I. Some words about figure of optical system
The question on figure объективов always is интригующе bewitching. Among technical questions of a photo it is impossible to find other similar aspect, around of which very many legends, errors, false interpretation and превратных of representations would be developed(unwrap). At the same time, any man having though any experience of photoshooting, begins to not deny that fact, that different объективы differently display a reality. The reasons this phenomenon has some. And main is, that объектив basically can not display a point of object as a point of the image. Объектив always carries out function of the converter any of points of a reality in a dim stain of this or that form and this or that size. And it is fair in the attitude(relation) as points which are taking place in focus, and points in area нерезкости.
The situation in addition is complicated хроматическими by distortions: the mentioned above dim stain besides other depend and on length of a wave of light. Therefore dim stain being an image of an initial point, can get also additional non-uniform colour distortions.
Ещ ё one essential factor — correct transfer of contrast, that is difference in light exposure of various points of the image.
Also is important to understand, that all mentioned above circumstances can differently be shown for:
1. Different sites of the staff (centre and periphery);2. For different areas нерезкости (нерезкость before a point exact фокусировки and behind her).
The set also forms all these неидеальностей figure of optical system.
The ideal optics has no any specific figure. She will transform points in focus to points of the image, and point outside of focus — in the in regular intervals painted circles of the same colour. Besides it, the ideal optics without distortions passes contrasts. But, fortunately or unfortunately, the ideal optics does not exist.
One important conclusion follows from all вышесказанного: it is objectively impossible to say, that any figure is perfect, and any another — is ugly. One can like one неидеальности, another — others. The judgements about aesthetic value of this or that figure (set неидеальностей) are always subjective. It is not good and not poorly. It is simple the fact of the validity, environmental us.
By virtue of that of a stain, in which the initial points are washed away, are rather small, figure of optical system is the thin characteristic and not always obviously rushes in eyes. He is swept most up in the field of strong нерезкости, as in these zones of a point are washed away in a rather large stain.
But, certainly, any figure of optical system is not capable to transform an apple into a pineapple, and Бабу Ягу in Кощея Immortal. The photo вс ё was and остаётся a quite good means for registration of the objective validity.; -)
II. Some words about a brick wall
Among the trivial tests of photographic optics the shooting of a brick wall borrows(occupies) the special place.; -) As far as such test is expedient from the point of view of an estimation of figure?
To estimate figure by result of such test — business ungrateful(thankless). But I, certainly, am far from announcing shooting a brick wall by vain expenditure of time. Such test, for example, not bad reveals дисторсию of optics and variation of sharpness on the area of the staff. Sometimes, on such pictures it is possible to notice traces хроматических аберраций. But for complete representation about figure it is desirable to photograph plots with extended areas нерезкости.
III. Planar ® and Tessar ®
The optical circuit Planar ® was developed in 1896 by the doctor Рудольфом (Dr. Paul Rudolph), working in the company Carl Zeiss. Such circuit allows to create светосильные объективы of high quality. Besides other she gives many opportunities for elimination various аберраций.
Сво ё the name Planar ® has received for the ability to form the flat image fine suitable to recording environment(Wednesday) as a photoplate and a film.
Planar ® and until now остаётся by one of the most widespread optical circuits (in view of various updatings).
Fig. 1. Planar ®
In 1902 the same doctor Рудольф has received the patent on ещ ё one successful optical circuit: Tessar ®. Объектив, executed on such circuit, consists of four elements. From here there is also his(its) name: тэссера — till four.
The basic advantages of this circuit: compactness and high резкостные of the characteristic. Last circumstance promoted occurrence of an epithet « орлиный of an eye », widely used for the characteristic it объектива. The compactness too has appeared is claimed: for example, many несветосильные телеобъективы were designed under this circuit.
Fig. 2. Tessar ® If to abstract from subtleties, in the first most rough approach(approximation) of distinction between тессаром and планаром it is possible to formulate as follows. If the compactness is the paramount factor, on the first place leaves тессар. The truth, large светосилы from him(it) to expect difficultly. If for the sake of светосилы we are ready to bring compactness in a victim, superiority(championship) — for планаром.
At more careful approach it is possible to discuss more thin things, for example, such as figure. To such analysis we now also shall proceed(pass) (within the framework of declared « of the unscientific approach »).
IV. The photoimages
So, I hope, with you have remained ещ ё of force after the so vast introduction?; -) If so, is perfect. It is high time to begin viewing the photoimages.
Unfortunately, I have no original pair объективов Tessar ® and Planar ® from Carl Zeiss. Therefore let, first of all, to present you the participants of the test:
1. In quality планара acts объектив Pentax SMC FA 50/1.4. In the essence it квази-планар with the rather high characteristics.
2. To a role тессара is invited ИНДУСТАР 50-2 50/3.5, being by almost copy legendary объектива from Carl Zeiss.
The shooting was conducted on a film KODAK GOLD 100. All photos were made from a support at диафрагме f/3.5. The received films were scanned on the scanner Minolta Dimage Scan Elite at the sanction 2820 dpi. The given scanner not too successfully consults(copes) with display of thin gradation in dark zones. Therefore on артефакты in the field of deep shadows to pay attention does not follow.
Any post – processing to the images was applied not. All below-mentioned photos are given in such kind, in what they were received from the film scanner (except for the function, used in some cases, Resize).
Fig. 3. Euphorbia Leuconeura. Pentax SMC FA 50. Resize 1:5
In a fig. 3 the photo of my home pupil Euphorbia Leuconeura, or is given, speaking simply, молочая беложилкового. For reception of the image was used объектив Pentax SMC FA 50 mm. In a fig. 4 same objects is photographed объективом ИНДУСТАР 50-2 50 mm.
Fig. 4. Euphorbia Leuconeura. ИНДУСТАР 50-2 50. Resize 1:5
In a fig. 5 and 6 the large fragments of the same images in scale 1:1 (are given that is at absence of operation Resize).
Fig. 5. Euphorbia Leuconeura. Pentax SMC FA 50Fig. 6. Euphorbia Leuconeura. ИНДУСТАР 50-2 50In a fig. 7 and 8 two unpretentious still-lifes are given which also can help to develop own representation about тессарах and планарах (within the framework of the declared accuracy).
Fig. 7. A simple still-life. Pentax SMC FA 50. Resize 1:5
Fig. 8. A simple still-life. ИНДУСТАР 50-2 50. Resize 1:5
Conclusions
Traditionally in section « small unscientific researches » I do not do(make) any conclusions. Think, look and decide(solve).
Yes the good luck accompanies you!