Field Review: The Pentax K-5 (Day 5)

We’ve come to the end of our time with Pentax’s premier 35mm DSLR. It’s a camera that has earned attention for it’s well-regarded image quality, rugged build, and top-tier ergonomics. I’ve enjoyed shooting with the Pentax K-5 and wanted to wrap up our review series with a detailed exploration of this camera’s image quality. I set out to test it at the limits of photography and am really impressed with the results.

Before reading you can check out my findings on this camera for portraits, used at a wedding, in tough weather, and my initial feelings.

Image Quality and the Pentax K-5

What I’ve found most remarkable about the Pentax K-5‘s imaging quality, is its ability to pull detail from the darkest of shadows. The K-5 has remarkable dynamic range for a crop-sensor 35mm camera. It also manages noise well, rendering a pleasant grain, not the purple TV static of cameras 6 years ago.

Our test camera, as discussed in previous entries, has trouble with purple fringing. I’ve found, though, that shooting PEF Raw files and processing in Adobe Photoshop Lightroom 3 offers a workable fix. The camera, along with our test lens, a 55mm f/1.4 DA*, is nicely profiled in Lightroom and the Defringe > Highlight Edges (as illustrated in the screen grab below) does a nice job in most cases. It worked even on a torture test of shooting a brightly backlit willow tree. I had better results with PEF files than DNG.

It’s one reason to stick with Pentax’s proprietary raw format. I still would like to see a firmware fix from Pentax regarding purple fringing, as it’s one big image quality concern for an otherwise very good camera.

Pentax users: consider leaving a comment below if you have a preference between DNG and PEF and let us know why.

Purple fringing aside, the Pentax K-5 gets high marks in every other area of image quality, most notably dynamic range. To illustrate the point, take a look at the following image, a PEF file, shot at ISO 200 on a tripod (0.8 s at f/10).  [As with all images in this post, click to see it larger in a new window.]

Dynamic Range

It’s not an especially interesting photo, though the camera’s dynamic range is being tested. The twilight sky is much brighter than the building (Oakland CA’s Chabot Space and Science Center). Take a look at this next image, however, which is the same file, cropped, and boosted by three stops in Lightroom:

It’s truly remarkable that the K-5 retains so much detail in its darkest shadows. Three stops is quite a lot. Certainly, a fine grain has been introduced with the extreme exposure boost, but it looks pretty darn good. Such range used to be unique to $20,000+ medium format digital cameras, and now we’re seeing it from crop-sensor 35mm cameras. The K-5 is evidence that imaging technology is still improving steadily.

Here’s another example image, a PEF file shot at ISO 100 (25s f/10):

This is another capture with an extreme difference in exposure between it’s brightest and darkest areas. The following is a crop from the darkest trees on the left side of the images: as shot (left thumbnail) and boosted by three stops (right thumbnail).

[click to enlarge in a new window]

What we’re seeing in the second crop is clear detail in tree branches lit only by the dim, indirect light of passing cars. Even in dark shadows, the K-5 captures good detail. Practically, and not just in weird extreme tests like these, it means the camera gives photographers the creative flexibility to change exposure several stops in either direction (and also to save files that might otherwise just be too far gone in either direction).

In-Camera Trickery: JPG-to-RAW and RAW-to-JPG

The Pentax K-5 offers a couple unique controls to help photographers to take advantage of its outrageous RAW files. First, a dedicated RAW button on the left side of the camera body sets the camera to grab its next image as a RAW file or RAW and JPG (it’s customize-able via the camera’s menus).

Secondly, and even more novel is the weird and wonderful ability to save the last JPG shot as a RAW file. Just took the best shot of your life and underexposed? Quick! press the AE-L button to retrieve and save the RAW data. It only works for the last image and doesn’t work once the camera has been turned off, but just having the feature is sure to be a comfort for those times when shooting JPG makes sense to save card space and post-processing time.

