Tag Archives: Nikon D2Xs

Manage the Background – Part three.

I previously discussed managing the background through Depth of Field and through contrasting tone values. This last discussion revolves around the third method of setting off the subject, using contrasting or complimentary colors.

To understand this color concept better, we need to review the theory revealed in the Color Chart. For purposes of discussion in digital photographic terms, we use the RGB (Red, Green, Blue) color chart (below), an additive color scheme.

RGB Secondary Color wheel

In the RGB color chart (above) we see the photographic Primary Colors of Red, Green and Blue labeled in white. You may notice they are spaced evenly in thirds, or 120 degrees, around the wheel. Across the wheel from each of the the primary colors we see the Secondary Colors of Magenta, Cyan and Yellow. These secondary colors are actually made up of equal parts of the two adjacent primary colors.

Colors that are opposite each other on the chart have maximum color contrast, and are called complimentary colors. Two colors commonly found in nature are blue and yellow, a maximum color contrast of two complimentary colors.

In this sunflower photo the yellow flower contrasts perfectly in color with the blue background. This is because the yellow is exactly opposite the blue on the color chart. That makes them complimentary colors and one of the most visible of color contrasts.

Sunflower-2014
_DSC6502-Sm Nikon D2Xs, 200mm F4.0 Micro Nikkor, daylight.

For this cone flower (above) we have the  secondary color of magenta petals against the primary green background. Based upon our understanding of the color wheel these colors are still complimentary, thus of maximum color contrast.

GalliardiaMoth-1533-SmNikon D2Xs, 200mm F4.0 Micro Nikkor, daylight.

However, in the Indian blanket flower photo (above) the reds and oranges are not complementary to the green background. This is because they are not opposite on the color wheel.They are in fact, analogous, meaning adjacent on the wheel. Analagous colors work well together and create a harmonious color scheme. Here, the yellow tips to the flower petals separate it from the background primarily by contrasting tones rather than color.

However , the Shinia moth near the flower  center, a symbiotic insect to the Indian blanket, does not contrast well with the flower. This is actually to the moth’s benefit- a color mimicry trait that protects this moth from predators.

So, what ever the method you can use to separate your subject from the background, it’s a good tool to help attract the viewer’s attention to the subject. If more than one technique can be used in a single image, that’s even better.

Good photographic composition begins with a visual preview of the scene. Do everything you can to find and use as many elements of good design to give your image as much impact as you can within the camera. That will make the task of post processing must easier and allow your images leave the viewer with a lasting impression.

Copyright © 2016 Brian Loflin. All rights reserved.

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Understanding the myth of “Crop Sensor” cameras.

Why crop sensor cameras do not produce greater subject magnification than their full-frame brothers.

I am disturbed by a lot of talk over the last few years stating that cameras with “crop sensors” produce larger in-camera subject size to cameras with full frame sensors. This thinking is both incorrect and continues to mislead the photography world. I feel this misleading language comes from two camps: One, the marketing folks who try to tell us that with a 1.6 crop sensor our 200mm lens is now a 320mm lens. And two, the wildlife photographers who want large in-camera images and who use a crop sensor camera believing the crop sensor somehow produces greater subject magnification.

Let me provide a couple of examples of that talk:

“For nature, wildlife and sports enthusiasts, it might make more sense to stick with a smaller sensor. You can take advantage of the crop factor to get maximum detail at long distances.” http://digital-photography-school.com/full-frame-sensor-vs-crop-sensor-which-is-right-for-you/

 “…the Mark IV has the 1.3 crop factor and a higher megapixel count than the D3s, which are nice for telephoto work.” http://www.deepgreenphotography.com/the-gear/

 “Focal length measurements on lenses are based on the 35mm standard. If you are using a crop frame camera the sensor is cropping out the edges of the frame, which is effectively increasing the focal length. The amount of difference in the field of view or focal length with a crop sensor is measured by its “Multiplier.” And,

 “…while a crop sensor DSLR doesn’t provide the same level of image quality as a full frame DSLR, it does [offers] sic. major advantages when it comes to cost. It can also be very effective for telephoto photography for the extra reach gained from the crop sensor multiplier. For example, this can be very useful when shooting sports, wildlife, and other types of photojournalism…” both from: http://www.slrlounge.com/school/cropped-sensor-vs-full-frame-sensor-tips-in-2/

 First let me state two facts: One, images from crop sensor cameras are not inherently of lower quality than those of full-frame cameras and, two, crop sensor cameras produce exactly the same in-camera image magnification as do their larger full-frame brothers.

