mh2000 wrote:
ok, thanks! Very good test... I was just confused what you were saying about MF. God, why can't they just fix the damn thing!
I realized that I didn't explain MF very well. When I did the manual focus I did it at either f/1.2 or f/2.8 (here adjusting focus at f/2.8 until I got a centered DOF at f/2.8). Thus in MF mode at f/2.8 my XTi showed a forward focus shift (the exact opposite of what occurs with AF (which is of course wide open at f/1.2).
Of course if you MF at the appropriate aperture then you'll have ok focus. My tests were just to show that if you change apertures after achieving focus using MF (say you're using DOF preview button to focus) then you will see the same focus shift.
Just went through the process of testing and selecting a 50 mm prime, as I have a need for one between the 28 F/1.8 and the 85 F/1.8, to be used as a low light, fast lens, at F/1.x to F/2.
1. 50 F/2.5 CM - very sharp from max aperture, but not fast enough
2. 50 F/1.8 Mk II - ok-ish, but build quality is appalling
3. 50 F/1.4 - only sharp from F/4 and upwards, although very sharp there, BQ not really very good: the inner barrel containign the optics wobbles quite a bit
4. 50 F/1.2 - lovely lens in daylight, object distances of 4-5 m and further away, from full opening, amazing IQ and BQ, much, much sharper and better IQ you'd expect reading all the reviews and tests. However, nearby, and low light, it is a disaster. Backfocus at any light except fluorescent light, where it goes to frontfocus, and MF is off at the nearby distances, and that is using an Angle Finder C at 2.5X magnification. This also seems to depend on the contrast of the frame you're trying to capture. Only medium contrast captures seem to do well.
BTW, I have tried several copies of the 1.8, 3 of the 1.4, and also 3 of the 1.2, shooting > 1000 test shots, and getting so desparate I even re-calibrated the 400D myself, and got a second body that wasn't calibrated except to standard factory specs.
I gave up, for now anyway. I may try a last time, with a lens from a different supplier, to see if it wasn't just a bad batch.
hahaha! I like your assessment of the 50/1.8 as being "ok-ish"
...I tend to think of it as "fine" as in "it's *just* fine," nothing more... but over a lot of photos I find it more reliably "fine" than my 50/1.4 was. FWIW, my TS-E 45 is very nice.
I had the same reactions as wimg to Canon's 50mm line-up. But I never shot with my 50L in dim light ML under controlled conditions (I shoot fast moving dancers and get a lot of OOFs).
I bought my 50L to use with my 5D which I must MF focus in very dim light (can't use the central AF sensor of the 5D which is the only one to work).
Now that I have the MkIII and use its wonderful AF I haven't used the 50L much because the (effective) FL of 64mm is not useful. Neither is the F 1.2/1.4 stop required because I set the MkIII's ISO one stop faster (3200). So maybe I should replace my 50L with a 1.8?
I ditched my 50/1.4 for the 1.8 and am happier with the results. Low light focusing is better, I don't get the hunt cycles that the 1.4 is so good at getting into... and I just prefer the look, even if it isn't quite as sharp... I just find it more pleasing for the subjects I shoot.
