Can I just say that everytime I read the advice to shoot M lenses in AV mode I am perplexed. When I have done this I get such wildly varing exposures depending on what aperture is set. Requiring a lot of exp comp changes.

I get much closer to a proper exposure by using M mode and green button metering. Am I the only one seeing a big difference between A mode and M + green button

[Lowell Goudge]

Can I just say that everytime I read the advice to shoot M lenses in AV mode I am perplexed. When I have done this I get such wildly varing exposures depending on what aperture is set. Requiring a lot of exp comp changes.

I get much closer to a proper exposure by using M mode and green button metering. Am I the only one seeing a big difference between A mode and M + green button

can you elaborate "M" lenses a little

do you mean M42 lenses or SMC Pentax and SMC-M lenses (i.e. K mount)

I have found that M42 lenses need exposure compensation in Av mode. (about +1.5 stops for my SMC Takumar 35mm F2) Never tried in M mode because it is more convenient to have the camera set shutter speed automatically as you stop down.

I am talking about metering non-A lenses in Av mode vs green button metering.

I could just be confusing the OP here...

But Lowell if you are in Av mode clicking thru the Aperture, letting the camera set shutter speed, but then have to use exp comp, how is that any easier?

Are you saying that you can set the exp comp for the lens in Av mode and then no matter what aperture you set it exposes correctly? I am not seeing that at all with my lenses.

[Lowell Goudge]

I am talking about metering non-A lenses in Av mode vs green button metering.

I could just be confusing the OP here...

probably

But Lowell if you are in Av mode clicking thru the Aperture, letting the camera set shutter speed, but then have to use exp comp, how is that any easier?

no, on M42 lenses, when you click the aperture it stops down so the metering thinks there is less light, BUT with my SMC Tak 35, the metering needs +1.5 stops at all apertures, the camera just gets it wrong. I think this is why many people short the 7th pin with tinfoil.

Are you saying that you can set the exp comp for the lens in Av mode and then no matter what aperture you set it exposes correctly? I am not seeing that at all with my lenses.

with M42 lenses yes. note in Av mode on K mount (non A) lenses, Av mode always exposes for the wide open aperture, the camera does not stop down the lens for expsoure

[Canada_Rockies]

I didn't know that about M42 lenses. Does the adapter affect this in any way? I suppose the viewfinder gets darker as one stops down. (Perhaps focus first wide open, then set the aperture as needed ..)

How far off is the exposure metering with M42 lenses? Some over-exposure seems to be the norm with stopped-down metering with M and K lenses, at least with K10d or k20d. From what I've read and been told, it seems to vary from lens to lens too. I've had better luck with my M lens by following sunny-16, 1/ISO method -- far less over-exposed pics.

Sunny 16 works quite well with M, K and M42 lenses. I did find (after following any number of threads about it) that switching to the LL-60 metering screen, my exposures came back into line at all workable apertures with my M lenses. I have a M42 > K adaptor on route, and will try my screw mount lenses when it arrives.

[flockofbirds]

Maybe I'm weird, but after I decide the aperture I fiddle a little bit in that area with 1/2 stops and Shutter speed to figure out where I need to be, and then just make changes on my own depending on the light.

[stevebrot]

I am talking about metering non-A lenses in Av mode vs green button metering...

Gus,
You can't really use Av mode for K or M series K-mount lenses. The body does not flip the aperture lever with the result that all shots are made wide open regardless of the setting on the aperture ring. Wide open, your exposure will almost always be off, particularly for faster glass. I usually see 1.5-2 stops underexposure.

Adapted M42 and other manual diaphragm lenses, on the other hand, work great in Av mode. They also have the flaky metering at the aperture extremes, but at least the picture will be taken at the set aperture with whatever exposure comp you dial in.

Steve