08-09-2020, 12:53 PM
(This post was last modified: 08-09-2020, 01:18 PM by Brightcolours.)
Especially a few years ago Tamron made some Sony lenses. Sony has or had a stake in Tamron. Tamron has made the AF film era Nikkor 70-300mm lenses too.
About the Olympus 100-400mm: It is clearly similar to the Sigma. The lens construction is similar, but not the same. Some lens elements/groups have a slightly different shape, and the back elements/groups are smaller (so that means that the lens is not an FF lens in disguise).
https://www.isolapse.com/wp-content/uplo...00x445.jpg
With tele lenses, the front elements are usually not smaller for APS-C and MFT compared to FF, when the max. aperture is the same, as the max. aperture is about the same size as the aperture itself. The aperture size is the opening as seen through the front of the lens. So, it makes sense that the front elements are the same size, and it is the back elements that have been shrunk because they only have to cover MFT sensor size.
About the Olympus 100-400mm: It is clearly similar to the Sigma. The lens construction is similar, but not the same. Some lens elements/groups have a slightly different shape, and the back elements/groups are smaller (so that means that the lens is not an FF lens in disguise).
https://www.isolapse.com/wp-content/uplo...00x445.jpg
With tele lenses, the front elements are usually not smaller for APS-C and MFT compared to FF, when the max. aperture is the same, as the max. aperture is about the same size as the aperture itself. The aperture size is the opening as seen through the front of the lens. So, it makes sense that the front elements are the same size, and it is the back elements that have been shrunk because they only have to cover MFT sensor size.