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Author Topic: Sigma DP Quattro  (Read 140300 times)

BernardLanguillier

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Re: Sigma DP Quattro
« Reply #60 on: February 11, 2014, 05:53:10 pm »

It'd have to be pretty eathshattering IQ-wise if that is the case.

Even if it is only a slight improvement at base ISO it will remain the camera delivering the second best absolute image quality short of a D800/a7r or digital backs. You can put 1 M$ on a lens for your 5DIII and will still not get that level of image quality...

So what we have is an incredibly under priced DPx Merrill. It seems only natural for Sigma to charge an amount more un line with the value delivered.

Cheers,
Bernard

MrSmith27

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Re: Sigma DP Quattro
« Reply #61 on: February 11, 2014, 06:12:56 pm »

Even if it is only a slight improvement at base ISO it will remain the camera delivering the second best absolute image quality short of a D800/a7r or digital backs. You can put 1 M$ on a lens for your 5DIII and will still not get that level of image quality...

So what we have is an incredibly under priced DPx Merrill. It seems only natural for Sigma to charge an amount more un line with the value delivered.

Cheers,
Bernard


So the worst thing that can happen is DPXM selling at $400. That's fine with me. Funny though how you get middle format + digital back quality for the price of a bad dslr....
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robdickinson

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Re: Sigma DP Quattro
« Reply #62 on: February 11, 2014, 06:33:35 pm »

Even if it is only a slight improvement at base ISO it will remain the camera delivering the second best absolute image quality short of a D800/a7r or digital backs. You can put 1 M$ on a lens for your 5DIII and will still not get that level of image quality...

Though with a 5d3 I could track moving subjects, shoot in near dark, shoot at 6fps etc etc. The difference in IQ wont be noticeable to most or in anything but very large prints.
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The Ute

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Re: Sigma DP Quattro
« Reply #63 on: February 11, 2014, 06:47:13 pm »

It should be interesting to see what they do to the SD1.

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MrSmith27

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Re: Sigma DP Quattro
« Reply #64 on: February 11, 2014, 06:50:41 pm »

Though with a 5d3 I could track moving subjects, shoot in near dark, shoot at 6fps etc etc. The difference in IQ wont be noticeable to most or in anything but very large prints.

so be happy with your bad prints
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LKaven

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Re: Sigma DP Quattro
« Reply #65 on: February 11, 2014, 07:18:33 pm »

The difference in IQ wont be noticeable to most or in anything but very large prints.

I don't agree!  Looking at the images in the DPxM enthusiasts threads, it's obvious this sensor really delivers on fine detail in a way that almost nothing else does.  The extra detail also enhances the shadow perception.  It's got a real look.  If the new sensor is better than /that/, I want one.

The Ute

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Re: Sigma DP Quattro
« Reply #66 on: February 11, 2014, 07:23:47 pm »

Before we anoint the Quattro maybe we should see what it can do first.

;)
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BernardLanguillier

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Re: Sigma DP Quattro
« Reply #67 on: February 11, 2014, 07:30:09 pm »

So the worst thing that can happen is DPXM selling at $400. That's fine with me. Funny though how you get middle format + digital back quality for the price of a bad dslr....

It can already be had new in Tokyo for 480 US$...

The cameras have huge shortcomings and are nowhere close to competing with the universality of a 5DIII, but at base ISO the image quality is simply out of this world.

Let's not forget that the initial price of the SD1 was 7,000 US$ and that the price was probably more than justified in terms of low ISO image quality.

Cheers,
Bernard

Quentin

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Re: Sigma DP Quattro
« Reply #68 on: February 11, 2014, 07:52:41 pm »

"Resolution is 30 percent higher" according to the "technology" tab on the Sigma-global website, so less really is more if this claim can be made good in practice.
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Quentin Bargate, ARPS, Author, Arbitrato

The Ute

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Re: Sigma DP Quattro
« Reply #69 on: February 11, 2014, 08:01:17 pm »

Resolution is only one component of an image.

Albeit a very important one.

The whole is greater than the sum of it's parts though.

Let's just see what the "images" look like.

Hopefully, they have not lost that "look" that made the Merrill's so unique.

I'm from Missouri on this one. "Show me".

;)



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Quentin

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Re: Sigma DP Quattro
« Reply #70 on: February 11, 2014, 08:10:25 pm »

What makes these cameras particularly significant is they use an exciting new sensor not manufactured or designed by Sony.

