Petzval Portrait objective. Jose Sasian College of Optical Sciences University of Arizona

Transcription

1 Petzval Portrait objective Jose Sasian College of Optical Sciences University of Arizona

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3 Announcement of the invention of the Daguerreotype by Arago at the meeting of the French Academy of Sciences and Arts Louis Jacques Mandé Daguerre Dominique François Arago August 19 th Prof. Andreas Ettingshausen,

4 Daguerre s camera and the achromatic landscape lens ½ hour to take a picture: F/16 It is known that the objectives used by Daguerre were achromatic plane convex lenses. Their plane side was turned toward the object, the convex side towards the image. They have an opening of 3 zoll, but this opening is reduced to 1 zoll by a diaphragm placed before at a distance of 3 zoll from the lenses. J. Petzval

5 Prof. Ettingshausen asked Joseph Petzval to explore the shape of the lenses Vienna University, 19 th century Prof. Andreas Ettingshausen Young Joseph Petzval It was in the year 1839, when the wonderful invention by Daguerre was made public, and incited the general interest to such a high degree. At that time I was first made aware of the strange shape of the objectives used in Daguerre s camera obscura by my dear friend and colleague Professor von Ettingshausen. I was asked to explore the reason for this shape. J. Petzval

6 Petzval Portrait Lens Greater illumination, one of the desired improvements, can only be obtained in two ways by enlarging the aperture and by diminishing the focal length, both which, however, will result from employing two converging lenses, instead of one. These lenses must of course be achromats; and by theory, in order that a good image may be produced, they must be separated from each other by a distance no less than one third of the focal length of the lens near the object. Petzval F/ seconds to take a picture

7 Joseph Eder s remark The commercial success of the Petzval portrait lens was immediate and extraordinary, and that it spread with unexpected rapidity.

8 Petzval lens imaging Beatrice Cenci with Kate Keown as the model, Wikipedia Photograph by Julia Margaret Cameron 1868 Wikipedia Bokeh is the aesthetic quality of the lack of sharp focusing in the images produced by a lens, especially In the outer parts of the field.

9 The question How did Petzval design his famous portrait lens Did he use real ray tracing? Did he use third order aberration coefficients? Did he have help? Petzval did not leave a record about how he did the designs The announcement of the Daguerrotype was on August 1939 Petzval had his designed done by May 1840

10 Prof. Ettingshausen suggests to P. W. Voigtländer to talk to Petzval P. W. F. Voigtländer, lens manufacturer in Vienna Prof. Andreas Ettingshausen,

11 P. W. Voigtländer meets Petzval and provides glass indices of refraction and dispersion values P. W. F. Voigtländer Young Joseph Petzval

12 Petzval produces by May of 1840 two objective designs (actually four) For views (landscapes) For portraits

13 First camera with the Petzval Portrait objective Voigtländer manufactured the objectives The portrait objective working at F/3.67 allowed taking photographs in seconds (~40) making portrait photography a practical reality. Anton Martin took photographs to evaluate the lens Anton Martin

14 Petzval s Original Prescription NATIONAL BANK OF SLOVAKIA The prescription has two sets of data for landscapes and for portraits. Written in ink and in pencil.

15 P. W. F. Voigtländer notarized copy NATIONAL BANK OF SLOVAKIA Akademiker Prof. Dr. Petzval, beleuchtet von Voigtländer, Drud und Berlag von Friedrich Biemeg und Gobn, Braunschweig 1859.

16 The two sets of prescriptions Given in linien, zoll, and zoll and linien old German units In ink and in pencil No indices of refraction, dispersion values, or thicknesses

17 Reconstructed specifications L. Ermenyi, Dr. Josef Petzvals Leben und Verdienste, Halle a. S., Verlag von Wilhelm Knapp, p. 25, 1903

18 Commercial camera: Voigtländer Petzval conical brass camera Plate D=92 mm ; f=149 mm Plate D=94 mm ; f=150 mm Measurements: 37 cm X 31 cm X 15 cm NATIONAL BANK OF SLOVAKIA

19 An early Petzval objective from 1846 #2761 (1846) Aperture stop was the rim of the first doublet

20 First order concept layout F1=16 Zoll F2=24 Zoll F=11 Zoll D=5.1 Zoll Aperture 3 zoll F/3.67 F1=8 Zoll F2=12 Zoll F=5 ½ Zoll D=2.55 Zoll Aperture 1 ½ zoll F/3.67 Petzval s report of 1857

21 Thin lens solution Given by J. Eder N Crown = N Flint = The secret of the thin achromatic doublet is that the ratio of the optical powers of the individual lenses must be equal to the negative of the ratio of the glasses v numbers.

