4 07 2008

For the record, this blog is now officially on pause.

There are several reasons why I am suspending (although not necessarily quitting) My DP1:

  1. It’s out there. When I started this blog, the DP1 was an overdue enigma, a highly anticipated great idea that kept slipping its release dates. But now it’s out there, for anyone to see and buy, so the need to rattle the cage has diminished.
  2. Now that it’s out there, a lot of other web sites with a lot more resources and a lot more clout are doing a great job of reviewing and discussing the DP1, making this blog sort of redundant.
  3. Even though it’s out there, I still don’t own one. (More on that below.)

Readers of this blog probably know that I live in Canada, where there doesn’t seem to be a lot of retailers pushing the DP1. Indeed, I had to go to France in order to see one in real life, and even then it was a non-functioning display model in the FNAC store at La Defense in Paris.

When I finally picked up that DP1, tethered as it was, and with a dead battery, I wasn’t sure what to think. After all that anticipation, all that reading and writing, and there I was with a DP1 in my hand. It didn’t feel very different from my Lumix DMC-LX2, actually. About the same size and dimensions, but with a bit more heft and a build quality that seemed more “beta” than refined. I knew I was holding something quirky and special, but by then my desire to actually own one had dwindled.

I admit that I was disappointed with the various reviews of the DP1. Almost unanimously they cheered the image quality but boo’ed the camera’s slow responsiveness and retrograde interface. Truth be told, pixel-peeping image quality is not the most important thing for me. I need a camera that handles well, is quick, and responsive. After all, getting the shot on a 1/1.7 sensor is better than missing the shot on an APS-C Foveon.

I feel like a heretic in my own religion for saying that, but there it is.

There are rumours of a DP2 and even a DP3 coming soon. There are also rumours of a Lumix DMC-LX3 coming out in the autumn of this year. In the meantime, I am still a fan of the DP1, and I applaud Sigma for sticking its neck out and trying something different. But in the end it’s not really the camera for me.

I’d be really happy — over the moon, in fact — if Sigma manages to make a DP2 or DP3 that handles like a Lumix DMC-LX2 but has the image quality of (or even close to) the DP1. That would be heaven for me.

“T.O.P.” Wishes for DP1

28 11 2007

Mike Johnson, over at The Online Photographer, mentions the Sigma Enigma DP1 in this post about his current wish lists. What’s most interesting is the graphic he uses to illustrate the difference in size of the DP1’s sensor versus that of a typical compact digital camera.

What’s The Big Deal With Foveon Sensors?

13 11 2007

One of the big selling points of the Sigma DP1 is its Foveon sensor. Why, you may ask, is that such a big deal? What follows is the short answer. (If you want the long answer, start Googling.)

Foveon is a company that makes sensors for digital cameras. The Sigma DP1 uses the Foveon X3 sensor, which is also found in larger cameras such as the highly anticipated and well received new Sigma SD-14 DSLR. Before we get into the specifics of the Foveon X3, what follows is a bit of background information.

There are basically two types of digital camera sensor; CMOS (complementary metal oxide semiconductor) and CCD (charge-coupled device). Each type has its advantages and disadvantages, which can be summarized as follows:

  • CCD sensors typically produce less “noise;”
  • CCD sensors typically are more light-sensitive;
  • CMOS sensors use far less power (up to 100 times less);
  • CMOS sensors cost less to produce.

Both types of sensor are currently in use, but CMOS seems to be gaining in popularity, due largely to market pressures to drive the cost of cameras down and to design for long battery life. Also, with evolving technologies, some people claim that the sensitivity and noise issues associated with CMOS sensors are becoming less apparent.

All that said, the Foveon X3 sensor that will be used in the Sigma DP1 is a CMOS sensor. In short, that means good battery life and a lower price (as if… – the DP1 will not be cheap). However, there is another factor that sets it apart from both CCD and other CMOS sensors. Without getting into a lot of technical details, suffice to say that the Foveon X3 uses a different array of photosensitive diodes on the sensor; an array that is said to provide better light sensitivity and image quality by mimicking color negative film in that the red, green, and blue (RGB) color sensitive pixels lie stacked on top of each other, in layers, instead of spread on a single layer as is found in conventional, mosaic sensors.

Foveon vs. Conventional Sensors

Conventional sensors (both CMOS and CCD) use what’s called the Bayer filter array. According to this Wikipedia entry, the differences between the Foveon X3 and Bayer array sensors can be summarized as follows:

In the Bayer sensor, each photosite in the array consists of a single light sensor (either CMOS or CCD) that, as a result of filtration, is exposed to only one of the three primary colors, red, green, or blue. Constructing a full color image from a Bayer sensor requires demosaicing, an interpolative process in which the output pixel associated with each photosite is assigned an RGB value based on the level of red, green, and blue reported by those photosites adjacent to it. The Foveon X3 sensor creates its RGB color output for each photosite by combining the outputs of each of the stacked photodiodes at each of its photosites. This operational difference results in several significant consequences.

