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Alan Kovarik

35mm frame vs full frame sensor - crop factor

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I dont have any experience with 35mm film cameras. I own Canon 5D MII full frame camera. I wonder what full frame camera lens would be equivalent to Hitchcock's favorite 50mm movie camera lens. If I am right, it would be something around 70-80mm on full frame sensor. I am a bit confused, because Hitchcock used the 50mm lens because it mimicks normal human vision. But if its equavalent on a full frame camera is around 70-80mm, it doesnt mimick human vision at all. Its more like a portrait lens.

Spielberg's favorite lens is 21mm. Lets say I want to mimick this focal length on my full frame Canon 5D camera. What lens should i use?

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Posted (edited)

I found this commentary on another forum:
 

Quote

While 35mm still cameras have a 24x36mm frame running length-wise on the film, in a
movie camera the film runs up or down and therefore the frame runs across the film, so
that, for a 3:2 format, the frame would be 16x24mm and, for a 4:3 format, the frame
would be 18x24mm. For these two formats the crop factor (measured by dividing the
diagonal of the 24x36mm :"ull frame" by the diagonal of the two aforementioned movie
frames, which is 1.4 and 1.5 respectively. This neans that the EFOV of a 50 lens would be
73mm and 75mm, which is hardly close to human vision. Perhaps a 35mm lens was used.

Did Hitchcock really shot the whole Psycho with 50mm?

Edited by Alan Kovarik

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Conversion factor is about 1.5X, close enough. I had heard that Spielberg's favorite lens was a 27mm, not a 21mm.

I heard that about "Psycho" too, if true than I'm sure the majority was done using that lens, but some oddball shots could have used other focal lengths, like some of the inserts in the shower scene, macro shots, maybe the wide vfx shot of the house on the hill, etc.  But maybe not, maybe it was all 50mm!  The lens would be rather close to get those eyeball shots...

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47 minutes ago, David Mullen ASC said:

Conversion factor is about 1.5X, close enough. I had heard that Spielberg's favorite lens was a 27mm, not a 21mm.

 

So that would be something like 40mm on Canon 5D?

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BTW,  what is the standard (non-wide, non-telephoto) lens for 35mm movie camera? For a full frame still camera it is 50mm, but I suppose for 35mm movie camera it would be something like 30mm?

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Yes, a 40mm in FF35, though Spielberg often uses the 27mm more for shots where he has to go from wide to a close-up of a face, or the reverse. 27mm is not too distorted-looking for a close-up. He'll use wider-angles than a 27mm for other shots.

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In standard 35mm cine, anything from 27mm to 40mm could be considered "normal" or standard in terms of view, or a 32mm / 35mm if you want to be more precise.  We use a 30mm Primo a lot of "The Marvelous Mrs. Maisel" but it is not a commonly-made focal length.  And we are shooting 3.2K on the Alexa, so the view is slightly wider than a 30mm on a 4-perf 35mm standard gate.

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23 hours ago, Alan Kovarik said:

I dont have any experience with 35mm film cameras. I own Canon 5D MII full frame camera. I wonder what full frame camera lens would be equivalent to Hitchcock's favorite 50mm movie camera lens. If I am right, it would be something around 70-80mm on full frame sensor. I am a bit confused, because Hitchcock used the 50mm lens because it mimicks normal human vision. But if its equavalent on a full frame camera is around 70-80mm, it doesnt mimick human vision at all. Its more like a portrait lens. 

Spielberg's favorite lens is 21mm. Lets say I want to mimick this focal length on my full frame Canon 5D camera. What lens should i use?

In a FF camera, a 50mm is a... 50mm, you don't have crop factor with FF.

Get a 50mm and start shooting.

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It's curious that Hitchcock often mentioned 50mm as having a "natural" perspective that "gives you what your eye sees", but he shot on various formats including silent aperture, Academy and VistaVision, where a 50mm would give different angles of view. 

It's possible he felt that looking through a viewfinder the magnification of a 50mm seemed to match what his other eye saw, but of course that depends on the magnification of the viewfinder optics too. Most likely I think he was talking about the distortion or sense of depth, as in how a long lens can flatten perspective while a wide angle lens stretches things out and makes spaces seem larger than they are. But again whether a lens is deemed long or wide is a function of the format size, and the distance then determines the perspective.

The question of what focal length/format combination (or field of view) mimics human vision is a tricky business. Peripheral vision extends out to about 140 degrees, which you can test by holding your arms out to the sides and while wiggling your fingers bringing your arms slowly forward until you notice the wiggling movement. But our area of sharp focus is only about 10 degrees or less. So where between those extremes do you choose an angle that seems "natural"?

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Yes, it's confusing regarding Hitchcock and the 50mm -- I think in the Herbert Coleman book on producing for Hitchcock, he mentions supervising a reshoot / pick-up for "Vertigo" and Hitchcock chiding him for shooting it on a 35mm instead of a 50mm, but being a VistaVision movie, a 35mm would be on the wider-angle side.  Perhaps Hitchcock did his VistaVision period mostly on a 50mm so when he did "Psycho" he used the equivalent to a 50mm view, i.e. closer to a 35mm, but was used to saying he used a 50mm after five years of shooting VistaVision?

