Pentax *ist-DPentax's first d-SLR is a winner, with good color, low noise, and excellent "hand feel," all in a compact body.
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ISTD Sample ImagesReview First Posted: 03/30/2004
Digital Cameras - Pentax *ist D Test Images
|I've begun including links in our reviews to a Thumber-generated index page for the test shots. The Thumber data includes a host of information on the images, including shutter speed, ISOsetting, compression setting, etc. Rather than clutter the page below with *all*that detail, we're posting the Thumber index so only those interested inthe information need wade through it!|
The extreme tonal range of this image makes it a tough shot for many digicams, which is precisely why I set it up this way, and why I shoot it with no fill flash or reflector to open the shadows. The object is to hold both highlight and shadow detail without producing a "flat" picture with muddy colors, and the *ist D did a pretty good job, although the default image is a bit more contrasty than I'd like.
The shot at right was taken with a +0.2 EV exposure compensation adjustment, which results in bright highlights and somewhat dark midtones. Because the deliberately harsh lighting of this scene produces such high contrast, I shot it with the camera's low contrast setting. This did a nice job of boosting midtone detail without over-brightening the image. (See below for a side-by-side comparison.) I chose the Auto white balance as the most accurate overall, though the Daylight setting produced nearly identical results.
The overall color is good. It's a bit less saturated than most consumer-level digicams, but I think in the process is more faithful to the original subjects. My main complaint here is that Marti's skin tones look a little pale and yellowish here. The blue flowers in the bouquet are a little darker than in real life, and with somewhat more purple in them, but are overall fairly accurately rendered. (This is a troublesome blue for many digicams, and the *ist D does show a bit more purple than is in the flowers themselves.) Although the skin tones are a little flat, saturation in the strong reds, yellows, and greens is pretty good. Resolution is high, with good shadow detail, but it looks like the camera focused primarily on the flower bouquet, rather than Marti's face, leaving details in her face and hair a little soft. Image noise is quite low, even in the dark shadows.
Higher resolution and detail, low-contrast setting helps handle the lighting.
Exposure and color are similar to the wider
shot above, with high contrast again from the harsh lighting.
The shot at right was taken with a +0.3
EV exposure compensation adjustment at the low contrast
setting. (See the comparison below for another side-by-side
showing the effect of the contrast adjustment.) Some distortion
is noticeable in Marti's face from the 16-35mm lens
I shot this with. (Keep in mind though,
that the *ist D features a standard Pentax K lens mount, for
attaching a wide range of lenses.) Resolution and detail are
much better in this close-up shot, with Marti's face and hair
showing a lot of fine detail.
To view the entire exposure series from zero to +1.0 EV, see
files ISTFACP0.HTM through ISTFACAP3.HTM on the thumbnail
Indoor Portrait, Flash:
A lot of exposure compensation required with the built-in flash, but good color.
The *ist D's built-in flash produced a very dark image at its
default exposure setting, requiring
a +1.7 EV exposure compensation
adjustment for a reasonably bright shot. Coverage is pretty
even across Marti's features, but the direct flash exposure
is somewhat harsh. Color is pretty good, if a little flat,
with a very good blue in the flower bouquet. The background
incandescent lighting results in only a faint orange cast
at the top of the back wall, and in the shadow areas on the
wall. I also shot with an external flash unit, bouncing the
flash for more even lighting. I found the best exposure with
a +2.0 EV exposure compensation
boost, although the image still came out somewhat underexposed.
The orange cast is a little stronger here, affecting the color
balance throughout the frame.
Indoor Portrait, No Flash:
Good color with the Manual white balance setting, but a *lot* of exposure compensation required.
This shot is always a very tough test of a camera's white balance
capability, given the strong, yellowish color cast of the
household incandescent bulbs used for the lighting. The *ist
D's Auto white balance setting trouble
with this difficult light source, though the Incandescent
and Manual settings performed pretty
well. I chose the Manual setting for the main selection here,
because overall color looked more realistic than the warm
tone of the Incandescent setting. Skin tone looks good, though
the blue flowers of the bouquet have a dark, purplish tint.
(Probably to be expected, given the light source.) The shots
at right were taken with a +1.7 EV exposure compensation adjustment,
which is higher than average for this shot.
High resolution, although details are quite soft, but good color.
