Thursday, November 13, 2014

Use Exposure to Enhance Deep Shadows

Boatyard, Maine: The sun was low in the sky and created a strong contrast lighting situation. If this scene had been read with evaluative (pattern) metering the shadow area would have become lighter but all the draama of the light and color would have been lost. To make this exposure in camera a spot meter reading was made off the yellow hull in the background and locked.


While there may be times when you want to expose so that the detail in shadows is “open” and reveals detail, deep, texture- and detail-less shadows can play an important role in composition.  Such shadows can also take on a life of their own and have shape and volume that can be as important to the composition as the visible content itself. They also can break the rectangular frame by spilling into the edges and making curved, triangular and truncated edges.

For this to work the scene contrast must be rather high, or high enough to have no detail or content within shadows when exposure is made to properly expose the highlight areas.

Exposure readings should be made from the brighter or brightest part of the frame alone, with the shadow removed from consideration.  This generally means use of spot metering pattern, or, if the brightness spreads through the frame enough, center-weighted averaging. If need be, a minus exposure compensation can be applied as well.

Tools to Use: Spot metering pattern; exposure lock; exposure compensation.


Artifacts, Cologne, Germany: Made outside the Roman-Germanic Museum in late day light, these artifacts and a post-war building in the background caught the last rays of light. Exposure was made with spot metering off the bright foreground column, which “drove down” the tonal values of the surrounding shadow areas. Standing there I could see detail in the entire frame, but by metering the brightest areas I created an abstract of light and form in the frame. You might want to bracket for insurance and perhaps add +1 exposure compensation when metering bright white areas.

Photos copyright George Schaub


Wednesday, November 12, 2014

Nikon D750 Review and Test Results




Nikon D750 Review and Test Results


These test results and comments are from Betternet, the testing lab for TIPA (Technical Image Press Association) in which I serve on the Technical Committee.
The Nikon D750 is a full frame DSLR with some features usually found APS-C sensor cameras (WiFi, swivel monitor). The D750 offers 24MP and closes the gap between the D610 and the D810. It is the follower of the six-year old D700, but has a completely new design (sensor, AF system and more).

The new Nikon D750 fills a niche between the Nikon D610 and the D810 cameras. It uses a new full-frame sensor with 24MP and of course a Nikon F-mount. It has some rather unusual features for a professional Nikon SLR such as a swivel monitor and an integrated Wi-Fi system. Until now Wi-Fi was only used in Nikon's entry level or APS-C cameras or was offered as an optional accessory system (the WT-5 for direct image transfer to a server or WU-1b for wireless connection to smartphones or tablet).

The Nikon D750 has a sealed body. The interfaces on the left hand side are covered by massive rubber caps. The camera offers USB, HDMI, plus a microphone jack and an earphone jack for sound control when recording video. In addition it has a Nikon interface for optional remote control.

The D750 is a rather large and robust camera with a sealed body that allows use under heavy rain or other challenging conditions.
The handling will be quite familiar to Nikon users. A large dial on accesses standard exposure modes, scene modes, image effects and two user defined settings. Directly beneath the mode dial is the setup dial to choose the drive mode (single frame, continuous shooting, self-timer and more). Five function buttons sit on the left hand side of the LCD screen, plus there are many other function buttons on the top and back of the camera that allow the user to change all image parameters very quickly and efficiently.

The large LCD screen can be flipped up- and downwards. Function buttons on the left of the screen prevent the ability to swivel the monitor side to side.

All function buttons and setup dials on the back are very robust and handy. The photographer can access all control elements very comfortably and easily.

The very handy and identified buttons on the body allow for quick changes to, for example, ISO speed settings and white balance modes. An 8-way control field allows for quick menu navigation, along with two setup dials to change image parameters like shutter speed and aperture. In addition, numerous individual settings and parameters can be changed in the menu.

