I've been experimenting with my new K-30, and figured I'd share some of my work with the forum. I just ran the K-30 through its ISO range today using two different scenes.
Test Setup
The photos were shot with my K-30 on a tripod with remote shutter release with 3-second mirror lockup. All of the images were shot in RAW, and were developed using Adobe Camera Raw into Photoshop CS5. No adjustments were made during developing, but I did add a light sharpening to the images shot at ISO 800 and lower since that is my normal process. At ISO 1600 and above I abstained from any sharpening, since grain had become prevalent enough by that point that sharpening tended to have the undesirable side-effect of also emphasizing the grain.
No noise reduction was applied in ACR or in Photoshop. Applying conservative noise reduction in ACR would give you cleaner images, with a minimal loss of detail. I usually find it to be a worthwhile tradeoff, but for this exercise I wanted to see the raw sensor output at each ISO level.
Daylight Series
The first scene was shot using daylight (but not direct sunlight) coming in through a window just to the left of the panda vase. I had a reflector on the other side of the vase to provide fill light. The lens was my Sigma 100-300mm setup approximately 4 meters from the vase. I wasn't sure how the 100-300mm would perform since it probably wasn't designed for close subjects, but I think the pictures turned out great, with abundant detail and contrast. Because of the ample amounts of daylight, this isn't the most demanding ISO test, but it's still good to see how high you can push the ISO with daylight since there are some situations outdoors where you will want a very high shutter speed in order to freeze a fast moving subject or compensate for a very long focal length.
I think the K-30 did very good with the daylight series. I later worked with some of the images in post-processing, and found that with some massaging I was able to clean up the ISO 12800 image enough to make a good 8"x10" print. And even the 25600 image could be used to make a very good looking web-sized image or a 4"x6" print if processed carefully. Here are the ISO 12800 and 25600 images after cleaning them up. Again, click on the image for the full size version.
Indoor Series
The second scene is intended be representative of indoor conditions and should be a bit more demanding. The scene was shot in a windowless basement room and was lit with incandescent lamps. I made sure the scene was lit/exposed in such a way as to include plenty of shadows and dark areas, since this gives the camera's ISO capabilities a real workout, and is typical of many photos shot indoors with available light.
The focal point was on the face of the red Russian nesting doll in the center of the frame. This scene was shot with the very sharp Tamron 28-75mm f/2.8 lens, so this is also a good chance to evaluate the resolution available from the K-30's 16MP sensor when paired with a good lens.
The K-30 also impressed with the indoor series. Like the Daylight images, I was able to clean up an ISO 12800 image enough for an 8"x10" print, and an ISO 25600 image for a 4"x6" print or web image. So although I would normally avoid the highest ISO settings, it's nice to see that they are not just included as a marketing gimmick.
One of my goals with this exercise was to discover the ISO ceiling which I would not want to exceed in the field. With my K-x I usually would not want to go above ISO 1600, but with the K-30 I will now consider ISO 3200 to be my upper limit. Below are the two ISO 3200 images after processing. Please be sure to click through to view the full size images to see how much resolution and detail was able to be preserved at ISO 3200.
Conclusion
I never got to use a K-5, but it seems to me that Pentax has definitely managed to improve over the K-x's already-excellent high ISO capabilities. The fact that they were able to do this while cramming in 33% more pixels is even more impressive. Noise is very well controlled up to ISO 1600, and even at ISO 3200 and 6400, images are still very usable in many applications. At ISO 12800 and 25600 noise is very noticeable, but color accuracy and saturation remain good and an amazing amount of detail is still preserved.
Something else that should be pointed out is the
quality of the noise from the K-30's sensor. While many sensors exhibit ugly splotchy noise and banding when pushed to their limits, the K-30 maintains its composure by producing grain that is very fine and uniform. When viewed up close, the noise is actually very reminiscent of film grain. Certain photographs may even benefit from the inclusion of this type of grain. I'll finish this up by posting the full-size Indoor 25600 ISO image converted to black and white, but with absolutely no noise reduction. This type of undramatic low-contrast scene is not the ideal candidate for black & white treatment, but you can still get an idea of the possibilities.
Last edited by Edgar_in_Indy; 08-09-2012 at 09:49 PM.