I chose the *ist D's Auto white balance
setting for this shot, as it produced the best overall color
and white value on the house trim. The Daylight
setting resulted in a warm cast, while the Manual
setting was a bit cool and reddish. Resolution is quite high,
even though details are rather soft throughout the frame.
A lot of fine detail is visible in the house front and shrubbery,
however, and comes out if you apply a fairly strong unsharp
masking operator to the image in Photoshop(tm). (Try 250-300%
at a radius of 0.4 pixel.)
High resolution, though details are again soft. Good color, but somewhat overexposed with the default camera setting.
(Apologies for the tilted image!)
This image is shot at infinity to test far-field lens performance. NOTE that this image cannot be directly compared to the other "house" shot, which is a poster, shot in the studio. The rendering of detail in the poster will be very different than in this shot, and color values (and even the presence or absence of leaves on the trees!) will vary in this subject as the seasons progress. In general though, you can evaluate detail in the bricks, shingles and window detail, and in the tree branches against the sky. Compression artifacts are most likely to show in the trim along the edge of the roof, in the bricks, or in the relatively "flat" areas in the windows.
This is my ultimate "resolution shot," given the infinite range of detail in a natural scene like this. The *ist D captures a lot of fine detail, but details are again quite soft throughout the frame. (Once again though, they respond well to strong unsharp masking in Photoshop.) The tree limbs over the roof and fine foliage in front of the house show strong detail, though leaf patterns aren't as clearly defined as they could be. The camera loses virtually all detail in the bright white paint surrounding the bay window, a trouble spot for many digicams, but perhaps as a result there's a lot of detail visible in the shadow area above the front door. Overall color looks just about perfect, despite the slightly over-bright exposure. The table below shows a standard resolution and quality series, followed by ISO, sharpness, contrast, and saturation series.
Lens Zoom Range
A 27-53 mm effective zoom range with the "standard" 18-35mm lens.
I routinely shoot this series of images to show the field of view for each camera, with the lens at full wide angle, at maximum telephoto, and at full telephoto with the digital zoom enabled. However, the *ist D doesn't offer any digital zoom, and the actual zoom range will be entirely a function of the lens in use, as the *ist D accommodates a range of Pentax K mount lenses. For that reason, I don't bother with these shots, but with the *ist D, the 18-35mm lens is likely to be a common companion to the camera, so I shot this series with it 18-35mm so readers could see what its zoom range looked like. Following are the results at the two ends of the zoom range.
Nearly accurate color with the Daylight white balance, though a little warm. Good detail.
This shot is often a tough test for digicams, as the abundance
of blue in the composition frequently tricks white balance
systems into producing a warm color balance. The *ist D's
Manual white balance setting responded
with a cool, magenta cast, while the Auto
and Daylight settings resulted
in warm color balances. Though it does have a yellow tint,
I chose the Daylight setting because of the more natural skin
tones. The yellow cast gives the blue background and robe
a greenish tint, but overall color is still pretty good. Resolution
is very high, with strong detail in the embroidery of the
blue robe, as well as in the instrument strings and beaded
The power of interchangeable lenses: A very tiny macro area with the 100mm macro lens.
This is another shot I don't commonly do for d-SLRs, as the
results are entirely dependent on the lens employed. In the
case of the *ist D though, I couldn't resist the lure of the
Pentax 100mm f/2.8 macro lens. As you'd expect, it did an
excellent job, capturing a very tiny minimum area of only
0.94 x 0.63 inches (24 x 16 millimeters). Resolution was very
high, with a lot of fine detail visible in the dollar bill.
However, details were again soft throughout the frame. The
camera's flash was pretty completely blocked by the lens when
shooting this close, so you'll need a macro ring or alternative
lighting for shooting at this close range.
"Davebox" Test Target
Some overexposure with the default settings, and difficulty with the more subtle tonal variation, but very good color.
The *ist D's Manual white balance
setting produced the most accurate results here, though the
Auto setting wasn't too far off
the mark. (The Daylight setting
was quite warm, however.) On a number of my shots, I found
that the *ist D tended to overexpose somewhat at its default
settings, and that's what happened again here. As a result,
the camera has trouble distinguishing the more subtle tonal
variations of the Q60 target, washing out the lighter color
blocks. The larger color blocks are also a little washed out
from the overexposure, but the color accuracy is good. Detail
is moderate in the shadow area of the charcoal briquettes,
with low noise.
