Minolta DiMAGE 7iMinolta updates their revolutionary 5 megapixel electronic SLR with numerous enhancements, keeps the excellent lens.<<Optics :(Previous) | (Next): Shutter Lag & Cycle Time Tests>> Page 6:Exposure & FlashReview First Posted: 6/15/2002 |
Exposure
The Dimage 7i offers excellent exposure control, with very fine-grained
adjustment of such image attributes as sharpness, contrast, and color saturation.
While I found the camera's user interface a little confusing at first, with
its myriad buttons, dials, and switches, I liked it quite a bit once I got the
hang of it. (The combined use of functional dials, selection buttons, and the
rotating command wheel is similar to the design of Minolta's film cameras, and
very reminiscent of the earlier Sony DSC-D770. While something of a departure
for the digicam market, this interface has proven very popular with users of
both Minolta's film cameras, and the (much) earlier Sony camera.)
The Mode dial on top of the camera controls the basic operating modes: Record,
Playback, Movie, Setup, or Data Transfer. Within Record mode, you have several
exposure options: Program AE, Aperture Priority, Shutter Priority, Manual, and
a handful of preset recording modes that I'll describe in just a bit. These
first four are all accessed by turning the Function dial on the left side of
the camera to the PASM position, holding down the button in the middle of that
control, and rotating the Control dial just to the right of the Shutter button.
It's definitely a two-handed process, but quick to execute once you become familiar
with the system.
In Program AE mode, the camera determines the best exposure for the current
shooting situation, setting both the shutter speed and lens aperture automatically.
Aperture Priority mode lets you select the lens aperture setting, from f/2.8
to f/9.5 depending on zoom, while the camera selects the most appropriate corresponding
shutter speed. In Shutter Priority mode, the user selects the shutter speed,
from 1/2,000 to four seconds, while the camera chooses the best corresponding
aperture setting. Switching to Manual mode gives you control over both shutter
speed and aperture, with a Bulb setting available for longer exposures. Bulb
exposure is determined by how long you hold down the Shutter button, up to a
maximum of 30 seconds. The Program Auto button, located on the top panel just
above the Mode dial, is a handy feature, instantly returning the camera to all
of its default settings and the Program AE exposure mode (especially helpful
if you've set a number of functions and are looking for a quick way to get back
to the default settings).
The Dimage 7i's maximum shutter speed requires a little explanation. Like many
shutter systems, the minimum shutter-open time is somewhat dependent on the
aperture setting of the lens, with the shortest exposures only available when
the lens is stopped down a bit. On the 7i, the maximum shutter speed of 1/4,000
of a second is only available when the lens is stopped down to f/8 or smaller.
(Although it also appears to be attainable with an aperture as large as f/5.6,
for some zoom settings.) You thus can't select it in Shutter Priority mode,
since the aperture there is under control of the exposure system. I'd expect
to be able to access the 1/4,000 speed in Manual mode, if I had a sufficiently
small aperture selected, but this seems not to be the case. The 1/4,000 speed
is only avialable when the camera is controlling the shutter speed itself, and
when the aperture is set to a high enough f-stop. In Program AE mode, this happens
automatically in bright enough conditions. In Aperture Priority mode, the camera
will select the 1/4,000 speed if the conditions are bright enough, and you've
manually selected a small enough aperture.
The Dimage 7i's default metering system is a 300-segment evaluative mode, which
takes readings throughout the image to determine exposure. Center-Weighted and
Spot metering options are also available via the Function Dial. Spot metering
is useful for high-contrast subjects, as it bases the exposure reading on the
very center of the image, letting you set the exposure based on a small portion
of your subject. Center-Weighted metering also bases the exposure on the center
of the image, but the camera takes its readings from a mucy larger area in the
middle of the frame. You can also hold or lock the exposure reading for a particular
part of the image by pressing the Spot (AE / AF Lock) button on the back panel.
This control can be set to control either exposure alone or focus and exposure
together. It can also be programmed to act as either a "hold" or "toggle"
control. "Hold" mode does just that, it holds the current setting
until you release the Spot button again. Toggle mode locks and releases the
exposure/focus setting with successive actuations of the Spot button. Halfway
pressing the Shutter button also locks exposure and focus, but only in autofocus
mode. When the camera is in manual focus mode, half-pressing the shutter button
obviously doesn't affect focus, but (strangely) it doesn't seem to lock exposure
either.
