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Sigma SD10 Digital SLR with 10 MegaPixel Foveon CMOS Sensor

Part II - The Performance

February, 2004

John E. Johnson, Jr.

 

The Performance

Two lenses were included with the Sigma SD10 review equipment. One is the 18mm - 50mm f/3.5-5.6 zoom lens, and the other is the 50mm f/2.8 macro lens. Like most other digital SLRs right now, the Foveon chip covers about 60% of the conventional 35mm film space. The viewfinder shows the area of the chip, and a grayed out region beyond that area which shows the entire 35mm film space. The front of the camera where the lens is attached has a coated glass cover that keeps dust out of the camera chamber, and off the sensor.

As you probably have surmised from my previous reviews, I like to take pictures of flowers. I was pleasantly surprised to find that even the 18mm-50mm zoom lens does well as a macro lens. I used auto exposure, but focused manually most of the time. The photos are unaltered except for size, and where otherwise specified.

Here is a shot of a Camelia blossom. The delicate white and pink gradations are very smooth. I used an ISO of 400 here, as I did for most of the photographs. There is a richness in the color with the Foveon chip that is not there with conventional mosaic sensors.

What I like to do with such photos is modify them in my photo editor, producing something like this (photo below). I have them printed for me at 20" wide by however high they turn out to be, depending on the cropping of the original. I have to say the Sigma is the first digital SLR I have used that allowed me to get as close to the blossoms as I want. Up until now, I have been using an older camera with low resolution, but with a lens that lets me get 0.5" from the subject.

Every detail of the leaf surface here has been captured.

It is nice having all those red pixels to capture this Camelia.

Here is a close-up of some coins sitting on a knit shawl. Notice the individual very fine hairs. This is the kind of thing where the Foveon chip excels because there is no blurring applied to the image processing to compensate for a mosaic pixel distribution.

The above photos were taken with the zoom lens. Using the 50mm macro lens, I could fill the photographic field with this quarter.

Vegetables in a supermarket make a good color test. The first one was taken using Auto white balance.

The second one (shown below) had the white balance set to Fluorescent. Notice that the fluorescent setting makes the photo appear much warmer, and perhaps more appealing, but the auto setting is what they actually look like in the cold case at the grocery store. In any case, I found I could make the top photo look like the bottom one by using RGB adjustments in my photo editor (PhotoImpact). I forgot to reset the white balance to Auto for some subsequent outdoor photos, so I decided to just use Auto all the time and make any necessary changes in the photo editor.

For flash work, I used the Sigma EF-500. It is a very powerful flash unit, and I found that I liked manipulating the flash settings manually and giving myself a variety of results to choose from. That is one of the nice things about digital cameras. You can take as many pictures as you want, keep the good ones, and throw the rest away. There are no wasted dollars in developing and printing of the thrown away photos.

As an example, I took a photo of some fruit sitting on a window shelf. I used the flash at several settings and selected among the resulting photos that gave me a close balance of flash and backlight from the window. It looked fine, but there was still just a bit of overlighting from the flash compared to the sunlight in back.

So, I used the Sigma Photo Pro software that Foveon supplies with the camera to make adjustments to the RAW file before I saved it to JPG. This is the main advantage of having the photos in RAW format in the camera. There is no loss of image quality by manipulating whatever you want before conversion to JPG. You can also use the Foveon program to save the files to TIF if you like, either 8 bits per channel or 16 bits per channel. However, I have found that 16 bit TIFs are not easy for photo editors to work with, so have stuck with 8 bit TIFs when I use that format. The RAW files were about 6 MB in size with the SD10.

When you boot the software, you get a main screen that allows you to browse your hard drive and select the directory where you have put the image files (I always move them from the Compact Flash card or other memory card to an images directory on my computer before doing anything to them).

You select the photos you want to convert on the right. They are labeled *.X3F. Selecting them one at at time will give you the following screen. In this case, I chose the photo with the fruit on the window shelf.

You can save it to JPG from there, or manipulate it first, with the following menu, shown on the left. In my case, I used the options to jazz up the file before saving it to JPG. The settings I made are shown on the right.

The resulting JPG looked like this (shown below). In other words, I made my adjustments in the RAW format, then saved it to JPG. This way, I was able to make some adjustments without having to take a JPG and then resave it with further compression.

Here is the same photo, saved as JPG from the Foveon software, but without any adjustments. It looks pretty much like the photo in the Foveon menu that is shown 3 photos above. So, the Foveon software shows you pretty accurately what you are going to end up with. The X3 fill light option in the adjustments menu is Foveon's method of adjusting the balance of lighting when the sun is coming from behind the subject.

In future versions of the software, I would suggest that Foveon add the capability to take photos in the JPG format in the camera, rather than only allowing RAW. Although RAW gives you the best ultimate results, if you are on the road with your camera, but without your laptop and software, and you want to print photos or use them for something, you are out of luck.

Click on selection below to go to other parts of this review.

Part I - Introduction, Design, and Features

Part II - The Performance

Part III - On the Bench and Conclusions

 

Copyright 2004 Secrets of Home Theater & High Fidelity
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