22 Petzval statement of 1857 Greater illumination, one of the desired improvements, can only be obtained in two ways by enlarging the aperture and by diminishing the focal length, both which, however, will result from employing two converging lenses, instead of one. These lenses must of course be achromats; and by theory, in order that a good image may be produced, they must be separated from each other by a distance no less than one third of the focal length of the lens near the object. Petzval Supports: Use of a thin lens model Use of third order theory

23 Third order thin lens solution Two achromatic doublets individually corrected for spherical aberration Front doublet contributing positive coma and positive astigmatism Rear doublet contributing negative coma and negative astigmatism Field was artificially flattened W 222 / W 220P = As a thin lens F1=8 Zoll F2=12 Zoll D=F1 / 3 Zoll W 222 / W 220P = A B k u 2 B W222 W 222 A 1 k ub 3 W131

24 Thick lens solution W 131 = 0 W 131 = 0 Separation is D = 2 Zoll (Rather than D = 2.67 Zoll) W 222 / W 220P = -0.44

25 Lens Adjustment Voigtländer wrote: Prof. Petzval and I finding that, by this ring (i.e. a spacer) we could compensate for some errors, which must have taken place in the calculation.

26 Petzval did not use real ray tracing. Some arguments are: His two criticisms of the calculating opticians in his 1843 report and his repetitive highlighting of aberration theory. His remark in his 1843 report that he had calculated 15 lens combinations with images of the fifth order (meaning a third order correction or several third order aberrations corrected). That the distance between doublets in the portrait objective is at odds with Petzval s remark of at least 1/3 the focal length of the first doublet. Further, this statement reflects a third order calculation. That as late as 1857 Petzval expressly remarked that his new lens was corrected to an image of the fifth order. The correction of chromatic change of focus using a thin lens model.

27 K. &. K Bombardier Corps Archduke Karl Ludwig of Austria 30 July May This first result was the motive, because of the hopes to which it gave rise, that I was given authority by the highest order of his majesty, his k. & k. Highness General Artillery Director Arch Duke Ludwig to have the members of the K. &. K Bombardier Corps namely the two Oberfeuerwerkers Löschner and Hain at my disposal. This Bombardier corps was well known to have mathematical knowledge

28 A common misunderstanding Petzval in his 1843 report explains that the first practical result of his dioptric theory was the portrait objective of He writes that this first result was the motive for which Arch Duke Ludwig provided to him the help of the K&K Bombardier Corps. Later in 1903 L. Ermenyi wrote that before the end of 1840 the portrait lens became vividly discussed in Vienna and that the imperial court showed such interest that Arch Duke Ludwig provided to Petzval help with the Bombardier Corps. Accordingly, and contrary to common belief, Petzval did not have calculation help from the K&K Bombardier Corps to design his famous portrait lens. The Bombardier Corps helped Petzval to calculate the 15 tables (lens prescriptions) for Telescopes, cameras obscuras, and microscopes he wrote about at the close of his report of 1843.

29 Petzval s drawings

30 L. Ermenyi [Dr. Josef Petzvals Leben und Verdienste], Halle a. S., Verlag von Wilhelm Knapp, "I have conquered the light, I have it firmly in my hands, because there is too much darkness in the world."

31 Petzval lens specs F/# 3.6 F=150 mm D=42 mm FOV=+/ 16.5 degrees All glass lenses

32 Conclusion Petzval, Voigtländer and Martin left enough information to understand how Petzval designed his famous portrait lens. In fact, we show that Petzval followed what it is taught in introductory lens design courses. This is first order layout, correction of chromatic aberration using doublets, correction of spherical aberration and coma, and artificially flattening the field of view.

33 On axis irradiance 2 ds ' da ' 4 d ' L0 ' cos 2 ' s ' ds ' di L s ' 4 ' 0 ' cos ' 2 a 4 U' L0 ' r L0 ' s' ' 0 r s' n 0 I ' 2 r dr 2 L ' sin cos d n' sin U' 2 2 sin 2 L0 ' 2 I0 ' NA 2 n' U ' 1 4 F /# 2 Radiance theorem L ' L n' n

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