"But at low ISO nothing can beat this camera." - CEO SIGMA Pt. 2

Started 5 months ago | Discussions thread
photoreddi
Senior MemberPosts: 3,724
Like?
Looking at the DP2 Quattro's senson in another light.
In reply to fishywisht, 5 months ago

fishywisht wrote:

crashpc wrote:

Guys, this is crazy. Don´t understand to this discussion.

Extreme understatement.

.

These people kid themselves that others are reading their spats and forming judgments of who wins. The rest of us only form negative judgments on these people filling up the screen before we put them on Ignore.

They don't even seem to be arguing about the newest sensor. Because they actually have no experience and have not even read a review of it.

Without applying advanced mathematics I can't help suspecting the new quattro sensor is a bit of a con. Sigma seem to be addressing arguments over its resolution by providing high resolution in only one colour, blue. Seemingly an odd thing to do, especially if Bayer design reflects that we are more sensitive to green. Are Sigma more trying to emulate black & white film? We were advised to put uv filters on b&w because it was more sensitive to the blue end.

A possibility. The highest resolution can be obtained from light having the shortest wavelength, which would be blue, not red or green. Apochromat lens designs greatly reduce chromatic aberration but they're not perfect. So perhaps to get the best result (focus accuracy) the complex apochromat formula was simplified to primarily correct blue light to get the highest possible resolution, and the much lower red and green resolution wouldn't matter very much since people aren't very sensitive to color resolution, only the luminance resolution that's determined by the blue light.

Chromatic aberration is the phenomenon of different colors focusing at different distances from a lens. In photography, chromatic aberration produces soft overall images, and color fringing at high-contrast edges, like an edge between black and white. Astronomers face similar problems, particularly with telescopes that use lenses rather than mirrors. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus in the same plane. Apochromatic lenses are designed to bring three wavelengths (typically red, green, and blue) into focus in the same plane.[1] The residual color error (secondary spectrum) can be up to an order of magnitude less than for an achromatic lens of equivalent aperture and focal length. Apochromats are also corrected for spherical aberration at two wavelengths, rather than one as in an achromat.

...

Apochromatic designs require optical glasses with special dispersive properties to achieve three color crossings. This is usually achieved using costly fluoro-crown glasses, abnormal flint glasses, and even optically transparent liquids with highly unusual dispersive properties in the thin spaces between glass elements. The temperature dependence of glass and liquid index of refraction and dispersion must be accounted for during apochromat design to assure good optical performance over reasonable temperature ranges with only slight re-focusing. In some cases, apochromatic designs without anomalous dispersion glasses are possible.

http://en.wikipedia.org/wiki/Apochromat

.

I think most people would welcome something new that adds something meaningful to the market, but I'm not sure a 5MP sensor with a perceptual fudge is it. I am concerned they are wasting r+d on something that will just be another curiosity at a fraction of its price on ebay in a few years time.

It's only the red and green colors that have 5mp resolution. The DP2 Quattro's blue resolution is supposedly 20mp. I suspect that the perceived sharpness of photos and prints will generally be excellent, but the results gotten from color resolution test charts and real world subjects that have lots of red and green but little blue (such as grass and leaves) need to be tested and might be its Achilles Heel.

Reply   Reply with quote   Complain
Post (hide subjects)Posted by
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
(unknown member)
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow