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Pentax K100D Digital Camera Review
by Howard Creech -  8/27/2006

The new Pentax K100D -- inexpensive, practical, and capable

In 1976 Pentax replaced its venerable Spotmatic 35mm SLR with a new camera called the K1000; a very basic manual exposure single lens reflex (SLR) designed to help neophyte shooters learn basic photography skills. The K1000 enjoyed one of the longest production runs of any modern camera because it was cheap, dependable, tough as nails, easy to use, and capable of producing consistently excellent results. Generations of student photographers, yearbook staffers, budding high school photo-journalists, and college sports shooters learned their craft behind a K1000. By the time production stopped in 1997 more than 3,000,000 K1000's had been sold.

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Thirty years after that first K1000 rolled off a production line in Japan, Pentax has introduced its digital doppelganger, the Pentax K100D. Point & shoot digital cameras have dominated the photography marketplace for most of the past decade, but reasonably priced entry level dSLRs are now the fastest growing segment of that lucrative market. Entry-level digital SLRs allow photographers to move to the next creative level by providing affordable access to modular imaging devices and interchangeable lenses.

The K100D is up against some pretty stiff competition including Canon's Rebel XT and Nikon's D50. At 6 megapixels the K100D looks to be holding the short straw in this contest since most of its rivals sport at least 8 megapixel resolution, but the K100D is fairly cheap ($699 with 18mm--55mm/f/3.5--f5.6 Pentax DA zoom), dependable and robustly built, simple to operate, and capable of producing consistently excellent results. The K100D also provides users with some unique capabilities and features including the ability to mount virtually all "K" mount lenses ever made (including lots of inexpensive manual focus optics) and image stabilization with every lens.

Some important notes for fist time dSLR Buyers

One of the long-term shortcomings of all fixed lens digicams has been their tiny (typically 1/1.8" or 2/3") image sensors. Camera makers have continuously boosted resolution by adding pixels to these tiny sensors exponentially increasing pixel density. As pixel density increases image noise rises dramatically - today's 8, 9, and 10 megapixel P&S digicams use sensors the same size as those that powered 2 megapixel digicams five years ago. Entry-level digital SLRs, on the other hand, have much lower noise levels, less chromatic aberration and luminance noise (purple fringing and blotching), and improved sensitivity because they typically use much larger APS-C (22mmx15mm) sized sensors (larger sensors typically generate less image noise than smaller sensors, everything else being equal).

The K100D's CCD sensor is still smaller (23.5 x 15.7 mm) than a frame of 35mm film (24mmx36mm) so the focal length of 35mm format lenses is multiplied by 1.5X - the good news is that telephoto lenses magically grow longer (a 200 mm telephoto becomes a 300 mm telephoto). The bad news is that the same thing happens to wide-angle lenses (a 28 mm wide-angle lens becomes a 42 mm normal lens).

The LCD screen on the K100D's rear deck can't be used as a viewfinder (like it is with point & shoot digital cameras) because the mirror used to reflect the image resolved by the lens up to the optical viewfinder blocks the light path (preventing the transmission of a live image feed). LCD screens on digital SLRs are used for menu navigation and for captured image review.

Digital SLRs do not include/provide video/movie modes, so if the video feature is an important selling point then an upscale prosumer P&S digicam may be a better choice.

Digital SLRs do not generally include a starter memory card in the box (like some P&S digitcams) so K100D purchasers should factor the cost of a fairly large (at least 512MB) SD card into their price calculations/comparisons.

NUTS & BOLTS

Viewfinder

The K100D features what appears to be the same pentamirror optical viewfinder as the Pentax *ist DL2 (available in the U. S. as the Samsung GX-1L). The K100D's optical viewfinder is fairly bright (noticeably brighter than the viewfinder of the Rebel XT). The Natural-Bright Matte II focusing screen is sharp and hue accurate. There's a comprehensive status/function readout and a diopter correction for eyeglasses wearers.

LCD

dSLR LCD screens generally can't be used as viewfinders (like they are with point & shoot digital cameras) so users must compose and frame their images using the optical viewfinder. The LCD screens on all digital SLRs (except one) are used for menu navigation and post exposure image review.

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The K100D's full info 2.5" (210,000 pixel) TFT LCD screen is bright (brightness levels can be adjusted), hue accurate, and shows almost 100% of the image frame (magnification is 0.85x). I didn't like the shiny hard plastic protective LCD cover (since it makes viewing more difficult in bright lighting), but I did like the wide (140 degree) viewing angle. There's a histogram (for checking over/under exposure and dynamic range) in case the need to re-shoot arises.