The Dimage 7i's sensitivity can be set to Auto, or ISO equivalents of 100, 200,
400, or 800. As with other consumer and prosumer digicams that sport ISO 800
options though, I didn't find the ISO 800 setting to be particlarly useful,
as the image noise level was so high. Exposure compensation is adjustable from
-2 to +2 exposure equivalents (EV) in one-third-step increments, and an auto-bracketing
option can snap three shots in rapid succession, varying the exposure between
each in steps of 0.3, 0.5, or 1.0 EV units. Exposure compensation is adjusted
using the DEC (Digital Effects Controller, while auto bracketing is activated
by rotating the Function Dial to the Drive position, pressing the center, and
then rotating the Control Dial until the auto bracketing icon appears in the
LCD or EVF display. Exposure step size for auto bracketing is set via the Custom
2 submenu of the record-mode menu system.
White Balance & Color Control
The Dimage 7i offers unusually flexible control over white balance,
color rendition, and tonal range. Its white balance system offers a total of
six options, including Auto, Daylight, Tungsten, Fluorescent, Cloudy, and Custom,
which is the manual setting. The Custom Set mode determines white balance by
snapping a picture of a white card. The camera then adjusts its color balance
to render the white card with a neutral hue, and saves the setting as the Custom
option.
Contrast and Color Saturation controls on the Dimage 7i provide a great deal
of flexibility. Both of these parameters are adjustable in seven steps across
a fairly broad range of settings, using the Digital Effects dial on the camera's
left side in conjunction with the Control Dial next to the Shutter button (the
same controls used for Exposure Compensation). To make adjustments, you rotate
the Effects dial to the parameter you're interested in changing, press the button
at its center, and then rotate the Control dial to choose the desired setting.
The large number of steps in both of these settings make them really practical
for fine-tuning the camera to match your shooting preferences. If you'd like
a bit less contrast, or a bit more color saturation (my preference in both cases),
it's easy to dial that in using these controls.
In addition to these subtle color and tonal adjustments, the Dimage 7i also
offers a handy new Filter setting on the Effects dial. Depending on the color
mode selected through the Custom Settings menu, the Filter option adjusts the
overall color cast of the image, also in seven steps. The color range here varies
from rather blue to rather yellow, exactly the color axis that you'd want to
adjust to compensate for different color temperatures in your lighting. When
Natural or Vivid Color modes are in use, the Filter effect adjusts from -3 to
+3. Positive adjustments warm the image, while negative adjustments produce
a cooler color balance. In Black and White mode, the Filter effect tones the
image in eleven steps, cycling from neutral to red, green, magenta, blue, and
back to neutral (zero position).
Through the Color Mode option of the record menu, the Dimage 7i offers the Natural
and Vivid Color modes listed above, as well as a Black and White mode and a
Solarization mode. Solarization partially reverses the tones in an image, and
the Exposure Compensation adjustment controls the intensity of the effect. The
record menu also offers a Sharpness adjustment, for controlling the amount of
in-camera sharpening applied to an image.
Subject Program Modes
The Dimage 7i provides five preset exposure modes, including Portrait, Sports,
Sunset, Night Portrait, and Text, accessed by pressing the Mode Select button
next to the small status display panel on top of the camera (an indicator highlights
each mode as it's selected). Portrait mode produces better-looking people shots
by enhancing skin tones and decreasing the depth of field (to create a slightly
blurred background). Sports mode provides faster shutter speeds to freeze action,
and maintains focus on quickly moving subjects. In Sunset mode, the camera employs
slightly slower shutter speeds to let in more of the ambient light, and lets
you record the warm colors of the scene without compensating for them in the
white balance system. In Night Portrait mode, the camera also uses a slower
shutter speed to allow more ambient light into the image, however it also records
true black values and preserves the bright colors of artificial lighting. The
final preset mode is Text mode, which optimizes the camera for capturing black
text on a white background, keeping the contrast level high so the camera doesn't
expose for neutral gray.
Continuous Mode
New to the Dimage 7i are several continuous shooting modes, all accessed
via the "Drive" setting on the left-side Function dial. In addition
to the standard Continuous Advance mode, the Dimage 7i also offers Interval
and UHS Continuous Advance modes. (Note that the Drive setting also access the
Self-Timer and Auto Exposure Bracketing modes.) In standard Continuous Advance,
the Dimage 7i captures a maximum of 40 consecutive frames at approximately two
frames per second, for as long as the Shutter button is held down (numbers are
for small/basic images). Depending on the resolution and quality settings, as
well as the amount of memory card space, the maximum number of frames and the
frame rate will vary. (It's good for five or six shots at the large/fine image
quality setting.)
