Locus is a computer program for Microsoft Windows that will help you master
the technology of your camera and lens. It calculates the things you need to
know to control the focus, blur, perspective and depth of your photos. It has
a large camera database and a great User Manual with Illustrated Dictionary.

Many gifted photographers have an amazing artistic "eye". They seem to instinctively know how to compose a beautiful shot. They often make the ordinary look extraordinary.

Yet many of these same gifted photographers struggle to make sense of their cameras. How to configure them to capture the images they envision. The desired perspective. The right amount of background blur. What lens to use? What focal length and aperture? What focus distance and perspective? What speed? What resolution? Locus will help answer these questions.

Many shots come only once and you'll have just the one chance to get it right. It may be a live event that will never be repeated. There could be big money at stake. How do you nail the shot the first time? How do you make sure that the subject will be in focus?

What if the subject is moving? How fast must your camera be to freeze the motion?

The best photographers rely on experience and planning. They've captured the "money shots" before and they know what to expect---what did and didn't work in the past. They may have spent hours or days doing test shots to prepare. Now there is a tool to calculate many of these answers for you and help you plan for the shoot before it happens. With Locus you can plan your shoot and shoot your plan.

Introducing Locus...
Locus is a low-cost computer program for Microsoft Windows. At its heart it is a photo geometry calculator and it "sees" the world through the lens of the camera. It calculates what is in focus and what is not with precision. But it goes much farther than an old-fashioned Depth of Field (DOF) or Depth of Focus table. It knows how blurry the out-of-focus areas are (the "bokeh") so you will know what to expect in the unfocused regions of an image. Consider the following photos. Locus will show you how to achieve each one before you ever fire a shot.

Using Locus is a 1-2-3 step process...
Step 1: Begin by entering information about your camera in the upper portion of the program's main window. Locus includes a database with the parameters for 1,438 cameras! It's the largest database of its kind and most of the time, you simply select your camera from the "Camera" list and your camera's information will be loaded into the program. Notice below that your camera manufacturer's logo will appear to aid recognition:

Step 2: Enter information about your lens in the middle portion of the program's main window. This includes the Focal Length, Aperture f-number and Focus Distance. Locus can help you determine the Focal Length with the program's Focal Length Calculator (shown below).

Simply enter one of the desired Field of View (FOV) dimensions and the Focus Distance in the center of the Calculator. It will then calculate the required Angle of View (AOV) and Focal Length at the top. In the example above, the photographer wants the FOV to be 7 feet (2.1 meters) wide and he plans to locate the camera 10 feet (3 meters) away from the point of focus. This will require a lens with a 50 mm Focal Length.

Once the Focal Length is known, Locus will draw the two "Lens Perspective" drawings along the right side of the main window. They estimate how quickly objects will seem to recede into the distance to indicate how "flat" or "deep" the perspective will appear. The program will also calculate the Angle of Videw of the lens and use it to classify the lens. Once the Aperture is known, Locus will calculate the Hyperfocal Distance to show how to get the maximum Depth of Field. Finally, once the lens Focus Distance is known, the program will have most of the information it needs to calculate many things about the scene.

Step 3: Evaluate the scene in the lower portion of the program's main window. Locus will calculate the Field of View (FOV), Scene Resolution and Magnification, Total Depth of Field (DOF), Near Focus Limit, Far Focus Limit and the percent of blur of the Bokeh at infinity.

The online User Manual of the program includes a great Illustrated Dictionary which explains this terminology. Here are all of the inputs and outputs of Locus' main window:

Locus main window inputs:

• Image sensor or film frame Format Size (the dimensions of the image area)
• Image Sensor or film Resolution (the native resolution of the image area)
• Optical Projection (most lenses are rectilinear and many fisheye lenses are equisolid)
• Lens Focal Length
• Teleconverter (magnification factor of the teleconverter)
• Aperture (f-number)
• Focus Distance (distance from the camera to the point of maximum focus)
• Foreground Distance (to calculate out-of-focus blur close to the camera)
• Background Distance (to calculate out-of-focus blur far away from the camera)

Locus main window outputs:

• Aspect Ratio of native pictures from the camera
• Megapixels of pictures from the camera at its native resolution
• Image Sensor Circle of Confusion (COC = defines when an object begins to go out of focus)
• Field of View Factor (compares the FOV of the present camera to a 35mm (135) film camera)
• Minimum Shutter Speed (to freeze movement)
• Angle of View (AOV - the angle of the scene that is viewable to the lens)
• Lens Classification (ultra wide, wide, normal, moderate telephoto, telephoto, super telephoto)
• Diffraction Limit (a smaller Aperture---larger f-stop---will cause the image to soften)
• Aperture Diameter (approximate diameter of the lens iris opening)
• Hyperfocal Distance (focus to this distance for the maximum Depth of Field)
• Lens Perspective (two perspective drawings to show how much objects will appear to recede with distance)
• Field of View (FOV - the portion of the scene visible to the camera at the Focus Distance)
• Scene Resolution (the size of a single pixel at the Focus Distance)
• Magnification (magnification of the image on the image sensor versus its true size)
• Total Depth of Field (DOF - total depth of the in-focus part of the scene)
• Near Focus Limit (distance to the closest in-focus point in the scene)
• Front Depth (in-focus depth in front of the Focus Distance)
• Far Focus Limit (distance to the farthest in-focus point in the scene
• Rear Depth (in-focus depth behind the Focus Distance)
• Near Bokeh (percent of blur at the Foreground Distance)
• Far Bokeh (percent of blur at the Background Distance)
• Bokeh at Infinity (percent of blur at infinity)

Locus Speed Calculator
Some subjects just won't hold still---like the airplane shown in flight above. Locus includes an innovative Speed Calculator (shown below) that enables you to calculate the Minimum Shutter Speed to freeze the movement of a subject.