Excellent low-light performance, with good color at even the darkest light levels. Excellent low-light focusing ability as well.
The *ist D offers full manual exposure control, with adjustable ISO and a maximum shutter time of 30 seconds. Thus, the camera can capture bright images in very low lighting. The *ist D produced clear, bright, usable images down to the 1/16 foot-candle (0.67 lux) limit of my test, with good color at all five ISO settings. However, some slight color shifts occurred depending on the brightness level. The *ist D's optional Noise Reduction system has a fairly subtle effect on noise levels, but the noise wasn't as bad as I imagined it would be, even at the ISO 3,200 setting. Here are sample images without Noise Reduction enabled at the 200, 400, 800, 1,600, and 3,200 ISO settings. Even though it has no autofocus-assist light, the *ist D can achieve focus lock at very low light levels - While the AF speed slows significantly at low light levels, I found that my test unit of the *ist D could routinely focus at light levels as low as 1/4 foot-candle, and sometimes focus as dark as 1/8 foot-candle, without using its focus-assist illuminator, and with a lens with a maximum aperture of f/4.0. (This is a pretty impressive performance, 1/4 foot-candle corresponds to an exposure time of 8 seconds at f/2.8 and ISO 100.) The table below shows the best exposure I was able to obtain for each of a range of illumination levels. Images in this table (like all sample photos) are untouched, exactly as they came from the camera.
(Note: If you'd like to use a light meter to check
light levels for subjects you might be interested in
shooting, a light level of 1 foot-candle corresponds
to a normal exposure of 2 seconds at F/2.8 and ISO 100.)
Flash Range Test
A powerful flash, Pentax's guide number of 15.6 meters at ISO 200 seems justified.
Since it's a removable-lens SLR, the *ist D's flash range will depend on the lens you're using. Pentax gives it a guide number of 15.6 meters at ISO 200. The shots below were taken with the 18-35mm f/4.0-5.6 zoom I used for most of my shooting, and most of them were shot with the lens at the 35mm end of its range. With an aperture of f/5.6, the range should thus be 15.6 meters divided by f/5.6, or about 9 feet. My results below seem to support that, with progressive falloff in all the shots, but holding reasonably well to the 9-foot level. With a faster lens or higher ISO setting, the range would be correspondingly greater. Below is the flash range series, with distances from eight to 14 feet from the target.
High resolution but a somewhat soft image, 1,350 lines of "strong detail." Average barrel distortion.
The *ist D performed well on the "laboratory" resolution test chart, with clean lines even as far as 1,000-1,200. I found "strong detail" out to at least 1,350 lines (some less conservative judges might argue for 1,400 lines). "Extinction" of the target patterns didn't occur until about 1,600 lines. This shot again shows Pentax's conservative approach to in-camera sharpening though, as the image as a whole is somewhat soft-looking. It does respond well to strong unsharp masking in Photoshop (try 250% at an 0.4 pixel radius or 300% at 0.3 pixel). This is arguably the best approach, as it avoids the introduction of any irreversible artifacts from the sharpening process, but many prospective users might pass over the camera if they don't take the time to play with its images a little in an image editor.
Optical distortion on the *ist D will vary with the lens in use. With the 100mm f/2.8 macro lens I used to shoot the res target with showed essentially zero distortion. The 16-35 mm zoom showed about 0.7 percent barrel distortion at its wide angle end. Chromatic aberration was quite low with both lenses, showing only a single pixel of fairly faint coloration around the target lines, and the 16-36mm about three to four pixels of color, also fairly faint. (This distortion is visible as a very slight colored fringe around the objects at the edges of the field of view on the resolution target.)
Resolution Series, Wide Angle
Viewfinder Accuracy/Flash Uniformity
A pretty accurate digital SLR.
The *ist D features a digital SLR (single lens reflex) viewfinder design, which shows about 96 percent of the final frame. I like to see SLR viewfinders that are 100 percent accurate, so the *ist D has a little room for improvement. Still, these results are pretty good, as "95%" viewfinders seem to be the norm on d-SLRs. Flash distribution is a little uneven here though, with strong falloff in the corners and at the edges of the frame. (This image was shot with the 16-35mm zoom at the wide angle end of its range, corresponding to a 27mm lens on a 35mm camera.)
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