Before I take this discussion of why these facts are true, let’s understand some things about cameras and their sensors.

First, a full-frame sensor gets its name from the fact that is physical measurements are, in round numbers, 24 x 36 mm. That’s the same size of our old standby, the full-frame 35mm film negative or transparency.

Second, I truly believe that the term, “crop sensor” is a misleading term. It is simply a sensor that is smaller than the full frame cousin. And there are now several sizes of “crop sensors”. They range from the APS-C (15.7 x 23.6 mm), the APS-H (19 x 28.7 mm), four thirds systems (13 x 17.3 mm), and even smaller. So there is really no “Standard” when it comes to identifying a sensor size.

Now let’s talk about the lens for a moment, the image forming device that projects our picture on to the sensor. Lenses have several characteristics. They affect:

  • Image size. This is governed by the focal length. Longer focal lengths produce larger subjectdetail on the sensor at any given distance,
  • Angle of view. This is the area of coverage in front of the lens that the lens may capture and project on to the sensor. It too is governed by focal length. Shorter focal lengths produce a wider angle of view that longer focal length telephotos for example. And finally,
  • Perspective. This is a relationship of components within the image to others within the same image. Focal length affects perspective, but only when the lens-to-subject distance is changed.

Crop sensor-Example 1

Let’s look at the image above to understand the physical relationship. The large frame is that of standard 35 mm film and also that of a full frame digital sensor. The yellow outline represents the area and magnification of an APS-C sensor, similar to that of a Nikon D2X or D7100 series camera body. The image was taken with a Nikkor 80-200 mm F 2.8 zoom lens.

Lenses have physical characteristics in addition to the optical characteristics above. One that is most important here is lens flange-to-sensor distance. This is the physical distance from the rear mounting flange of the lens to the sensor. That distance is specific to allow the lens to be focused at infinity. This distance is somewhat different between manufacturers, but it is standard within a manufacturer family so that all lenses will work properly.

In order for a lens of any particular focal length to produce larger image details on the sensor, the lens must be moved farther from the sensor or closer to the subject. Since the flange-to-sensor distance must be the same for cameras of a particular brand, any given lens (of that brand) will produce an image of the same magnification at the sensor regardless of the sensor dimension. What changes is the area of the projected image, not its magnification.

So let’s look at how this works.

The set-up

A standard, single focal length 200mm prime telephoto lens is mounted on a tripod. A subject is placed at a constant, pre-measured distance from the lens for all images. And two camera bodies, Nikon D90 with its APS-C sensor and Nikon D800 with its full frame sensor, were used.

The Process

Two photos of a mounted scaled quail are made from the same spot. Nothing changes but the camera bodies. Both images are processed in Photoshop in the same manner. A new composite file was made using both images together. Each image was reproduced at the same magnification for comparison. The APS-C image is produced at a six times multiple of its actual size of 15.7 x 23.6 mm, and the full frame image is printed at the same six times multiple of its actual size of 24 x 36 mm.

The Result.

One can clearly see the subject is the same magnification on both sensors and the reproduction sizes of the bird are the same for both sensors. The full frame sensor on the left captures significant additional area than the smaller sensor. This is the source of the term “Crop Sensor”.

Crop-Full Comparison

Left: Full frame sensor, Nikon D800. Right: Nikon D90 APS-C sensor. Initial enlargement (left) = 6 times sensor length 36 mm x 6= 216 mm. Initial enlargement (right) = 6 times sensor length 23.6 mm x 6= 141.6 mm.

The Misconception

When both images are reproduced at the same dimensions, the APS-C subject is reproduced at a larger size. This is only because the image is blown up to be the same reproduction size. This is why some people think there is actual in-camera magnification increase.

When viewed in the camera through the viewfinder or in live-view the smaller sensor frame is filled with the subject at a given distance than the full frame sensor. Therefore, the APS-C camera appears to produce a larger image. This is simply because the frame is filled faster with any given focal length and subject distance. What actually happens here is that the APS-C (crop sensor) image is blown up to match the outer dimensions of the full frame image.

Same enlargement comparison

Left, Nikon D800 full frame sensor. Right, Nikon D90 APS-C sensor.

