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Don't overestimate the value of full frame. Unless you're trying to get a shallower depth of field than you can achieve with your MFT lenses, a full frame camer
by sjwright 8y ago
Don't overestimate the value of full frame. Unless you're trying to get a shallower depth of field than you can achieve with your MFT lenses, a full frame camera doesn't offer much inherent advantage.
For example, the Panasonic 42.5mm f/1.7 lens is visually equivalent to a hypothetical 85mm f/3.4 lens on a full frame (35mm) sensor. When I say equivalent, I mean these combinations would have the same practical field of view, the same depth of field, and—this is the part which trips people up—the same overall quantity of photons falling on the sensor area.
Historically, larger sensors have been more efficient at converting said photons into data, but the difference has narrowed greatly to the point where it doesn't matter so much, particularly at the relatively modest resolution of 4K video (approximately 8.3—8.9 megapixels) where the limits of lens diffraction don't tend to come into play.
Of course on full frame systems you can easily find inexpensive 85mm f/1.8 and very high quality f/1.4 lenses. But if you don't use the extra depth of field and you shoot FF at f/3.4 or greater, there was no fundamental benefit. (Of course you should never discount the glass advantage, as the mid-range FF glass tends to be optically superior to high-end MFT glass... but does that benefit apply to a new lens mount? Will these cameras do a good job focusing EF and/or F mount glass?)
- romed 8y agoDoesn't the availability of speed boosters somewhat counteract the advantage of access to Canon and Nikkor lenses? I switched from a Nikon system to an Olympus m43 body and kept using all my old glass. Except for one particularly snazzy macro lens, I don't have any native m43 lenses.
- sjwright 8y agoThat is 100% correct. Another way (a better way in my opinion) is to think of a speed booster is it's a sensor size increaser. In effect a GH4 with a Metabones EF speed booster attached is effectively comparable to an EF camera with an APS-H size sensor (1.3x crop factor).
- dllu 8y agoYes, but only somewhat. A speedbooster is not optically perfect and may degrade image quality by introducing aberrations.
- reneherse 8y agoLower noise levels at high ISO are an advantage of FF. Very useful for shooting action in low light (e.g. sports and dance), where you need high shutter speeds to freeze motion.
- romed 8y agoI think what you meant is that low noise and high ISO are advantages of large pixels. Larger sensors just happen to have more such pixels. If you where willing to eat the reduction in resolution, you'd get the same noise and sensitivity from any size sensor. For example, a 10MP APS-C sensor has the same sensitivity as a 25MP full frame sensor, all other things held equal.
- NikolaNovak 8y agoPer pixel. Not overall. 25MP (or any resolution) full frame sensor with a (say) 1.8 lens will gather more photos than 10MP (or any resolution) APC sensor with a 1.8 lens.
- romed 8y agoThe amount of light falling on each sensor pixel is the only thing that matters in digital photography. The roof of my house also gathers a lot of light but it's not a good camera.
- sjwright 8y agoThe quantity of photons captured and usefully turned into data by the total area of the sensor is what matters in digital photography. The physical size of each sensor pixel is irrelevant, except insofar as current technologies favour physically larger pixels in order to capture larger quantities of photons before the pixel is fully saturated.
- reneherse 8y agoYes, that’s a more precise description. For a given resolution and ISO, a larger sensor has larger pixels, which generally produce less noise than smaller ones.
- bufferoverflow 8y agoA full frame sensor catches more photons, generally resulting in cleaner images. The most light sensitive cameras are all full frame (and larger).
- dingaling 8y agoThe images are only cleaner if the pixel size is larger. But then fine detail reduces. There's no magical bigger-sensor-better rule. For example the Canon 5DS full-frame has the same pixel size as the 7D2 cropper and very similar noise and ISO limits. The 5D4 full-frame has much lower noise but also 20MP less.
- dllu 8y agoYou are right that per-pixel noise mainly depends on pixel size (most digital cameras are shot noise limited at high ISO). However, we should be comparing images at the same size, rather than at 100% pixel crops. If you print the high resolution 5Ds images in the same size as the 5D4's, the noise will be finer and less distracting. You can also denoise and downsample the image to the same number of megapixels as the 5D4's and get a similar amount of noise per pixel. In this sense, a high resolution sensor with smaller pixels is always better because you get the freedom to have finer detail in bright light and still get clean images at lower resolution in dim light.