You'll not have heard of a 17-60mm f/2.5-3.2 lens for the Fuji X system, interesting as that might be, but that's what fitting my Nikon 24-85mm f/3.5-4.5 to my X-Pro 1 via a Metabones Speed Booster ULTRA gives me. Well not exactly, since the aperture doesn't actually change, but the light gathering properties of the lens are increased by up to 1 stop. So manual focusing of course, but a pretty useful zoom none the less. Compared to the 16-50mm f/2.8, it's not that far away in specs., Not quite as wide, though slightly faster at that end, but slightly longer though and around 1/3rd. of a stop slower at the telephoto end. Significantly cheaper, though the cost of the Metabones adapter has to be taken into consideration.
So how does it perform?
Now that looks pretty good to me. Firstly showing that this old Nikon zoom is a pretty good lens and secondly that any issues about the Metabones Speed Boosters having soft corners are now resolved. Using the previous model I was aware that there was a slight softening of those corners, but I've nothing to complain about here.
As I mentioned in my previous article about the Sony A7r, this adapter alternative isn't for everyone and there are many circumstances in which it would just be too slow and fiddly to use, but in the right place at the right time this remarkable piece of kit is worth it's weight in gold. Because, you get a whole batch of 'new' lenses. 'Full-frame' / 35mm lenses behave virtually the same as they do on 'Full-Frame' cameras. The greatest advantage for me being that the struggle to find wide-angle lenses to adapt to the APS-C format isn't a struggle anymore. The lens I used above has an approximate 'equivalence' to a 24-85mm 'FF' zoom and on the X-Pro 1 that's pretty much what I'm getting (It's probably closest to a 25-90mm.) Add in the up to 1 stop speed boost and the enhanced quality you get by focusing the whole light gathering area of a lens made for 35mm film onto an APS-C sensor and you can see just what is on offer here. All of a sudden those cheap old 35mm lens on ebay can show what they can really do on the smaller sensor Fuji's.
You can pick up old prime Nikons for not a lot. For example I bought a Series E 50mm f/1.8 for just under £30 on ebay. Using the speed booster I would get a 53mm f/1.2 'equivalent' (approximate) on my Fuji X cameras. Just imagine how one of those in a native mount would cost, or a Zeiss version, or a Leica M-mount. And this happens across the lens range. My 100mm series E f/2.8 turns into a pretty good imitation of a 106mm f/2. Plus of course if I fit it to a 'normal' adapter it becomes an (again approximate) 150mm f/2.8. For me this is all good news. I get a series of useful focal lengths with enhanced light gathering for not a lot of money. I seem to able to get decent images without the benefit of either AF or IS, so for me there really isn't much of a disadvantage.
As I said, this certainly isn't a universally good thing and there are many who simply would never consider it. But I grew up photographically manually focusing lenses and making sure I selected fast enough shutter speeds and doing that without the aids I have at my disposal these days. Using the speed booster means I can keep the lenses I take out with me 'back friendly' and I don't need to have lots of money tied up in various lens ranges. I've got a Voigtlander 58mm f/1.4 arriving soon and I must say I'm looking forward to turning that into a '41mm' on my Fuji's. If you want the 'FF' / 35mm approximate 'equivalence' this is like having a 62mm f/1 lens on my cameras, which is mouth watering to say the least.
So I will be doing a lot more of this, since my testing is showing me that it produces very good results indeed. It also simplifies my gear, which is much needed as well as giving me interesting options to explore. And if there is one particular benefit for me from mirrorless interchangeable cameras it's this. The fact I could use my Nikon lenses on my Panasonic G1 a few years ago was why I got heavily into m4/3 in the first place, shooting stills and video with a Nikon MF 50mm f/1.2 (imagine that with a speed booster!) and 85mm f/1.8. It's something I've been doing on and off for years now and I imagine I'll be doing it for the next few years as well.
And talking about imagining things, just think of the implications if Metabones come up with an AF version of these speed boosters. I know they are working on it, but I'm sure there are many problems to resolve, not least a size issue. However, they may well succeed and if they do the implications will be interesting, to say the least.