How Olympus Tricked Me, and why I let it go.

Started 3 months ago | Discussions thread
bobn2 Forum Pro • Posts: 67,157
Re: How Olympus Tricked Me, and why I let it go.

Danielvr wrote:

Please define "telecentric" to us dumb folk

It means the rays of light leave the lens running nearly parallel to eachother, hitting the sensor perpendicularly.

It's can't mean that, because parallel rays could never form an image.

That way, light will have no problem reaching the bottom of each photon-well, even in the corners of the sensor.

Yes, it does, but no Four Thirds or micro Four Thirds lens has ever been remotely telecentric. To be 'telecentric' the exit pupil is placed at infinity, in front of the plane of focus. I'm afraid that it's another case of Olympus marketing spinning an existing technical term to create a misleading idea about their technology. In practice, the distance of the exit pupil is lengthened (maybe to 100mm or so) for 'designed for digital lenses' and the Four Thirds lenses are not exceptional in that respect. The MFT lenses often abandon this design goal altogether, since offset microlenses are available, as you note below.

Back when the Four Thirds standard was developed, this was important because it resulted in a uniformly lit sensor. Legacy systems like those by Canon and Nikon, with their designed-for-film lenses, suffered from vignetting, in particular with wide angle lenses.

Yes, but they replaced them with designed for digital quite quickly. This had the advantage that the legacy lenses were still usable, whilst designed for digital lenses provided optimal performance on digital cameras.

Telecentricity became more or less irrelevant thanks to improved micro lenses (a layer of miniscule lenses on the sensor) that funnel and direct the light into the photon wells.

The innovation was offset microlenses, which built in an allowance for the exit pupil position in the microlens placement.

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