This is something that comes up a lot and I get many questions about. In part because I designed the MTF B4 to Canon, FZ and E-Mount adapters. Budget adapters that allow you to use a 2/3″ B4 ENG lens on a Super 35mm sensor by using the lenses 2x extender or on a center crop sensor without the 2x.
The question is… what will the pictures look like?
The answer is… it depends on the lens.
Not a very helpful answer perhaps, but that’s the truth of it. Different lenses perform very differently. For a start I would say forget 4K. At best these lenses are suitable for HD and you want to have a great HD lens if you want good HD pictures.
But what about the “look” of the images? My experience is that if you put a wide range ENG zoom on a S35mm camera the look that you get can be best described as “2/3″ ENG look with maybe shallow depth of field”. Lets face it, ENG lenses are full of compromises. To get those great big zoom ranges with par-focal focus there are a lot of glass elements in those lenses. Lot’s of elements means lots of places where CA and flare can occur. The end result is often a lowering of contrast and color fringing on hard edges, the very same look that we are used to seeing on 2/3″ cameras. Typical cine or DSLR lenses tend to have simpler optical designs. Prime lenses are normally sharper and show better contrast with less flare than zooms due to there simpler internal design.
So don’t expect to put a typical B4 ENG lens on your S35mm camcorder and still have that crisp, high contrast digital cinema look. Of course B4 zooms are handy for the ability to zoom in and out through huge ranges while holding focus. So an adapter and lens may well make your S35mm camera more versatile. But if you want the best possible images stick to cine style lenses, DSLR lenses or zooms designed for S35.
Question about using a B4 lens on Super 35…
How does the depth of field compare? Let me offer a specific situation that should get to the heart of the matter. Camera setup #1 – a 2/3″ ENG camera with the lens at f/1.8 (essentially wide open), and Camera setup #2 – a Super 35 sensor camera with an adapter-mounted 2/3″ B4 at f/1.8 (now effectively f/4 with 2.5 stop loss). At the same effective zoom and distance to the subject, will the depth of field look the same? Or will the Super 35 sensor produce a shallower focus? If so, how much softer will the background look? Dramatically softer or just a little bit more?
I ask because simply because I already own a good (not great) ENG lens and would like to use it with a large sensor camera, but the adapters and accessories really add to the cost. I’d love to have a more cinematic depth of field, but will I really see a difference by the time I go to all the trouble building the rig? Or would I be just as happy with a new 2/3″ ENG camera shooting at a really wide aperture?
If you want the film look you won’t get it with a typical ENG zoom. The lens design is a compromise to provide a very large zoom ratio above all else. This leads to more flare, CA and other artefacts compared to stills lenses or proper cine lenses.
DoF wise when you multiply the focal length via an adapter you reduce the aperture by the same ratio. So to get from 2/3″ to s35mm you must add 2.5 – 2.7x of focal length magnification, that reduces the effective aperture by the same amount so an f1.8 eng zoom becomes approx f5.6.
Never loose sight of the fact that a very large proportion of the look of an image comes from the lens. As a general result video shot with ENG lenses looks like “TV”. Video shot with photo lenses tends to look more like photographs and video shot with good quality cinema lenses tends to look like “film”. While this is a very big generalisation and there will always be exceptions you can’t get away from the fact that the lens will almost always determine the look.