The camera uses a new AF system called Multi-CAM 3500FX. It has 51 AF sensors and is remarkably fast. It will keep even very fast moving objects in focus and works efficiently and decisively. This makes it fun and rewarding to work in high-speed continuous mode, with up to 6.5 frames per second. The focusing system is highly configurable, among them a choice of groups of AF sensor areas for precise focusing. It is also very easy to focus manually because the camera has a very large and bright viewfinder. When using the LCD screen as viewfinder, the D750 can magnify an image area for very precise control.
The Nikon D750 has a large status LCD on top. Note the second shutter button for video recording. A large setup dial on the left allows settings for standard exposure modes, scene modes and user defined settings.

The D750 has a very large 3.2-inch LCD screen that can be flipped up- and downwards. The resolution of the screen is very high (1.2 million RGB dots).

Comments on Image Quality
Color: The automatic white balance system of the D750 worked very well regardless of the ambient light conditions. In some shots it showed a slight shift into the yellow and green direction, but these are only minor effects. Our standard test image is reproduced with a very neutral gray background. The portrait shot shows a slight shift into the yellow direction in the background.

The average color errors are on a low level. Only blue nuances are extremely boosted and the reason for the high result of the average saturation (111.9 percent). While the blue nuances show a large shift the red, yellow and green nuances have a much lower error level. Skin tones are reproduced nearly perfectly.


Our color test chart shows a high average saturation, which is based on the very intense blue nuances. The portrait shot shows that the Nikon D750 has a much lower saturation in red and yellow colors as well as in skin tones.

Sharpness: Somewhat surprisingly, the camera uses a sensor with low pass filter: many other current Nikon DSLRs eliminated this filter. Nevertheless, the resolution result is very good. The camera reproduced the test chart with 3899 lines of 4016 lines, which is a very high result. Both test images are reproduced with sharp structures without any aliasing or moiré effects. Fine details like the hair of our model are reproduced very clearly and naturally.


The standard test box shows colors reproduced in a neutral way (gray background), and only blue nuances are boosted. The camera reproduced fine details, like the structure of the red spool, with very clear and natural color differentiation.

Noise: The D750 showed a very good result in our noise tests. Luminance noise is slightly higher than in images taken with other Nikon or Canon cameras, but keeps on a very low level even at the highest ISO speed settings. Even at ISO 12,800 mode it’s way below 1.0 percent. The color noise is very good. Up to ISO 3200 it is nearly invisible; at ISO 6400 and ISO 12,800 mode some anti- noise filtering effects get visible, but are still quite good. The dynamic range results are extremely high. The camera gained a maximum of 11.9 f-stops and keeps a high level of more than 10 f-stops up to ISO 3200 mode.

Comments on Video Capabilities
 The new D750 the camera has some new video features. It records video in full HD resolution, but now is able to record at higher frame rates of 50 or 60 frames per second. In addition, it offers a 24p mode, which is compatible to Blu-ray discs.

All video files are saved as Apple QuickTime MOV files and H.264 video compression. It is also able to send a “clean signal” without any overlays to the HDMI interface for external video recording in higher quality/less image compression.

Shooting videos with the D750 is quite easy. The photographer can switch between photo and video mode by using the “LV” button on the back. When using the Live View in video mode the second shutter release button on the top starts video recording.

The camera allows the use of all numerous modes for video recording such as P, S, or A, plus manually-chosen ISO settings between 100 and 12,800. The sound can be controlled manually via a microphone jack and an earphone jack for better sound quality and control.

Video Quality
The Nikon D750 showed a good result in the video resolution tests. It reproduced the full HD frame with 836 of 1080 lines, which is very good and near the top of its class. Fine details are reproduced very clearly, with the camera showing only very minor Moiré effects. The color reproduction is similar to the color reproduction in photo mode. The test chart showed boosted blue nuances, but other colors are reproduced very naturally. The skin tones are very accurate and natural. Noise test results and dynamic range are also similar to photo mode. The camera gained a maximum of 11.9 f-stops in lower ISO modes and showed video images with very good contrast reproduction.

Scorecard
Pro
very good image quality
excellent results in resolution and sharpness tests
massive body
large optical viewfinder with 100 percent field
swivel monitor
Wi-Fi
enhanced video capabilities

Con
monitor cannot be moved sideways (can only flip up- and downwards)

Price: $2299 (Nikon Store, price as of this posting)