LensFever

Table Of Contents ✓ Introduction Leica's first Elmar 9cm (90mm) f/4.0 was introduced in 1930. The lens construction was very similar to that of the Zeiss Tessar, with the main difference being that the Elmar had the aperture positioned in front of the second lens element. After several cosmetic changes, the optics of the popular Elmar 90mm lens remained unchanged until the early 1960s. In 1962, a new version of the Elmar 90/4.0 was released, designed by Walter Mandler in Canada using newly invented rare-earth glass, which elevated the performance of this classic lens to another level. Lens Versions There is only one version. It comes with either a Leica M mount (11830) or a Leica screw mount (11830). Leica Elmar 90mm f/4.0 3-element M mount Lens Specifications Lens mount: Leica M Focal length: 90mm Aperture adjustment: f/4.0–f/22 (with half-stop clicks) Number of aperture blades: 10 Minimum focus distance: 1 meter Filter size: E39 Hood: IUFOO or 12575 Weight: ~220g Leitz Sales...

Sharpness is the most important factor of modern lenses as the pixel density of the sensor in digital cameras becoming higher and higher. With digital correction and good sharpness, the image captured by the camera become more perfect than ever. Is getting the perfect image our only requirement? Table Of Contents ✓ Introduction More than thirty years after Taylor Taylor invented the Cooke Triplet lens in England, Hugo Meyer & Co. in Görlitz Germany also began to manufacture and sell its Cooke Triplet lens series “Trioplan”. Here is the 1930 Lens Catalog from Meyer showing the details of the Trioplan lens series. Hugo Meyer Catalog (1930) p.8 In the beginning, the Trioplan lenses are made for 16mm and 35mm cine cameras, with focal length ranging from 15mm to 8¼”. The catalog mentioned the lens correction has been carried out for astigmatism, color and spherical aberration. By 1938, the aperture of the Trioplan series was standardized to F2.8, except for the Trioplan F2.5 made fo...

Table Of Contents ✓ Preface In 1983, British lens designer Harold Dennis Taylor (1862–1943) (hereafter “Taylor”) designed a 3-element lens consisting of two convex lenses and a concave lens (Cooke Triplet)[1], opening a new page in modern design of photographic lenses. Cooke Triplet Patent US568052 (includes variation) Features of the Cooke Triplet lens The triplet designed by Taylor are arranged in order of postive – negative – postitive. The focal power of the negative lens must be more or less equals to the focal power of the two postive lenses. The triplet has enough degrees of freedom for the lens designer to correct monochromatic aberrations(spherical, coma, astigmatism, field curvature) and chromatic aberrations(axial and lateral). Alternatively, apart from the simplest three-element design, the lens designer can replace any of the element with a glue doublet or splitting any of the element into multiple elements. Brit. Pat. 22,607 When Taylor published his des...

  The second-generation Leica M to Nikon Z AF lens adapter TZM-02 from Techart will be officially released soon. I am fortunate enough to borrow this engineering sample for testing, let’s see how the autofocus performs. Table Of Contents ✓ Specification: Weight: ~150g Diameter: ～68mm *Compatible with all the latest Nikon Full Frame & APS-C camera models (Z9, Z7II, Z7, Z6II, Z6,Z5, Z50, Zfc, Z30, etc) *not applicable to LTM/M mount lenses with a infinity lock button near the lens mount In-Body Image Stabilization (IBIS) Settings By adjusting the aperture value, we can change the focal length value transmitted to the camera to obtain better image stabilization. The relationship between the aperture value and the focal length value transmitted is shown on the following table: Aperture Value(F) 1.0 1.1 1.2 1.4 1.6 1.8 2.0 2.0 Lens Focal Length(mm) 135 90 85 75 55 50 40 30 Aperture Value(F) 2.5 2.8 3.2 3.5 4.0 4.5 5.0 5.6 Lens Focal Length(mm) 28 25 24 21 20 18 16 ...