Lens Mount/Optics

PENTAX KAF mount (compatible with KAF2, KAF, KAJ, and KA mount lenses) K-mount lenses are usable (with restrictions) S (M-42) mount lenses and Pentax 67/645 optics are usable with adapters.

There are literally thousands of cheap used manual focus K-mount and M-42 (S mount) lenses available (from ultra-wide to super telephoto) and that exponentially expands creative possibilities for K100D users. Nikon's famous backward compatible F/AF mount doesn't even come close to providing the astonishing optical versatility offered by the K100D - and every lens (no matter how ancient) benefits from the K100D's image stabilization technology.

My K100D tests were conducted with the nifty pancake-thin new PENTAX DA 21mm F3.2 AL Limited prime lens (provided by Pentax) and an SMC Pentax f4.0-f5.6/18-35 FAJ zoom (thanks to Chuck -- www.chuckrubin.com for the extended loan of the zoom).

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Image Stabilization (IS)

The K100D's most impressive feature is its image stabilization system. Pentax's IS system (Pentax calls this SR -- shake reduction) neutralizes camera shake by stabilizing the CCD sensor. The K100D analyzes input from motion detectors embedded in the camera body and then produces a precisely equal and opposite shift in the CCD to counteract camera shake. Most camera manufacturers (including Canon and Nikon) accomplish IS by shifting lens elements to counteract camera shake. The greatest benefit of camera body IS systems is that they work with every lens mounted, not just with (more expensive) IS or VR lenses.

With image stabilization enabled, K100D users can shoot at shutter speeds up to 3 stops slower. For example if a shutter speed of 1/125th of a second is required to avoid the effects of camera shake - the K100D can capture a sharp picture at 1/15th of a second. K100D purchasers will immediately notice the benefits of Pentax's nifty (Minolta like) IS system - sharp handheld action-sports/low light images can be captured even with long telephoto zooms. The K100D's IS system produces dependably sharp images at shutter speeds that would normally generate blurry pictures, but IS is not a magic bullet - it won't neutralize sharp camera movements or reduce blur caused by rapidly moving subjects or too fast panning. There is no free lunch - IS is a very power hungry feature and appreciably shortens battery life and IS is NOT instantaneous - the IS process adds to the time interval that passes between pushing the shutter button and the moment when the shutter actually fires.

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(view medium image) (view large image) Does IS work? This night shot (K100D with SMC Pentax f4.0-f5.6/18-35 FAJ zoom -- IS enabled) is a bit dark, but substantially sharper than this:

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(view medium image) (view large image) Similar shot made at the same time with a Kodak V610 (faster f2.8 maximum aperture, but no IS)

Auto Focus (AF)

The K100D uses the same TTL phase-matching 11 AF point contrast detection auto focus system as the Pentax ist* DS2. The camera automatically selects the closest AF point to the subject (closest subject priority) and the selected AF point glows red once focus is locked. AF is consistently fast and accurate even in dull lighting, but occasionally there is a noticeable pause between the moment the camera locks focus and the moment when the shutter fires. Since there doesn't appear to be a specific trigger event for this delay it can be quite frustrating, especially when shooting rapidly unfolding action or trying to precisely time the "decisive moment" when all the elements of a composition align perfectly. Continuous AF (which continually adjusts focus as the shooter tracks a moving subject) works pretty nicely in most action/sports shooting situations.

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(view medium image) (view large image) This grabshot of a feisty puppy nicely illustrates the speed and accuracy of the K100D's AF system -- I had no trouble tracking this pooch and when he decided to get cute the K100D's AF locked on (from scratch) him in less than half a second

Manual Focus (MF)

Manual focus is dead simple - just flip the A/M focus switch to the M position, grip the focusing ring and adjust focus manually like "old school" photographers did in those primitive times before auto-focus.

Flash

The K100D's built-in pop-up multi-mode (auto, flash-off, flash-on, auto + red-eye reduction, flash-on + red-eye reduction) automatically pops up when needed - if ambient lighting isn't sufficient or to add fill-flash in back lit situations. The K100D's built-in flash provides a barely decent selection of lighting options and the fastest flash synch speed is only 1/180th of a second - which is fairly pedestrian when compared to the Nikon D50's on-board speedlight's fastest flash synch speed of 1/500th of a second. Guide Number is 15.6 @ ISO 200/m. Coverage is equivalent to 28MM and the maximum flash range (with an f2.8 lens) is about 16 feet.

