From 5D Mark II Team
Description of the problem:
When a Canon EF 100mm f/2.8 Macro USM lens is mounted on the camera and the user manually changes focus (rotates focus ring), the lens changes the iris/aperture “by itself”, even when the camera is in full manual mode.
It is not normal, and should not happen. The tests were made by several users with many copies on many camera bodies, so it’s not an isolated lens problem.
▪ This malfunction always occurs in this situation:
When the camera is set to M (Manual) mode and in Live View mode (Still+Movie – Movie Display), which is the correct mode for “full manual control” in movie mode.
Read more about the issue below.
http://5dmark2.wordpress.com/2010/04/05/malfunction-in-firmware-2-0-4/
thanks everyone that sent this in
cr
72 Comments
If this phenomenon really is due to a macro lens design, why is it happening on my EF 300/4L IS, which is NOT a macro lens?
http://www.youtube.com/watch?v=APgK5gdM69M
What many of you are not understanding is that ‘effective aperture’–the loss of light due to high magnification–does not mean the physical aperture is stopping down. Please read my post on Fred Miranda for an explanation:
http://www.fredmiranda.com/forum/topic/885884/0#8327335
You can’t abuse it to hide what you don’t like, you only get one vote.
Incidents like this, and the very negative feedback it generates make it less and less likely that firmware upgrades will be offered in the future. Apple, Microsoft, Adobe (who just public beta tons to save money) etc take huge amounts of man hours alpha and beta testing software and still nobody expects version .0.1 to be anywhere near finished. Yes with hindsight all these “issues” could be caught in testing but how many testers and in how many situations, lenses, settings etc do you want tested for your free upgrade? Firmware is definitely becoming a four letter word.
“What many of you are not understanding is that ‘effective aperture’–the loss of light due to high magnification–does not mean the physical aperture is stopping down. Please read my post on Fred Miranda for an explanation:”
Wrong wrong wrong. What you are not understanding is that for a macro lens that focuses right up to infinity needs to lower its focal length to get the magnification. A 100mm macro lens is 100mm only at infinity or close to it. It’s more like ~60mm at MFD. That’s why the aperture size changes to keep it a constant f/2.8 physically.
Loss of light is another issue. Even though the aperture is f/2.8 in size, you might not get that amount of light hitting the sensor. The math behind this is something like: effective aperture = current aperture x (magnification +1)
This is not what we’re talking about here. The MP-E doesnt focus to infinity so it’s focal length stays at 65mm all the time even if magnification changes, in theory. All the MP-E does is add air between the lens elements and the sensor increasing the magnification which affects the effective aperture.