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Mark Sawyer
12-May-2014, 10:11
I think most people here know what actually defines a telephoto lens is: it's a lens that gives an angle of view of a certain focal length, but focuses at a shorter distance than that focal length. Most people here also know that most people in general think a telephoto lens is just a long focal length lens.

I was talking with a "professional photographer" yesterday, and this came up. He didn't know what the term "telephoto lens" really meant, and when I told him, he didn't believe me. So I told him, "Google it". Which he did. And here's what we found:

Wikipedia: "A telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length."

Merriam-Webster: "a camera lens system designed to give a large image of a distant object."

Cambridge Dictionary: "a camera lens that makes objects far away look nearer and larger when they are photographed"

Yahoo! Answers, ("best answer"): "tele means distant or distance, tele is used to describe a "longer" view - a tele lens will make things appear closer ."

Answers.com: "a photographic lens or lens system used to produce a large image of a distant object."

We quit searching there, with him satisfied that any lens over 50mm on a 35mm frame is a telephoto. If only I was as smart as the internet... :p

Mark Woods
12-May-2014, 10:51
Hello Mark,

In your first statement I think you're confusing a retrofocus lens where the center of the lens design is not the center of the lens, but moved forward in a wider lens and further back in a longer lens. Look up retrofocus lens and it's pretty clear what it is. Ron Dexter also makes a very clear explanation.

Heroique
12-May-2014, 11:14
Look up retrofocus lens and it's pretty clear what it is.

On the Internet, retrofocus usually means manual focus. ;^)

Emmanuel BIGLER
12-May-2014, 11:24
It would be interesting to know when the words 'telephoto lens' first appeared in the technical vocabulary of photography.

I have looked at the entry "télé-objectif" in the French on-line reference dictionary, Le trésor de langue française informatisé
http://atilf.atilf.fr/tlf.htm
and the definition is perfectly correct explaining both the aspects of a long focal length (magnifying distant objects, hence 'tele') and the short flange-focal distance obtained using a rear negative lens group. Hence, the Internet is not always wrong ;-)
The French on-line dictionary credits Zeiss in 1899 for the word "telephoto" and mentions the entry "télé-objectif" as early as 1904 in the French Larousse dictionary.

According to the English wikipedia, the principles of the telephoto lens can be credited to Barlow (1834) and Dallmeyer (1860-1890) but the word "telephoto" might be a more recent addition to the vocabulary.

This German book mentions "Teleobjektiv" in 1896 referring to a lens built by Ernst Miethe in 1891. (http://www.deutschestextarchiv.de/book/view/samter_erfindungen_1896?p=1014)

Mark Woods
12-May-2014, 11:26
Telescope?

ic-racer
12-May-2014, 11:48
I think most people here know what actually defines a telephoto lens is: it's a lens that gives an angle of view of a certain focal length, but focuses at a shorter distance than that focal length. Most people here also know that most people in general think a telephoto lens is just a long focal length lens.

I was talking with a "professional photographer" yesterday, and this came up. He didn't know what the term "telephoto lens" really meant, and when I told him, he didn't believe me. So I told him, "Google it". Which he did. And here's what we found:

Wikipedia: "A telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length."

Merriam-Webster: "a camera lens system designed to give a large image of a distant object."

Cambridge Dictionary: "a camera lens that makes objects far away look nearer and larger when they are photographed"

Yahoo! Answers, ("best answer"): "tele means distant or distance, tele is used to describe a "longer" view - a tele lens will make things appear closer ."

Answers.com: "a photographic lens or lens system used to produce a large image of a distant object."

We quit searching there, with him satisfied that any lens over 50mm on a 35mm frame is a telephoto. If only I was as smart as the internet... :p

I studied the 'dark ages' while in college. I remember thinking how could people be so stupid. However, I am now convinced we will have another 'dark ages.' You have given a perfect example. The elements are already in place for the next age of ignroace , for example, the most popular internet search engine (Google) is already so corrupt it is not even a secret that top hits from searches are to sites that pay Google.

Heroique
12-May-2014, 12:16
I studied the 'dark ages' while in college. I remember thinking how could people be so stupid. However, I am now convinced we will have another 'dark ages.' You have given a perfect example. The elements are already in place for the next age of ignorance , for example, the most popular internet search engine (Google) is already so corrupt it is not even a secret that top hits from searches are to sites that pay Google.

:D

The Dark Ages:
If she sinks and drowns, she's innocent.
If she floats, she's a witch and must be executed.