UHS Continuous Advance mode captures a much more rapid burst of images, though
resolution is automatically forced to 1,280 x 960 pixels. Images are captured
at a maximum of seven frames per second (7.14 fps in my own tests), though again,
quality settings and available memory space may limit the speed and number of
images in the series. If the UHS Movie function is activated in the record menu,
the camera also records a 640 x 480 movie clip, with audio, simultaneous with
the 1,280 x 960 image series.
Interval mode captures a series of images at specific intervals over time, providing
a built-in time-lapse capability. The Dimage 7i captures a maximum of 99 images
in the sequence, with frame intervals ranging from one to 60 minutes.
As I mentioned, the Drive setting also accesses the Self-Timer and Auto Exposure
Bracketing modes. The Self-Timer counts down from 10 seconds between the time
the Shutter button is fully pressed and the shutter actually fires. An LED lamp
on the front of the camera blinks to indicate the time. Auto Exposure Bracketing
mode captures a series of three images (one at the metered exposure, one underexposed,
and one overexposed). You can set the exposure variation between exposures to
0.3, 0.5, or 1.0 EV. The Effects dial must be turned to the Exposure Compensation
position for an exposure series. If the dial is set to Filter, Contrast, or
Color Saturation, the Bracketing series will bracket the effect selected. (Another
slick capability.)
Movie and Sound Recording
The Dimage 7i has a Movie mode that records moving images with sound, for as
long as 60 seconds per movie. The amount of recording time appears in the LCD
or EVF monitor display. Movies are recorded at 320 x 240-pixel resolution. Through
the Record menu, you can set the movie mode to Auto, Standard, or Night. Night
mode records black and white movies in low lighting situations. The Auto setting
tells the camera to automatically decide between Standard and Night modes, based
on the exposure conditions.
A Voice Memo mode records either five or 15 seconds of audio to accompany still
images. The mode must be enabled before image capture. A microphone icon appears
in the LCD/EVF display. Immediately after image capture, the camera begins recording
audio for the specified time.
Flash
The Dimage 7i features a built-in, pop-up flash, which operates in either Fill-Flash,
Red-Eye Reduction, Rear Flash sync, or Wireless modes. (Wireless flash sync
is a new option on the Dimage 7i.) To release the flash from its compartment,
pull on the two small tabs on either side of the casing and lift up the flash
head. The Flash mode is changed through the Record settings menu. In Fill-Flash
mode, the flash fires with every exposure, regardless of lighting conditions.
Red-Eye Reduction fires a series of small pre-flashes before firing the flash
at full power with the exposure. This makes your subjects' pupils contract and
reduces the occurrence of the redeye effect. The Rear Flash Sync mode fires
the flash at the end of the shutter time, rather than the beginning. If you
have moving objects in a relatively brightly lit environment, this will produce
a sharp image of your subject, with a "motion trail" following behind
it. The flash is in the Off position when it's closed. The Wireless mode lets
the camera work with wireless remote flash units, with four channels available
through the settings menu, so different camera/flash setups working in the same
area won't interfere with each other. (Minolta makes two flash units that support
the D7i's wireless capability, the Program Flash 5600HS [D] and 3600HS [D].)
The Dimage 7i is unusual in that it offers two methods of flash metering. Its
default mode is called ADI, which stands for Advanced Distance Integration.
In this mode, it apparently bases its flash exposure on the lens aperture and
feedback from the autofocus system, as well as on the light reflected back from
a pre-flash. By determining how far away the target subject is, the camera knows
how much flash power is required to illuminate it. As a fallback, a Pre-Flash
TTL (through the lens) method bases the exposure determination solely on a small
metering flash before the main exposure. Used in conjunction with the spot autofocus
option mentioned earlier, the ADI flash metering should be much more accurate
with small subjects against a different colored background than the pre-flash
method.
For use with studio strobes and conventional slave triggers, the Dimage 7i
has a manual flash power option. This lets you set the flash power to Full,
1/4, or 1/16 power manually. In this mode, the flash fires only once, at the
moment of exposure. The single flash prevents false triggering when working
with conventional slave triggers.
The Dimage 7i also includes a top-mounted hot shoe for attaching an external
flash unit. The shoe design and contact arrangement are set up for Minolta's
own dedicated flash units, but I imagine that compatible units are available
from the major third-party flash manufacturers (Sunpak et. al.). Minolta's own
Program Flash models 3600HS(D) and 5600HS(D) both work with the Dimage 7i, and
two macro flashes (Macro Twin Flash 2400 and Macro Ring Flash 1200) will work
with an accessory macro flash controller.
