ITC InfraMation - = October 2004

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October=20 2004

Volume 5, Issue=20 10

In This=20 Issue:=20

Welcome

What is 35mm = Equivalent Focal=20 Length?

IR News you can=20 Use

ITC Message Board=20 Posts

Brainteaser of the=20 Month

Last Month's=20 Brainteaser

Past = Issues

Course=20 Calendar

About the=20 ITC

Conference in=20 Progess right now!

Hi=20 {{user("firstname")}},

This=20 newsletter comes to you right from the middle of our InfraMation=20 Conference Week in Las Vegas. We are all having a great time = learning from=20 each other, making new friends, and renewing old = acquaintances.

This month our=20 technical article demystifies the meaning of "35mm equivalence" = for optics=20 and explains some of the specs that thermographers really need in = order to=20 compare and evaluate optics.

As=20 usual we have our IR News, Message board posts, and our monthly Brainteaser for you to solve.

As with all images in this newsletter, = click each=20 image to see a larger version.

If you want to=20 save this newsletter for viewing off line in your computer, just = go to the=20 web page = using=20 your browser and select File....Save As or save this email = page as html in=20 your email software.

See you in Las=20 Vegas,

Gary=20 Orlove,
Editor and = Publisher

What is 35mm=20 Equivalent Focal Length? = [top]

Gary = Orlove,=20 P.E.
ASNT NDT/PdM Level III
Infrared Training = Center

When you look at = lens=20 specifications for infrared cameras, you'll see all sorts of = different=20 things. Some camera makers list the lens by focal length while = others list=20 them by Field of View (FOV) and still others may list them by=20 magnification power. Here are some examples:

3X=20 Telescope
20 x 15=20 degree FOV
13mm focal=20 length
100 mm=20 =93equivalent focal length=94

Sometimes you=20 will see the same lens, for instance a 13mm, in two different = camera lines=20 expressed with different Fields of View (FOV)! So what's going on = here?=20 How can a 13mm lens have an FOV of 40=B0 for one camera and 63=B0 = for another?=20 And just what is "35mm equivalence=94 anyway?

This article=20 explains the focal length specifications for infrared cameras and = explains=20 why you can't really compare focal lengths between different = cameras.=20

What is=20 "focal length?"
The "focal length" of a lens is the = distance=20 between the optical center of the lens and the place where it = focuses its=20 image. For film based cameras, this is the film plane, for digital = and=20 modern infrared cameras, it is the imaging sensor (for instance a=20 microbolometer array).

An = easy way to=20 think about this is to pretend that all the rays of infrared light = pass=20 through the optical center on their way to the infrared = sensor.

Simple imaging = configuration=20 illustrating focal length

What does=20 the 35 mean in a "35mm camera?"
The 35 in "35mm camera" = doesn't=20 refer to the focal length or even to the size of the image on the = film. It=20 is the measurement of the width of the film including the = sprockets. Take=20 a look at the following figure for the dimensions.

Dimensions of 35mm film

What makes=20 a lens wide angle or telephoto?
The relationship between = the focal=20 length of the lens and the size of the sensor array determines the = field=20 of view of the camera. If the focal length is smaller, the field = of view=20 is wider and vice versa.

For example,=20 think about a 35mm camera. The image formed on the film by a 35mm = camera=20 is 36mm wide and 24mm high. So, for example, if the focal length = of the=20 lens is 28mm, the horizontal field of view is 65=B0 -- a wide=20 angle.

28mm lens field of = view

If = the focal=20 length is 100mm, the horizontal field of view reduces to 20=B0. = This=20 produces a higher magnification, and is considered a telephoto = lens. Put=20 another way, the 100mm lens offers a 3.25x magnification over the = 28mm=20 lens. The so called =93normal=94 lens for a 35mm camera has a = focal length of=20 50mm and a horizontal FOV of 40=B0.

100mm lens field of = view. Note the=20 increased size of the arrow on the image plane compared to the = 28mm=20 lens.

What about=20 infrared cameras?
The IR sensitive arrays on IR cameras are = typically much smaller than the imaging area of 35mm film. This = means that=20 the focal length that produces a "normal" field of view is much = smaller=20 than 50mm.

Unlike 35mm=20 film which is the same regardless of what camera you use, the size = of the=20 IR array can vary from camera to camera. This poses a problem. You = cannot=20 tell what FOV a particular focal length lens will produce without = knowing=20 the dimensions of the array. Even then you may not be able to = calculate it=20 because sometimes the active imaging area doesn=92t even cover the = entire=20 array!

Because many=20 people are familiar with focal lengths of 35mm camera lenses, many = digital=20 camera manufacturers often specify their lenses in relation to = what focal=20 length of 35mm camera lens would produce the same FOV. This is = what is=20 meant by the term =9335mm equivalence=94.

Consider, for=20 example, a digital camera with a CCD array measuring 8mm by 6mm. = What=20 focal length lens would produce a horizontal FOV of 40=B0 (the = same as a=20 50mm lens on a 35mm film camera)? A little math tells us that an = 11mm lens=20 would produce the same FOV. So the 11mm lens on this camera has a = 35mm=20 equivalence of 50mm.