The "New" Dark Ages of Google:
If it pays, the definition is correct.
If it doesn't pay, it's false and must be suppressed.

Bob Salomon
12-May-2014, 12:36
But telephoto is also in common usage as a longer then normal focal length lens. So while technically your friend was wrong he was also right by the common usage definition.

Scotch Tape is also in common usage. 3M made scotch tape and other companies made cellaphane tape but all brands are commonly called "scotch tape".
Kleenex is another. Many people call all facial tissues a "kleenex".

Mark Woods
12-May-2014, 12:37
xerox=copy

ghostcount
12-May-2014, 12:48
...the most popular internet search engine (Google) is already so corrupt it is not even a secret that top hits from searches are to sites that pay Google.


:D
...
The "New" Dark Ages of Google:
If it pays, the definition is correct.
If it doesn't pay, it's false and must be suppressed.

Tosh is an acquired taste but this one is funny.

Google Autocomplete (https://www.youtube.com/watch?v=n4JHZETKfes)

Mark Woods
12-May-2014, 13:02
Very funny ghostcount

Struan Gray
12-May-2014, 13:38
I gave up when those whippersnappers started writing 'an adder' instead of 'a nadder'. Some folks have no respect for tradition.

The online OED gives a Westminster Gazette quote from 1895. Google books has - but won't show me - a lecture given to the Franklin institute in 1893 on the 'Parvin' tele-photographic lens (http://books.google.se/books?id=z3dEHAAACAAJ). Kingslake credits, among others, Booth for the history of the type, who gives the nod to Dallmeyer, Dubosq and Miethe simultaneously producing tele lenses in 1891 - all inspired by the use of negative lenses to give more magnification in telescopes. (https://archive.org/stream/telephotography00landrich#page/6/mode/2up)

A 'telephoto image' was also used from the 1920s onwards to mean one sent by wire.

David Lobato
12-May-2014, 16:13
Let's be glad the word "telescopic" is seldom used these days to describe a camera lens. Well, so I thought. Dare to google telescopic lens. Arghhh.

Jody_S
12-May-2014, 16:27
:D

The Dark Ages:
If she sinks and drowns, she's innocent.
If she floats, she's a witch and must be executed.

The "New" Dark Ages of Google:
If it pays, the definition is correct.
If it doesn't pay, it's false and must be suppressed.

But does the lens weigh more than a duck?

8x10 user
12-May-2014, 18:07
A true telephoto lens has a significantly shorter flange distance then the focal length. I believe the first was the Adon and the best was the Bergheim ;)

Most long lenses, especially digital ones are telephoto. I guarantee you that all of the 600-800mm digital lenses today have elements much closer to the sensor then 600-800mm.

In LF we also have non-telephoto, long ,and very long lenses (such as the apo ronars). Nikkon and Schneider both made telephoto lenses for LF... Although I think that one of the Apo Tele Xenars (compact) is actually a dialyte and not a true tele-focus lens. If you look at Rodenstocks literature on the Ronar it mentions that it makes for a good long focal length lens when stopped down and that it is better then telephoto type lenses.

ic-racer
12-May-2014, 18:10
I would discount any 'common use' definition for a term specific to a specialty like photography. The iPhone 'photographers' can use 'telephoto' filters or whatever, but when communicating with other educated persons, I'd expect a common understanding of our fields nomenclature.

8x10 user
12-May-2014, 18:13
Are you talking about optical filters? Because if you add something to the front of the lens which makes the focal length longer without requiring more extension then it sounds like you are technically converting a lens to telephoto... I think Schneider was making a set of iphone lens modifiers...

ic-racer
12-May-2014, 18:24
Are you talking about optical filters? Because if you add something to the front of the lens which makes the focal length longer without requiring more extension then it sounds like you are technically converting a lens to telephoto... I think Schneider was making a set of iphone lens modifiers...

I was actually thinking of something like digital manipulations from the phone to make it look "telephoto." However, the terminology in this website may be using "Telephoto" as a combination of the words "Telephone" "Photograph"
http://populagram.appspot.com/tag/telephoto

Mark Woods
12-May-2014, 18:26
How did we get from LF to iPhone???? iPhone has nothing to do with LF. Any lens mod can be applied to any format. The focal length of the lens really doesn't reflect the distance of the rear element to the imaging area. The distance to the imaging area is determined by the lens design and the distance from the center of the lens design to the imaging area. Some telephoto lenses center of the lens design may be in front of the front element. The same as some wide lenses center of design may be behind, or close to the, imaging area.

jb7
13-May-2014, 05:36
Be careful what you search for- had you searched for "telephoto design" your friend might have been more convinced. That said, had you stopped at the Wikipedia article and read further into it then that definition might have been sufficient, but nobody likes to stop at a Wikipedia article...

My own favorite is 'tilt shift'; I was talking to an expert recently who discovered that function in the menu of her first camera, recently purchased, and tilt shift is now a de facto digital effect. The fact that it usually doesn't display any shifting at all, without a further off axis crop, just goes to prove that pedants are simply irritating and useless.

Jac@stafford.net
13-May-2014, 06:12
We quit searching there, with him satisfied that any lens over 50mm on a 35mm frame is a telephoto. If only I was as smart as the internet... :p

Excellent humor!

For LF folks who use front tilt, a true telephoto would be a bit of a pain because its nodal point is in front of the lens. Tilting the telephoto lens changes the focus. But who tilts a telephoto?

So, any long lens that does not have a nodal point in front of the lens is just a long lens.

Retrofocus is what we olde phartes use when trying to recall what we looked like with hair.

Retrofocus - Try to keep this in your head all at once (http://www.freepatentsonline.com/6791765-0-large.jpg).

ic-racer
13-May-2014, 08:06
How did we get from LF to iPhone????

The miracle of Google.

Bob Salomon
13-May-2014, 08:11
What does the internet have to do with the term "telephoto"? When I started in the retail camera business in 1957 a lens longer then normal was commonly referred to as a telephoto lens. Not a long lens.

This isn't a modern use of the term. It goes back decades.

Corran
13-May-2014, 08:36
That's not as bad as a lot of the new photographers I run into calling flashes or any light modifiers "lightning gear."

John Schneider
13-May-2014, 09:28
Scotch Tape is also in common usage. 3M made scotch tape and other companies made cellaphane tape but all brands are commonly called "scotch tape". Kleenex is another. Many people call all facial tissues a "kleenex".


xerox=copy

http://en.wikipedia.org/wiki/Generic_trademark. And aspirin and jello and…

Bob Salomon
13-May-2014, 10:01
That's not as bad as a lot of the new photographers I run into calling flashes or any light modifiers "lightning gear."

Or accessory shoes a "hot shoe". I have seen them described as a "hot shoe without contacts"

One of the best was the GSA. When we were on the GSA contract we wanted to list the Kaiser copy stands as the government really bought a lot of them from us. The GSA examiner found that the GSA had no category for a copy stand and wanted to know if we had any objection to them listing the copy stands under tripods since they both support a camera!

Mark Sawyer
13-May-2014, 10:59
What does the internet have to do with the term "telephoto"? When I started in the retail camera business in 1957 a lens longer then normal was commonly referred to as a telephoto lens. Not a long lens.

This isn't a modern use of the term. It goes back decades.

I can understand that in popular usage. I can even understand that today's professional photographers don't know the term. But I'm surprised that the first five internet reference sites got it wrong too. The distinction between a true telephoto and a long conventional lens is very important to large format photographers, and I suspect in other areas as well.

hoffner
13-May-2014, 11:18
I can understand that in popular usage. I can even understand that today's professional photographers don't know the term. But I'm surprised that the first five internet reference sites got it wrong too. The distinction between a true telephoto and a long conventional lens is very important to large format photographers, and I suspect in other areas as well.
But LF photographers are just a small part of the photographers community and do not have any proprietary rights to the expression "telephoto lens". Try to understand it. It seems that the internet is smarter than you, after all.

Bob Salomon
13-May-2014, 11:39
I can understand that in popular usage. I can even understand that today's professional photographers don't know the term. But I'm surprised that the first five internet reference sites got it wrong too. The distinction between a true telephoto and a long conventional lens is very important to large format photographers, and I suspect in other areas as well.

It might be "very important" to some but in the 34 years that I have represented Linhof and first Linhof Schneider lenses and since 1986 Rodenstock lenses this simply isn't a question that came up. Or comes up today. Yes customers used to ask for the Tele Arton and Tele Xenar 360 and 300mm lenses when they discovered that the 300.mm and 360mm Sironar and Symmar lenses would not fit a Technika. But they only wanted to know if the Tele lenses physically fit the camera. They rarely, if ever, asked what the flange focal length distance differences were.

