    Originally Posted by Ian Grant
    The same source? Zeiss? Now I am really interested!

    You know it is optics 1.0.1.
    So you really should know this, and not find this interesting, but old hat.


    Quote:
    Originally Posted by Ian Grant
    Nice table. Anything to do with diffraction?

    It is about nothing else but diffraction.

    Quote:
    Originally Posted by Ian Grant
    I understand some of the factors that influence lens design... What happened to "diffraction"?

    What are you asking?


    Quote:
    Originally Posted by Ian Grant
    Well, that really says it all. There is only ONE definition recognized as "Circle of Confusion" - an important criteria in lens design.

    Only one? You think so?
    I think 'the place where your head is (was?) spinning' qualifies as a perfectly good definition.

    Now just stop digging.

    Quote Originally Posted by Q.G. View Post
    Well, there we are!

    Based on your bragging, you should though.

    That's perhaps because we cannot all be as learned as you, right?


    Nice quote.
    But it says absolutely nothing about this matter.
    So not well chosen.

    Who is?


    Who said anything about an infallible test?

    But you do know (i assume, but tell me if i am wrong) that photography is a visual medium, and that what you see is what you get?
    Good!

    Yes.
    It has everything to do with diffraction (you really need to get those books out again)
    And yes, it is available online.


    That's why you started by pointing out your personal qualifications?


    I don't doubt your personal qualifications. So not even an ad hominem.
    But given that your argument is based on authority, it is not possible to dismiss your mistake as such without touching your proffered authority.

    You know it is optics 1.0.1.
    So you really should know this, and not find this interesting, but old hat.

    It is about nothing else but diffraction.

    What are you asking?


    Only one? You think so?
    I think 'the place where your head is (was?) spinning' qualifies as a perfectly good definition.

    Now just stop digging.
    At no point do you acknowledge that Zeiss, Rodenstock, Schneider and other manufacturers large format lenses are designed to give optimum performance at f22/f32, there's a vast difference between diffraction in a 50mm standard lens for a 35mm camera used at f22 and a LF lens at f22.

    Ian

  7. #27

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    One thing to remember: the "practical limit" of any lens system is not entirely and wholly dependent on "diffraction"... it would be, IF the remaining parameters were all perfect... and the chances of that happening are not great.
    Noone said that diffraction was the only limiting factor. Would be great if it was.

    But, despite you not knowing, it always is there, getting worse when you stop down.
    So the "f/22 and be there thing" comes at a cost. At f/22 it is the limiting factor.
    And it's there, without chance for a let off. There is nothing design can do about it.


    I will ask one favor: Direct me to web site where I can find Zeiss's formula for determining "diffraction limitation". Until I can check that out, I will not continue to discuss their assumptions.
    Heck, no!
    This is in all of your books and you should have learned this "many moons" ago..
    Whether Fraunhofer, Abbe, Fresnel, Young, wave optics or Fourier optics, Kirchhoff, Keller, Dawes, Rayleigh or Sparrow, and what or who have you: whenever diffraction is mentioned this is too.

    Assumptions?
    Optics 1.0.1!

    Why don't you apply for a job at Zeiss? Your job interview should be fun.

    It is interesting that you consider "Diffraction" as one of the simple. basic phenomena. I think it is one or two notches above "basic".
    Then it is perhaps interesting too that you put words in my mouth.
    I never said i consider diffraction (both in or not in "") "as one of the simple, basic phenomena".

    BTW... I've been considering the "tone" and syntax of your posts ... in some way, vaguely familiar. Would you happen to be posting from St. Louis, Missouri?

    Ad hominem, again. You do know ad hominem means, don't you?
    Apparently that too better than you do.

    You are still trying to find refuge in that extremely silly "ad hominem" defence?

    You made your expert knowledge the thing that gives weight to your mistaken view.
    Argue using authority as 'proof' and face will be lost when you are wrong. There's no way around that.

    It was your (!) choice to do so.
    Don't you forget. Take a risk, bear the consequences. Don't blame anyone but you.

    I hate to break the news, but, that time span is about 15 minutes.
    "hate to ..."?
    Your understanding of "many moons" (your words) is "about 15 minutes".
    I can see why you hate to reveal that too.

    About 15 minutes ago, you should have found that your books do not agree with your view.

    Sounds good to me --- WHERE??
    In those books you said you put down 15 minutes ago perhaps?


    Hilarious. Indicative of your sharp wit, I suppose.
    Who knows.
    Indicative of a rather dull wit (now is that ad hominem?) that you needed it to be repeated to get it.

  8. #28

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    Ian,

    Yes, the quote-thingy got mixed up badly.
    My apologies for that.

    Everything quoted should be attributed to Ed.

  9. #29

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    Quote Originally Posted by richard ide View Post
    Ed,

    I thought it could be HIM also.
    Then you too might want to stick your nose in some books, and learn a bit.

  10. #30
    richard ide's Avatar
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    "Then you too might want to stick your nose in some books, and learn a bit."
    That is a rather silly statement as you have no idea what I do or do not know. I know that I can produce a negative that resolves over 300 lppm with what I have at home. Diffraction be damned.
    I guess you have no idea who "HIM" is. ;>)
    Richard

    Why are there no speaker jacks on a stereo camera?

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