So what=20 specification should thermographers be looking at?
For all = of us in=20 the IR business, the most important specification for a lens is = the=20 horizontal and vertical fields of view (there are others but = that=92s=20 another article). Always ask your infrared camera supplier to = provide you=20 with this data in order to compare lenses from different camera=20 models.

IR News you can Use = [top]

In the Dark: The blind feed the blind = at new=20 Paris restaurant
Twin=20 Falls Times-News, ID - Sep 24,=20 2004
... Nobody can see. An infrared=20 camera carried in by a TV crew caught many couples using = the=20 darkness to smother each other with affection. ... =
NASA Urged for Infrared = Camera in=20 Hubble
Newsday, NY - 20 hours=20 ago
... time when light first filled the = universe urged=20 NASA on Thursday to ensure a Hubble Space Telescope servicing = mission=20 includes a next generation infrared camera = ...=20
InSb-based camera improves train=20 braking
Compound=20 Semiconductor, UK - Sep 20,=20 2004
... Working in partnership with = infrared=20 camera specialist CEDIP, and brake pad manufacturer = Flertex, they=20 aim to improve management of the heat load on brake discs = ...=20
Power's on, but the work has just=20 begun
St. = Petersburg=20 Times, FL - Sep 19, 2004
By = COLLEEN=20 JENKINS, Times Staff Writer. Chuck Pruett aims the handheld=20 infrared camera at his target: row after row of = power=20 lines. ...
ICS Infrared Roof Consultants Help = Government=20 Agencies Save ...
Emediawire (press release) - = Sep 16,=20 2004
... surveys, infrared electrical surveys, = roof=20 consulting, roof evaluations, building envelope performance = surveys,=20 infrared thermography, infrared photography ...=20
CenterPoint Energy Minnegasco Offers = Tips to Help=20 Minnesotans 'Get ...
PR Newswire (press release) - = Sep 15,=20 2004
... 1) a blower door test to determine air = leaks;=20 2) a combustion safety test and CO check; and 3) an infrared = inspection=20 that uses and infrared camera to further = ...=20
Zoo has tall and small = arrivals
Scoop.co.nz (press = release), New=20 Zealand - Sep 14, 2004
... = built a=20 special off-display exhibit to encourage three-year-old female = Hoi-An=20 and 14-year-old male Hari to mate, and installed an = infrared=20 camera to track ...
Likely First Photo of Planet Beyond = the Solar=20 System
Space.com - Sep 11,=20 2004
... The photograph was made at ESO's = Paranal=20 Observatory in Chile with an infrared camera, = which=20 records heat rather than visible light. ...
Robot defuses tense = situations
Raleigh = News, NC -=20 Sep 8, 2004
... It has eyes: four cameras = with=20 different points of view sending video to its operator. An=20 infrared camera even sees in the dark. ...=20
Experts work to monitor volcano's=20 rumbles
Anchorage Daily=20 News (subscription), AK - Sep 4,=20 2004
... Waythomas visited the vent on Spurr's = Crater=20 Peak last Monday. Using an infrared camera, he = said he=20 found no unusual heating or steaming. ...
Brazil Release: Alien vs = Predator
Gringoes.com, Brazil -=20 Sep 1, 2004
... Using thermal=20 imaging satellites, Weyland believes to have discovered = the ruins=20 of an ancient pyramid temple that predates the Egyptian and = Aztec=20 pyramids ...
Archaeologists use new tools in = search for Fort=20 Louis
Columbus=20 Ledger-Enquirer, GA - Aug 29,=20 2004
... Center for Archaeological Studies, led = the=20 search using three noninvasive remote sensing technologies - = earth=20 conductivity, magnetometry and thermal imaging. = ...=20

ITC Message Board = Posts=20 [top]

Here is a selection = of recent new=20 threads by IR Community members. Feel free to click the links, see = how=20 people have responded, and post your own response if you = like.