Sony are everywhere.  They are even making 50mp CMOS sensors for use in new backs from Hasselblad and Phase One.  That's great but it's good to have a different option.  More strength to Sigma.
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Quentin Bargate, ARPS, Author, Arbitrato

capital

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Re: Sigma DP Quattro
« Reply #71 on: February 11, 2014, 09:58:19 pm »

"Resolution is 30 percent higher" according to the "technology" tab on the Sigma-global website, so less really is more if this claim can be made good in practice.

I think this 30% number comes from the marketing math as the prior DP Merrill specified 30 MP equivalent, and the Quattro claims 39 MP equivalent. However if you go by actual megapixels increase it is 33%. Not sure why they specify a slightly lower boost. Be that as it may, I think the new Quattro will be penalized by diffraction earlier than the older model. I'd also like to know if they modified the thickness of top layer to absorb more green.

If I am understanding this correctly, from earlier tech reports on Foveon technology (quote below) the junction depths are 0.2, 0.8 and 3.2 μm for top middle bottom respectively, it seems that top layer is a bit thin to disallow a large green absorption but this was a good thing in old Foveon tech because it allowed greater separation.
http://alt-vision.com/documentation/5210-14.pdf
Quote
2.2 Spectral characteristics
Even with the large changes in absorption depth with wavelength, the response curves of devices using the
semiconductor material overlap considerably (Figure 2) 3. The steep slope in the silicon curve in the 400-475 nm range
provides substantial separation of the blue signal from the red and green below, but the relatively shallow slope above
475 nm results in a significant contribution of longer wavelength illumination to the top two signals. Fortunately, the
relatively thin absorption regions of the top two diodes minimize this. In addition, some of the short-wavelength
photons will make their way into the middle diode. It is this overlap that makes possible the discrimination of
wavelength below 450 nm that is so difficult using color filters.The extended response at both ends of the visible
spectrum also makes incorporation of a sharp-cut visible filter essential. The curves in figure 6 include the effects of a
filter with cutoffs at 400 and 660 nm.
« Last Edit: February 11, 2014, 10:09:26 pm by capital »
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Pete_G

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Re: Sigma DP Quattro
« Reply #72 on: February 11, 2014, 10:16:49 pm »

Quattro pixels = 5,424×3,616, approx 20 MP, Merrill pixels = 4,704×3,136, approx 15 MP, so the difference would seem to me to be 25 per cent.
Quite high.
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capital

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Re: Sigma DP Quattro
« Reply #73 on: February 11, 2014, 10:51:01 pm »

Pete, I think we're saying the same thing, 33% more over the older sensor is the same as 25% difference on the new sensor. Either way it is sliced this increase is about 15% more linear resolution (720 pixels long dimension, 480 pixels on the short) and it brings back the fond memories of the "actual" gain from 12MP to 24MP sensors. :)
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capital

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Re: Sigma DP Quattro
« Reply #74 on: February 12, 2014, 01:32:01 am »

I think I've come across why Sigma did what they did in the DP Quattro as disclosed in the Foveon Patents (specifically: 7,339,216)

"VCF" means vertical color filter.

What Foveon ideally would like but not really feasible:
Quote

"1-4-1" arrays of VCF sensor groups have an advantage in that their green channel response is not very far from a theoretically ideal luminance spectral sensitivity curve, and thus they can adequately capture high frequency luminance information while also realizing their implementation advantages relative to 4-4-4 arrays having red, green, and blue sensors of the same size as the green sensors of the 1-4-1 arrays. However, the full-resolution readout of green in such 1-4-1 arrays undesirably requires four separate contacts to the green layer (per each contact to the red layer). Each contact to the red or green layer undesirably occupies much space in the array.


What they might like to manufacture in the future:
Quote
U.S. patent application Ser. No. 10/738,484 discloses an array of VCF sensor groups in which each group includes a blue sensor, a green sensor, and a red sensor. Each of the red sensor and green sensor of each group is larger than the group's blue sensor and is shared with at least one other VCF sensor group. The blue sensors are typically implemented near the top surface of a semiconductor wafer and the red sensors deeper in the wafer. The size of each red sensor is roughly four times the size of each blue sensor, and sets of four adjacent VCF sensor groups share a single red sensor. Each green sensor's size can be about half the size of each red sensor (or can be the same as each blue sensor's size or can be any of a variety of other sizes). An implementation of such an array in which the each red sensor's size is four times the size of each blue sensor, the size of each green sensor is about half the size of each red sensor, the top layer is the blue layer, and the bottom layer is the red layer is a "1-2-4" array (or an array having "1-2-4" organization) in the sense that the resolution of its green layer is higher by a factor of two than that of its red layer and the resolution of its blue layer is higher by a factor of four than that of the red layer.

