Automatic Opening

Here are some more information for Automatic Opening:

Many new photographers assume that  the term automatic diaphragm refers to the automatic aperture adjustment offered by their dSLR.

In fact, the term auto diaphragm has nothing to do with automatic exposure. An automatic aperture is designed to remain at its maximum opening for focusing and composing, no matter which f/stop is selected.   The lens only stops down to the desired aperture at the moment the shutter fires.

 

If you have ever used a camera with a manual  diaphragm, you will understand why this is so important. A fully automatic  diaphragm is a delight to use,  particularly  in dim light or when the lens is stopped down to maximize depth of field.

 

The term diaphragm is used to describe the system of blades that create the adjustable aperture. Many photographers use the terms aperture and  diaphragm  interchangeably. They are closely related, but the aperture is actual lens opening, while diaphragm is the collection of  components  that comprise the aperture assembly.

 

Turning the clock back to the early days of photography, you will find that early optics did not have adjustable apertures -- at least not the adjustable openings you and I are used to. When the first adjustable diaphragms appeared, they allowed the photographer to change the lens opening to allow more or less light through the lens. The diaphragm contained a number of preset openings, which became known as f/stops or f/numbers. Smaller f/numbers actually indicate larger lens openings, while the smallest lens openings are represented with higher numerical f/stops. This system continues more or less today.

 

The thing that sets modern lenses apart from the older  adjustable  aperture lenses is that the older units use a  completely  manual  diaphragm. As you change the lens opening from say f/4 to f/11, the amount of light passing through the lens is  reduced  accordingly. That regulates the exposure properly, but it causes problems for focusing and composing. A SLR is designed to show you exactly what the lens sees. If you reduce the lens opening in a manual diaphragm lens, the image in the view finder becomes dimmer. In low light conditions it may be impossible to see anything through the viewfinder. Even in bright sunlight, a lens stopped down to f/22 or smaller is  difficult  to see through.  

 

Camera designers solved this problem by creating an automatic  diaphragm. This design has been more or less standard on SLR cameras for the last fifty years. With an auto diaphragm, the aperture remains wide open, no matter which lens opening is selected. You may select an f/stop of f/16, but the lens will remain  opened  to it's maximum  aperture at all times. This provides the  brightest  possible image in the viewfinder.  

 

When you actually fire the shutter, a  mechanical  or electrical devise rapidly stops the lens down to the chosen aperture, creating the proper exposure. You don't see this happening, because at the same time the camera is stopping down the lens, the viewing mirror is swinging up. As the mirror moves up to allow light to reach the sensor, the viewfinder turns black for an instant. It is during that time that the auto  diaphragm  goes to work and stops the lens down. As soon as the exposure is made, the  diaphragm  springs wide open again, presenting you with a bright viewfinder when the mirror returns.

 

Of course if the selected f/stop  corresponds  to the lens maximum aperture, nothing happens; the lens cannot be stopped down, so it  simply  remains wide open.  

 

Is this just some interesting photography trivia? Not at all. Even though all of your current lenses probably contain an automatic diaphragm, there are several reasons you should  familiarize  yourself with how a manual diaphragm works.  

 

1: Many teleconverters and lens mount adapters do not offer an automatic diaphragm. Thus when you use these adapters, your modern new dSLR reverts to a manual  diaphragm  camera.

 

2: There are numerous manual aperture lenses still on the market. Some of these are new, special purpose lenses, while others are older (but still  usable) optics. You need to understand just what using a manual diaphragm entails before investing in one.

 

3: Many new dSLR's lack a proper depth of field preview option. When you stop a lens down, DOF grows wider, while opening the aperture up causes  DOF to appear shallower. Since an automatic  diaphragm  lens is always wide open, you cannot see  DOF in the viewfinder. Even if you have a lens that will stop down to f/32, you won't see the effect in the viewfinder unless your camera allows you to switch to a manual  diaphragm  preview  mode.  

 

4: If you understand about how an automatic  diaphragm  works, you will understand why a DOF preview is worth having. This could influence your future camera buying decisions.