I did find one noteworthy flash problem - when using fill flash outdoors while shooting in Sports Scene mode there is a consistent 0.5 -- 1.0 second delay from the time the shutter button is pushed until focus is locked and the flash fires. I'm guessing that this occurs because the flash metering function cycles completely before the AF kicks in or because the flash metering function can't cycle until the AF system acquires the subject. This won't be a major fault for most photographers, but it may be an important consideration for sports/action shooters. This minor anomaly can be corrected by programming the flash (via the custom function menu) to fire without focus confirmation and then pre-focusing the camera on the spot where the peak action is most likely to occur.

Hot Shoe

The K100D also features a dedicated flash hot shoe for mounting Pentax Speedlights like the AF360FGZ or the more powerful AF 540FGZ. Third party flash units can be used, but not with full compatibility.

Storage/Image File Formats/Connectivity

The K100D saves images to SD memory cards.

Images are saved in JPEG or RAW formats

USB 2.0HS and A/V out and DC in

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Power/Battery Life

The K100D (unlike most of its competition) draws its juice from four universally available Alkaline, Lithium, or rechargeable NiMH AA (or 2 long-life CR-V3) batteries. Power management appears to be excellent. Pentax claims 430 exposures with four fully charged 2500 mAh NiMh rechargeables and based on my use that seems like a fairly accurate assessment. I didn't keep track of exposures so I can't provide any specific numbers, but I did use the included alkaline AA's through a full weekend of moderate shooting before getting a low battery warning.

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EXPOSURE

The K100D offers users a comprehensive range of exposure options including: Auto (automatically selects one of four common scene modes by assessing the scene in front of the lens and then calculating the optimum aperture, shutter-speed, white-balance, saturation, contrast and sharpness settings for that type of subject), program (P&S mode with user input), shutter priority mode (users select the shutter speed and the camera selects an appropriate aperture), aperture priority mode (users select the aperture and the camera selects an appropriate shutter speed), and manual mode (users select all exposure parameters). In addition the K100D provides four basic scene modes (Portrait, Landscape, Sports, and Macro) and eight more specialized Scene Modes (Night Scene, Surf & Snow, Sunset, Kids, Pets, Candle-light, Museum, and Text). Based on my use, the K100D's auto (Auto, Program, and Scene) modes deliver dependably accurate exposures in practically any outdoor lighting. Pentax invested some obvious effort in the K100D's usability engineering and that sort of dedication to detail results in an imaging tool that becomes an extension of the individual behind the lens. Exposure accuracy in the camera's manual exposure (aperture priority, shutter priority, and full manual) modes is largely dependent on the skill of the photographer. Native contrast interpolation is a bit hard and there is a very slight tendency toward over-exposure and occasional burnt out highlights, but shadow detail is consistently excellent.

Metering

The K100D provides users with TTL open-aperture 16-segment (default) evaluative, center-weighted & spot metering. Light metering and the default evaluative metering mode is consistently accurate and easily covers most outdoor lighting situations. The K100D's target audience will probably use the other two metering options only rarely.

White Balance

The K100D's white balance options include: TTL (through the lens) Auto, and user selectable settings for Daylight, Shade, Cloudy, Tungsten, Fluorescent, Flash, Manual, and Custom white balance.

Sensitivity

The K100D provides an adequate selection of sensitivity settings including TTL Auto and user selectable settings for 200, 400, 800, 1600, and 3200 ISO. It would have been more useful if Pentax had included settings for ISO 50/64 and ISO 100, rather than the ISO 3200 setting.

In-Camera Image Adjustment

In camera image adjustment options are very important because they allow savvy shooters to immediately counter environmental/lighting problems and to more precisely reflect their personal creative vision by tweaking exposure compensation, exposure bracketing, color saturation, contrast, sharpening, and white balance controls.

The K100D's Exposure Compensation option allows users to adjust exposure (which incrementally lightens or darkens the image) + /- 2EV in or 1/3 EV increments to compensate for difficult lighting.

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(view medium image) (view large image) Early afternoon lighting on this midway shot (from the Kentucky State Fair) was a little too bright and contrasty, but minus 0.3 EV of exposure compensation darkened the picture just enough to tone down the harsh mid-day light.

The K100D's auto exposure bracketing function permits users to capture three images of the same subject (in rapid sequence) and vary exposure slightly @ +/-1.5EV (in 1/2EV increments) or +/-1EV (in 1/3EV increments).

