Squirrels Go Like This

Manual Lenses, EOS Bodies

Pentax K to EOS EF adapter

Christmas arrived a little late this year, but today, I finally got the Pentax K manual lens adapter for Canon EOS cameras I’ve wanted for some time. A less paranoid friend of mine, Kent, ordered one from some random guy in Hong Kong via eBay and PayPal for me. Fortunately, he had no problems with the transaction, as it arrived about 8 days after clicking on “buy it now” and paying. The only sketchy thing about the whole process is that the seller marked on the customs form “gift”. However, that’s up to him, as it’s up to the person shipping an item to sign off on it.

K to EOS EF adapter on Pentax lens

Over on the above left is how it looks. The metal looks well-machined; not flimsy at all. The K-mount lens mounts securely to the adapter, and the adapter snaps into place on the camera just as securely as a Canon-branded lens would. Impressive. If anything, the fit of the adapter to the lens is a little too tight, as it’s a little difficult to remove from the lens when you’re done with it. This seems preferable to a loosey-goosey design that feels untrustworthy, though, so I’m not complaining. The autofocus confirmation chip is just expoxied on there, but it feels very secure.

Pentax SMC 50mm f/1.4 on a Canon Rebel XTi

That’s all nice; how’s it work? I’ll cut to the chase: very well! Beyond being a nice, precision chunk of machined metal, infinity focus is perfect and Canon’s camera firmware makes it surprisingly un-painful to use the lens with it. It’s easier to use than I thought it would be, which is a pleasant surprise. Basically, you set the camera on “Av” aperture priority mode, focus and shoot.

That’s an oversimiplification of the process, as there’s a few gotchas. First of all, the Canon EOS system does all lens functions electronically: focusing; identifying the lens; setting the aperture for a picture, etc. Manual focus lenses can’t do any of this, so not only do you have to focus yourself, but you have to play with the aperture control to take pictures. SLR cameras allow you to compose with the lens “wide open” (at the maximum aperture) so what you see in the viewfinder is bright, and easier to focus. With this adapter, you have to open the aperture yourself to compose; then close it down to whatever you like, before you take your picture.

Infinity Focus works fine

This is where Canon makes it easy: the camera is always figuring out the correct exposure for a scene, regardless of what aperture you’ve manually set. This is called “stop-down metering”. Once you’ve got your composition, focus and aperture chosen, you just press the shutter button.

The other gotcha is that even though it has a focus confirmation chip on it, Canon cameras won’t focus with an f-stop slower than f/5.6. (I don’t think any brand of camera does, for that matter.) So, it really is best to focus and compose with the lens aperture set wide open, and then set the aperture down at the last moment when you’re ready to take your picture. This is all stuff that happens automatically with SLR cameras made since the 1960s (well, except for autofocus).

A few final notes about all of this.

If I owned Nikon cameras, I wouldn’t need an adapter to use old manual Nikon lenses; and the whole process would be easier. In theory, all Nikon lenses made since 1977 should work on newer Nikon cameras; and lenses made between 1959 and 1977 can be converted to “AI” (auto-indexing) to have that same compatibility. In reality, the list of caveats and exceptions is about a mile long, and varies from camera body to camera body. The cheapest Nikon DSLRs, the D40, D40x and D60, are also the worst offenders when it comes to incompatibility, so your mileage with that will vary greatly.

I can’t imagine being a pro and putting up with any of this. Certainly, a pro will just buy the latest Canon glass and forget all about this adapter stuff. The glass is all an investment and a write-off, so there is absolutely no point to any of this playing around. Good thing I’m not a pro; this is just fun!

And now, for the whole point of the exercise: Using nice, (relatively) inexpensive old Pentax glass with my DSLR. So far, I’m very pleased with the results. See for yourself:

Horse Head, at f/4; Pentax SMC-M 50mm f/1.4 lens

Nice and sharp, isn’t it? I like the quality of the background blur, too.

Scary Thornbush, at f/2; Pentax SMC-M 50mm f/1.4 lens

Oh yeah. This is verrry nice!

And now, for a few shots showing the same scene with different apertures. (The lighting was kinda weird, a combination of cloudy light through the window and incandescent overhead, so don’t read too much into how the colors turned out… that isn’t the point to this group of pictures.)

Kalanchoe Trellis at f/1.4; Pentax SMC-M 50mm f/1.4 lens

Kalanchoe Trellis at f/2.8; Pentax SMC-M 50mm f/1.4 lens

Kalanchoe Trellis at f/4; Pentax SMC-M 50mm f/1.4 lens

Kalanchoe Trellis at f/5.6; Pentax SMC-M 50mm f/1.4 lens