Enter the Direction of Travel, Speed and Distance to Subject and the program will calculate the Minimum Shutter Speed with the assumption that the camera will be stationary. In the example above, a subject traveling at an angle of 245 degrees with respect to the camera at a speed of 100 mph (161 kph) and a distance of 50 feet (15.2 meters) from the camera will require a shutter speed of 1/2227 seconds for the selected camera and lens. The closest 1/3 EV step (a common increment for cameras) would be 1/2500 second.

Locus Crop Calculator
Another feature of Locus is its Crop Calculator (shown below) that enables you to calculate the number of pixels you need for your image depending on the intended output. For example, if you want to create a very high quality photo print, you may want a resolution of about 300 pixels per inch (ppi). If the print size will be 8 x 6 inches, then your photo will need 2400 x 1800 pixels (the Final Crop Size). Notice that the Crop Calculator draws a box inside the Field of View (FOV) of your camera to show how many pixels are needed versus how many pixels are available.

And there's more: If you enter the Actual Size of the area you plan to photograph and the Focal Length of the lens you plan to use, the Crop Calculator will tell you how far away to locate your camera (the Focus Distance).

The secret of Locus' Precision
The secret to Locus' pin-point accuracy is knowing when something is in focus and when it is out of focus. This is calculated with the "Circle of Confusion" parameter or COC. It defines the maximum fuzziness that a dot can have before it begins to look out of focus. Why a "dot"? Because a very small point-like object provides a good standard for comparison. Since objects appear bigger as they go out of focus, the in-focus dot grows into a fuzzy circle. The COC is the maximum size that a dot can be and still look in focus. For many years the photography industry treated the COC more or less as if it were a fixed value for each Format Size and its value was based on old pre-World War II film, photo prints and viewing distances. That's why traditional Depth of Field (DOF) tables---even the ones provided by lens makers today---are of little value. Why? Because the size of the photo and the viewer's distance from it have changed a lot and have a dramatic effect on when an object will appear out of focus. Locus includes a COC Calculator (shown below) so you can adjust the COC to your specific situation.

Begin by entering either the Output Size or the Enlargement Factor. Then enter the Viewing Distance. The effective COC will be calculated for those conditions. Plus it will calculate the size of a single pixel in the photo so you will know if the resolution of your camera is a constraint on the apparent focus (i.e. the size of a pixel is larger than the COC). Now Locus' calculations will accurately reflect the size you plan to display your photo and the distance of your viewers from it. You'll know what will really look in focus to your viewers and what won't. You'll know the real Depth of Field (DOF) and how to set the Aperture f-number of your lens to achieve it. Without Locus, you'll just be guessing.

Additional Features
Locus also provides a variety of printouts and output to other programs through the Windows clipboard. You can print all of the information in the main window, including perspective drawings, and you can print accurate DOF, focus limits and FOV tables. That way you can carry the information you need to a remote photo shoot without the need of a notebook computer.

One of Locus' best features is its detailed User Manual that is loaded with great information and illustrations, including "How To" and "Reference" sections, and an awesome illustrated dictionary of the photography terms used in the program. Our users tell us that the manual, alone, is worth the price of the program.

For more information, please visit our website at www.ht-locus.com.

Computer Requirements
Locus is designed to run under 32-bit and 64-bit versions of Windows 7, Vista and XP and it requires about 61 MB of hard drive space. All purchases are final---there are no refunds. So we recommmend that you download the program from our website at www.ht-locus.com and test it to make sure that it runs on your computer before you purchase it. The program's "demo mode" will give you 30 days to launch the program up to 12 times to make sure that it runs okay.

eBay Special: A 21% Discount off our already low price...
In this sale, we are offering a 21% discount from the normal price on our website. A Locus single-user license and program CD normally costs $37.90 plus shipping. You can get them both for only $29.95 plus shipping in this eBay special. We'll send you an authorization code via email so you can begin using the program right away if you've downloaded the demo from our website. Plus, we'll mail the program on CD so you'll have a backup in case you ever need to install Locus again. This is the only place where you'll get a discount like this so please don't delay---purchase today! Note: This sale is for the Locus software only. No camera or lens is included.

This is an authorized sale direct from the manufacturer, Harris Technologies, Inc. Locus and all images of it in this ad are copyrighted by Harris Tech and all rights are reserved worldwide. All images of cameras and camera manufacturer logos are the property of their respective camera manufacturer. Harris Tech is not affiliated with any camera manufacturer.

Life Outreach International
A portion of all profits from Locus are donated to the highly respected Life Outreach Int'l organization (www.lifetoday.org) and we encourage our customers to become regular financial supporters of this important charity.

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Locus and all images of it in this ad are copyrighted © 2010 by Harris Tech and all rights are reserved worldwide. All images of cameras and camera manufacturer logos are the property of their respective camera manufacturer. Harris Tech is not affiliated with any camera manufacturer.