The motivation behind using an M42 or Canon FD lens on your Nikon comes from the fact that these mounts can be found in rather cheap prices (especially M42). Adapters that allow you to mount such a lens on a Nikon are cheap ($15-$20), but there are some things you need to know:
- Due to design reasons, infinity focus is not possible with most adapters.
- Some adapters contain a correcting glass that does allow infinity focus. However, optical quality is reduced every time you add extra glasses in front of your lens (especially when, more often than not, these adapters are cheaply made.
|Macro is a very probable application for these kinds of lenses.|
So, what does that leave us with? Well, obviously enough, two pretty good applications are a) portraits; b) macros. Keep in mind two other important things:
- Self-obviously, these are manual-focus lenses. If by "portraits" you had in mind anything like small children or animals that won't stay still, you'll be disappointed
- Also keep in mind that you will not have metering with all cameras. Only upper-level DSLRs will give you metering*
So, having said all that, do I recommend M42 and FD lenses for use with Nikon? I bet that's what you've been waiting for, so let's cut to the chase.
My answer might surprise you. No, I do not recommend M42 or FD lenses for use on a Nikon DSLR body. You can find some pretty sweet lenses out there - such as some Takumar for the M42 mount, and some pretty great 50mm FDs. The cheap M42 ones are bad - some are abysmal - and the good ones are as or more expensive than the AI-S Nikkors. So, what would be the point - apart from losing infinity focus?
People often have this erroneous belief that if a lens is old and manual-focus (and all-metal), it must be a good, professional lens. Nothing could be further from the truth. There are plenty of spectacularly great manual-focus lenses (the AI-S micro-Nikkors come to mind), but that doesn't mean their modern equivalents are not as or more great. Paired with the fact that they also give you autofocus and metering (and infinity focus, let's no forget), the scale is tipped in their favor