The K-5 allows a few tricks for going the other direction too. Last week, I found myself with the K-5 and a laptop (a laptop with an SD card slot, but without Adobe Lightroom). I was able to shoot a RAW file, process it in camera and output a JPG for a quick, and professional-looking Facebook update about my dog. When working with RAW files, the K-5 allows access to a nice range of conversion tools (exposure, white balance, saturation, etc.) as well a palate of creative filters.

Though a few filters will make your photos look like visuals we saw when Photoshop first hit the scene in the 1990s (remember “Posterize”?) at least a couple of the filters are pretty cool and eminently useable in 2011. Though it’s no replacement for a full-size monitor and actual post-processing software, It is a way to have fun experimenting, create quick print files for a nearby drugstore, or for a quick social networking status update and in-camera processing saves a new JPG and leaves the actual RAW file untouched. Below are a few in-camera takes on a snapshot from this morning. It’s worth noting, also, that any of the camera’s creative filters and RAW-processing trickery can be applied to JPGs while shooting.

Night Photography and the Pentax K-5

With it’s compact size and tough build, the Pentax K-5 is a great choice for travel. I enjoyed using it for a few long-exposure night shots, something that seems, for me anyway, to come up more frequently when traveling. The K-5 offers Bulb mode for extra-long exposures, mirror lockup to remove mirror-jiggle camera shake (which is minimal to start with) and an impressive ISO range (once extended in the camera’s custom menu) of 80-51,200.

I’m still disappointed with the camera’s processing time. Even with a brand new San Disk Extreme SD card I bought just to be sure, the camera takes too long to pull up previews once a photo is taken. I spent a lot of time staring at the little hourglass icon, waiting to check an exposure before adjusting the tripod. For this type of work, it isn’t as significant an issue as when shooting a wedding (like I did with the K-5 in December) but it’s annoying.

Above is another image demonstrating the K-5‘s dynamic range and also its Auto White Balance setting which was able to make sense of this mixed light situation. The camera does as good a job as any at selecting White balance and offers a wide range of preset options, including Kelvin or Mired scale numbers and manual measurements. White balance selection is certainly a professional-quality element of the K-5‘s design and is quickly accessed via one of the 4-way buttons on the camera back.

Other camera tricks that are likely to aid in travel and night photography include the camera’s in-body image stabilization. It’s a different strategy than that taken by Canon and Nikon who offer stabilization in lenses instead. I don’t like that you can’t see the effect through the optical viewfinder (as you can on a Canon or Nikon).

I do like that the effect is added to all your lenses, and that the lenses are smaller and less expensive. In practice, though, Pentax’s stabilization doesn’t work as well as that from either Nikon or Canon. I had forgotten all about it until it badly blurred a tripod shot early in this test shoot. Unlike Nikon and Canon, there is no tripod setting or passive setting for the anti-shake. Intuitively, it seems excessive and redundant to have stabilization built into every lens but, currently, lens-based stabilization – be it VR or IS – really does work better.

Some day, Pentax may prove me wrong and come out with a camera that has amazing stabilization and then it will apply to every Pentax 35mm lens ever made while Canon and Nikon photographers are forced to keep buying every lens in their collection over and over again.

The K-5‘s mobile sensor offers a few advantages besides mediocre stabilization. It can shake off dust and slightly recompose images. I found the dust removal to work very well. In a typical month of shooting, I normally end up with the lens off, puffing away with a blower at least a few times (I must have a dusty studio); not once with the K-5.

Test Images (click to enlarge)

Conclusion (Day 5)

To sum up the night shoot experience, the Pentax K-5 is a creatively inspiring and fun to use camera. It is very well built, easy to customize, compact, and captures clean, nicely-detailed files with minimal noise. I like that it mixes professional versatility and functionality with features that make it fun to experiment with. Pentax needs to address the K-5’s purple fringing issue, though in the meantime, Adobe Lightroom offers an easy remedy for most images with unsightly fringing. The camera also seems to take longer-than-normal to process previews. Complaints aside, the image quality of the K-5 is top tier for a 35mm crop-sensor DSLR and it offers an especially wide dynamic range. I would be quick to recommend it to a photographer seeking a compact and capable DSLR.

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