Category Archives: Q&A

Remote Wireless Photoflash Switches

A Reader Asks

“I own a Nikon strobe. Can I use the same radio trigger I use on the Nikon to power my Canon strobe?”

Firstly to clarify: Radio Triggers really do not “power” anything. One cannot easily transmit power wirelessly (although Nikola Tesla would argue that fact). They are basically relays or switches that are controlled by a radio signal.

Radio controlled flash triggers are “device agnostic.” It is just an extension of your camera’s synch switch and circuitry. They have worked with most any photoflash device I have teamed them with — Canon, Nikon, Norman, Photogenic, Lumedyne, Broncolor and more. 

One thing to consider, some wireless flash triggers will serially transmit your camera’s exposure data along the  data stream in multi-lighting setups using the same flash and camera system (i.e. Nikon to Nikon, Canon to Canon) If you cross systems you will likely still be able to trigger the remote flash but it may not or will not be able to transmit the exposure data. -33-

Advertisements

Using Video in a Theatrical Application

A Reader Asks

“I’m debating using projections or a series of stacked televisions for an upcoming theatrical production.  I’m picturing a tower of televisions of multiple sizes on either side of the stage. The images on the televisions would be the same.  Nothing fancy like an image traveling down from the top to the bottom or one image being stretched over multiple televisions.
 
Initial thoughts: They are all daisy chained together and hooked to a single DVD or VCR.  But, how do you control them if there are periods where they wouldn’t be used?”

What you are describing is a pretty common setup. I would not recommend simply turning your video monitors on and off because some televisions will reset to a default state if they are disconnected from power and that default state might not be what you want it to wake-up in. What you need is a vertical interval video switch and a black burst generator. These devices will send black video to mute the screen when not in use. You also may want to mute the sound too. A solution for this would be a vertical interval “Audio Follow Video” switch. All “vertical interval” means is that it will switch your video seamlessly without a big break-up (glitch) on the screens.  
 
As far as interconnection, when you are sending the same source signal to all the video monitors it is seldom a good idea to “Daisy-Chain” an audio or video signal, especially when it comes from a relatively weak source device like a consumer DVD or VCR. I strongly recommend a device called a Video Distribution Amplifier. You also would need an Audio Distribution Amplifier if you are going to send the same audio to all the television monitors.  
 
I know you said you had a single source but if you wanted to send a different signal to all the monitors or do fancy images that would go from a different picture on every screen to a big blow up of a single image using all the screens there is a solution for that too. You could get software driven system that would do this automatically for you. They are expensive but rentable at a fairly reasonable cost if you are a one and done kind of user. -33-

DTMF Touchtone Telephone Tones Relating to Notes on a Piano

A Reader Asks

 

“Which Piano Notes do Touch-Tone Dial Frequencies Generate?”

 

There are 8 frequencies that, when set in an X-Y Matrix combine to produce 16 dual tones. The frequencies are set in two groups. (All frequencies are in Hz).

 

High Group

 

1209

1336

1477

1633

 

Low Group

 

941

852

770

697

 

The combinations and what they create are as follows:

 

1=697+1209

2=697+1336

3=697+1477

A=697+1663

4=770+1209

5=770+1336

6=770+1477

B=770+1663

7=852+1209

8=852+1336

9=852+1477

*=941+1209

0=941+1336

#=941+1477

D=941+1663

 

SIDEBAR — The letters A, B, C and D are not commonly found on your typical telephone set. They are used for special signaling and switching operations the consumer might need with special software or home equipment.

 

Let’s use the given that A4 is 440Hz and Middle C is 256Hz. These also happen to be standard audio calibration frequencies used for certain calibrations and setups.

 

Cheating a bit an equation was not used to calculate the frequency vs. musical notes. I did a comparison against some technical information I have in my Standards and Practices tech files. This will get us in the ballpark. Most of these have a tolerance of +/- 50 cents. Here is what we discover:

 

1209 (High side of D6)

1336 (High side of E6)

1477 (Low side of F#6)

1633 (Low side of G#6)

 

941 (Low side of A#5)

852 (High side of G#5)

770 (Low side of G5)

697 (Low side of F5)

 

As you can see the frequencies do not match musical notes exactly. This is because the frequencies were chosen by design to avoid dialing mistakes by familiar ambient sounds picked-up by the telephone’s receiver (microphone). Technically, if the frequencies matched exactly, misdialing might occur if there was music playing while one was dialing. The frequencies were also chosen so as not to interfere with other telephone tones used in the network for operations like billing, call transfers and other telemetry used to advance telephone calls. -33-

 

 

IPTV Explained

A Reader Asks

 “I recently heard of television programming that is available on IPTV. Can you please tell me what that means?”

