1

In the John Wayne movie Rooster Cogburn (1975), there is a dramatic focus fall off at least 10% of the vertical height at both the top and bottom of the lens. Why does this happen?

enter image description here

steel
  • 1,286
  • 1
  • 10
  • 29

1 Answers1

5

This is most likely caused by field curvature. Whether it was introduced when the footage was shot or later when the film was digitized or even when converted to the still image above is impossible to say from only looking at the sample image above.

At the time Rooster Cogburn was filmed plenty of lenses did not correct very much for field curvature. This might particularly be the case for lenses selected by a cinematographer for use to film mostly outdoors in daylight the way most westerns were shot.

In the 1970s budget considerations were often tighter for westerns than other types of films. The marquee value of the actors, rather than pure cinemagraphic quality, drove the box office performance of a genre that was fast falling out of favor with the moviegoing public. With the fairly narrow apertures used in daylight shooting conditions the effects of field curvature could be largely ignored. The photo above, however, was likely a single 24x16mm frame from footage shot in a much dimmer environment to simulate an indoor scene and the aperture would have probably been opened up more than would normally have been the case for most of the other scenes in the film.

Although as of late field curvature seems to most photographers to have become an undesired aberration to be avoided at all costs when considering a new lens, there are times when it is a desired quality for getting a shot to look a certain way. For the photographers who are in the know about what such a lens can do for certain types of shots field curvature isn't necessarily a problem at all.

The demise of the attractiveness of lenses with field curvature seems to be the current obsession with how sharply a lens can photograph a flat test chart as seemingly the only criteria upon which to base a judgement of a lens' quality. When the center is in best focus, a lens with field curvature will look softer on the edges. That doesn't mean, however, that the lens is really 'soft' on the edges. It just means that when aiming at a flat test chart with the center of the chart in sharpest focus the focus distance at the edges is somewhere in front of the surface of the chart. With some very high quality lenses that are designed to have field curvature, the edges of a flat test chart can be rendered very sharply by adjusting the focus distance. Of course this makes the center of the flat test chart slightly out of focus and now the center looks a bit soft!

In the case of the example image in the question, the field curvature appears to have an oval, rather than circular shape. This would indicate that the lens used to film the scene and any lenses used to convert the film to a later format were anamorphic lenses.

