With the arrival of full frame cameras like the Sony A7R, lens adapters hold out great promise for using other-brand lenses—I feel as eager as anyone there. But lens adapters come with all kinds of potential issues; here are some to be on the lookout for:
- Mount locking—can the lens fall off? This is not speculation and not user error; it happened to me. Fortunately I noticed it in time.
- Sample variation—do two adapters of the same brand give the same results? Are they even the same length (this can throw off distance and infinity settings).
- Flare—is the internal of the lens adapter blackened and ideally with light traps, or might it introduce flare of its own?
- Parallelism—that lens being soft on one side or corner might just be the lens adapter. Moreover, the effects can be additive or subtractive or canceling with other system tolerances, and thus vary with different focusing positions. It can be “ok” with 3D images, but shoot a distant landscape and you might feel grumpy with the results.
You get what you pay for.
As an example of superb quality, the Leica R-adapter M stands head and shoulders above most. I’ve used various Novoflex adapters including the Novoflex Adapter for Sony E-mount, which is of as good a quality as I’ve found for adapting to Sony A7R.
For all of these reasons, “lens tests” with an adapted lens are system tests, and thus need to exercise great care in not making inappropriate conclusions about the lens, should an apparent issue arise.