 IPTV (Internet Protocol Television) is a method of delivering television services in the form of IP (Internet Protocol) Packets. When these “Packets” reach your home the converter box on top of your TV converts, or more technically “Decodes” these to a signal that your television can translate and deliver programming to you.

 IPTV is a very secure, closed system with content controlled by the service provider. There is a high level of quality and control connected with IPTV. This is totally different from a confusingly similar sounding technology named Internet TV where video is streamed over the Internet to your computer. An example of Internet TV might be YouTUBE® or some of the many other similar services available on the Web. These services are typically presented at a much lower quality than IPTV.

 IPTV allows a two-way street promoting interaction with the program materials and On-Demand services. Typically streaming video is a one-way street with few viewing options. This two-way street also allows the service provider to “sneak a peek” at the viewing trends of their viewers and adjust offerings and advertising accordingly.

 Unlike current Cable and Fiber technologies being transmitted directly to the user’s home IPTV content is transmitted to a central office where the analog or digital television signals are “Encoded” into data packets, indexed for searching and stored in memory waiting for the consumer to call-up their favorite show. These data travel to the consumer’s home and are “Decoded” to standard television signals for use on a standard TV receiver.

 Eavesdropping on your viewing habits is not the only benefit of IPTV’s interactive nature. This can also help engineers optimize the signals delivered across the service provider’s entire region. For example, let us consider five communities in a particular area. If areas one and three are heavy users but two, four and five are not consuming as much of the bandwidth, adjustments to the system could be made instantaneously to divert more signal resources to the heaver use areas and balance the unused bandwidth against the demanded bandwidth. When the lower use communities demand increases they could be fed more bandwidth to meet demand.

 Basically IPTV technology provides much greater control over technical resources and allows for customized, technical quality control as needed by demand. This allows for a much more cost effective network than one that sends the same “Power” to all consumers without regard to usage trends.

 In the United States IPTV is not a widely embraced technology. There are about 1.2 Million IPTV subscribers in the United States. In comparison there are approximately 90 Million subscribers to satellite, cable and fiber services. -33-

Video Archiving

A READER ASKS 

What can I do to obsolete proof my video archives? Most of them are on Beta SP®. Do I need to go to a Duplication House to have copies made?

  Just a few quick thoughts:

  • There is no real “obsolete proof” archival format.

  • Beta SP® is still a very active format used by broadcasters, industry, education, media professionals and some hobbyists around the world.
  • You do not need to go to a duplication house to have your Beta SP® materials dubbed (copied). Will the format be here 20-, 40- or 60-years from now is anyone’s guess.
  • Most any television station, cable company, corporate facility, editing house or even your local event (wedding/party) videographers have the equipment to do this for you. The format is rather ubiquitous.

FORMAT HOP

If you are looking for long-term storage of your program materials your best bet is to format hop as new formats develop. Beta SP® (A Trademark of Sony) is an analog format. An important issue with analog is that it does not copy into multiple generations well, although Beta SP® is one of the better formats for multi-generation duplication because signal quality holds up through several copies.

GO DIGITAL

You should consider converting your program materials to a digital format (this is called “Digitizing”). To do this you would have your Beta SP® original digitized and placed on a DVD as a MPEG file. This is not a complicated process. You can simply go to your favorite electronics store, purchase a DVD player/recorder and connect it to a Betacam® VTR and you are on your way. 

Once it is in a digital format it can maintain the visual and audio quality of the original software. This means that you can make copies of copies with little to no loss in quality.

