« on: September 09, 2013, 07:25:35 PM »
I use black electrical insulating tape on the barrel of my 24-105L. It's still working fine; I'm pleased with the fix.
Does anybody know if OM lenses rest wide open, or rest at set aperture?With my cheap OM to EOS adaptor (no chip; purely a mechanical piece of machined metal), there's a little screw/pin in the right place, so that the OM lens stays at the aperture you set. So when the shutter goes, the OM lens' aperture doesn't need to change. Also it helps with metering, cos the camera has no way of knowing what aperture the lens is set to anyway, so it pretty much has to work this way.
Seen a OM tilt adaptor to EF-m, just windering about practicalities (i.e. am I stuck wirh a wide open aperture always, or can I control it, I know there is an aperture ring on less, I just recall someting anout the shutter being cocked bon OM bodies)
Very good point about the sensor acceptance angles. I'm also wondering if periferal illumination correction also might have had an effect in this case.No, because I always leave it switched off. And I just turned on the camera to double-check, and it was, and is, off.
The 'sneaky' ISO boost with fast primes it done to compensate for loss of light transmission through the microlenses over the sensor pixels that occurs at high incident angles of light. As such, it's specific to digital (vs. film), and more boost is needed for smaller pixels. The issue has been documented (and quantified) by DxOMark. It's not just Canon, by the way - Nikon and Sony do it, too.
Of course, you would expect the f/1.2 lens to be brighter than a f/1.4 lens but this is NOT what Fleetie observed. When the camera communicates with the lens, it boosts its internal ISO (without telling you) so that the f/1.4 image becomes brighter than the f/1.2.
Do you have simulate exposure or whatever it's called turned on for LiveView? When it communicates with the lens it may get more information and so might also apply the peripheral correction information (which generally will affected the outer portions of the frame, not the overall frame).
As for Olympus f/1.2, it should be brighter than a f/1.4. You're talking a full stop there, no duh it'll be brighter.