I had a chance to play a bit with a couple of Minolta's dedicated flash units
while I was testing the Dimage 7i, and must say I was impressed. I only shot
with the 5600 model (a conventional hot-shoe mounted unit, but with the added
capability of wireless control) in a fairly small area, so didn't test the maximum
range over which the wireless TTL control would work with the D7i. (I'm sure
it has some maximum range over which it's effective, but don't know what that
is.) That said though, the camera/flash combination worked exceptionally well.
Very slick, given that no extra controller or other hardware is needed to establish
the wireless link between the flash and the camera. This has to be of the neatest
flash arrangements I've seen yet on a digicam.
For closeup work, the T2400 macro twin flash is a very capable setup too. -
A large ring mounts to the front of the lens, and serves as a support mount
for a pair of tiny flash heads. The litle flash heads are powered by a flash
controller that looks just like a normal hot-shoe flash unit, but has two sockets
on its front instead of the flash tube. The ring has multiple mounting points
around it for the little flash heads, so you can direct the light to come from
top, bottom, or either side with equal ease. The flash controller also lets
you set the power ratio between the two heads, so you can have a "main"
and "fill" light on your macro subject. Very flexible, very
slick (if not a little odd-looking). Highly recommended if you intend to do
any really extensive macro work. (This should be a great solution for people
selling tiny objects (coins, jewelry?) on eBay, looks like a sure winner for
dentists looking to document their work, entomologists wanting really good bug
pictures, etc, etc.)
Color Space
This is probably as good a place as any to talk about the Dimage 7i's color
space. The original Dimage 7 used a proprietary color space with a much wider
color gamut than the sRGB space used by most digicams. (As well as by most computer
monitors, consumer-grade printers, etc.) The result was it could capture a much
broader range of colors than other cameras, but this also meant that the raw
JPEGs straight out of the camera looked rather flat and dull when viewed on
a typical computer monitor. To get the full color to appear, you needed to run
the image files through Minolta's Dimage Viewer software utility, and convert
their color space back to sRGB. (Or whatever other working space you wanted
to use. - Many graphics professionals work in the so-called "Adobe RGB"
space popularized by Photoshop(tm), which is supported by many graphics programs
and printers, and also offers an expanded color gamut.)
While the expanded color gamut was a real boon to graphics professionals and
others interested in breaking free of the constraints of sRGB, for the average
amateur it amounted to just one more step to go through before they could fully
enjoy their photos. Worse, if someone wasn't aware of the color space issue,
they'd probably write off the Dimage 7 as having rather flat, undersaturated
color.
With the Dimage 7i, Minolta has stepped back closer to the mainstream in the
color space department. They still use a proprietary color space in the 7i,
but it's one that's much closer to sRGB. The result is that most images look
just fine straight out of the camera, even viewed on an sRGB computer screen.
If you want the absolute maximum in color quality though, you'll still want
to go through the conversion process to map the color onto whatever color space
you're using.
I have to admit that when I first looked at the images from the Dimage 7i, I
had a hard time seeing any visible differences between the raw JPEGs and ones
that had been converted to sRGB for onscreen viewing. As an aid to my readers
in seeing just what the differences are, I've prepared the samples below. The
first sample is a before/after sample, showing the MacBeth chart from my "Davebox"
test target. There are two images there, one exactly as it came from the camera,
the other converted to sRGB. Roll your mouse over the image to switch back and
forth between the two. (As you can see, there's really precious little difference
between the two.)
The second image (below) shows the color differences (significantly amplified) between an sRGB image of the Davebox and the original from the camera. I prepared this by subtracting the original camera image from the sRGB version channel-by-channel in Photoshop. I then took the resulting file and cranked the white point way up in Photoshop, setting it to a brightness level of only 8. (Yes, the maximum difference between the two images was only 8 brightness units, out of a possible range of 255.) This image shows the contaminant colors that Dimage Viewer subtracted from the original camera file to map it into sRGB color space. Thus, a brighter, more saturated yellow was made by subtracting a little blue from that color swatch, blue being the complement of yellow. (This is only one crude way of looking at the result. - A full discussion of color theory is obviously beyond the scope of this review.)
Reader Comments! --> Visit our discussion forum for the Minolta DiMAGE 7i!
Follow Imaging Resource: