# focal plane location and filter size



## malbec (Sep 29, 2009)

please describe the symbols for focal plane location and filter size.  what is the difference between the two?


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## Flash Harry (Sep 30, 2009)

you don't get a "symbol" to describe where the focal plane is located, filter size(lens) on my nikons are on the base of the lens but sometimes on the ring. The focal plane is basically where your shutter is, the rear of, this is the point of focus of all lens made for the camera model you own. H


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## musicaleCA (Sep 30, 2009)

Cardinal point (optics) - Wikipedia, the free encyclopedia

Photographic filter - Wikipedia, the free encyclopedia

Lens filters and focal planes are not related to one another. In physics (optics), the focal plane is indicated by an F and F'. Filter size of a lens is usually indicated with a capital Phi (&#934, succeeding the filter size in millimetres, and is usually written on the rim next to the front element.


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## Dwig (Sep 30, 2009)

musicaleCA said:


> Cardinal point (optics) - Wikipedia, the free encyclopedia
> 
> Photographic filter - Wikipedia, the free encyclopedia



Good definitions of what they define, but the don't relate to the OP's question

The OP was not asking for definitions of the terms, but instead inquires as to what the symbols were.

The focal plane in a camera is indicated, if indicated by a small circle with a line drawn through the center parallel to the focal plane. The line is usually about three times as long as the diameter of the circle.

Filter diameters do not have any photographic specific symbol. You do often see the standard mathmatical symbol for "diameter" either preceding or following the number indicating the diameter in mm. This symbol is a circle with a diagonal line though its center. The line is rotated from vertical by about 30-45 degrees clockwise. The symbol is described about half way down this page:
Diameter - Wikipedia, the free encyclopedia


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## Big Mike (Sep 30, 2009)

From what I've seen, the focal place symbol is a circle with a horizontal line through it....the line representing where the plane is.



> Diameter symbol
> 
> The symbol or variable for diameter is similar in size and design to ø, the Latin small letter o with stroke. Unicode provides character number 8960 (hexadecimal 2300) for the symbol, which can be encoded in HTML webpages as &#8960; or &#x2300;. The character can be obtained in Microsoft Windows by holding the [Alt] key down while entering 8 9 6 0 on the numeric keypad. On an Apple Inc. Macintosh, the diameter symbol can be entered via the character palette (this is opened by pressing &#8997;&#8984;T in most applications), where it can be found in the Technical Symbols category.
> 
> ...


Diameter - Wikipedia, the free encyclopedia


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## Garbz (Oct 1, 2009)

The filter size is not indicated by phi but rather by "Ø" which is a Cyrillic letter.

The focal plane symbol is &#632; which as far as I know really is a symbol and not used in any language.

/EDIT: &#981; is the mathematical interpretation of the letter phi which is actually presented like &#934; in the language.


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## musicaleCA (Oct 1, 2009)

Noooo, it's Phi, or at least it is on all Canon lenses. Below is a shot of the front of my EF-S 10-22/3.5-4.5 USM. All Canon lenses I have illustrate the filter diameter in the same way. Perhaps Nikon is different?







Eugh, I really need to clean that lenses...Stupid 18MP making everything show-up (for the curious, that's what 6400 looks like on the 7D without any PP noise-reduction).


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## Dwig (Oct 1, 2009)

musicaleCA said:


> Noooo, it's Phi, ...



The proper symbol has a diagonal slash. It should _*not*_ be exactly vertical. Typography being what it is, most fonts will lack the symbol. Some creations made from the proper lower case Latin "o" and a slash, "/", may have an overly vertical slash that is a characteristic of that font.

The Canon lens you use for an example seems to have a slight slant to the slash. Not as much slant as would be proper, but not vertical either. It is just a rather poor rendition of the symbol. Its as if it was assembled using a slash from a rather condensed font where the slash was more vertical than in a more normal font.


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## Derrel (Oct 1, 2009)

...is Dwig finding fault with Canon's implementation of the filter size symbol and its incorrectly oriented slash??? He must be an anti-Canon, Nikon-using fanboy or something!

Actually, I know what he means: for a long time, the filter diameter symbol slash's angle has been a decided diagonal, running from seven o'clock to one o'clock. The symbol on new Canon lenses has the slash running almost straight up and down,relative to the other lens inscriptions; the new Canon symbol has a very slight diagonal, with a slash that runs from, "six thirty to twelve thirty".

Hey, I get it: Canon is ahead of everybody else! They start their slash at 12:30--while other,slothful lens makers begin their slashes at 1:00. Very subtle marketing message there, hidden in that Canon filter dia. symbol!


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## musicaleCA (Oct 1, 2009)

As long as we all realize we're arguing semantics here. How about we settle on it being a circle with a line thingy through it?


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## Dwig (Oct 1, 2009)

Derrel said:


> ...is Dwig finding fault with Canon's implementation of the filter size symbol and its incorrectly oriented slash??? He must be an anti-Canon, Nikon-using fanboy or something!...



I guess I somewhat resemble that remark. If I don't count the "look prettys" that I once had in a rather large camera collection (300+, most long since sold off), I've owned and used only 3 Canons (Dial 35 and two QL-17s) while I've owned and used some 8 Nikons (RF, SLR, & digital) and two Leicas.

I'm married and its a mixed marriage. I'm Nikon/Windows/tall/blond (when I had hair) and my wife is Canon/Mac/petite/brunette. The big difference, though, is "religion"; I was raised Warner Bros. and my wife was raised Disney.


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## musicaleCA (Oct 1, 2009)

Dwig said:


> I'm married and its a mixed marriage. I'm Nikon/Windows/tall/blond (when I had hair) and my wife is Canon/Mac/petite/brunette. The big difference, though, is "religion"; I was raised Warner Bros. and my wife was raised Disney.



:lmao::lmao::lmao::lmao::lmao: You're killing me man. Killing me!


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## Garbz (Oct 2, 2009)

Maybe canon made a NEW symbol! Phi is a perfectly vertical bar like so: &#981; in mathematics or &#934; in written language. 

But really this is all Greek to me.


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## grafxman (Oct 4, 2009)

Dwig said:


> I'm married and its a mixed marriage. I'm Nikon/Windows/tall/blond (when I had hair) and my wife is Canon/Mac/petite/brunette. The big difference, though, is "religion"; I was raised Warner Bros. and my wife was raised Disney.



That's hysterically funny and, I believe, original.  :thumbup:


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## JamesMason (Oct 4, 2009)

Dwig said:


> I'm married and its a mixed marriage. I'm Nikon/Windows/tall/blond (when I had hair) and my wife is Canon/Mac/petite/brunette. The big difference, though, is "religion"; I was raised Warner Bros. and my wife was raised Disney.



Im a nikon/mac/tall/brunette are you my real parents ?


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