I wonder how many people will even notice the backfocusing, do you think Canon will even address it if only a minority complain? I mean, I didnt really think to stop it down to check for it. It seemed fine wide open and most of my shots over the past month or so were at distances where it isn't an issue. I cant remember how Canon addressed the 24-105 flare, were there a lot of complaints also with that lens?
I still cant understand how awhile back when I first recieved the lens I took some shots of my wifes eye and it seemed OK(2.8). I did use a flash on that occasion but when I tested with the flash today it was a different story. I may try again tonight, but I doubt I will have any luck. Im kinda bummed now because I dont think it will help to send it in and I am way out of the exchange date from B&H.
I sincerely hope that there are "good copies" out there, but I find that highly questionable still. I wish I had tried both lenses on a 5D or something while I was at the shop last. I may try to do so before I send it off to Canon, just for the hell of it.
Well you've seen the results of mine Sam, on a 5D. I can't get it to behave any other than I'd expect from any such fast lens with that sort of DOF, and the test shots are nothing like what I'll use it for. Try as I might I can't get it to do anything but nail focus and do it very quickly....
Wade, I am on copy two of the lens. While it does it occasionally it doesn't do it all the time, but I am still at odds over what to do with this one.
I DO have shots that are acceptable and not backfocused. That could explain why you might not have ever noticed it.
And as Gary has noted, I've been making sure Canon has heard me (and us).
As for perfect copies of this lens, we had a Canon rep at our monthly meeting the other evening who had a 50/1.2 fresh out of the box. I had the opportunity to put it through the paces and that thing was damn sharp at any aperture I tried. I was floored. So, in any event, it should give us a glimmer of hope. The rep also told me they doesn't get any special treatment with lenses, it's the same luck of the draw as us consumers.
Ok, heres another one that turned out, I took another one previous to this that backfocused I had a little better light on this one and again used the speed flash, one shot mode f2.8. Definately is a hit or miss with mine. Maybe I should just keep it in rapid fire and blaze away.
Keep in mind that variation in focusing is normal. So, not all misfocusing is abnormal. This is why testing on a test chart, tripod, etc. is good if you feel like enough "practical" shots are problematic. It's very easy to give a false negative just by your subject or yourself moving, for instance. Whenever I do this test, I do between 3-5 shots right in a row, ideally with my subjects sitting down and myself very stable. In my case, the lens is misfocusing in essentially the same way every single time, with slight variation.
Well I just got my 50 1.2 today and it seems sharp and fast AF but I haven't tried it in lowlight action yet so we'll see. Seems sharp enough at f/1.2 1/60 ISO 400 here with my dog trying to chew my foot off
The other ones were a bit soft but he was only a couple of feet away and moving. Can't wait to try this in a gym. Sales guy at B&H said it would be very fast for AF, hope so.
OK, I've run another battery of tests, and I now see the progressive backfocus with stopping down, and I think you may also see why it sometimes isn't obvious.
I used the far left focus point, to simulate what I commonly do in vertical portraits (except that I would use the right point - set up the batteries in the wrong direction, no difference...)
1DMkII, the focus point was directly over the upper central portion of the nearest (left most) battery, focus was manually put on infinity before AF each time, solid tripod, self timer, mirror lock up.
Pretty much, the AF seems to be keeping the target at the near end of the DOF until stopping down substantially, although in pixel peeping it could certainly be argued that the target is slightly softer than the second battery at certain stops. I'm not suggesting that the AF is designed to do that, just that this is the practical effect at distances around 3 feet.
I'll be interested in re-calibration at some point, but after reading about others' experiences, I plan to keep using the lens as is for now.
Have I helped at all? Am I blind? Nuts? Is this every bit as bad as the worst you've seen, or was I a bit luckier than some folks with my UU1000 lens?
Frankly, a better test if you're going to do the battery test (which I'm not a fan of) is to focus on the second battery from the left so you get some sort of idea of where the plane of focus is actually sitting. In your example here there's no way to really tell where it is since there's nothing in front of it that you can look at. This is where a more formal focus test chart comes in handy, since it's really unambiguous in terms of what you're looking at. Here's my focus test chart results again (oversharpened to better illustrate the plane of focus)...
1D MKII, AF, f/2.8
1D MKII, split-screen manual focus, f/2.8
In the example above you can see the DoF is identical, but the plane of focus is moving - being severely backfocused when used with AF. As you stop down, the DoF is getting greater and greater so the effect of the misfocus will be lessened, which can give a false positive for focus accuracy improving, which is not necessarily the case. This explains William Castleman's initial, unintuitive test results which show the lens being relatively sharp wide-open in comparison to the 50/1.4, dropping off in relative sharpness after f/2 with the 50/1.4 being significantly "sharper" at f/2.8 and then regaining "sharpness" closer to f/4 (due to the DoF being great enough to make up for the misfocus). That's exactly the kind of results one would expect with a lens malfunctioning in this manner.
Sam, the implication of your reasoning is that William's and other's measurments of a dip in sharpness of the 50 1.2 can be attributed to the AF error phenomenon, and therefor the dip in sharpness of the 1.2 lens should be recanted until the AF issue is resolved. To your knowledge, has William so recanted his test results?
They send the duff lenses where the cheap prices are....
I had a little better light on this one and again used the speed flash, one shot mode f2.8. Definately is a hit or miss with mine. Maybe I should just keep it in rapid fire and blaze away.