In the case of the Foveon array, the consequences are essentially:

  • Color artifacts normally associated with Bayer sensors are eliminated.
  • Light sensitivity is increased (although color noise may also be increased in low light situations).

Here’s another view of the differences:

Foveon vs. Conventional Sensors

In this illustration you can see that with the Foveon X3 array, there are actually three pixels in each location (stacked on top of each other). This is tricky, because it can confuse the whole pixel count issue, which is highly over-rated anyway. In short, the DP1 bills itself as a 14 megapixel camera, but you need to divide that by three to arrive at a real sense of the dimensions of the sensor. In other words, it’s really a 4.6 megapixel camera times three (or, three layers of 4.6 megapixels).

Wait a sec… before you scream “What? Only 4.6 megapixels?” keep in mind that we’re talking about 4.6 megapixels, times three, on a really big sensor. And remember, as I mention in another post, sensor size is more important than pixel count – you are better off with fewer pixels on a big sensor than lots of pixels on a small sensor. In other words, forget about counting pixels; what counts is sensor size and (according to Foveon), pixel array.

There is still the question of noise on the Foveon X3, since it is a CMOS sensor. That issue is contentious; some reviewers of cameras using those sensors claim the resulting images are noisier than with comparable non-Foveon sensors. However, it is unclear if that is due to the sensor itself, or the image processing algorithm of the camera’s software. This review of the Sigma SD-14 on implies the images have very little noise. And remember; the Foveon array supposedly eliminates the color artifacts (a type of noise) that one gets with Bayer array sensors.

When it comes right down to it, the big deal as it pertains to the Sigma DP1 is not so much that it comes with a Foveon X3 sensor as that it comes with a big sensor. A “DSLR-sized” sensor in fact, which is revolutionary for any pocket digital regardless of whether it’s a Foveon or a Bayer array.

After all, when it comes to digital, size does matter. (I’ll say more about relative sensor sizes in a future post.)

Further reading:

The Sigma Enigma DP1

8 11 2007

In the fall of 2006, Sigma Corporation (known primarily as a manufacturer of after-market lenses for SLR cameras) announced it was developing a revolutionary new point-and-shoot camera; the Sigma DP1.

The DP1 would be different from other small point-and-shoot cameras in several ways, but the most import is that it would use a large image sensor – the same Foveon sensor that is found in several digital SLRs. This is significant for several reasons, including the fact that sensor size is one of the most important factors in determining quality in digital photography. Forget megapixels; sensor size is the key.

Simply put, most small digital cameras have suffered a loss of image quality as a result of the race for megapixels. The more pixels you jam onto a small sensor, the less able each one is to absorb and record the light that strikes it. To compensate, the cameras have to crank up the gain on the sensor, which result in image noise. Image noise is sort of like the grain that one finds on high ISO photographic film, except grain can be nice while noise tends to be ugly.

The above explanation is over-simplified, but it will do for now. Suffice to say, the gorgeous detail you see in photos that come from digital SLRs (or DSLRs) is not just the result of nice lenses and lots of megapixels. It is because a DSLR image sensor is generally about four times bigger than the sensor in a point-and-shoot camera. Ten megapixels on a sensor the size of a 35mm frame will give you a lot more detail than ten megapixels on a sensor the size of your pinky fingernail.

So that’s the big selling point of the Sigma DP1; DSLR quality images from a camera that can fit in your shirt pocket. There’s only one problem – a year after the camera was announced, it has still not been released. Worse, nobody seems to be able to get a straight answer from Sigma on when it will finally hit the market.

It had previously been scheduled for spring 2007, then summer 2007, then some people said fall 2007. Well, it’s almost winter 2007 and we still haven’t seen the elusive and enigmatic Sigma DP1, or as I call it, the Enigma DP1.

This blog will attempt to give some background information on the development of the camera, why some people find it so desirable, and with any luck, information on when the thing will finally be released. It will also discuss photography in general, at least with regard to themes that are relevant to this camera and ones like it.

I should state up front that I am a fan of the camera, at least on paper (since I’ve never actually seen or held one). However, I am not immune the camera’s potential flaws and down-sides. For example, the lens will likely not be very fast (f4), and the camera will likely be quite expensive for a point-and-shoot (possibly more than $1000 US). I am also not fond of Sigma’s tight-lipped development approach, especially after dangling the marketing pitch in front of our noses for more than a year.

However, I do hope to someday own one; hence the name of this blog (“My DP1”). In upcoming posts I’ll talk about prime lenses versus zooms, more about sensor size, “ultimate DMD” cameras, image quality, the downside of “pixel peeping,” and more.