On the fp Sensor & vintage lenses.

Started Jul 12, 2019 | Discussions thread
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saltydogstudios Senior Member • Posts: 2,201
On the fp Sensor & vintage lenses.

I'd posited that Sigma would introduce a small FF Foveon camera to position themselves apart from the large Panasonic and Leica cameras. Specifically to go after the Leica M-Mount market.

I'd wondered, though, how - knowing the Foveon's reliance on luminosity for the color algorithm, it would deal with wide angle lenses. Specifically with wide angle lenses that had a propensity to vignette.

In the fp teaser video I noticed they had a Leica 50mm Summicron Collapsible lens. This is a very specific signal to Leica M-Mount aficionados.

The 50mm Summicron Collapsible is just that - collapsible. It would collapse into the camera body for easy transport.

Modern cameras can mount it - but you can't collapse the lens into the camera without damaging the shutter mechanism or the light meter or something.

By putting a collapsible lens on this camera, Sigma is telling the world "Because this camera has no shutter, you can put your collapsible lenses on this camera without fear of damage."

Them stating that it's effectively silent was another not-so-subtle hint to Leica shooters who are obsessed with the sound of their Leica shutters.

This leads to an interesting line of thought.

The other type of Leica lens that cannot easily be mounted on modern cameras are wide angle lenses. Certain Leica wide angle lenses have rear elements that protrude into the body - so you have the same problem.

This also leads to a very steep angle of incidence - light hits the "film" at a very steep angle (as far from telecentric as you can get).

Digital sensors, with their thick filter stacks, don't deal with these lenses well because the filter stack "smears" the details as they hit the sensor - light from the red pixel may smear into the green pixel, the IR filter can smear details, the pixel "well" itself may lose light that hits the side of the well and never reaches the bottom.

(digital sensors are complex things with 3 dimensionality to them that many of like to pretend doesn't exist.)

Leica, in their M-Mount cameras have "solved" this problem with a very thin sensor - from the front of the filter stack to the thing that "counts photons" (as I like to joke) - the sensor is very thin. They say that they don't even need microlenses (another solution to this issue).

Sigma, being part of the L-Mount alliance must be very aware that people will want to put classic Leica lenses on their cameras. One wonders if they've engineered this sensor to play well with vintage lenses.

Specifically this is interesting because Cine lenses are rather telecentric (I believe). They're certainly large enough to be, so if there are compromises introduced by making a sensor that handles vintage wide angle rangefinder lenses that would make it a less good cine sensor - they probably wouldn't opt for that.

I think Leica's solution (thin filter sensor + stack) does a reasonable job at what it sets out to do & I don't see why it would suffer from a more telecentric lens.

Also on the name - Fortissimo Pianissimo.

The Harpsichord was a very loud instrument - because mechanical levers "plucked" the strings at the same intensity every time, you couldn't vary the volume.

Then someone came up with a system of hammers that could strike the strings at different velocities, depending on how hard one played. This invention was called the Pianissimo Forte - Soft and Loud because you could vary the volume. This was later shortened to Piano, which is how we know the instrument today.

A young Mozart popularized the piano - traveling Europe playing Bach to the aristocracy on this newly invented instrument.

I hereby dub this the "Mozart" sensor and I hope Sigma reads this and adopts that name too because - why not.

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