Conventional wisdom states that in low light situations m43 cameras are inferior to their full frame counterparts because more noise is evident at higher ISO settings. This argument is flawed because, for a given amount of light, it assumes both camera types would need to be set with the same shutter, aperture and (hence) ISO.
For a particular ISO, there is not question that noise tends to increase as the sensor size (and hence pixel dimensions) shrink. Some claim that a m43 sensor is about “2 stops” noisier than the full frame equivalent. As such, a m43 sensor at ISO800 would be expected to produce noise roughly on par with a full frame sensor at ISO3200. This is simply physics and can be accepted as true.
That all being said….
Technologies found in many m43 cameras, and the sensor size itself, enable significantly lower ISO settings than that on a full frame camera in the same situation. In fact, we will see scenarios where ISO can be reduced 2 stops or more to effectively eliminate the “2 stop noise advantage” offered by full frame sensors.
Case 1 – Technology removes the shakes
Irrespective of sensor size, many lenses and some bodies incorporate image stabilization technologies. Not all technologies are equally effective, however. Anyone doing a bit of research will reach the conclusion that Olympus’ IBIS (in body image stabilization) is leaps ahead of the in-lens stabilization technologies found in (many, but not all) larger sensors lenses (in fact, it is also considered more effective than the Sony A7ii IBIS).
How effective is the Olympus’ stabilization? Take a look at the photo below hand-held at 1/6s. The absence of any sign of camera shake is quite incredible. It is even more amazing because it was taken with a 75mm lens (150mm equivalent angle of view on full frame bodies).
Two things two consider:
- With a full frame camera and a 150mm lens would anyone expect to get a decently sharp photo at 1/6s? Even with an in-lens stabilizer, I suspect it would be difficult to achieve the same results at 1/25s – two stops faster. If the full frame lens has no stabilizer, then the golden rule of thumb dictates 1/150s minimum shutter to avoid camera shake which will require an ISO increase of about 4.5 stops
- Second, I am not aware of many full frame lenses offering f1.8 at 150mm. If you are lucky, f2.8 is the max. In order to compensate, another 1 stop ISO increase is required.
In summary, the IBIS technology in Olympus cameras is key to sharp photos several stops slower than that of full frame counterparts. To compensate, the full frame camera will require several stops higher ISO. Though a lessor argument, m43 offers some telephoto primes with extremely wide apertures that simply do not exist in larger formats. This further allows lower ISO settings. The full frame noise advantage is essentially lost.
And, the technology is improving – though perhaps lucky, this Russian photographer’s blog documents sharp handheld photos at 15s using the new OM-D E-M1ii and 12-100mm f4.0 lens (with its own stabilization).
Case 2 – More depth of field can be good
Razor-thin depth of field lovers correctly state that m43 photos have 2 stops increase in depth of field compared to shooting with a full framed camera at the same aperture for identical angle of views. So, an m43 camera with a 25mm lens at f2.0 will have the same depth of field as a full frame camera with a 50mm lens at f4.0 (2 stops smaller).
Irrespective of whether you like razor-thin depth of field or not (I certainly do not), take a look at the photo below. It simply will not work with less depth of field, and could probably benefit from more.
Even with my m43 body, a relatively small f8.0 aperture was used at 32mm. On a full frame body, f16 would be required to maintain the same depth of field (i.e. two stops slower). To compensate, either the shutter is reduced to 1/10s or the ISO is increased to 6400. Lowering the shutter speed is not an option. Even if the camera was on a tripod to reduce shake, the photo is of a cat and cats move. Therefore, the ISO on a full frame camera would need to be increased 2 stops to provide the same depth of field necessary for this photo. Again, the full frame noise advantage is essentially lost.
For a given ISO setting m43 sensors tend to have about 2 stops more noise than full frame sensors. However, technologies found in m43 bodies and the 2 stop increase in depth of field resulting from the reduced sensor size create situation where ISO can be lowered for m43 cameras thereby eliminating much, if not all of the full frame noise advantage.
Do these capabilities carry over in all situations? Certainly not – sports photography, or anything requiring fast shutter speeds to freeze action, will put m43 at a disadvantage. If the subject is relatively stationary, or if it requires significant depth of field then m43 can be a very compelling option for low light photography. Of course, do not forget the m43 size and weight advantage when carrying your camera around during dark nights!
Does m43 really embarrass full frame in low light situations? I wouldn’t go that far, but certainly I would give m43 more consideration than it has thus far received for low light photography.