Image quality

Image quality is not entirely based upon image size at the sensor, but is based upon in-camera processing technology, pixel size and pixel density. Many “crop sensor” cameras have better sensors and processing engines than full frame cameras. But that’s another story. (Maybe later.)

Copyright © 2014 Brian K Loflin . All rights reserved.

Small, smaller, smallest: A work in progress

Commonly, when we think of close up images we envision filling the frame with subjects the size of a butterfly. When we think of macro, that subject size becomes smaller by a factor of five or so. That might be a small beetle or maybe a fly. There is a vast world that is much smaller that is worthy of our photography prowess. That is the world of ultra macro or indeed micro photography.

There are many tools used for life-sized images. The macro lens, extension tubes, bellows attachment and even microscopes. Each has its advantages,  disadvantages and limitations. Some of the major considerations when doing image capture at magnifications vastly greater than life-size include, image resolution, focus, depth of field, lighting and vibrations to name a few. The micro world is a challenging one indeed.

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The above image is the head of a bee. It is magnified about 1.6 times on the sensor. This is not a very great magnification, but in order to capture sufficient depth of field in this image 53 individual images with a different point of focus from the antennae to the rear of the head were made. Each image was spaced 0.005 inch from one another from the front to the back. These multiple images spanned the overall distance of o.265 inch.

Image making like this calls for a stable specimen and camera platform, precise and uniform movements in focus and absolutely uniform, clean lighting. In order to accomplish this a bellows and true macro lens was used with a micrometer specimen stage and electronic flash. All this apparatus may create a big problem: movement through vibrations. This really reduces image resolution.

To overcome the problems, I am assembling a specialized piece of equipment to enable the precision required. This is my work in process. The idea is not new, per se, but getting all the pieces together has been interesting. It looks like this:

Micro-6098-Sm

This micro set up is designed for versatility and for use from magnifications of 1:1 or life-size on the sensor with a 55 mm macro lens to magnifications of close to 40:1 with a true microscope lens on the bellows.

Camera movement is facilitated by a geared linear positioner with provisions for a stepper motor, an Arca-style plate on the positioner table and the focusing rail of the Nikon PB-4 bellows.

Subject positioning  is possible in all three X, Y, and Z planes. A cannibalized AO microscope stand provides coarse and fine movement in the vertical direction. A linear motion micrometer stage provides movement in X and Y directions. The specimen is held by an articulating holder mounted on the linear stage. (See Variable macro specimen holder) This holder will facilitate the use of pinned insects in addition to other larger materials fastened to the stage itself.

All this assembly is mounted together on a platform to reduce independent vibrations. The weight is substantial, providing additional aid in mitigating vibrations. While the current prototype mounting base is dimensional lumber, future refinements include an all-metal positioning table and the addition of a stepper motor for automating focus stacking.

The clean design without bulky tripods and other equipment in the way allows the use of SB-800 or SB-910 electronic flash on articulated arms in a unobstructed manner.

A future post will visit images made in much greater magnifications. Improvements to image resolution will be measured and discussed. Stay tuned!

Are you using your lenses effectively?

Zoom lens photography is somewhat fairly understood. But, a lot of deep understanding is missed by the casual photographer. Sure, everyone knows that a wide angle lens, like a 24 mm, will cover a lot of countryside. Hence the name, wide angle. And it is relatively well understood that longer lenses, like a 150 mm produce a telephoto effect, bringing distant objects apparently much closer to the viewer.

But many shooters miss a lot of the benefits of zoom lenses. Remember, lenses do three things: they affect angle of view, affect image size, and perhaps most importantly, they can affect perspective. Lets examine three photographs of a farm house with fresh round hay bales.

Normal lens

The first is with a “normal” focal length lens of 50 mm. This lens produces an image size and a perspective similar to the unaided eye. But the angle of view is far from that of our eyes because we humans have such exceptional peripheral vision of 140 degrees or more.

So let’s understand what we can “see” here. First we can see several of the hay bales, we can see the house and tractor surrounded by the trees. All appear reasonably sized. The background sky takes up a nice portion of the frame. Good. But there is more to understand. Let’s look at the three “grounds”, or visual zones in this photo. The row of bales make up the foreground, the home and surrounding trees, the midground and the sky and clouds become the background. These three layers are very important in a photo like this.