 

The automatic diaphragm, although it has been around for decades, is just as important to modern SLR  cameras as auto focus, auto exposure and image stabilization. Understanding how it works and why it is needed is crucial to getting the most out of your dLSR.

Visit the basic photography area at Alphatracks.com to see photos and information detailing how the auto diaphragm operates.

Tom Bonner is the author of the Sony Alpha DSLR -A300/A350 Digital Field Guide, published by Wiley Publishing. A photographer for more than three decades, he offers photography and web design services to clients in the Charlotte, NC area.

Automatic Sliding Gate Hazards

Automatic sliding gates are very, very dangerous to children and adults.Many homes, apartments and/or homeowner associations use automatic sliding gates for security reasons. Children and adults can be severely injured or killed if they become entrapped in the gates as they are automatically opened or closed. The injuries include cuts, broken bones, brain injuries and amputations. Many older gates do not have sensing devices or reversing mechanisms to prevent these entrapments.

Some think that these tragedies only occur to children or foolish people. That is not the case. Many responsible adults have been injured or killed due to defective sliding gates. Take Chicago Judge Joan Corboy. Judge Corboy was tragically killed by a sliding gate with a defective Stanley operator. The Stanley gate operator had no safety devices and/or reversing devices. Judge Corboy was killed in the same way many folks are with unsafe automatic sliding gates. She tried to reach through the gate in order to activate the button to open the gate. The automatic gate opened suddenly and entrapped her on the gate, killing her.

Gate entrapment injuries often occur to children. We have received internal Stanley documents which indicate that Stanley Works has notice of dozens and dozens of consumers have become entrapped in Stanley sliding gate operators. Stanley, like the rest of the sliding gate manufacturers, had safety devices available since the 1960's. However, it has only been in very recent years that gate operator manufacturers have informed consumers of gate operator hazards and have placed internal and external anti-entrapment devices on sliding gate operators.

The Consumer Product Safety Commission has issued safety alerts over defective automatic sliding gates. From 1990 to 2000, CPSC has estimated that nearly 25,000 people were involved in automatic gate-related injuries, including 9,000 children under 15 years old. Each year over 2,000 people, including 800 children, are treated in hospital emergency rooms for injuries to the head, neck, arm, or hand due to automatic sliding gate defects.

CPSC worked with Underwriters Laboratories (UL) to develop tougher safety standards that require automatic gates to have at least two mechanisms to prevent entrapment. These UL 325 provisions are similar to the standards in effect for automatic garage doors. The UL 325 standard, which UL adopted in March 2000, requires an internal sensing device that will reverse the gate if it encounters an obstruction when opening or closing; and a secondary external sensing mechanism, such as an electric eye or an edge sensor that will reverse the gate if an obstruction is detected.

Additional safety measures related to gate installation include:

* Do not use vertical posts gates. Eliminate all gate post gaps over 2.25 inches.
* Make sure gates use a mesh pattern.
* Installation of controls far enough from the gate so users cannot come into contact with the gate while operating the controls.
* Installation of controls where the user has full view of the gate operation.
* Elimination of pinch points.
* Make sure gate operators have both internal and external anti-entrapment devices
* Posting of warning signs on each side of the gate.

The problem with automatic sliding gate is this: there are still hundreds of thousands defective and dangerous automatic sliding gates in the United States. These gates that don't have entrapment safety devices are tragedies waiting to happen. "If your apartment or condominium complex has an older gate, contact a manager or your homeowners' association and have it replaced with a safer automatic gate that meets the new standard. It could save a life," said CPSC Chairman Ann Brown.

About the Author

William Turley is a Past President of Consumer Attorneys of San Diego and has been on the Board of Governors of the Consumer Attorneys of California for over 10 years. For more free information regarding consumer safety and consumer law click here =>
http://www.turleylawfirm.com

how do I change the push button code on a door king 6002/6400 automatic gate opener?

my customer got a under ground automatic gate opener we need to change the code to lessen the amount of people who now know it , as construction has made it neccesary to release the code to others
so now he'd like to regain his security,
only we didnt get that information from the
installer thanks.

Here is tech support from DKS:

http://www.dkaccess.com/

Kabum

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