So I question how "very important" this really is to large format photographers. It certainly isn't important to medium format and 35mm photographers.

Mark Sawyer
13-May-2014, 12:06
It might be "very important" to some but in the 34 years that I have represented Linhof and first Linhof Schneider lenses and since 1986 Rodenstock lenses this simply isn't a question that came up. Or comes up today. Yes customers used to ask for the Tele Arton and Tele Xenar 360 and 300mm lenses when they discovered that the 300.mm and 360mm Sironar and Symmar lenses would not fit a Technika. But they only wanted to know if the Tele lenses physically fit the camera. They rarely, if ever, asked what the flange focal length distance differences were.

So I question how "very important" this really is to large format photographers. It certainly isn't important to medium format and 35mm photographers.

If someone bought that 360mm Tele-Xenar thinking "oh, a 360mm lens will certainly cover my 8x10", they might find it important when it didn't because of the shorter bellows draw.

Michael Chmilar
13-May-2014, 12:10
C'mon, you guys.

We all know that the correct term for a long lens is "zoom lens", because it zooms in closer to stuff.

Mark Woods
13-May-2014, 12:19
"If someone bought that 360mm Tele-Xenar thinking "oh, a 360mm lens will certainly cover my 8x10", they might find it important when it didn't because of the shorter bellows draw."

I think that's why technical specifications sheets exist.

Mark Sawyer
13-May-2014, 12:32
My point is, if the customer asked Bob the difference between a 360mm telephoto lens and a 360mm conventional lens, he'd have a better answer than, "a telephoto lens makes far away things look closer". But the internet reference sites people turn to for answers give about that level of information. And I guess that's fine with us.

Bob Salomon
13-May-2014, 12:37
"fit a Technika"

Not a problem with a Technika. The last 810 Technika was made in 1938/1939 and only 6 are still known to be around. Modern Technika users were using 23, 45 and 57 models and the 360 Tele Arton and the 360 Tele Xenar both more then covered 5x7 and allowed movements.

goamules
13-May-2014, 12:38
I thought this was a telephone photo (or "telephoto")?

http://ak4.picdn.net/shutterstock/videos/2249197/preview/stock-footage-two-young-female-friends-taking-photo-with-cellphone-in-the-park.jpg

Len Middleton
13-May-2014, 12:49
I think that's why technical specifications sheets exist.

Ah the days when you could phone up a manufacturer's rep and he would send out spec sheets in the mail, unless you had one of those new fangled fax machines...

Unfortunately, Schneider seems to be the main source for info on their old lenses, and not much manufacturer's info is available. So there is a dependence upon old brochures, experience of others, and folklore, although separating the last two can be difficult...

And add to that using lenses in ways they were not originally developed for (e.g. process lenses).

So knowing characteristics of the basic design are important, but as indicated by others, in LF one should know or may soon find out the critical issues.

Bill Burk
13-May-2014, 22:40
I learned my lesson the hard way when I made a box to watch the eclipse. After I built the box and mounted my 12 inch Dallon I found it's not 12 inches to focus that lens at infinity.

alexn
16-May-2014, 20:02
When you think about it, any 50mm lens or longer on a 35mm camera is technically a telephoto design, as all major brand DSLR cameras (Canon and Nikon) have the lens mount less than 50mm from the sensor/film plane. So technically speaking, they reach infinity focus closer than their focal length from the film plane. a 300mm lens on 35mm still mounts only 50mm from the film plane. However you're right.. The days of technology are causing the population to forget the days of intelligence. the days of discovery... People take for granted what technology affords them, without remembering that people much smarter than them had to think, envision, plan and create the devices that are now common place devices, to discover things most people today simply do not know.

Take the telescope - perfect example. So many people take the word of the internet that there are planets in the solar system, planets with moons that orbit them, stars, galaxies, black holes, nebulae, gravitational lensing effects.. How many people have watched the moons of Jupiter orbit the planet through a telescope. how many people have seen, with their own eyes, the rings of saturn casting a shadow on the face of the planet? how many people have looked at distant galaxies or nebulae? I know I have.. I know, not because I've been told, but because I've done it myself.. Now go back 400 years when Galileo first decided to point a telescope at the night sky as opposed to across the distant horizon... When I looked through my telescope, I know what it is I'm looking at, because of the knowledge and wisdom of those who came before me..

Its too easy for people to say they know things because the internet says so these days.... Its really kind of sad that the time of learning things for yourself and the age of discovery seem to be coming to an end...

