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I happen to have in my possession a couple of 40+MP cameras for a little testing. I’ll be writing reviews on each in due course, but, as this was a first time playing with gear of this caliber, I thought you might like to see what is possible with sensors so big.
First, let me explain this is not a full review nor a complete sharpness test. I leave those to the likes of DXOMark.com as they do an excellent job of lab based tests. This is simply to show examples of what is possible with newer sensors and gear because, frankly, I was amazed at what I saw on my computer screen when I started testing these cameras. Then I started thinking; One camera is 1/10th the price of the other, can it be just as sharp? This is also not a test of all the camera’s functions as that would be an apples to oranges contest.
The first camera is a medium format Pentax 645D with a 55mm lens. It retails for $10,100USD with lens. The second camera is a Sigma DP2 Merrill which sports a 30mm lens and retails for $1000USD. I have a “First Impressions” post up on the DP2 Merrill on The Phoblographer if you are interested to read more.
Because of crop factors, the two lenses are fairly close. In 35mm equivalents, the Pentax is a 43mm lens and the Sigma is a 45mm lens. This means there will be ever so slight variations in the shots, but I have attempted to keep them to a minimum.
The Pentax 645D sports a 40MP sensor (44mm x 33mm and 7,264 x 5440 pixels) while the Sigma DP2 claims 46MP (23.5mm x 15.7mm and 4,800 x 3,200 x 3 layers….I’ll explain). Some people have asked if the Sigma propaganda machine is bending some numbers and pumping out BS when it claims 46MP and my answer has been: no.
You have to think about light capture and that ‘magical’ number people like to throw around when comparing one camera to another; megapixel. The Pentax captures light in a traditional Bayer patter, where each pixel can only read one part of light (red, green or blue (RGB)). To figure out what color actually existed over each individual pixel, black magic and mathematical algorithms are employed to surmise, based on surround pixels picking up the other two colors, what was really going on at that pixel. That’s ‘traditional’.
The Sigma captures light in a new way and doesn’t conform to the old way of counting megapixels because it truly captures more detail. The short of it is the Foveon X3 sensor employed in the Sigma DP2 Merrill captures red, green and blue at each and every pixels. Wikipedia actually does a good job of explaining this. So it’s not marketing BS, but they also want to help people understand this is more than just a 15.3MP (4,800 x 3,200) sensor.
What does this mean in practical terms? It means the Sigma DP2 Merrill captures 46 million bits of light data, while the Pentax 645D captures 40 million. In the end, the image dimensions are larger on the Pentax 645D (because it interpolates the missing data for two colors for each pixel) than the Sigma (which ends up with just 15.3 million pixels of information, but without the interpolation). Let’s take a look at how this plays out.
For some side by side comparisons I have left the images as unadulterated as I could. Sigma’s SPP software used for initially processing the X3F RAW files has a slight bit of sharpening on by default, but I otherwise turned off sharpening in Lightroom for the other files. I shot the Pentax 645D in RAW format using Adobe RGB as the color space and DNG for the file type. The Sigma used Adobe RGB as well. This isn’t a color test, though.
Click on each 100% cropped zoom for a full sized JPG. I will also make some RAW files available at the end of the post. Because the Pentax sensor takes up more physical space, you will notice the zooms on those images are closer. All images were shot at f/8, ISO 100 and either 1/100th of a second (rust and spider) or 1/400th (vitamins and prayer flags).
And what about comparing either camera to a 35mm DSLR?
In one last test, I include a Canon 7D with 28-300mm L lens set to 28mm ( for a 45mm equivalent). This camera’s sensor is 22.3mm x 14.9mm and has 5184 x 3456 pixels for a total of 18MP. It currently retails for $1500 (another $2400 for the lens).
While I personally would love to keep all the cameras, I would love to own the Pentax 645D because it is big and sexy. It’s images are big and clear.
That being said, for $9000 less, the Sigma DP2 Merrill is not only portable, it is very sharp. Yes, it’s sensor takes up less space and outputs less pixels when printing. But, the quality is amazing for this size package and price point, to be honest. It’s not a camera for everyone, but those looking for a small body and high quality, would do themselves a favor to give one a try.
Now for the RAW files! Here is a link to all of them (you will also find some other sample Pentax 645D images there). You will need SPP, free and downloadable from here, to view the Sigma files. I have included TIFF versions of the Sigma files if don’t wish to convert them.
Of special note: While the Sigma sensor takes up less space (15.3MP large as compared to 40MP large) the files sizes RAW out of each camera are comparable, indicating the Sigma version does include far more information than the 15.2MP moniker would indicate alone.
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