As I mention in the above video, it's a long running and popular debate. DSLR 'versus' Mirrorless. I've already made my position on this clear, I see virtues and faults in both and use both. However as time passes there are always new people coming to photography and it does no harm to look again at what the differences are. The video above deals with the handling and practicalities of using the different classes of camera and in the downloadable file samples below the difference in image quality between the 24MP 'full-frame' sensor of the Nikon D750 and the 20MP 4/3 sensor of the Panasonic GX8.
IMAGE QUALITY AND ISO COMPARISON
For the purposes of this comparison I used my Nikon 20mm f/1.8 G lens fitted to the GX8 via a Metabones 0.64x Speed Booster and my Nikon 18-35mm zoom fitted to the D750. I shot raw and jpg. files at the following ISO's - 200, 640, 1600, 6400 and 25600. All those files are downloadable via the following link.
Now I've put this first so that you are able to check for yourself the following, which some may find somewhat hard to believe. So if you struggle with what I'm about to show, then check it out for yourself. The D750 files were shot with an Nikon 18-35mm zoom lens at 26.5mm and f8. The GX8 with a Nikon 20mm f/1.8 fitted with a Metabones 0.64x speed bosster which gives an approximate 'full-frame equivalent' of 26.5mm. As the speed booster has gradations on it which don't equate with the normal aperture numbers, th setting is approximately f8. In my tests of these two lens they are pretty even in terms of sharpness. The 20mm is a prime yes, but the 18-35mm lens is a superb lens, one of the best zooms I'ver used. As you will see I've kep the image sizes the same as the different cameras produce and the D750 file is larger.
Here's the two cameras compared at ISO 200 from raw - identical processing for each via Photoshop and ACR.
So no real surprises here, m4/3 is very simliar to 'full-frame' at base ISO. However, you will notice that the GX8 is slightly sharper.
Now in terms of high ISO's I've ignored 12800 and 25600 because, for me, these are emergency use only. I can get a usable file from both cameras by applying my own noise reduction, but those files are somewhat soft. If you are interested in those settings then you can have a look at the raw and jpg. samples yourself. So below is a comparison at ISO 6400.
As I said the results are somewhat surprising, in that the GX8 produces a file that compares very well with the D750. And is in fact very useable indeed. I have to make it very clear that this is processing to my taste and once again would urge you to do it your way with the raw samples to see how they look after applying your own parameters.
But I think I can draw a general conclusion from this, which is that this new 20MP 4/3 sensor in the GX8 produces very good files at ISO 6400 and if processed carefully can not be disadvantaged by a 'full-frame' sensor.
So, with the video and these images samples I've attempted to show that Mirrorless (in this case m4/3) may well have caught up with 'full-frame' under most circumstances. DSLR battery life will always be better because of the nature of how each type of camera works, but in terms of speed and image quality, how much real difference is there any more? Well. certainly less than there was and in terms of the images I produce and what I produce them for, nothing significant. Now I'm perfectly prepared to concede that under different circumstances and with a different kind of photographic situation, those differences may become somewhat wider and in favour of the DSLR, but there is no doubt that Panasonic (and let's not forget Olympus) are now producing cameras which are a genuine, real-world alternative to their supposed larger and superior competitors.
Now I have to say I was surprised by this, as I still believed that my Nikon DSLR's offered me something that my mirrorless cameras didn't. But now I may well have to reassess that view. What it does prove conclusively however, is that things move on and making assumptions based on past performance is to deny the very real improvements that small(er) sensor cameras have made. In many ways with the dominance of the smartphone in the camera marketplace, perhaps that is no surprise and I've always maintained that this is where the most significant improvements are being made. Which of course is an advantage for us all.