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What’s So Magical About Full Frame – Or Is It all Just ANOTHER INTERNET MYTH?

FIRST THINGS FIRST:
The only way to change the perspective of a shot is to change the position of the camera relative to the subject or scene.  Just put a 1.5x wider lens on a s35camera and you have exactly the same angle of view as a Full Frame camera. It is an internet myth that Full Frame changes the perspective or the appearance of the image in a way that cannot be exactly replicated with other sensor or frame sizes. The only thing that changes perspective is how far you are from the subject. It’s one of those laws of physics and optics that can’t be broken. The only way to see more or less around an object is by changing your physical position.

The only thing changing the focal length or sensor size changes is magnification and you can change the magnification either by changing sensor size or focal length and the effect is exactly the same either way. So in terms of perspective, angle of view or field of view an 18mm s35 setup will produce an identical image to a 27mm FF setup. The only difference may be in DoF depending on the aperture where  f4 on FF will provide the same DoF as f2.8 on s35. If both lenses are f4 then the FF image will have a shallower DoF.

Again though physics play a part here as if you want to get that shallower DoF from a FF camera then the lens has to be the same aperture as the s35 lens. To do that the elements in the FF lens need to be bigger to gather twice as much light so that it can put the same amount of light as the s35 lens across the twice as large surface area of the FF sensor.  So generally you will pay more for a comparable FF like for like aperture lens as a s35 lens. Or you simply won’t be able to get an equivalent in FF because the optical design becomes too complex, too big, too heavy or too costly. This in particular is a big issue for parfocal zooms. At FF and larger imager sizes they can be fast or have a big zoom range, but to do both is very, very hard and typically requires some very exotic glass. You won’t see anything like the affordable super 35mm Fujinon MK’s in full frame, certainly not at anywhere near the same price. This is why for decades 2/3″ sensors and 16mm film before that, ruled the roost for TV news as lenses with big zoom ranges and large fast apertures were relatively affordable.
Perhaps one of the commonest complaints I see today with larger sensors is “why can’t I find an affordable fast, parfocal zoom with more than a 4x zoom range”. Such lenses do exist, for s35 you have lenses like the $22K Canon CN7 17-120mm  T2.9 which is pretty big and pretty heavy. For Full Frame the nearest equivalent is the more expensive $40K Fujinon Premista 28-100 t2.9. which is a really big lens weighing in at almost 4kg. But look at the numbers: Both will give a very similar AoV on their respective sensors at the wide end but the cheaper Canon has a greatly extended zoom range and will get a tighter shot than the Premista at the long end. Yes, the DoF will be shallower with the Premista, but you are paying almost double and have to deal with a significantly heavier lens with a reduced zoom ratio. So you may need both the $40K Premista 28-100 and the $40K Premista 80-250 to cover everything the Canon does (and a bit more). So as you can see, getting that extra shallow DoF may be very costly. And it’s not so much about the sensor, but more about the lens.
The History of large formats:
It is worth considering that back in the 50’s and 60’s we had VistaVision a horizontal 35mm format the equivalent of 35mm FF, plus 65mm and a number of other larger than s35 formats. All in an effort to get better image quality.
VistaVision (The closet equivalent to 35mm Full Frame.
VistaVision didn’t last long (7 or 8 years) as better quality film stocks meant that similar quality could be obtained from regular s35mm film and shooting VistaVision was difficult due to the very shallow DoF and focus challenges, plus it was twice the cost of regular 35mm film. It did make a brief comeback in the 70’s for shooting special effects sequences where very high resolutions were needed. VistaVision was superseded by Cinemascope which uses 2x Anamorphic lenses and conventional vertical super 35mm film and Cinemascope was subsequently largely replaced by 35mm Panavision (the two being virtually the same thing and often used interchangeably).
65mm formats.
 At around the same time there were various 65mm (with 70mm projection) formats including Super Panavision, Ultra Panavision and Todd-AO These too struggled and very few films were made using 65mm film after the end of the 60’s. There was a brief resurgence in the 80’s and again recently there have been a few films, but production difficulties and cost has meant they tend to be niche productions.
Historically there have been many attempts to establish mainstream  larger than s35 formats. But by and large audiences couldn’t tell the difference and even if they did they wouldn’t pay extra for them. Obviously today the cost implication is tiny compared to the extra cost of 65mm film or VistaVision. But the bottom line remains that normally the audience won’t actually struggle to see any difference, because in reality there isn’t one other than a marginal resolution increase. But it is harder to shoot FF than s35. Comparable lenses are more expensive, lens choices more limited, focus is more challenging at longer focal lengths or large apertures. If you get carried away with too large an aperture you get miniaturisation and cardboarding effects if you are not careful (these can occur with s35 too).
Can The Audience Tell – Does The Audience Care?
Cinema audiences have not been complaining that the DoF isn’t shallow enough, or that the resolution isn’t high enough (Arri’s success has proved that resolution is a minor image quality factor). But they are noticing focus issues, especially in 4K theaters.
 So while FF and the other larger format are here to stay. Full Frame is not the be-all and end-all. Many, many people believe that FF has some kind of magic that makes the images different to smaller formats because they “read it on the internet so it must be true”. Once they realise that actually it isn’t different, I’m quite sure many will return to s35 because that does seem to be the sweet spot where DoF and focus is manageable and IQ is plenty good enough. Only time will tell, but history suggest s35 isn’t going anywhere any time soon.

Today’s modern cameras give us the choice to shoot either FF or s35. Either can result in an identical image, it’s only a matter of aperture and focal length. So pick the one that you feel most comfortable with for you production. FF is nice, but it isn’t magic.


What’s So Magical About Full Frame – Or Is It all Just ANOTHER INTERNET MYTH? was first posted on December 26, 2019 at 5:38 pm.
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