I had an assignment to do for class, involving equivalent exposures. I had to take five shots at differing apertures of a group of five objects (one behind the other) at different apertures and adjusting the shutter times accordingly to keep the same exposure.
I used f/2, f/3.5, f/5.6, f/11 and f/22.
I tried the exercise several times and on each occasion, at f/2 I was getting an over exposure of about 1 stop. On each occasion both incident meter and camera meter agreed and all the exposures at the other apertures equivalised ok.
I'm assuming at the wider apertures, it becomes increasingly harder to be 100% accurate.

[stevebrot]

Gary,
"M" mode? What aperture did you use for your base measurement? Were you using the aperture ring or the thumb wheel? Stock focus screen?

Steve

'M' mode but thumb wheel for aperture Steve and stock focus screen.

[stevebrot]

'M' mode but thumb wheel for aperture Steve and stock focus screen.

That is seriously weird. I will have to see what mine does!

Steve

[cousinsane]

Frankly I can't really imagine that happening, considering all camera meter wide open. Can you upload some pictures?

[Ratmagiclady]

Did the shutter speeds actually end up coming out in EXIF as the same EV for each aperture?

I'm wondering if perhaps you confused yourself somehow by progressing from f5.6 to 3.5 to 2: 3.5 is a half-stop out of the sequence, and if you corrected the wrong way when opening up, that could add up to a full stop of error?

It's the kind of mistake I can make when I get a bit muddled about trying to hold too many actual numbers in my head at once.

[Ash]

Gary, this phenomenon happens with a few of my lenses, particularly the FA 100/2.8 macro.
It gives well exposed images at EV0 from f/2.8 to about f/4, then at f/5.6 it starts to overexpose by perhaps half a stop, but by f/11, it overexposes by 1.5-2 stops. I find it a blessing when shooting macros handheld, and 'know' the character of the lens so I immediately know what EV to dial up when shooting with it.

Similarly the DA 55-300 produces dark images at EV0, less so wide open, but more obvious when stopped down. I've gotten used to it by dialling up EV to +0.7-1.0 in most instances to avoid loss of shadow detail, but it can be a bit of a nuisance. Still not enough to complain about with this little gem.

Frankly I can't really imagine that happening, considering all camera meter wide open. Can you upload some pictures?

Yes.
Exif should be intact, you can see the obvious difference in exposure in the sky.

[Ash]

And ISO was fixed between all the shots? (sorry if this is blooming obvious Gary...)
Outdoor lighting conditions do change quickly depending on the cloud cover too.

Did the shutter speeds actually end up coming out in EXIF as the same EV for each aperture?

I'm wondering if perhaps you confused yourself somehow by progressing from f5.6 to 3.5 to 2: 3.5 is a half-stop out of the sequence, and if you corrected the wrong way when opening up, that could add up to a full stop of error?

It's the kind of mistake I can make when I get a bit muddled about trying to hold too many actual numbers in my head at once.

No, I tried the exercise several times on different days and double checked each time.

Gary, this phenomenon happens with a few of my lenses, particularly the FA 100/2.8 macro.
It gives well exposed images at EV0 from f/2.8 to about f/4, then at f/5.6 it starts to overexpose by perhaps half a stop, but by f/11, it overexposes by 1.5-2 stops. I find it a blessing when shooting macros handheld, and 'know' the character of the lens so I immediately know what EV to dial up when shooting with it.

Similarly the DA 55-300 produces dark images at EV0, less so wide open, but more obvious when stopped down. I've gotten used to it by dialling up EV to +0.7-1.0 in most instances to avoid loss of shadow detail, but it can be a bit of a nuisance. Still not enough to complain about with this little gem.

I only shoot manual Ash and don't bother with EV adjust. This exercise isn't something I'm going to be repeating, I just found it interesting that there was such a difference when wide open.

I think I recall having a similar response with my FA 50 1.4... but my test was not nearly as controlled as yours... but wide open seemed to confuse the camera some.

ps exif is not intact for me.

pss when did you get the fa 35??? and more importantly, when can I borrow it

[Ash]

I only shoot manual Ash and don't bother with EV adjust. This exercise isn't something I'm going to be repeating, I just found it interesting that there was such a difference when wide open.

The concept I was trying to illustrate though was that those lenses I mentioned produce varying image exposures based on the aperture of the lens, and does this despite the same apparent total exposure settings for each shot. The scenes I'd observed exhibiting this phenomenon weren't subject to varying ambient light intensity as a cloudy sky.

[stevebrot]

Can we see a blank wall series? That is the acid test!

Steve

And ISO was fixed between all the shots? (sorry if this is blooming obvious Gary...)
Outdoor lighting conditions do change quickly depending on the cloud cover too.

Yes ISO was fixed.

The concept I was trying to illustrate though was that those lenses I mentioned produce varying image exposures based on the aperture of the lens, and does this despite the same apparent total exposure settings for each shot. The scenes I'd observed exhibiting this phenomenon weren't subject to varying ambient light intensity as a cloudy sky.

The ambient light wasn't that variable Ash. Also it happened on three separate days and always only when wide open. Under normal shooting conditions it would be a non issue because I wouldn't be trying to attain equivalent exposures and the overexposure is within the realms of PP correction.

You have to remember also that this isn't a metering issue, camera and light meter both agreed, it's the resulting image using the lens wide open that is the anomaly.

I think I recall having a similar response with my FA 50 1.4... but my test was not nearly as controlled as yours... but wide open seemed to confuse the camera some.

ps exif is not intact for me.

pss when did you get the fa 35??? and more importantly, when can I borrow it

I got it last year, you can borrow it when you get a camera.

Can we see a blank wall series? That is the acid test!

Steve

Blank, you sure you don't want bricks Steve?

If I get a chance I'll do it tomorrow, but I'm not that bothered, testing (acid or otherwise) won't change anything and won't affect anyone unless I sell it to a first year photography student.