Image sensor format: Difference between revisions

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Revision as of 22:01, 4 March 2023

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== Sensor format and lens size ==

It might be expected that lenses appropriate for a range of sensor sizes could be produced by simply scaling the same designs in proportion to the crop factor.<ref>{{cite journal|last=Ozaktas|first=Haldun M|author2=Urey, Hakan|author3=Lohmann, Adolf W.|title=Scaling of diffractive and refractive lenses for optical computing and interconnections|journal=Applied Optics|year=1994|volume=33|issue=17|pages=3782–3789|doi=10.1364/AO.33.003782|pmid=20885771|bibcode=1994ApOpt..33.3782O|hdl=11693/13640|s2cid=1384331 |hdl-access=free}}</ref> Such an exercise would in theory produce a lens with the same F-number and angle of view, with a size proportional to the sensor crop factor. In practice, simple scaling of lens designs is not always achievable, due to factors such as the non-scalability of [[manufacturing tolerance]], structural integrity of glass lenses of different sizes and available manufacturing techniques and costs. Moreover, to maintain the same absolute amount of information in an image (which can be measured as the space bandwidth product<ref>{{cite book|last=Goodman|first=Joseph W|title=Introduction to Fourier optics, 3rd edition|year=2005|publisher=Roberts and Company|___location=Greenwood Village, Colorado|isbn=978-0-9747077-2-3|pages=26}}</ref>) the lens for a smaller sensor requires a greater resolving power. The development of the '[[Tessar]]' lens is discussed by Nasse,<ref>{{cite web|last=Nasse |first=H. H. |title=From the Series of Articles on Lens Names: Tessar |url=http://www.zeiss.com/C12578620052CA69/0/58D501E36518AFC9C12578D2004104E1/$file/cln_39_en_tessar.pdf |publisher=Carl Zeiss AG. |access-date=19 December 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120513162446/http://www.zeiss.com/C12578620052CA69/0/58D501E36518AFC9C12578D2004104E1/%24file/cln_39_en_tessar.pdf |archive-date=13 May 2012 }}</ref> and shows its transformation from an f/6.3 lens for [[plate camera]]s using the original three-group configuration through to an f/2.8 5.2&nbsp;mm four-element optic with eight extremely aspheric surfaces, economically manufacturable because of its small size. Its performance is 'better than the best 35&nbsp;mm lenses – but only for a very small image'.

In summary, as sensor size reduces, the accompanying lens designs will change, often quite radically, to take advantage of manufacturing techniques made available due to the reduced size. The functionality of such lenses can also take advantage of these, with extreme zoom ranges becoming possible. These lenses are often very large in relation to sensor size, but with a small sensor can be fitted into a compact package.