FarmHouse-7410-Sm

The human eye enjoys this layering effect. We like to wander around in the frame inspecting what we see. But a normal lens is not our only compositional tool. We have other focal lengths at our immediate disposal. Let’s look at others.

Wide angle lens

Let’s see what happens when we change focal lengths of our lens. For this next image an 18 mm wide angle setting was used. But, more importantly, the image was composed by moving much closer to the hay bales. This did two real important things for the view: first the bales are more emphasized in the foreground, and second, the more distant home and trees of the midground became quite small. This is an effect of changing perspective. This happened because to recompose, the point of view changed and became much closer to the bales. This results in the midground and background receding and becoming substantially smaller.

In photography, perspective is a relationship of elements within the image to other elements of the image and to the frame of the image in size and apparent distance between the elements. Perspective is dependent first, upon distance to the subject and then, lens focal length. Generally, when various focal length lenses are used from the same spot, the perspective is unchanged. That is why the more creative photographers compose with their feet, not just their lens.

Telephoto lens

The next view was made with a 180 mm lens. Some would say it is a telephoto view, bringing distant objects much closer to the viewer. Here we keep the bales as foreground interest. The house and tractor are now much larger with more detail visible. And this view produces more emphasis on the foreground and midground. The background sky is less important. It is important to know that to achieve this view, the composition had to be made from much farther back than either of the two previous views.

FarmHouse-7406-Sm

So the lesson learned is to work every scene thoroughly. Certainly, use a variety of focal length lenses. But in addition, it is of paramount importance to vary the subject distance as well. Remember that changing the focal length from the same spot results in a different crop only through angle of view and image size. But to get the best results from any lens, you must vary the lens to subject distance.

Foreground elements are very important in composition. They anchor the scene and can be used to lead the eye into the scene. Depending upon their importance, the size may be easily manipulated through varying the focal length of the lens and most importantly, the lens to subject distance. Just don’t forget to compose with your feet instead of simply zooming your lens. Do both and your images will quickly improve.

Where’s the aperture ring?

ApertureRing-5018-Sm

Modern Nikkor lenses: 60mm F2.8 Micro Nikkor with manual aperture ring (left) and 18-200mm F3.5 – 5.6 VR zoom. Notice the absence of the aperture ring on the zoom. Image made with Nikon D2Xs and 200 mm F4.0 Micro Nikkor and flash.

With today’s electronic technology-driven cameras, many of our exposure controls are as convenient as a finger push on the camera body. And with experience, we never have to remove our eye from the viewfinder.

The shutter speed and aperture selection is controlled electronically through the selector wheel on the camera body. However, in natural science photography there are cases where electronic aperture selection is not possible because the electronic connections between the lens and the camera body are not workable.

Do I mean the camera malfunctions? No, not at all. What I mean is that, through the addition of some components between the camera body and lens, the electronic circuitry is interrupted. This happens with some extension tubes and bellows (below), as well as microscope adapters. This is not uncommon, nor does it really pose a problem when you are aware of what’s really happening.

Tube-1083

Bellows-1727-sm

So without electronic aperture selection, apertures need to be selected manually with the aperture selector ring and the exposures made in Aperture Priority (or Av) shooting mode. The camera will measure the light that falls on the internal metering sensor and set the shutter speed appropriately.

There may be one problem, however. Some lenses do not have a manual aperture selection ring on the lens barrel. Nikon calls these lenses “G” lenses. We fondly call them “gelded” lenses. Many Canon lenses are without the ring as well. So, it ends up that these are not really appropriate for this type of photography. We need to look for those lenses with aperture rings available. There a number of current Nikkor optics with the aperture ring. The 60 mm, 105 mm, and 200 mm macro lenses still have the aperture selector ring. Also the series of manual Nikkor lenses from 20 mm to 105 mm also retain the aperture selector ring.

Fortunately, under the correct circumstances, many older lenses (Canon and Nikon, too) may be used on modern D-SLR cameras. These lenses frequently have the aperture selector ring. And with adapters, Nikkor lenses may be used on Canon EOS series camera bodies. This is a nice option due to the great selection available  of Nikkor optics.

Move the Mole Hill, not the Mountain

In macro photography we are supplied with a variety of components for fine-tuning focus. This equipment includes focus slider rails and built-in sliders as part of a bellows. All of these devices facilitate changes in focus by moving the camera closer or more distant from the subject.

