Признаю, что коэффициент пропускания имеет место.
Признаю и то, что мои объективы кроме одного либо имеют пропускание 99%, либо на лимбе эффективная диафрагма "Т".
от:nebrit
Я сам читал в "Советском Фото" лохматых годов статейку, где чёрным по белому было написано, что Гелиосы не уступают Никкорам по качеству картинки. Вы верите в это? А автор верил.
Неужели не надоело цитаты цитировать?
Всем интересно одно: достоверное описание методики измерений, производимых на фабриках, воспроизводящих объективы. Хотя б киношные. Или текст стандарта, описывающего таковую (таковые). Всё остальное личное дело автора книжки. В одной написано одно, в другой другое и даже противоположное по смыслу. Какой книжке будем верить?Подробнее
от:Superka
Подсказка - если два объектива на одной и той же камере использовались, то описанную разницу в цветах нельзя было не заметить еще в видоискателе. А если этой разницы не было, значит это 100% твой/минилабовский косяк.Подробнее
от:ISO 517:2008
ISO 517:2008 Photography — Apertures and related properties pertaining to photographic lenses — Designations and measurements
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 517 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 1, Fundamental standards.
This third edition cancels and replaces the second edition (ISO 517:1996) which has undergone minor technical revision.
1 Scope
This International Standard pertains to apertures and related properties of photographic lenses affecting the illuminance at the centre of the image.
This International Standard specifies aperture markings for all types of lenses used in still cameras, and gives tolerances for the stop numbers. It also defines aperture stop, entrance pupil, focal length, relative aperture and stop numbers, and gives methods for their measurement or determination.
This International Standard applies only to lenses focused on objects at infinity; that is, at least 50 times the focal length of the lens.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
aperture stop
physical stop that limits the cross-section of the light beam that can pass through the lens to reach the centre of the on-axis image
2.2
entrance pupil
image of the aperture stop as viewed from a point in the object space on its optical axis (the image of the aperture stop formed by the front elements of the lens)
2.3
exit pupil
image of the aperture stop as viewed from a point in the image plane of the lens and on its optical axis (the image of the aperture stop formed by the rear elements of the lens)
2.4
focal length of the photographic lens
f
limiting value of the image size h′ of a sharp imaged far-distant object h divided by its angular extension ω in the object space i.e.
mml_m1
SEE: Figure 1
2.5
relative aperture of a photographic lens
twice the numerical aperture where the numerical aperture is the sine of the semi-angle subtended by the exit pupil at the focal plane
Note 1 to entry: For photographic applications, the relative aperture is equivalent (within a 1/3 stop) to the ratio of the diameter of the entrance pupil to the focal length.
2.6
f-number
stop number
the reciprocal value of the relative aperture (2.5)
2.7
true f-number
unrounded standard f-numberПодробнее
от: tim78rus
http://filmdev.org/recipe/search?developer_id=1009&search=hp5
с примерами