antithesis

If you already bought the FD lenses and adapter, should you get the helios or another M42, consider getting the cheap and thin M42->FD adapter, instead of a new M42->FX adapter. Aside from saving weight, and likely money, another advange is FD is relatively short flange so you can also fit Nikon, etc to it. Also, if you ever decide to get a speedbooster, you can get an FD->FX one, and have evertyhing go through the FD mount, native or adapted. Cons would be: - 2 adapters are more likely to mess with infinity focus, though not if they are both good and solid - Not evertyhing can be adapted to FD (some have a shorter flange, but long enough that it would fit FX with a native adapter). Anyhow, enjoy your lenses!