Mark Woods
16-May-2014, 20:42
Maybe the masses will forget it all and then will have to relearn it. The ones in low lying areas will learn it first.

Len Middleton
17-May-2014, 06:57
When you think about it, any 50mm lens or longer on a 35mm camera is technically a telephoto design, as all major brand DSLR cameras (Canon and Nikon) have the lens mount less than 50mm from the sensor/film plane. So technically speaking, they reach infinity focus closer than their focal length from the film plane. a 300mm lens on 35mm still mounts only 50mm from the film plane.

Alex,

In your description, it seems like you are describing the flange to film distance of the lens, not its actual focal length (i.e. rear nodal point to film).

If I have misunderstood your description, please clarify.

Regards,

Len

Dan Fromm
17-May-2014, 21:09
Len, I think Alex was playing with us. Lenses for a 35 mm SLR all have the same flange-focal distance. In the case of Nikons, 46.5 mm. Long ones are, in effect, on extension tubes. Not a fair comparison with lenses that don't have integral focusing helicals.

What makes a telephoto lens is rear node in front of front node. This is achieved by making the first group converging and the rear group diverging (or have I got it backwards? If so, apologies all round).

The tele definition "flange-focal distance shorter than focal length" makes a very strong assumption about where the flange should be.

Alan Gales
17-May-2014, 22:09
Ok. Let me explain it to you people. Back in the 80's I used to sell cameras. The Kodak 110 cartridge cameras were popular among the cheap crowd. We sold three models, the basic, the basic with flash and the upscale telephoto camera. The telephoto camera was actually the basic with flash but had a sliding plastic telephoto lens that would slide in front of the standard lens and make everything look closer but unfortunately less sharp if that was possible.

People used to actually ask me which to buy. I told them that the basic camera was for float trips. The one with flash was to buy if you planned on using it indoors. They would then ask, "What about the telephoto model?".
I would then reply that they should skip it and put the money they saved in a piggy bank for the Canon Sureshot.

That's my experience with telephoto lenses. Of course if you want a serious read, check out Dan's post above about nodal points.

Dan Fromm
18-May-2014, 05:17
Alan, I'm surprised that our resident DofP hasn't brought up Century's TeleAthenars. They're long stovepipes with an achromatic doublet at the front and a piece of flat glass (why?) in the middle. And they're teles 'cos their name says so.

rdenney
18-May-2014, 05:38
My definition, entirely empirical: a telephoto lens has an image circle smaller than its focal length.

People define things by how they see them. Jargon with a specific meaning gets ruined by that all the time.

The Internet is no worse than the printed word, which has always included examples of technical ignorance, confusion, and error. The good old days aren't as good as you guys are remembering. Just read any 70's edition of Pop Photo.

Rick "who walked to school in the snow, uphill...both ways" Denney

Tim Meisburger
18-May-2014, 06:54
Hey Rick. You must be from northern Virginia. I attended that same school and tell my kids about it all the time. You were lucky though, as I had to go barefoot...

Len Middleton
18-May-2014, 07:07
But in Virginia it would not be like in Canada, with the snow waist deep all year round and with daytime temperatures with a high of -40... :D

koh303
18-May-2014, 07:24
I think most people here know what actually defines a telephoto lens is: it's a lens that gives an angle of view of a certain focal length, but focuses at a shorter distance than that focal length. Most people here also know that most people in general think a telephoto lens is just a long focal length lens.

I was talking with a "professional photographer" yesterday, and this came up. He didn't know what the term "telephoto lens" really meant, and when I told him, he didn't believe me. So I told him, "Google it". Which he did. And here's what we found:

Wikipedia: "A telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length."

Merriam-Webster: "a camera lens system designed to give a large image of a distant object."

Cambridge Dictionary: "a camera lens that makes objects far away look nearer and larger when they are photographed"

Yahoo! Answers, ("best answer"): "tele means distant or distance, tele is used to describe a "longer" view - a tele lens will make things appear closer ."

Answers.com: "a photographic lens or lens system used to produce a large image of a distant object."

We quit searching there, with him satisfied that any lens over 50mm on a 35mm frame is a telephoto. If only I was as smart as the internet... :p

Your internet must be different that mine.
Wikipedia has the exact, and correct answer (as it always has, even when its wrong, its right, after all - its wikiperdia).
You just had to keep on reading one more line, or skip to the diagrams. Is there enough attention span in a young mind to actually do that? Who cares.