The K100D also allows users to select Color Space and adjust color saturation, contrast, and sharpness.

CONTROLS, DESIGN, & ERGONOMICS

The K100D shows a very clear family resemblance to the Pentax *ist DS/DL series. The pro black body looks tough and functional, there's nothing effete here. This camera was clearly designed by photographers for photographers. The polycarbonate body shell over a metal alloy frame (stainless steel lens mount) should stand up to anything short of armed conflict and extreme climates. The built-in handgrip provides a secure hold and very nice balance (for right handed shooters). Controls are minimal, logical, well placed, and intuitive. The Fn button (sensitivity, flash, white balance, and drive mode) , exposure compensation button, and thumb wheel (Pentax calls this an e-dial) are well placed, easily accessible, and very responsive.

PERFORMANCE

Image Quality

dSLR image quality is actually much more dependent on the quality of the lens mounted than it is on the efficacy of the camera's processing and exposure systems. Based on the two lenses I used for my tests, the K100D's image quality is consistently excellent (especially at the ISO 200 sensitivity setting) with very good detail capture in highlight areas, superior detail capture in shadow areas, and crisp edge transitions. Noise is virtually non-existent up to ISO 400, well controlled at ISO 800, and visible but not objectionably so at ISO 1600. ISO 3200 is very noisy. The K100D's native color interpolation is almost perfect, colors are vibrant, bright, well saturated, hue accurate, and close to neutral. Caucasian skin tones are a tiny bit warm, but that is fairly common in amateur and entry level digital cameras. Native (default) contrast is well balanced, but slightly hard. Images show a wide dynamic range and good tonal balance. Chromatic aberration (purple fringing) was remarkably well controlled with the two lenses I used. I didn't notice any luminance/chroma noise (blotching).

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(view medium image) (view large image) The color of these heirloom President Tyler Morning Glories is Royal Purple, but many digital cameras shift purple toward blue -- the K100D renders purple perfectly.

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(view medium image) (view large image) This colorful street rod is rendered very accurately -- the hand buffed bright orange paint and super shiny chrome are just as I saw them

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(view medium image) (view large image) The K100D makes a great close-up camera - Giant Tiger Swallowtail on Budelia

Timing/Shutter Lag

If the K100D had an Achilles heel, it would be timing. The K100D is quick and for most users the slight occasional shutter lag/AF lag/flash metering lag won't be a problem. Start up is virtually instantaneous. The K100D's IS system and AF system work together almost seamlessly - very quickly with little noticeable IS lag. AF lock is essentially real time with pre-focus and about 1/4 to 1/2 a second from scratch. The K100D's slight shutter lag won't prevent savvy shooters from capturing dramatic shots of rapidly moving action, but the ability to anticipate the moment of peak action by about 1/2 a second will noticeably increase the "keeper" ratio.

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(view medium image) (view large image) This vertical skateboarder is about 13-14 feet up the side of a 24 foot full pipe. The K100D stopped the action, perfectly exposed the mixed full sun and full shade lighting, colors are just as I saw them, and shadow and highlight detail are both excellent.

Shot-to-shot and write to card times seem marginally faster than average when shooting JPEGs, but noticeably slower than average when shooting RAW images. The buffer is too small, it can only hold 3 RAW images before users must wait for it to dump to the SD card. Overall, the K100D provides consistently exceptional performance, especially for an entry level digital SLR.

Technical Specifications

A Few Concerns

I don't have any serious concerns, the K100D has a few minor warts, but nothing genuinely significant for its target audience. I do wonder why Pentax didn't drop an 8 megapixel sensor into the K100D, but I'm sure that's already in the works for its successor.

Conclusion

Serious amateur shooters may have a few issues, but family snap-shooters, P&S digicam users just making the jump to a dSLR, student photographers, casual shutterbugs, and old timers with a collection of Pentax glass will appreciate the K100D's reasonable price, robust construction, operational simplicity, use of available anywhere AA batteries, image stabilization, and solid performance. Institutions that teach basic photography should very seriously consider the K100D since no currently available dSLR offers a better balance of features and capabilities and compatibility with thousands of KAF, KA, K, S (M42), and Pentax Medium Format optics. The K100D may actually be a more practical and useful imaging tool than its illustrious predecessor. Shooters who don't need image stabilization can opt for the Pentax K110D (which is identical to the K100D -- minus IS) and save a hundred bucks.

Pros

Solid build-quality, excellent image quality, uses universally available AA batteries, depth of field preview

Cons

Slight shutter lag and minor AF lag