FocusRailDuo-Sm

All of these components work quite well; some better than others. A well-made slider (above) can provide infinite adjustments in focus with extremely small changes in distance.  These are ideal for gross specimens or single shot macro images.

DA01-bloflin0312

Bee head. 53 images stacked in Helicon Focus. Nikon D2Xs, 50 mm flat field EL Nikkor lens on bellows, two SB-800 flashes, tripod. Image magnification in camera: 1.6X.

However, when enhanced depth of field of tiny subjects is required through focus stacking, moving the camera may not be the most ideal method of changing point of focus. With very small insects like the bee above for instance, many exposures–perhaps 50 or more– must be produced over a distance of less than one centimeter.

Bellows-1727-sm

Several problems are presented. First, the mass of the camera, bellows, and lens assembly is great. Moving it smoothly and accurately may not be possible. Second, the focusing rack and pinion may have coarse threads, not suitable of minute adjustments.  Further, the camera, bellows and lens combination when moved is subject to unwanted vibrations. The answer therefore, is to move the subject, leaving the camera solidly stationary.

Macro subjects like those encountered for focus stacking are most frequently tiny and present no above mentioned problems. They are small, lightweight and can be easily and smoothly moved. And making repeated movements at uniform dimensions is practical. All this suggests that moving the subject instead of the camera is an ideal solution.

In my photography, I use two devices. For single shot macro I have converted an Olympus microscope stage for an X-Y-Z motion platform in the image below. It has a movement of 3 inches in left-right and fore-aft directions and a vertical movement of just under 1 inch. In addition, it has a 2 x 3 inch hole for sub stage illumination. All movement controls are under the stage so they are perfectly out of the way.

Macro platform-0964-Sm

For focus stacking I use a single-axis micrometer linear positioning stage. Movements are possible along the lens axis for focus stacking in uniform increments as small as 0.001 inch. The movement for this stage is only one inch, but that is more than adequate for most focus stacking tasks. To center and align the subject, I use the gear head on my heavy duty Gitzo tripod. As illustrated in the photograph below, everything is locked down tight. Consistent, vibration-free images are possible with this set-up.

Micrometer positioner-0981-Sm

For the ultimate in focus stacking, a motorized linear positioner like StackShot® by Cognisys makes life easy. The price is affordable if a lot of focus stacking photography is required. Even with the StackShot it still makes perfect sense to move the mole hill not the mountain!

© 2013 Brian Loflin. All rights reserved.

Bosque del Apache NWR, New Mexico

I had the pleasure to lead a photography trip to this fabulous New Mexico birding hot spot for a few days in early December. Bosque del Apache NWR lies on the Rio Grande about halfway from Las Cruces to Albuquerque, NM. This National Wildlife Refuge is an amazing photography destination as it is the resting spot for migratory water fowl in late winter. The birds are there by literally tens of thousands, always an impressive sight! As it turned out, the weather was somewhat mild and photo perfect. I thought I would post a few images from the trip.

SHCrane-9298-Sm

One of nine thousand Sandhill cranes takes off in the early morning light. The birds slept overnight in a shallow pond right by the roadside. They would take off by ones and twos and in very large masses, often right over our head.

SandHill BIF-1166-Sm

With a wing span of six feet, Sandhill cranes are elegant fliers. They feed in dry fields during the day and return to shallow water at night. At Bosque del Apache the massive numbers of these large birds presented many photographic opportunities as well as a cacophony of sound as they vocalized to each other.

SnowGeeseLiftoff-1611

Snow geese were everywhere! Frequently they would take flight in an explosive liftoff by the hundreds. Often, they would circle and come right back. Later, they may explode again and move to another field or other part of the refuge system.

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My good friend and photographer, Dolph McCranie with poster enumerating Bosque’s bird count for the time we were there. As you can see by the numbers, finding a subject was an easy task.

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A bobcat was a very lucky find. This cat was stalking a small group of Mallard ducks when I spied it near a small canal. A slow, careful approach resulted in a relatively nice image.

CapBar-1496-SmBw

After shooting birds, many of the group photographed other sights in and around Socorro, NM, like the interior of the Capitol Bar, one of the oldest in the Southwest and in business since 1896.

All images Nikon D2Xs and Nikkor optics including 600 mm F 4, 80-200 mm F 2.8, 28-70 F 2.8 and 15 mm F 3.5.

© Copyright Brian Loflin 2012. All rights reserved.