I think this one goes to the photo geek with the digital camera.

Mark Woods
18-May-2014, 10:09
Hi Dan, I sold my cameras about 10 years ago. The "telephotos" I had were the following: 80mm, 135mm (Ziess Super Speeds), & 300mm Canon. I also had a 1.5 "doubler." This was all for a 35mm MovieCam Compact. The Canon was a little flarey, but I used them all. With my current LF packages, I have both extremely sharp lenses & pictorialist lenses. I've never used telephotos much, I'm more of a wide lens type of guy. I've shot whole films 90%+ shot with a 25mm or 35mm lenses.

Emmanuel BIGLER
18-May-2014, 10:41
What makes a telephoto lens is rear node in front of front node.

Whaououou ! Thanks, Dan!
I'm glad to have learned today that
1/ some of my Tessars (and some are also zooms ;) ) as well as my 100 mm Hasselblad Planar are telephoto designs!

2/ that my faithful 360 mm Tele-Arton is NOT a telephoto! (http://www.largeformatphotography.info/forum/showthread.php?17775-Center-of-perspective-and-nodal-point&p=169156&highlight=arton+pupil#post169156) (H=N = at 137 mm in front of the first lens vertex; H'=N' at 63 mm in front of the first lens vertex; effective focal length = 353)

Hence I would prefer this simpler definition: if your lens has a focal length longer than the diagonal of the format and longer than the distance between the first lens vertex and the focal point, there is a high probability that this is a telephoto design ... with this definition, my tessars and my 100 mm planar are no longer telephotos :cool:

Mark Sawyer
18-May-2014, 11:19
Your internet must be different that mine.
Wikipedia has the exact, and correct answer (as it always has, even when its wrong, its right, after all - its wikiperdia).
You just had to keep on reading one more line, or skip to the diagrams. Is there enough attention span in a young mind to actually do that? Who cares.


My young mind (that turns 58 in a few days) is calling you on this one. Here's the opening statement (both sentences) defining a telephoto lens directly from Wikipedia at: http://en.wikipedia.org/wiki/Telephoto_lens

"In photography and cinematography, a telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a telephoto group that extends the light path to create a long-focus lens in a much shorter overall design."

Now lets look at the first sentence, the one that defines the telephoto lens: "the physical length of the lens is shorter than the focal length".

Do you have a 300mm lens? Is it physically shorter than a foot long? If so, it's a telephoto. Wikipedia says so, and after all, "Wikipedia has the exact, and correct answer".

Gee, every large format lens I have seems to be a telephoto, even the wide angles...

Jac@stafford.net
18-May-2014, 11:43
A telephoto lens has its nodal point in front of its front lens (the element towards the subject.)

It is that simple.

Now look at retrofocus for the complimentary.

It ain't rocket science.

koh303
18-May-2014, 11:50
My young mind (that turns 58 in a few days) is calling you on this one. Here's the opening statement (both sentences) defining a telephoto lens directly from Wikipedia at: http://en.wikipedia.org/wiki/Telephoto_lens

"In photography and cinematography, a telephoto lens is a specific type of a long-focus lens in which the physical length of the lens is shorter than the focal length. This is achieved by incorporating a special lens group known as a telephoto group that extends the light path to create a long-focus lens in a much shorter overall design."

Now lets look at the first sentence, the one that defines the telephoto lens: "the physical length of the lens is shorter than the focal length".

Do you have a 300mm lens? Is it physically shorter than a foot long? If so, it's a telephoto. Wikipedia says so, and after all, "Wikipedia has the exact, and correct answer".

Gee, every large format lens I have seems to be a telephoto, even the wide angles...

Not sure what 300mm have to do with a foot but I'de rather not get into the silliness of the American measurement system, which aside from Burma is the only other country in the world not to use the metric system (and burma has recently begun a conversion scheme...).
So i will just leave you with this:
115545

It might help with other things like using the inter web down the line... :)

Mark Sawyer
18-May-2014, 11:57
Not sure what 300mm have to do with a foot...

