by Tom Barrance | Updated January 2024
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Panasonic MFT (micro four thirds) cameras like the G85/G80 and GH5 , and the BlackMagic Pocket Cinema Camera 4K, are 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.
New or used?
I buy most of my lenses used from MPB (US/UK). They offer a six-month warranty and I’ve found them very easy and reliable to deal with. You can save a lot over the new price.
The simplest solution: use the kit zoom
The G85/G80 kit lens covers a useful 12-60 range (with a f/3.5-f/5.6 aperture).
You can get the GH5 with the same lens, or the faster, higher quality Leica 12-60 f/2.8-f/4.0.
Constant aperture zoom
Constant aperture zooms are better for filmmaking, as exposure doesn’t change when you zoom in and out. The Panasonic 12-35 f/2.8 is a great lens for news, documentary, events and travel. It’s not cheap, so I bought mine used from MPB.
It produces great images and it’s fast for a zoom, so it’s fairly good for low light and shallow focus.
The Dual IS image stabilisation is very effective. On my GH5 II, with ‘IS Boost’ selected, I can film handheld shots of stationary subjects that look as if I was using a tripod.
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Medium telephoto prime lens
Zoom lenses are convenient. But I’d recommend getting a fixed focal length, medium telephoto (‘prime’) lens as well. The wide maximum aperture makes it easier to put the background out of focus. This is particularly important with the small MFT sensor.
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.
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You could also consider the cheaper, unstabilised Olympus 45mm f/1.8. It’s very compact but has good image quality – I own one.
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Standard lens
A ‘standard’ lens fits in more of the scene, but you can still blur the background if you get close enough. The Panasonic 25mm f/1.7 is good value. It’s the lens I mount on my G80 when I use it as a webcam.
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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.
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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.
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Telephoto lens
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.
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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.
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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.
- With the 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 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 lenses 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. (Some Panasonic lenses, like the 12-35 II and III, have a ‘linear focus’ option which imitates mechanical focus rings.
Rokinon manual focus lenses for Micro Four Thirds
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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 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.
Viltrox adapters are a cheaper alternative.
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