Michael C
  • 175,039
  • 10
  • 209
  • 561
  • It was filmed in Panavision by Harry Stradling Jr., a two-time Oscar-nominated American Cinematographer and the son of Cinematographer. It would be most likely a choice and not due to error or technical limitations. – Rob Jul 10 '17 at 19:56
  • 1
    @Rob Budget is often the overriding factor in Hollywood. Cinematographers rarely own their own equipment. They use whatever the producers are willing to pay to rent, or sometimes what the backing studio has available in their inventory. Not every film made is produced with the intent to be a visual masterpiece. – Michael C Jul 10 '17 at 20:24
  • Unless you're their pal Panavision Lenses are rented only. The Film was processed in Technicolor and shot with Panavision Lenses. Which point did I make are you confirming or disputing, or which point of yours are you concerned that I am confirming or disputing? – Rob Jul 10 '17 at 22:52
  • It seems you are taking the position that the issue can only be that way because Stradling wanted it to look that way. I'm simply saying sometimes cinematographers have to work with what is available to them, not necessarily what they would choose to work with given unlimited choices. There's also the possibility that the field curvature was introduced somewhere in the conversion process from an anamorphic film frame to a publicity poster, rather than at the time the footage was shot. – Michael C Jul 10 '17 at 22:58
  • And not all Panavision lenses are equal or rented at the same rate, are they? – Michael C Jul 10 '17 at 22:59
  • Forget the part about the publicity poster. I got this question confused with something else. But the field curvature could have been introduced in the film to digital conversion process as well as when shot. – Michael C Jul 10 '17 at 23:03
  • No problem, we're all on multiple Sites keeping multiple conversations going. On point with the subject the Budget for RC was $30.5M - The Webpage https://en.wikipedia.org/wiki/1970s_in_film says this about another Film "... The Towering Inferno teamed Steve McQueen and Paul Newman against a fire in a San Francisco skyscraper. The film cost a whopping $14 million to produce (expensive for its time) ..." - So they spent 'double whopping' on the Film. Hollywood had a # of fails and was hurting financially. The doesn't preclude a mistake. Soft edge, or pronounced falloff is a Style. Anamorphic t – Rob Jul 10 '17 at 23:14
  • Gottschalk didn't adopt the rental only business model until the mid-1960s. For the first decade or so Panavision did sell lenses. The fact that a film made in 1974 had the Panavision seal on the end credits would have indicated the optics were all current Panavision stock. But there were still a few of the older pre-rental lenses floating around at that time. – Michael C Jul 10 '17 at 23:20
  • Budget was only $10M (still higher than I would have guessed - but then Hepburn didn't come cheap even at that age and neither did Duke). Global box office was $30.5M. – Michael C Jul 11 '17 at 01:10
  • 1
    This discussion implies Panavision couldn't have made a lens with soft edges... this is not the case, especially in the 70s. – Brandon Dube Jul 11 '17 at 03:41
  • Yeah, the Primos didn't come out until 1989. Some of the lenses Panavision was renting in the 1970s were old CinemaScope lenses made by Bausch & Lomb that had been retrofitted into PV housings with an additional astigmatic element added. No one found out about it until much later, many years after Gottschalk's death. – Michael C Jul 11 '17 at 04:40
  • @Michael Clark - I agree with U$10M budget, U$30M domestic (Source Wikipedia); apparently 8-17.5 domestic (so it didn't do excellent). A Book: https://books.google.ca/books?id=aVdOAQAAQBAJ&pg=PA127&lpg=PA127&dq=Panavision+1975+Harry+Stradling+Jr.+Lens&source=bl&ots=j3lCekb-Pi&sig=4LV2OrJokdflcDdfBPlsE4TvZts&hl=en&sa=X&redir_esc=y#v=onepage&q=Panavision%201975%20Harry%20Stradling%20Jr.%20Lens&f=false showing Stradling's Grip with a Camera from a different Film. ShotOnWhat: https://shotonwhat.com/lens-manufacturer/panavision-lensmaker/page/2?order=ASC&orderby=date&view=more says (continued) – Rob Jul 11 '17 at 05:43
  • Well, keep in mind that rentals at that time were usually about 25% of box office, so 30.5M only returned about 7.6M to the backers who spent 10M to make it. – Michael C Jul 11 '17 at 05:49
  • @Michael Clark - (continuation) that the Panavision C-Series: http://uk.panavision.com/products/uk/c-series-anamorphic-prime-lenses was popular in 1975 -- but it is extremely speculative to suggest that he used that Lens. – Rob Jul 11 '17 at 05:49
  • As mentioned above more than once, some of PV's lenses in the 1970s were fairly crappy compared to their later offerings. I still don't buy that the field curvature is in that shot because Stradling wanted it there. There's no artistic reason for it. – Michael C Jul 11 '17 at 05:52
  • Although the OP doesn't say, if it is evident throughout the entire film I think it far more likely that the transfer to digital process is to blame. If it is only present in the dark, indoor scenes then it was probably shot that way. – Michael C Jul 11 '17 at 05:54
  • In reply to your penultimate comment. The OP said "dramatic focus fall off", not "field curvature"; which is an attribute of the C-Series (that I do NOT know was used). The link says: "... optical quality and small size of the C Series appeals to cinematographers striving for the visual signature that defines the credit “Filmed In Panavision”. Characterised by a graduated depth of field, predictable full field performance at all apertures, a pronounced anamorphic flare, and a flattering bokeh, these lenses impart an organic feel that many cinematographers prefer over the sterile look ...". – Rob Jul 11 '17 at 06:40
  • @Rob What does a lens described as having "... full field performance..." (i.e. a flat field of focus) have to do with the image above? For someone not familiar with the term 'field curvature' one way to describe its effect would be something like... oh, I don't know... what could it be?... maybe... DRAMATIC FOCUS FALLOFF!! – Michael C Jul 11 '17 at 11:40
  • 1
    @Rob If you have a fundamental disagreement with the answer, rather than argue endlessly with me about it, perhaps you could put all of that in your own answer and let the community do their thing? – Michael C Jul 11 '17 at 11:43