(for part 1 of this article, please check here)
Let's continue where we left off, with the user review of the Camdiox focal reducer. Let me reiterate that this is just that, a user review and not an excessively methodological evaluation, although we'll briefly examine the technical specifics behind the concept. This review centers on the Fuji version but I see no reason the Sony version of this adapter would be different. It would also be relevant to the m43 version, taking into account crop differences between formats.
Another point, as can be seen by the pics, is that I use the Canon EOS adapter plus additional "ring" adapters for other systems. This is purely practical and I have done it with other "dummy" adapters (without optical elements) in the past. The EOS focal distance is one of the shortest among SLR designs, making it ideal for stacking additional adapters for other systems (e.g. Olympus OM or Nikon F). There is also a plethora of cheap adapters from other systems to EOS. This does not compromise performance in any way, as long as adapters are of an adequate built quality. The Camdiox comes in several versions, such as Canon, Nikon, Minolta MD, M42 and others (see end of article for related ebay links).
Starting with build and operational quality, there is nothing to whine about. The Camdiox looks and feels like a number of adapters I've used e.g. Fotodiox. That means very good but not state of the art construction. It's all metal, of course, fits great, without any wiggles and it generally inspires confidence. It goes without saying that, having an optical element, you just can't throw it around like a dummy adapter (which is a bad idea anyway; a tiny chip of metal detached from an adapter and into the sensor chamber can really ruin your day). Just treat it like any other (small) lens you might have in the bag. It is also heavier than non-optical adapters, but this is probably a positive: legacy lenses are much heavier than modern ones, and the weight of the adapter shifts the balance a bit towards the camera body.
A word about focal length substitutions: if you calculate the focal reduction and multiply by the crop factor, the result is not exactly the same as the actual length of the lens. For example, a 50mm lens becomes a bit longer than 53mm. This is insignificant to me personally, imagine something similar to the difference in crop between Canon and Nikon APS-C bodies, but it's worth mentioning.
Claims about increased sharpness/resolution are admittedly the most difficult to accept for most people, since it is a common belief that any adapter with optical elements is detrimental to image quality. This may be true, for the majority of circumstances, but, as determined by real-world results, it seems that this is not the case. First off, it's interesting to note a remark by Mr. Caldwell, the inventor of the original focal reducer technology, as offered in this review of the Metabones adapter. As a rule of thumb: don’t compare with FF directly, but rather what a FF lens produces on crop bodies.
Concerning center sharpness, here is an example followed by a 100% crop of the same image. Knowing the performance of the lens used (which isn't known to be particularly sharp wide open), I'd say this is a great showing, giving highly usable results, for this super-shallow DoF demonstration.
Please note that, as with some other photos, a slight vignette has been added in post, to show off center performance. There is no abrupt vignetting or other anomalous border/corner behavior with the adapter. In fact, if nothing else, perceptual sharpness seems to be improved in the corners, over the lens by itself.
The assertion about gaining a stop of light is totally true. This may be very important for available light photography, since it means gaining a stop of either shutter speed or ISO. Bear in mind that different mirrorless systems meter differently and there might be occasions that the metering system is fooled into overexposure (see below, for such a case with X-M1, in some instances). Fortunately, always having a true live-view helps in deciding proper exposure; one could also potentially bracket exposures for mission critical applications.
Personally speaking, there is a huge advantage in using this or any other focal reducer, and it has to do with preserving as much of the original lens character as possible. When adapting a lens with 35mm coverage on a APS-C sensor camera, only the center portion of the lens is used. This is a plus in the sense that corner/border performance is practically improved, for some lenses, but then again, something of the original lens signature is lost in the process (not to mention, of course, the produced frame/angle of view being different). With the reducer, because light is optimally gathered (and compressed) from the whole image circle, such character is retained at a higher degree.
There is a common misconception among less experienced photographers about using different focal lengths. While using a camera with a crop sensor, you can certainly take a few steps back and get the same frame as with a FF camera, using the same focal length. The problem is, distance to subject changes also, which changes DoF; but apart from that, a longer (equivalent) focal length compresses the background more. It is this background compression (and different foreground perspective) that gives the final image the desired look.
We should probably demonstrate the difference apropos to in-and-out of focus areas in relation to focal lengths. The following two photos were taken at minimum focusing distance; the first is with the Fujinon 27mm f/2.8, the second is with the Olympus OM Zuiko 24mm f/2.8. As we said, using the Camdiox provides a working focal length slightly longer than the actual lens focal length, in this case it is probably about 26mm or so, such as the two lenses are very similar, even in f-number. As a result, we can see the aesthetic difference, in terms of perspective, in this particular case. Please also note the much thinner DoF with the adapter. I believe this is one the best examples I can find, on why one will use a FF or larger sensor camera (or, an adapter in our paradigm) for DoF control.
As with any optical device, there are concerns, justified or not, and reported problems. For example, with some focal reducer adapters there has been mention of the "blue spot" problem; a pretty ugly blue blob appearing when shooting against strong light sources. Bear in mind that this can also appear with some lenses, irrelevant of system, so it's not an adapter specific issue. I'm happy to report that, having tried to replicate it with a number of lenses, I have found no incident of such a behavior with Camdiox.
There were a couple of times, under specific lighting scenarios and lenses, that I had some severe overexposure with the X-M1. The X-M1 is known, in rare cases, to overexpose even with native lenses, and it may be that its metering is in some way fooled by some adapter/lens/lighting combination. I never had the same experience with the X-E2. In any case this is easily fixed by intentionally underexposing; it just can be disorienting at times.
Another thing I noticed is that, because sharpness is improved vs using a dummy adapter, there are cases where even out of focus elements in the picture may show some weird distortions, if one overdoes post processing detail processing. This comes mostly from habit, I'd say: since older adapted lenses (esp. faster ones) are rather soft wide open, we are inclined to boost detail in post. Since focal reducers improve this aspect, it's better to be modest with that Clarity slider; in any case, use your eyes.
The adapter does de-magnify aberrations, as claimed, but that doesn't mean it completely eliminates them. As can be seen by the example below, they can still be visible, but, again from experience with the lens used, somewhat subdued.
Reaching a conclusion:
I opted for such an adapter for my Fuji cameras because, given the APS-C sensor, 135 format lenses become "what they say" on the tin. In other words, I don't have to occupy myself with crop-factor calculations for specific focal lengths. I especially like using legacy lenses with the Fuji X-System; that is because I think rendering characteristics of the X-Trans are playing very well with the character certain old lenses exhibit. It wouldn't be an exaggeration to say that it is perhaps the closest I've got to achieving a film look directly from digital media. So it's mostly an "artistic" choice in my book.
Granted, the X-System now offers an extensive variety of native lenses, for any need, and they are all excellent in build and optical quality as well as having fast apertures. Sonys E-mount on the other hand could benefit more, from a practical standpoint, since there are still obvious holes in the lens lineup. Furthermore if one is using both APS-C and FF E-mount Sonys with adapted lenses, the focal reducer would provide for the same user experience (i.e. same frame with a certain lens, in both systems).
If you like to take advantage of shallow DoF, which basically means shooting your lenses wide-open, and would like to use some fine old quality glass, this is an extremely good idea. I personally cannot recomment one brand of focal reducer over another; I can only testify that, for the specific application, the Camdiox is a fine investment. But please check around for other brand reviews in order to make an educated decision.
Hope you enjoyed this review! Let me apologize for unintentionally leaving out something of importance; I'll be glad to hear from you in the comment section. Below is a small gallery of random shots with various lenses.