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2

The block diagram for your lens appears to be a variation of the Zeiss Tessar design created by Dr. Ralph Rudolph. Roger Cicala, in one of his excellent blog entries at lensrentals.com says: Literally dozens of today’s excellent lenses are simply modifications of the Tessar: Leitz Elmars, Zeiss Sonnars, Kodak Ektars, Schneider Xenars, Voigltander ...


1

The only way to get your lens to focus to infinity, is to move the lens further from the film/sensor plane, to where it was designed to be. I assume it can be made to focus if i change distance between lens elements? What elements i need to space out to restore focus ability, can correct spacing be figured out mathematically? What is the basis of your ...


3

Lens designs, even in the olden days, are highly optimized for sharpness and several kinds of optical aberrations. Even small changes, including distance between elements, are bound to degrade image quality. So, usually, you don't want to tamper with the existing design. Instead you add lenses, either in front (fish eye lens) or between lens and camera (...


5

This is exactly what a telecompressor/focal reducer/"speed booster" is for. It can be bought as a ready made unit with a choice of mirrorless camera mounts on one side and a choice of SLR/DSLR mounts on the other. Since these devices are more expensive than normal adapters, it can be worth buying strategically in case you have multiple legacy ...


2

All this confusion comes from the old "bad habit" to express field-of-view values not by themselves, but by the focal length that gives this field of view on a "standard" 24*36 film area. Now that sensors come in all sizes (FF, cropped, M43, whatever), that habit fails miserably. The focal length given with any lens means exactly that, ...


0

The Sony 18-55mm OSS f/3.5-5.6 NEX E-mount has focal lengths of 18-55mm. On a APSC 1.5x crop sensor the field of view is approximately the same as 28-85 mm on full frame 35mm.


3

Typically, if a lens is removable it is normally labeled with its true/actual (rounded) focal length, without any consideration for what it might be attached to (I don't know of any exceptions). That is true for the 18-55 kit lens you have as well; it is not adjusted for crop factor. Conversely, if the lens is not removable the focal length is generally ...


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