Does aperture priority mode work with a manual aperture lens?

Question

I'm interested to know if there are any limitations when shooting with a manual aperture lens in aperture priority mode, compared to shooting with a fully automatic lens.

In case this isn't clear, the lens has a ring that sets the aperture. There is no wiring to communicate aperture information to the camera, so the camera does not know what the aperture is.

Questions I have when using aperture priority mode:

• Is the camera able to calculate the exposure with this lens?
• Does TTL flash metering work?
• Can I bracket the exposure?

Edit: while I'm interested in general about how cameras support this configuration, I need to have this information for Canon DSLRs, specifically the 60D.

Answer 1

Aperture priority mode works just fine with a manual lens (or no lens at all) on my Canon 550D so I assume it will work on a 60D

What happens is that the camera display shows an aperture of "F00" and the camera will set the shutter speed based on the amount of light it can see (making the result picture exactly the same as if you set the aperture in the camera).

Note that the viewfinder will be darker than with an electronic lens because it will also use the aperture you set (normally the viewfinder always uses the max aperture and the camera only stops down when you press the shutter or the DOF preview button)

My experience with this is in shooting macro pictures with an hand held reversed lens (from the point of view of the camera no lens at all) and the metering works just as well as it does with a lens attached.

So:

• Can the camera calculate exposure - absolutely yes.

• Does TTL flash metering work - yes, with the same rules as Av mode with a lens (shutter speed will be the same as with no flash, flash used for fill).

• Can I bracket exposure - Yes (just tested it now, never tried to use bracketing with no lens before).

Answer 2

My 30D works fine in Av mode with manual focus lenses; I'd be surprised if the 60D didn't but I don't have a reference handy to back that up. On my 30D the LCD reads "0.0" for the aperture when it can't communicate with the lens.

My camera meters in Av mode without any problems (though some of my manual focus lenses expose differently by half a stop or a full stop at different apertures (I'm not sure why), but they do it consistently, so it's just a matter of learning the lens or chimping for exposure and setting exposure compensation to correct for it).

I just tested, and exposure bracketing works correctly in Av mode.

I can't answer the flash question.

If you haven't already seen it, there is a good site on manual focus lenses on Canon DSLRS here: http://www.bobatkins.com/photography/eosfaq/manual_focus_EOS.html

As far as limitations:

• you can't use Tv mode, P mode, or any Auto mode (anything where the camera will try to set the aperture), of course
• you're most likely looking at lenses without Auto Focus or Image Stabilization.
• you'll lose the aperture Exif field, so if you want to know later what aperture you used for a picture, you need to either take good notes or infer the aperture from other clues in the picture (shutter speed, how much light there was, etc.).
• If you're looking to buy manual focus lenses for a cheap way to get a fast lens, realize you won't be able to see the actual DOF beyond about f/2.8 through the viewfinder (also true of modern lenses). I've heard that Live View shows the actual DOF.
• If you're looking to buy manual focus lenses for a cheap way to get a sharp lens, realize that older lenses don't have modern coatings and are often outperformed by newer, cheaper lenses.
• If you're going to focus at the widest aperture for the most-accurate focus then stop down to take the picture, you have to (of course) physically move the aperture ring. For just taking pictures while wandering around that's not a big deal, but for fast-moving subjects (like birds) it can be a little difficult; for macro work it can be a major pain.

Make sure you choose a lens (mount) that doesn't require optics to focus to infinity, or you'll just end up disappointed with the image quality.