How should one compare lenses for new mirrorless cameras vs established best of class?

Question

As someone recently new to photography, I am curious for those jumping on the mirrorless bandwagon what concrete things (especially re: quality) are sacrificed moving to these cameras.

Take for example the new Fujifilm X-T1 which has a bunch of lenses made for it. What difference would those lenses on that camera have versus the L-series lenses from Canon or something comparable? Aside from a wider selection or specific use-cases (fish-eye etc) is measurable quality lost?

When you see some of the photos from these cameras, I'm wondering if it's worth lugging some of these big L-series glass or if there are benefits I'm not yet aware of.

Answer 1

Mirrorless cameras come in smaller bodies and can come with smaller sensors as well. Sony has a full frame mirrorless. Fuji has some APS-C size sensors, and then there is an array of micro-four thirds cameras, such as Olympus OMD line.

Everything is a tradeoff, but the smaller sensors let you use smaller lenses. Some of those lenses are incredibly good.

The fuji with APS-C sensor is well regarded as having image quality as good as a DSLR. The Olympus OMD EM1 is considered a high performer as well.

Typically, you'll see poorer low light performance with smaller sensors. However, the Olympus OMD EM1 is an excellent performer in the 95% case range for up to the advanced enthusiast.

I'm using the Olympus OMD EM1 with the Olympus 12-40 f/2.8 and it produces excellent images.

Samples (Olympus OMD EM1 with 12-40 2.8)

Image 1

Image 2

With the larger sensors, you get more shallow depth, because with a crop sensor, you need to be at a greater distance to achieve the same field of view, so if you're used to the DOF of an f/2.8 on a full frame, you'll need an f/1.4 to get the same DOF on a micro four thirds camera.

Other considerations are that the current MFT cameras aren't necessarily as good as DSLRs in the autofocus department, although the Oly OMD EM1 is remarkably fast and accurate. It's the perfect camera for me.

I used to carry a Canon 5D mk iii with L lenses. I sold all that gear for the OMD EM1 and have never looked back.

Answer 2

You compare them the same way you compare any other two lenses. There is no reason for them to be inherently better or worse. The bigger difference is sensor size. Smaller sensor size means smaller lenses, but also less bokeh and lesser low light performance. There is no reason that the image quality (sharpness, aberrations, etc) should suffer though and a lens that produces a sharp image with little aberration is actually cheaper for a smaller sensor.

The lenses really aren't so much a deciding factor as whether or not you need a micro 4/3rds sensor, an APS-c sensor or a full frame sensor. Optics are just optics.

Answer 3

There is no inherent quality loss in a mirrorless system - if by the comparison to Canon L lenses you mean mounting them on a Canon APS-C DSLR (e.g. a 7D) then there will be no inherent difference just because the Fuji system is mirrorless. There are two factors which matter:

• The sensor size of the system. As sensor size increases (m43 < APS-C < FF), low-light performance increases and depth-of-field decrease. The latter means more background blur/bokeh at a given aperture, but less of the picture in focus.
• The quality of the lens. This usually, but does not always, increase with price - but there are some excellent inexpensive lenses and some terribad expensive ones. Also, primes tend to be better quality than a zoom lens of similar price. In answer to your question, the Fuji X prime lenses are amazing - but then so are most if not all of Canon's L primes.