New Forum - Building=20 Science
We started a new = forum=20 recently for Building Science Applications. If you posted or = were=20 following a thread for a building application, you will find = them moved=20 to the new forum.
IR Risk/Method statements
I have been=20 asked to write a risk assessment and method statement for = insurance=20 purposes for IR surveys. The surveys will be mainly electrical=20 distribution systems in building services.
Temperature of molten iron.
We are=20 trying to use our camera to determine the eth feasibility of = molten=20 iron. The temperature of the iron is approximately 2650 deg. = when we set=20 the emissivity at .29 our camera will not read high enough. We = have a=20 flame filter which will read up to 2732 deg. None of our other = measuring=20 devices states that it is that high so i was just wondering if = anybody=20 has any suggestions.
Buss bar severity criteria questions
Generally speaking, what severity criteria should = apply in a=20 heavily loaded buss bar? I'm looking at one rated for 3000A, but = currently with 2000A fuses installed. With emissivity set = conservatively=20 at 0.70, I get a rise over the ambient temp inside the cabinet = on the=20 order of 46=B0F, and greater than 60=B0F compared to ambient = room temp. The=20 B phase is slightly warmer than the others, but not by more than = a few=20 degrees.
This is in a creamery that operates 24/7, with = virtually=20 never a scheduled shutdown -- this being the main plant = switchgear, it's=20 highly critical, but a forced shutdown would be extraordinarily=20 expensive for them.
I did not have the means to measure such = high=20 loads, but I am given to understand that it was running at about = 70 to=20 80% of peak at the time.
Reporter Software
I use a = PM 575, and=20 Reporter Software. No matter which palette I use when I save an = image,=20 it always reverts back to Iron when downloaded onto the PC. I = have tried=20 to make a Report, change the palette to grey, copy the image, = and save=20 it in IMG format using grey: it still saves it as Iron, although = once=20 into a Report and saved, it saves correctly. I desperately need = to save=20 some images in Grey, for onward transmission to another = colleague, any=20 solutions please.
Flash Thermography
I was = wondering=20 where I could get more information on the flash thermography kit = that is=20 shown in the IR for nondestructive testing found in the link = section of=20 this site. Specifically where I could get a flash heat source = like that=20 for the FLIR P-60 camera and what the cost factors might be.=20

And of course=20 if YOU have a question or want to start a discussion on a = topic, we=20 would love to hear from you. Just post a new thread on a mes= sage=20 board.

Brainteaser of the=20 Month =20 [top]

Here is this month's = brainteaser.=20 Readers who email us the correct identification and explanation of = the=20 object(s) in=20 the thermograms are entered into a drawing to win a prize from = ITC. Please=20 put "Brainteaser" as the subject of the = message.

Click here to email your = guess

Do you have an interesting image that you think would = stump other=20 thermographers? If so please email me your image (preferably in = native .img,=20 .jpg, .tif, .tgw, or .tmw format) with an accompanying visible = photo and=20 explanation. If your image is used, you receive a gift as=20 well.

Last Month's=20 Brainteaser [top]

This = a thermogram of=20 a transformer (115kv high side) where a bad "tap changer" = compartment was=20 detected. This is usually indicative of bad internal contacts = elevating=20 the temperature of the internal oil in the tap changer compartment = as=20 compared to that of the main body of the transformer. Quite a = serious=20 find.

Congratulations to our winner, Dan = Roark from the=20 Knoxville Utilities Board in Tennessee; and a thank you to Peter = Bruder of=20 National Grid in Massachusetts for the thermogram. Both Dan and = Peter=20 receive a = special low=20 emissivity traveling coffee=20 mug.

Past=20 Issues =20 [top]

Click the links = below to view=20 past issues of this newsletter:

All past issues from February = 2000=20 through September 2003

May = 2004

March=20 2004

February 2004

January 2004

December 2003

November 2003

October=20 2003

Course Calendar =20 [top]

Click the links = below to see our=20 latest course calendars (in local language).

Americas - Level I

Americas - Level II

Americas - Level III

Americas - E Series

Americas - Building Science

Americas - Electrical

Americas - Roof

Americas - R&D

Eurasia

Deutschland

France

Italia

United = Kingdom

About the Infrared Training=20 Center =20 [top]

The Infrared Training Center offers training and = certification in=20 all aspects of infrared thermography use. Our world-class training = headquarters are located near Boston, Massachusetts, USA and = Stockholm,=20 Sweden and have the world's most extensive hands on laboratories = for=20 infrared applications. In addition, we have training centers = around the=20 world. Please join us in exploring the fascinating world of the = infrared!=20

Your comments and suggestions about this newsletter are = welcomed=20 and encouraged. If you have an interesting application or case = study to=20 share, we encourage you to submit it for publication. Published = articles earn credit towards IR = recertification.

Please e-mail Gary = Orlove or=20 send regular mail to the Americas office.

Visit our website:

ITC Americas, BOSTON

16 Esquire Road
N. Billerica, MA 01862, = USA

Tel: +1-978-901-8405
Toll free:=20 = +1-866-TRAINIR
&= nbsp; =20 (866-872-4647)
Fax: +1.978.901-8832
E-mail: mailto:info_us@infraredtraining.com

ITC Eurasia, SWEDEN

Rinkebyv=E4gen 19
SE-182 11 Danderyd, = Sweden

Tel: +46 (0) 8 753 25 00
Fax: +46 (0) 8 753 26 = 01
E-mail:=20 mailto:itc@flir.se

THIS DOCUMENT IS FOR INFORMATIONAL = PURPOSES ONLY.=20 INFORMATION PROVIDED IN THIS DOCUMENT IS PROVIDED 'AS IS' WITHOUT = WARRANTY=20 OF ANY KIND. The user assumes the entire risk as to the accuracy = and the=20 use of this document. The Infrared Training Center newsletter may = be=20 copied and distributed subject to the following conditions: 1. All = text=20 and images must be copied without modification and all pages must = be=20 included; 2. All copies must contain the Infrared Training Center=20 copyright notice and any other notices provided therein;
3. = This=20 document may not be distributed for profit

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