Full frame "simulation" vs. the "real thing"
My article/review from a while ago, about using focal reducers with a Fuji camera (as well as the follow-up), are among the most read in the blog, with almost daily hits and having gathered several thousand views overall. Having the Sony a7 in the house, I figured I'd devise a quick test, aiming to show how well using a focal reducer stacks up to a proper FF sensor camera.
First let me say that both Fuji and Sony are an absolute delight while shooting manual lenses. They have a very similar way of doing things: on the Sony, you can assign a Fn button to display a focusing rectangle, which you can then move around your frame. Pressing the same button again magnifies the view, allowing for precise critical focus. Half-pressing the shutter button returns to normal view, which, of course, can include customizable focus peaking. Fuji (I'm using the X-E2) is very similar, but you have to press one button to display the focusing rectangle and push in the back wheel for magnification. In both cameras the whole process is very fast and accurate.
With rather limited time, I made up a small shooting scene which could give an appropriate indication of DoF rendering, as well as color and detail reproduction. And this signaled the Dreaded Return of The Infamous Porcelain Dolls ® from earlier shooting tests. :-)
A few remarks about the methodology:
For this test, I used three different Olympus OM Zuiko lenses; the 24mm f/2.8, the 50mm f/3.5 macro and the 135mm f/2.8. I wanted to cover several focal lengths and all these lenses are famous for their rendering and sharpness, and are very representative of the kind of older manual lenses one should use on modern mirrorless cameras, should one be in that kind of thing. All lenses were shot wide open.
Since I didn't bother using a tripod (which would make the whole procedure technically more correct, but not as "real life" as I wanted), I just tried to approximate the same frame for both cameras. The focus point was also as close as I could get it between the two cameras; loosely on the eyes of the first doll. At this point, please keep in mind that the Camdiox (as well as other reducers) doesn't provide "exact" focal length reproduction. For example, a 24mm lens becomes approx. 26 something mm.
ISO was set to 200 for both cameras. I know Sony has a base ISO of 100, but I opted for 200 in order to ensure adequate shutter speed and, after all, there is minimal to none final difference between these ISOs. All files were processed in LR from RAW, which, as we've seen in a previous article about Fuji's RAW conversion, introduces a slight disadvantage for Fuji. Still, I wanted to level the playing field as much as possible and, after all, perhaps Sony files could be converted even more efficiently using another RAW converter.
Files have been corrected for WB and minimally processed for shadows/highlights. Sharpness was also adjusted to optimal levels for both, but no clarity or color corrections applied. You may notice slight lighting variations, this is because this was a natural light shooting, where light was slightly changing throughout. The files were exported to the same size (2000 pixels on the longer edge, a proper size for online use), which means the Sony files were downsized considerably more, whatever that means for the final result. Neutral picture profiles were enabled for both cameras.
Here is a collection of shots (picked for most precise focusing, between 5-10 for each camera/lens combination):
All readers are more than welcome to chime in with their own remarks. Here are my notes on the results, based on the overall impression as well as a fair amount of pixel peeping.
1) Both cameras display excellent results overall. I can't imagine anyone having complaints from the IQ. Please remember lenses were shot wide open, should they'd be stopped down a couple of stops, overall sharpness would be even better (not that it's nothing short of fantastic, in my opinion, as it is).
2) I can't find any difference at all regarding DoF between the FF camera and the focal reduced APS-C camera. Both depth and rendering seem the same to me. This is very encouraging for those concerned that using a focal reduced may alter the character of a particular lens. Vignetting and border/edge sharpness characteristics, are also effectively the same, for both cameras.
3) The Fuji X-Trans sensor, although now a few years old (in its original conception), punches well above its weight class. To be honest, I prefer Fuji's rendering in the details, as well as the out of focus areas. I know from experience that results would be even more in favor of Fuji, if a higher ISO (above 1600) was used, since Fuji files are virtually devoid of chromatic noise and OOF areas have a more "filmic" character. Sony, on the other hand, uses a 24mp sensor but with a AA filter, which, I believe, is not as "weak" as those on other versions of the same sensor. This means it loses effective resolution vs. the Fuji, which looks more like a "regular" (standard Bayer-array sensor with AA filter) 20-24mp camera would look.
Basically, it's a draw between both cameras, and you'd be splitting hair trying to find advantages in either one's images. Personally, I prefer the Fuji, but this is mainly because I already use the system, and the capability to adapt lenses and still gain the "full frame advantage" is a welcome bonus.
But this is not a comparison to determine which is best, but rather an evaluation on whether a focal reducer, when used on a APS-C camera with top image quality, can be a valid option. In my opinion the answer is definitely yes; if you already have good quality manual lenses which you'd like to use in their (almost) "proper" focal lengths, and get the same field results as with a FF camera, a focal reduced (the Camdiox, in this instance) is a terrific deal.