4 July 2017
Panasonic mirrorless cameras like the G7, G85/G80 and GH5 are increasingly popular for filmmaking. But which lenses should you buy for shooting video? And how does filming 1080p and 4K video affect the crop factor?
This page shows how lenses with different focal lengths affect the image. The same closeup was filmed with wide-angle, ultra wide, ‘standard’, medium telephoto and telephoto lenses.
The simplest solution: use the kit zoom
The easy option, especially if you’re on a budget, is to buy your camera together with the standard kit zoom lens. These zoom lenses cover the range from wide angle to medium telephoto, and have Dual IS for easier handholding. They’re excellent value when you buy them bundled with the camera: they’re usually much more expensive to buy on their own.
The G7 normally comes with a 14-42 (f/3.5-f/5.6) lens, but the G85/G80 kit lens covers a wider 12-60 range (it’s also f/3.5-f/5.6). You can get the GH5 with the fast, expensive, high quality Leica 12-60 f/2.8-f/4.0 Leica lens, or the longer Lumix 14-140 f/3.5-f/5.6 lens which would be useful for travel.
Medium telephoto prime lens: 42.5mm f/1.7
Zoom lenses are convenient. But I’d recommend getting a fixed focal length (‘prime’) lens as well. The wide maximum aperture makes it easier to put the background out of focus. This is particularly important with Panasonics, as the small MFT sensor has greater depth of field at a given aperture than an APS-C or full frame camera.
The Panasonic 42.5mm f/1.7 is equivalent to around 90mm (medium telephoto) on a full frame sensor, so you can get far enough away for undistorted closeups. It’s stabilised and works with the Dual IS system on the G85/G80 and GH5.
Bargain alternative: classic manual focus lenses
50mm primes were the ‘standard’ lenses on old film SLRs. They were good value then, and they’re an absolute bargain now. You can pick them up on eBay for a fraction of the price of a modern lens, and use a simple adapter to mount them on your Panasonic camera.
I use an Olympus OM Zuiko 50mm f/1.8 myself. It’s a medium telephoto on MFT, great for closeups of people. It’s small, light and sharp. You could also try other focal lengths: the 85mm f/2 would make a fast, compact 190mm equivalent telephoto on MFT.
Fotodiox make adapters for mounting manual focus lenses to mirrorless cameras.
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One lens to rule them all: 12-35 f/2.8 zoom
The Panasonic 12-35 is fast for a zoom, so it’s relatively good for low light and shallow focus. It has a constant aperture so exposure doesn’t change when you zoom in and out. And it has Dual IS, though not the latest version. It’s a convenient, high-quality option for news, events and documentary. There is a newer version which works with the latest version of Dual IS, but it’s a lot more expensive.
Wide angle lens
The Panasonic Lumix 7-14 f/4 is a constant aperture, wide angle zoom. It’s useful for documentary situations where you’re working in confined spaces, and like most ultra wide lenses it’s easy to handhold.
If you’d rather have a prime lens, the Rokinon/Ssamyang 12mm f/2.0 is good value (and two stops faster than the 7-14) though it’s only manual focus.
I rarely use a long telephoto lens, but the advantage of the MFT system is that even long lenses are relatively compact.
The Panasonic 35-100 f/2.8 zoom is fast, sharp, and works with Dual IS. It covers the range from medium telephoto to ‘serious’ telephoto. But it’s expensive.
If you don’t need constant aperture, the much cheaper 45-150 f/4-f/5.6 is very good value, and also has Dual IS.
Focal length, crop factor and MFT
Crop factor means how much smaller the sensor is than a ‘full-frame’ 35mm still camera frame. This lets you compare lenses on different sensors.
For example, 24mm is a useful wide angle lens on a full-frame camera. Panasonic’s smaller MFT sensor is usually quoted as having a crop factor of 2 when you’re shooting stills. That means you’d need a 12mm lens on your Panasonic camera to get the same effect as that 24mm lens.
But with most Panasonic cameras (except the GH5s, which has a bigger ‘multi-aspect’ sensor), video is different. The aspect ratio (shape) of the full Panasonic sensor is 4:3. HD video is widescreen, with an aspect ratio of 16:9. Because this doesn’t use the whole sensor, the crop factor increases to 2.2. So your 12mm lens is now about a 26mm equivalent. That’s still a useful wide angle, but not quite as wide.
It gets more complicated if you’re shooting 4K Ultra HD, and it’s different depending on which Panasonic model you’re using. The GH4 captures 4k ‘pixel for pixel’ (just recording from the 4K-sized area in the middle of the sensor) which increases the crop factor.
- The GH4 has the biggest crop when shooting 4K: it’s 2.6, or 2.5 in ‘Cinema’ UHD. So a 12mm lens would be equivalent to a not-that-wide 31mm.
- With the newer G7 and G85/G80, the crop factor is 2.4.
- The GH5 uses the whole sensor. So its crop factor is 2.2, the same as when recording HD.
- The new GH5s has a multi-aspect sensor, so the crop factor is 2 (except when shooting HD at 240fps).
Fly-by-wire or mechanical focus
All the Panasonic zooms above are ‘fly-by-wire’. They have focus rings, but they’re coupled to electronic motors. This is fine if you’re happy with autofocus, setting focus using the touchscreen, or using the pre-programmed pull focus in some models. But if you want to do precise, traditional focus pulling you may prefer lenses with a mechanical focus rings: vintage primes, a set of Cine lenses, or the Rokinon/Ssamyang manual focus prime lenses.
Rokinon manual focus lenses for Micro Four Thirds
Boost your lens in the camera
Most Panasonic mirrorless cameras have the option of Extra Tele Conversion. This lets you record a crop from the middle of the sensor, effectively increasing the focal length without losing quality. This is really useful for extending the reach of a telephoto lens.
With the G7 and G85/G80, the effective focal length increases by 2.4x in 1080p HD; on the GH5, it’s 2.7x. The GH5 has this feature (at 1.4x magnification) when filming 4K.
Use other makers’ lenses with a Speedbooster
You can also use optical converters to mount lenses designed for full-frame or APS-C sensors. These adapters reduce the image to fit on the MFT sensor. They also effectively increase the maximum aperture of the lens, which is useful for working in low light. Metabones’ Canon EF adapters even maintain autofocus, though it won’t be as fast as on a Canon body.
The Speedbooster Ultra has a focal length reduction of 0.71, which means you’ll get roughly the same field of view as if you were using the lens on an APS-C body, assuming that you’re shooting HD.
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If you’re shooting exclusively 4K footage on a GH4, you could use the Speedbooster XL instead. This has a higher reduction to allow for the 4K image crop on the GH4 body.