BE READY TO JUMP SHIP 

Format hopping comes in when you begin to see DVDs and MPEG formats slipping in popularity. Always go with the latest stable format to duplicate your materials. It is a lot of follow-up but well worth the effort to protect today’s program materials for generations to come. This is a big problem for still photographers. Many question if archived images taken today will be able to be opened for viewing 50, 75, 100… years from now. -33-

The File Frenzy

A READER ASKS

I create television graphics for broadcast. I typically save my files for use in the JPEG format (.JPG). My question is how stable are digital formats like .JPG. Can we ever expect obsolescence of these seemingly ubiquitous files?

It is always suggested that one maintain a cautious posture when it comes to formats. There are really no guarantees. You can print a photograph from a negative that is over 100 years old but some computer files created a few short years ago cannot be processed on today’s computer systems.

BLASTS FROM THE PAST

Consider what happened to the Sony BetaMax® video format. The general thought was that there would always be a machine on which to playback the tapes produced in this format. How many home movies were made by early video users only to have them sit on a shelf with nothing available to play them? Conversions are possible but the companies that do them are few and far between and the cost is high. VHS® could be destined for the same end now that DVDs are all the rage. There is a possibility that DVDs will be replaced in the next 10 years. HD DVD® and Blu-Ray® are already beginning to edge them out.

Considering software applications: If you had Native files created in an early version of a illustration application that let’s say ran on DOS or the Windows® 3.1 operating system, the Native files from that version may not open in today’s operating systems. Some early JPEG files might be incompatible too.

Many applications and operating systems have become obsolete over the years. Unless you have the original software, opening files created in these obsolete packages today might be a challenge or even impossible. How about 8” and 5” floppy discs? If you have files on those formats you are out of luck also. Time marches on, formats and applications change.

ANTICIPATE

 The best rule of thumb to follow is to watch the formats, anticipate obsolescence and do conversions as required to keep your files up to date. Do not fall victim to changes. To ignore this simple fact one puts their files at risk. -33-

Calibrating New Televisions

A Reader Asks:

Do I need my new flat panel television calibrated in my home? I’m told this is something that should be done with new sets, but I have to tell you so far the picture seems pretty good.  In your opinion is this something that should be done with these new sets…?

Excellent question! If you feel a calibration is right for you. That is exactly what you should have done. As for my opinion: If you are satisfied and happy with the image and sonic performance of your new TV I wouldn’t change it.

The “need” sometime comes from some retailers who not only want to sell service contracts and expensive, high tech cabling that has the same performance as good quality, standard cabling costing much less, they also want you to consider having them come out and set up your new purchase in your home to “customize it for your personal viewing and listening space.” There is usually a fee attached to this service call.

SELLING ON THE NEW CAR SMELL

This “gotta have it” sales pitch is much the same when buying a new car as it is when buying a top of the line “Uber-Television.” Most vehicles today offer a nice “standard” package with many creature comforts. The dealer makes some profit on the cars but the aftermarket “dealer installed” items like undercoating and rust proofing are their big money makers.

The car leaves the factory with a warranty. In 5-, 10-, or 15-years when you trade your care in for a new car, aftermarket rust proofing won’t make any difference in value and you likely would have gotten the same performance if you did not choose the dealer installed option. Did you need it? Probably not but the dealer made you think you did and made a hansom profit to boot.

From the tens of thousands of LCD, DLP, CRT and Plasma televisions seen in professional dealings with clients, it has been observed that a consumer level set comes out of the box ready to roll.

RESET THE DEFAULTS

There is one recommendation that I do like to offer–Go into your setups and change from the brightest most vivid setting to another setup that pleases you. Do not change anything else but that setting and live with the set for about a week or two before you decide you need to change it back or have it calibrated. TVs leave the factory defaulted to pumped color and contrast because the factory wants it to look its best if it should be put in the bright lights of a store showroom display. Another reason for moving the set from the brightest setting is it will prolong the life of the unit’s internal lamp.  

WHEN IS A FULL CALIBRATION REASONABLE?

The only calibrations that I normally recommend are in critical production applications where a wall of television monitors in a television control room need to be critically color matched. Other areas are in hospitals and operating rooms, photographic applications and graphics workstations where critical technical color observation is required for a medical/surgical diagnosis, printing application or digital photographic processing. Corporate displays usually need critical color matching too. Corporations are very fussy about proper reproduction of their corporate identity, including color. -33-