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3 hours ago, David Mullen ASC said:

...Perhaps Hitchcock did his VistaVision period mostly on a 50mm so when he did "Psycho" he used the equivalent to a 50mm view, i.e. closer to a 35mm, but was used to saying he used a 50mm after five years of shooting VistaVision?

This is what I was thinking too. I don't know much about Hitchcock's knowledge of photography, but if he did a bit of still 35mm photography he might simply have meant his "natural" or normal focal length lens transferred to motion picture and his cinematographers of course knew what he meant by that.

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According to this the standard lens for 35mm is 50mm.
https://en.wikipedia.org/wiki/Normal_lens#Cinema

http://neiloseman.com/the-normal-lens/

SMPTE (the Society of Motion Picture and Television Engineers), or indeed SMPE as it was back then, decided almost a century ago that a normal lens for motion pictures should be one with a focal length equal to twice the image diagonal. They reasoned that this would give a natural field of view to a cinema-goer sitting in the middle of the auditorium, halfway between screen and projector (the latter conventionally fitted with a lens twice the length of the camera’s normal lens).

A Super-35 digital cinema sensor – in common with 35mm motion picture film – has a diagonal of about 28mm. According to SMPE, this gives us a normal focal length of 56mm. Acclaimed twentieth century directors like Hitchcock, Robert Bresson and Yasujiro Ozu were proponents of roughly this focal length, 50mm to be more precise, believing it to have the most natural field of view.

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When you say "diagonal" though you have to remember that 4-perf Super-35 full aperture was only used in the Silent Era, and today Super-35 is cropped to 1.78, 1.85, or 2.40 so the diagonal is shorter.  And Hitchcock shot "Psycho" in 4-perf 35mm Academy, not Super-35, cropped to 1.85, so even a shorter diagonal.

Anyway, the tradition has always been a 50mm for FF35 as being "normal".

From Wikipedia: "For still photography, a lens with a focal length about equal to the diagonal size of the film or sensor format is considered to be a normal lens" / "For a 35mm camera with a diagonal of 43 mm, the most commonly used normal lens is 50 mm, but focal lengths between about 40 and 58 mm are also considered normal. The 50 mm focal length was chosen by Oskar Barnack, the creator of the Leica camera."

Also the wider the aspect ratio, the shorter the view vertically is compared to horizontally so often there is a tendency to split the difference in terms of what would be considered a normal view and go with something a bit wider in view horizontally to compensate for the reduction in view vertically.  Hence why the 50mm in 4-perf 35mm Academy felt like it saw "more" of a view compared to a 50mm when cropped vertically to 1.85.

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Posted (edited)

This is also interesting. Maybe Hitchcock was thinking about this:
https://en.wikipedia.org/wiki/Optimum_HDTV_viewing_distance#Visual_angle
 

The ideal optimum viewing distance is affected by the horizontal angle of the camera capturing the image. One concept of an ideal optimal viewing distance places the viewer where the horizontal angle subtended by the screen is the same as the horizontal angle captured by the camera. If this is the case, the angular relationships perceived by the viewer would be identical to those recorded by the camera. A mismatch in this regard is traditionally disregarded, but some rotating motions can make these distortions very noticeable as a pincushion effect. This is likely in 3d video games, so gamers are likely to adopt close viewing positions matched to a game's fixed field of view.

If the camera's angle were always the same, an optimal viewing distance could be easily calculated. However the camera's horizontal angle varies as the focal length of its lens changes. If the camera's sensor has fixed dimensions, a shorter focal length (wide angle) lens captures a wider angle of view, requiring the viewer to sit closer to the screen. Conversely, a longer focal length (telephoto) lens captures a narrower angle of view, demanding a more distant viewer position.

Such opposing viewing distances would not only be impractical, but would negate the very purposes of telephoto shots (for example, to see a distant object in more detail, or minimize distortion in facial images) and wide-angle shots (causing the viewer to sit too close to the screen, where undesirable image artifacts would be visible).

One compromise assumes the lens is "standard" (a 50mm focal length, for a standard 35mm format). A "standard" lens preserves the same spatial relationships perceived by a spectator at the camera location. For a "standard" lens image, viewing distance should be equal to the diagonal length of the screen.

It has been demonstrated that viewing a display that occupies a greater visual angle (also referred to as field-of-view) increases the feeling of presence.[8] More importantly, the wider the visual angle (to approximately a plateau point of 80 degrees), the greater the feeling of presence.

190px-Angle_of_view.svg.png
 
Horizontal, vertical and diagonal field of view.

 

Edited by Alan Kovarik

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By coincidence, today I ran across an article on using focal lengths in a 1966 issue of "American Cinematographer" -- Though it doesn't talk about the 50mm, at one point, it says "The 35mm lens, once considered strictly a wide-angle lens for 35mm cinematography, is now utilized as the standard lens in several studios, especially when scenes are being shot to be masked off for the 1.85:1 aspect ratio of projection. This lens has also become standard for much of the filming done specifically for the small format of television. It lends better modeling to sets and actors, while creating a more dramatic depth perspective. Faces, however, are definitely not flattered by this lens and it should not, therefore, be used for closeups."

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