More on why they are making what they made this go-round:

Quote

In some such embodiments, the array consists essentially of solid material including a semiconductor substrate, each low layer of sensors is implemented between the substrate and the top surface, and a contact (e.g., plug or trench contact) extends from each sensor in each low layer to the readout circuitry. For example, a "1-1-4" implementation of such an array having two low layers (a bottom layer and an intermediate layer between the top and bottom layers) can include 4Y blue sensors in the top layer, Y green sensors in the intermediate layer, and Y red sensors in the bottom layer, and a total of 2Y vertical contacts between the red and green sensors and the readout circuitry.

...

For example, when S=4, each cell can include six sensor selection switches: one coupled to a shared sensor in a first low layer; another coupled to a shared sensor in a second low layer below the first low layer; and each of the other four coupled to different non-shared, top layer sensor. In this example, the sensor selection switches are controlled during readout to accomplish sequential readout of the four non-shared sensors and two shared sensors of each set by circuitry coupled to the sense node. Such use of sensor selection switches for each cell can allow the array to be implemented with much simpler surface layer geometry than can a conventional VCF sensor group array having the same number of VCF sensor groups.

The relatively low resolution at which each low layer of the inventive array is read out allows the array to be implemented on a semiconductor substrate with fewer contacts (e.g., plug or trench contacts) to the low layer(s) than if each low layer were configured to be read out with full resolution, and can result in a better signal-to-noise ratio than can be achieved by conventional arrays. Because each plug, trench, or other contact to a low layer undesirably occupies space in the array and typically increases the array's cost and complexity, it is desirable to minimize the number of such contacts.

The upshot on Quattro:

Quote

In preferred implementations in this class in which each top sensor is a blue sensor, full resolution readout of the blue (top) layer and lower resolution readout of green and red layers can generate luminance information having the same spatial frequency for incident blue light and incident green light, although the blue channel's spectral response is less ideal (farther from a theoretically ideal luminance spectral sensitivity curve) than is the green channel's spectral response, because the full resolution blue layer of each such implementation responds to green and red light as well as blue light. These implementations of the invention can adequately capture high resolution luminance information, while their full resolution readout of the top (blue) layer and lower resolution readout of the other (green and red) layers also provides advantages (e.g., compactness, noise improvement, and reduction in the number of contacts that must be provided to sensors in the green and red layers) that cannot be realized by full resolution readout of the intermediate (green) layer of a "1-4-1" array and lower resolution readout of the blue and red layers of the "1-4-1" array.

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BJL

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Sigma (and Panasonic) keep fighting the sensor duopoly
« Reply #75 on: February 12, 2014, 11:05:22 am »

What makes these cameras particularly significant is they use an exciting new sensor not manufactured or designed by Sony.

Sony are everywhere.  They are even making 50mp CMOS sensors for use in new backs from Hasselblad and Phase One.  That's great but it's good to have a different option.  More strength to Sigma.
Agreed: even if no camera with a Foveon "X3" style sensor has yet won me over as a customer, I am happy that Sigma continues to pursue alternatives to "Sony, and a bit of Canon".

In related news, I am happy to see that Panasonic is staying competitive as a supplier of 4/3" sensors, with Olympus switching back from Sony in the E-M5 to a Panasonic in the E-M1; the same sensor as in the forthcoming GH4:
http://chipworks.force.com/catalog/ProductDetails?sku=OLY-E-M1_Pri-Camera
http://www.luminous-landscape.com/forum/index.php?topic=87043.msg707750#msg707750

I also miss Fujifilm's sensor experiments like Super-CCD; X-trans experiments with non-Bayer CFAs, but puts them on Sony sensor chips as far as I can tell.
« Last Edit: February 12, 2014, 11:08:55 am by BJL »
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Hulyss

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« Last Edit: February 12, 2014, 05:30:22 pm by Hulyss »
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henrikfoto

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Re: Sigma DP Quattro
« Reply #77 on: February 12, 2014, 06:35:54 pm »

How was the af in the previous models?

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BernardLanguillier

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Re: Sigma DP Quattro
« Reply #78 on: February 12, 2014, 06:50:04 pm »

How was the af in the previous models?

The AF of my DP2m is extremely accurate and reliable in good light on static subjects, still very decent indoors but totally unable to do any tracking on moving subjects.

Cheers,
Bernard

The Ute

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Re: Sigma DP Quattro
« Reply #79 on: February 12, 2014, 07:02:18 pm »

If the Sigma people have really aimed to improve the low light performance of the new DP's they also should have upgraded the autofocus system to accommodate it.

;)





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