History of the Film Plane Indicator

[twvancamp]

I'm not sure what made me think about this, but I'm curious how the Φ symbol became the standard film plane indicator. I'd also like to know when it was first adopted and by what maker.

My oldest cameras are from the 60's and 70's and all seem to share the same symbol. Wondering if folks with older pieces can help trace the history back further.

 

[twvancamp]

I still haven't figured this out! I'd love to know which manufacturer/designer takes credit for this symbol.

 

[Chriscrawfordphoto]

A lot of modern digital SLR and mirrorless cameras have them too. My Olympus OM-D E-M1 Mark II has one showing the plane of the sensor.


I don't know the history though. Interesting question!

 

[css9450]

The early Nikons (I, S, S2 etc) had a red dot instead of the symbol; if I remember right the S3 and SP have the symbol we all know and love.

 

[Godfrey]

I imagine the origin of the film plane indicator symbol is related to the plimsoll mark used on ships' hulls to indicate the maximum safe loading to maintain safe buoyancy.

The plimsoll mark gives a reference line on the hull for maximum draft (minimum safe freeboard). My conjecture is that the mark's design origin was considering looking at a hull along its axis from bow or stern, showing the hull as a circle and the waterline as a line bisecting the hull.

This symbol has come to be used as a distance reference mark for many things, for example: motion picture production where camera operators and focus pullers use them in annotated scripts so that actors know where to start and where to end up in a take. Most of the cameras I've owned made since the 1950s have used the symbol for a focus plane indicator.

G

 

[Pál_K]

Maybe someone from the field of Optics or Photogrammetry might know for certain.

I'll have to check what is the oldest camera I have that has this indicator.

 

[Ted Striker]

Has anyone actually used this measurement?

 

[Godfrey]

Has anyone actually used this measurement?

It's a reference mark, not a measurement. I use it quite frequently when I'm doing high magnification macro photography. It's useful for getting my setup roughed in for the correct magnification before critical focusing.

G

 

[twvancamp]

I imagine the origin of the film plane indicator symbol is related to the plimsoll mark used on ships' hulls to indicate the maximum safe loading to maintain safe buoyancy.

This is really interesting, and I never would have made the connection. Maybe Samuel Plimsoll is who we owe our debt of gratitude.

 

[twvancamp]

The early Nikons (I, S, S2 etc) had a red dot instead of the symbol; if I remember right the S3 and SP have the symbol we all know and love.

Thank you! It's helpful to know there was a time it wasn't in use. I'd love to know which company was the one to standardize.

 

[Doug]

Relevant or not, the symbol is the Greek letter Phi, equivalent to our letter F, which stands for Film... 🙂 Similar logic to Music Man's "trouble starts with t, which rhymes with p, which stands for pool"?

 

[ChrisPlatt]

On every camera body I've seen it on the film plane indicator is located off-center.
This would make accurate critical measurements unlikely or very difficult, which seems to contradict its purpose.

Chris

 

[Pál_K]

Has anyone actually used this measurement?

It's a reference mark, not a measurement. I use it quite frequently when I'm doing high magnification macro photography. ...

As have I, photographing watch mechanisms and other small items.

On every camera body I've seen it on the film plane indicator is located off-center.
This would make accurate critical measurements unlikely or very difficult, which seems to contradict its purpose...

That's true, and I found it annoying in actual use.

 

[Beemermark]

It's a reference mark, not a measurement. I use it quite frequently when I'm doing high magnification macro photography. It's useful for getting my setup roughed in for the correct magnification before critical focusing.

G

Not to quibble but it is a measurement. In my Nikon F2 manual it is given as 46.5mm from the mark to the flange.

 

[charjohncarter]

Has anyone actually used this measurement?

I have many times.

 

[Godfrey]

Not to quibble but it is a measurement. In my Nikon F2 manual it is given as 46.5mm from the mark to the flange.

I'm not quibbling. That's just wrong.

The symbol indicates a location—where the focal plane is—from which a measurement can be made. It isn't the measurement itself. It is a reference mark.

For a Nikon F2, you obtain the measurement you speak of by measuring from the reference mark to the lens mount flange surface. That is the mount register for that camera. You can obtain the same measurement by removing the lens and measuring from the lens mount flange to the film itself.

The reference mark allows you to make other measurements from the film plane to the subject with the camera and lens assembled to make a photograph. Such a measurement will not be 46.5mm. That's why the reference mark is useful. 🙂

G

 

[css9450]

On every camera body I've seen it on the film plane indicator is located off-center.

Off center.... Left or right? Or above the lens axis? I don't think there's any way to avoid the latter.

 

[Takkun]

Has anyone actually used this measurement?

In cinematography, frequently. My Panasonic camcorder, and many other cine cams, has a hook for a measuring tape. Like with macrophotography, makes setup easier.

 

[Beemermark]

I'm not quibbling. That's just wrong.

The symbol indicates a location—where the focal plane is—from which a measurement can be made. It isn't the measurement itself. It is a reference mark.

For a Nikon F2, you obtain the measurement you speak of by measuring from the reference mark to the lens mount flange surface. That is the mount register for that camera. You can obtain the same measurement by removing the lens and measuring from the lens mount flange to the film itself.

The reference mark allows you to make other measurements from the film plane to the subject with the camera and lens assembled to make a photograph. Such a measurement will not be 46.5mm. That's why the reference mark is useful. 🙂

G

OK, as an Engineer you've confuse me. A reference point is only useful as a point to take a measurement from. So maybe we are saying the same thing. The film plane mark is a reference mark to a measurement from (to the lens mounting flange), which for a Nikon is 46.5 mm as described in the Nikon manual. Then again maybe it's maybe it's because it's after midnight and I've had two dirty martinis -🙂

 

[farlymac]

OK, as an Engineer you've confuse me. A reference point is only useful as a point to take a measurement from. So maybe we are saying the same thing. The film plane mark is a reference mark to a measurement from (to the lens mounting flange), which for a Nikon is 46.5 mm as described in the Nikon manual. Then again maybe it's maybe it's because it's after midnight and I've had two dirty martinis -🙂

Okay, try seeing it as an "indicator" then, showing the location of the film plane, a starting point for many critical measurements, especially in macro/micro photography.


PF