Well, I guess I could try to explain basic metric-English conversion to you, but I think I'll just presume that without a point you've resorted to insults and trolling...

djdister
18-May-2014, 12:23
Rather than compete with Internet searches about Britney, Justin or Kim on the web, some of us can just pull a book or three off the shelf:

"Telephoto lenses are characterized by having a shorter lens to film distance than a normal lens of the same focal length. ... Telephoto lenses have a classic basic structure that results in the placement of the image nodal plane in front of the lens rather than within the body of the lens." View Camera Technique, 3rd Ed. 1976, Les Stroebel

"A true telephoto lens is designed so that the rear nodal point of the lens is located in front of, rather than within, the lens." Photography With Large-Format Cameras, 1988, Eastman Kodak

"... a telephoto lens is the opposite of a retrofocus lens: it is physically shorter and closer to the film than its focal length indicates (the rear nodal point may be in front of the lens)." The Camera, 1980, Ansel Adams

Corran
18-May-2014, 13:07
Do you have a 300mm lens? Is it physically shorter than a foot long? If so, it's a telephoto. Wikipedia says so, and after all, "Wikipedia has the exact, and correct answer".

Gee, every large format lens I have seems to be a telephoto, even the wide angles...

Well hold up, obviously to measure the length of the lens, one would include the bellows it requires to focus it to infinity. At least, that would be implied, no?

Mark Woods
18-May-2014, 13:32
My 300mm Canon was 14"-16" long to the flange. When you add the Flange Focal Distance in, the whole works was longer that 11.8". Again, I think the Wiki poster is confusing the lens design of a retro focus lens with a more "normal" lens design.

Peter_Jones
18-May-2014, 13:45
American measurement system, which aside from Burma is the only other country in the world not to use the metric system

Had to laugh at that - being English, I use imperial measurements for distance, weight, and things like fuel economy (mpg) but am forced to buy things in metric to appease the mathematically challenged, then convert back to imperial measurements. I know my height in feet/inches, and my weight in stones/pounds but cannot guess what they would be in Napoleonic measurement. Oddly, temperature in England (when referring to weather) is usually measured in Centigrade (Celsius) except in a summer heatwave when it magically converts to Farenheit :)

8x10 user
18-May-2014, 13:52
This is slightly off topic but:

My telephoto is missing the front part with the aperture but it seems to take great pictures anyway. Do I have to worry about using thick optical resin filters (cokin) in front of the lens. I'm concerned there could be an issue of it affecting the focus or worse the "character" of the lens (because it is behind the nodal point)?

koh303
18-May-2014, 13:53
My 300mm Canon was 14"-16" long to the flange. When you add the Flange Focal Distance in, the whole works was longer that 11.8". Again, I think the Wiki poster is confusing the lens design of a retro focus lens with a more "normal" lens design.

can you explain this again? i think there is a typo that makes it hard to follow.
In any case corran has answered your question above as to the physical size of your LF lenses. As they do not have any moving parts, like say, smaller format cameras do, and rely (in most cases) on a focus helical inside the lens to adjust the optical center, whereas a LF lens (in most cases), regardless of its design will have to include the bellows draw to calculate its actual focal length.

Mark Sawyer
18-May-2014, 14:44
Well hold up, obviously to measure the length of the lens, one would include the bellows it requires to focus it to infinity. At least, that would be implied, no?

Wikipedia's definition was "the physical length of the lens is shorter than the focal length". I'm presuming that "the physical length of the lens" implies the physical length of the lens.

Corran
18-May-2014, 15:03
Well maybe you should edit it to say "the physical length of the lens when on the camera, measured from the lens to the image plane."

Personally I find it obvious that the definition is written from the viewpoint of the SLR/RF. The bellows is an integral part of the equation, when looking from the viewpoint of a LF shooter. But of course there are much less of us than the aforementioned group. So it was written without regard for this subset of photographers.

Mark Sawyer
18-May-2014, 15:40
If you sold a Petzval lens described as having "a physical length of 12 inches" and included the focal length behind it as part of the physical length, I suspect the buyer might call shenanigans. The lens is only a part of the whole imaging system.

Dan Fromm
18-May-2014, 15:52
What makes a telephoto lens is rear node in front of front node.


1/ some of my Tessars (and some are also zooms ;) ) as well as my 100 mm Hasselblad Planar are telephoto designs!

2/ that my faithful 360 mm Tele-Arton is NOT a telephoto! (http://www.largeformatphotography.info/forum/showthread.php?17775-Center-of-perspective-and-nodal-point&p=169156&highlight=arton+pupil#post169156) (H=N = at 137 mm in front of the first lens vertex; H'=N' at 63 mm in front of the first lens vertex; effective focal length = 353)

Interesting. In fact some OPIC type 6/4 slightly asymmetrical double Gauss type lenses are in fact lightly telephoto. This is why relatively early modern era OPIC type "normal" lenses for 35 mm SLRs (57 and 58 mm lenses from Konica, Minolta and Topcon come to mind) are longer than the standard generally accepted normal focal length for 35 mm still.

