Turn Your Crop Sensor Camera into Full Frame*

*Sort of. When I first discovered that I could easily adapt legacy manual focus lenses to my Sony a6000, I was over the moon. A whole new world opened up to me and I began searching out vintage lenses to try out. But the crop factor was a bit of an issue. Field-of-view and depth-of-field are affected: a 50mm lens becomes a 75mm equivalent on an APS-C sensor. It’s not a huge problem, you just need to account for it. Beyond that, getting the same shallow depth-of-field is trickier unless you use really fast glass.

Enter, the focal reducer or “speed booster”. I came across a few YouTube videos about this product and I quickly realized what an advantage it could provide. How it works is: the light entering the lens gets magnified and focused onto the smaller sensor. This provides an additional full stop of light gathering ability and roughly the same field of view as on the full-frame equivalent. So a legacy 50mm f1.4 lens which would roughly be the equivalent of a 75mm f2 on an APS-C sensor paired with a focal reducer now becomes a 50mm f1.4 again! Keep in mind that these are typically ‘dumb’ adapters so it’s manual focus only (but if you’re working with legacy glass, no surprise there). Focal reducers work with mirrorless APS-C bodies (Sony’s Nex, a5xxx or a6xxx series and FujiX) as well as Micro Four Thirds (Olympus and Panasonic) and you can even adapt legacy medium format glass to full frame with a focal reducer too.

My daughter Frankie shot with Canon FD 55mm f1.2 on Sony a6000
My daughter Frankie shot with Canon FD 55mm f1.2 on Sony a6000

There is a price to pay for going this route. Because there’s another glass element involved, a relatively inexpensive focal reducer will diminish a lens’ optical integrity slightly. You won’t be getting tack-sharp images corner to corner (assuming your legacy lens is sharp in the first place). But for me, it’s a fine trade-off. I don’t think people are examining corner sharpness when looking at a dreamy portrait shot wide open. It should be noted that there is another limitation with going this route. If you have a bunch of Minolta, Canon or Nikon legacy glass, you’ll need a focal reducer for each mount if you want to “boost” all of your lenses. Compared to simple “dumb” adapters that cost around $20 to $30, focal reducers are pricier: anywhere from $80 to $300. Despite these limitations, this is still a really cheap and easy way to get the full-frame look without spending full-frame money.

If you’ve tried this, congratulations, you’ve now entered the realm of full frame with it’s razor-thin depth of field, lusciously smooth out-of-focus areas and buoyantly brilliant bokeh balls! Get ready to give your manual focus skills a workout!