Monday, July 6, 2009

Will the Pentax K-7 be a high-ISO disappointment?

I have written before that I would like to use a camera capable of generating high ISO (well above 1600) images with negligible digital noise and artifacts (like banding). Such cameras exist in the full-frame sensor range, the Nikon D700 being an extraordinary example. Even some cameras with APS-C sized sensors show quite "clean" results, like the Nikon D300.

The announcement of the new Pentax K-7 has created a lot of fuss around it's noise performance. After all, the official news release announced: "With the adverse effects of digital noise greatly reduced, the sensitivity can be increased from ISO 100 up to the highest level of ISO 6400 (via a custom function) without worry." When photos taken with pre-production cameras started showing up all over the internet, people started closely inspecting the quality of the pixels originated at high sensitivity levels, burning their eyelashes against computer screens over countless sleepless nights. A lot of the commentary seems to indicate that, in terms of digital noise, the K-7 is similar to the K20D, which is not exactly spectacular (but is not that terrible either). Many Pentaxians went into deep depression after knowing this. I'll wait to see the first "official" reviews from the sources I trust - a few photography magazines and websites - before making my own opinion. But I find all this discussion a bit... let's say... irritating.

I like to look at an image as a whole - admiring the noiseless smoothness of 100% crops seems a bit geeky.

I have a K10D, which can only go up to ISO 1600 (the K20D goes up to 6400, same as the new K-7). At ISO 800, noise is already so evident that many "pixel-peepers" would vomit over the computer screens, unable to control their repugnance. At ISO 1100-1600 the images are considered unusable by many, unless they can be saved by some specialized noise reduction software. Actually, many consider that ISO 1600 is unusable even on the K20D!

Even though - allow me to repeat - I would appreciate being able to experiment with a camera capable of producing cleaner images, I'm far from despising the high ISO output from my K10D! Let's look at a quick and dirty example. I've taken the photo below (two objects placed on our black dining table, under the room's regular tungsten lighting) with the camera set to ISO 1100 and the in-camera noise reduction turned off, even though I think it only kicks in at longer exposure times. Note that similar results were obtained with ISO 1600, I'm showing this example just because I like the composition better. The photo was taken at 1/15 sec and f5.6. The exposure was set manually, as I didn't want to go lower than 1/15 sec in this handheld shot. The image below was converted from the original RAW file, using Silkypix 3, setting all the noise reduction parameters to zero (that means no noise reduction applied) and without any exposure or color adjustments.

Pentax K10D + Zeiss Sonnar 85/2.8 (ISO 1100, unprocessed RAW file)

It doesn't look very good, really, but that isn't necessarily because of the noise. So I used Silkypix to make some modifications and try to obtain the result I had in mind. But I kept all the noise reduction settings at zero - I actually was going for a "grainy" image - except for the false color control, which stayed at the default value of 30%. I used the tone curve to adjust contrast, making the table top darker and the coffee cup lighter. I also adjusted the white balance. It is a known fact that the auto white balance in Pentax cameras does not (intentionally?) correct the yellowish tint caused by tungsten lighting. That's OK, sometimes one want's to preserve that warmer tone.

Same photo as before, after tone curve and white balance adjustments

So how does the image look like now? Quite nice, in my humble and biased, opinion. How did this happen? Darkening the shadow areas helped a lot. The table top became closer to solid black and the noise speckles less intrusive. The image is still noisy, as you can see it in the crop on the left - the cup was outside the depth of field, so please don't comment on sharpness. But does this mostly untreated digital noise render the photo unusable? Not at all, I actually think it looks nice and fitting to the context of the image. Some professional photographers work at high ISO specifically to get some "grain" on their images. Others use software to simulate that fabled "film grain" look.

The K-7 seems to be an interesting camera in many aspects. High ISO perfection might not be one of them. How important is that, though? Digital noise can be seen as an image property, just like exposure or white balance. As long as one is shooting RAW, it can usually be manipulated within a reasonable range, in order to produce results in accordance to the photographer's personal taste. Complete elimination of visible noise is not necessarily the desirable goal. There are exceptions, of course - I would avoid a noisy output if I were trying to preserve detail in a macro shot. A different issue is when one wants to shoot JPEG straight out of the camera. In that case, the post processing possibilities are much limited and a camera with a "cleaner" output might be a wiser choice, if one intends to work at high sensitivity levels.

1 comment:

jayKayEss said...

The samples I have seen online so far have a grainy, "film-like" look up to about ISO 1600, with no obvious streaking or chroma noise. My K10D has a tendency to output smeary blue blotches in the shadows at 1600. To me, that's a major improvement.