As for your beloved and of course faithful 360 Tele-Arton, well, I wonder about it. The latest Schneider documentation I can find for it (see https://www.schneideroptics.com/info/vintage_lens_data/large_format_lenses/tele-arton/data/5.5-360mm.htm) says that the principal points are 74 mm apart. Distances for the other f/5.5 Tele-Artons at that site also give unsigned presumably positive separations. But slightly older documentation (see http://web.archive.org/web/20111002115228/http://www.schneiderkreuznach.com/archiv/pdf/tele_arton_tele_xenar_2.pdf) gives -32.5 mm separation for the 250 mm f/5.6 (sic) and 74.3 mm (no sign, presumably positive) for the 360 f/5.5. It gives nearly the same flange-focal distance for the two lenses.

Many are the possible explanations. Typographical error. Different prescriptions and untrustworthy trade names. ... I don't know what to believe.

Sorry, Emmanuel, the only thing that's clear at the moment is that I still am and always will be an ignorant barbarian.

koh303
18-May-2014, 16:28
Well maybe you should edit it to say "the physical length of the lens when on the camera, measured from the lens to the image plane."

Personally I find it obvious that the definition is written from the viewpoint of the SLR/RF. The bellows is an integral part of the equation, when looking from the viewpoint of a LF shooter. But of course there are much less of us than the aforementioned group. So it was written without regard for this subset of photographers.

took the words out of my mouth.

Dan Fromm
18-May-2014, 19:35
I cheated and went to the library. Per S. F. Ray, Applied Photographic Optics, 3d edition, p. 302


The use of a long focus lens, where the BFD of simple two- or three-element designs is similar to the EFL gives a large image size, but this configuration also requires a long lens mount and focusing barrel or a long extension bellows. The telephoto configuration of a front positive lens followed by a rear diverging lens gives a more compact design, since the rear nodal point (N2) is now located in front of the front of the lens (Figure 30.1). The BFD is shortened but the lens barrel may be quite long.

A telephoto lens is defined as one where the ratio EFL:BFD is greater than unity and is at least of value 2.0 (Booth, 1926).

The definition above is an old one, now replaced by telephoto power, the distance from the lens' front vertex to the film plane (S, in his notation) divided by focal length. P = S/f. He mentions in passing that the 400/5.6 and 800/12 Apo-Tele-Xenar's telephoto powers are 1.0 and 0.92 respectively.

Ray adds (pp. 303-4):


Some classic designs such as the Tessar and double Gauss configurations have been adapted into telephotos, but bear little resemblance to earlier designs.

This is a polite way of saying that the lenses Zeiss sold as Tele-Tessars aren't what ignorant barbarians like me would recognize a Tessars. Trade names have nothing to do with design type. The same is true of Schneider's Tele-Xenars and jes' plain Xenars.

And to get back to this discussion's start, he writes:


Erroneously, most long focus lenses are simply called 'telephotos', although they may not be.

koh303
18-May-2014, 20:33
If you sold a Petzval lens described as having "a physical length of 12 inches" and included the focal length behind it as part of the physical length, I suspect the buyer might call shenanigans. The lens is only a part of the whole imaging system.

From the wiki page (4th paragraph):
...But such simple lenses are not telephoto lenses, no matter how extreme the focal length – they are known as long-focus lenses.[1] While the optical centre of a simple ("non-telephoto") lens is within the construction, the telephoto lens moves the optical centre in front of the construction.

Bill Burk
18-May-2014, 21:11
I don't have the nerve to edit the article, but added some discussion... The Wikipedia "Angénieux retrofocus" article clearly explains retrofocus (inverted telephoto) design. Should be easy to make the definition in the telephoto article as clear.

Jim Andrada
28-May-2014, 10:03
Not sure what 300mm have to do with a foot but I'de rather not get into the silliness of the American measurement system, which aside from Burma is the only other country in the world not to use the metric system (and burma has recently begun a conversion scheme...).
So i will just leave you with this:
115545

It might help with other things like using the inter web down the line... :)

Well, it's a little known factoid that I-19 from Tucson to Nogales is marked in Kilometers, not miles. At least it was last time I drove it. They keep talking about changing it to miles, but most of the folks locally kind of like it as it is.

Picked up a rental car in CA last week and the speedometer read in km/hr.