85L and AF question

I recently had the opportunity to add a used 85L to my bag, and I have been playing with this lens since . Awesome piece of glass, and the IQ is of the WOW and OMG kind, as is the bokeh. Almost unbelievable, it is as sharp at F/1.2 as the 85 F/1.8 at F/2.8, and at F/2 it is out of this world, I found.

The DoF at F/1.2 obviously is razor thin, and when shooting with the lens, at F/1.2 I found I had problems getting the focus exactly there where I wanted it. This lens could seriously use IS if you ask me, with the size, weight and aperture! If things were in focus, things were awesomely sharp, I must say. Further away, at F/2, it was all a lot easier, obviously, so those shots were always fine.

Anyway, as a result of my close focus experiences at F/1.2, I tested it against a focus chart, and a few items fairly close by. Indeed it frontfocused a little, which I tried to correct without upsetting the focusing with my other lenses too much. So I set it to DoF of 7 mm after the focus point, and 3 mm before focus point, at F/1.2. Note: this was fluorescent (yellow-green) light. BTW, there is a slight variation in AF, of about 3-4 mm, further towards the front. This corresponds more or less with the 1/3 of DoF rule for the centre focus point, so I guess that is ok. Test shots proved it was working fine.

Today I shot some test shots outside, in the garden, when it was getting a little later already, overcast, so in principle quite bluish light. This was doen deliberately . I noticed that the AF was focusing slightly more towards the front, which I expected of course, after my tests with the 50L a few weeks ago, so I had the focus test chart at the ready . And yes, AF was slightly further towards the front, about 1/3 of DoF at F/1.2, from slightly out (2 mm out, front focus) to just in DoF at the far end. This is what I noticed in the photographs as well, so it just confirmed that.

I still have to test with tungsten light, because I would expect it to backfocus a little further now, maybe just in focus, but don't know that yet.

Of course, I am using this lens on a 400D/XTi, so I don't know whether this lens does AF a lot better on a 5D or 1D, but I would expect similar behaviour on a 30D.

Did any of you notice similar behavior?

Furthermore, there is a little play in the fitting. I can turn the lens a little from left to right and back, while the little lock is engaged. Is this normal?

Thanks in advance for your replies!

Kind regards, Wim

wimg wrote in post #3751358
Did any of you notice similar behavior?

Furthermore, there is a little play in the fitting. I can turn the lens a little from left to right and back, while the little lock is engaged. Is this normal?

Thanks in advance for your replies!

Kind regards, Wim

On the 5D and 1DMKIIN, I haven't had any issues. There is a little play in the fitting, that's not an issue.

Mark

Its huge aperture doesn't need IS that much.

When I first got mine, at f/1.2 on a 1Ds, I thought it was front focusing then back focusing then focusing ok. I backed off and remembered that this lens took some getting use to. I started at f/1.8 and shot my way down to f/1.2 over a day and a half. It worked, lens is fine, my fault. On the 1DmkIIn the focus accuracy is a bit better. When I did use it for some portraits, it worked great. A younger photog friend, tried my 85mkII and hit his mark every time at f1.2 right off the bat.

Mark_Cohran wrote in post #3751410
On the 5D and 1DMKIIN, I haven't had any issues. There is a little play in the fitting, that's not an issue.

Mark

Thank you Mark. That's reassuring! It's the only lens in my bag that does that.

Kind regards, Wim

iknow wrote in post #3751420
Its huge aperture doesn't need IS that much.

No, not so much for the speed. I did mean for the image shake when holding this heavy beast. I find it very hard to keep it still, and with the very thin DoF, even in the viewfinder, at F/1.2 that makes things rather difficult ...

Kind regards, Wim

GGordon wrote in post #3751452
When I first got mine, at f/1.2 on a 1Ds, I thought it was front focusing then back focusing then focusing ok. I backed off and remembered that this lens took some getting use to. I started at f/1.8 and shot my way down to f/1.2 over a day and a half. It worked, lens is fine, my fault. On the 1DmkIIn the focus accuracy is a bit better. When I did use it for some portraits, it worked great. A younger photog friend, tried my 85mkII and hit his mark every time at f1.2 right off the bat.

Thank you! I'll keep on persevering. I do get sharp shots at F/1.2 nearby, with pin point focus, just not all of them. If you see the results, it certainly is worthwhile to practice more, and it is fun anyway .

Kind regards, Wim

One other question: there is a bit of play in the focus ring. Is that normal, too?

Kind regards, Wim

I'm not sure what you mean by play, but on mine the focus ring as just a little slack before it engages .

Mark

Mark_Cohran wrote in post #3754414
I'm not sure what you mean by play, but on mine the focus ring as just a little slack before it engages .

Mark

What I mean is that it "wobbles" a little. There is no slack when it engages, after focusing of course, it won't engage before obtaing AF . In MF there is no slack either, just the little wobble.

Kind regards, Wim