How do you shoot wide open?

Well, if you shoot the portrait horizontally rather than vertically, you'll naturally have to be further back to frame the subject the same way.

Bracetty wrote in post #16841449
Im shooting completely manual, no af on lens. Can you elaborate a bit more, I don't have that luxury

Try to get magic lantern on your camera and use either the "focus peaking" or "focus zoom" feature. It helps immensely when using my M with my Rokinon. It has made the lens a much more valuable and accurate tool than it was through a viewfinder. I don't know a whole lot about the 1100D, so your milage may vary.

Bracetty wrote in post #16841449
Im shooting completely manual, no af on lens. Can you elaborate a bit more, I don't have that luxury

Actually, when shooting at very wide apertures, I've pretty frequently switched to Manual Focus, and tweaked the focus until I can see in the viewfinder (or, if you have it, Live View) that the focus "snaps in" where I want it. Paying close visual attention is important when dealing with tricky focus issues, whether in MF or AF!

I shot F4 for a few years. Going to 2.8 was a bit of an adjustment but even shallower was a real challenge. I agree that don't refocus/recompose, selecting a single AF point and place it exactly where focus needs to be. Out of all the things shallow DOF was and still is the most challenging to me. Thing is people never sit still. Don't they realize they need to do that when I'm taking a picture of them

Some good examples.

http://i33.photobucket​.com …_zps3dcf609e.jp​g~original

The OP's situation is different because the lens he is asking about is all manual.

Sorry about that.

BenjaminMH wrote in post #16842215
The OP's situation is different because he is asking about is all manual.

No I wasn't talking about an all manual lens or any lens in specifically. Just gave an example of the 135, which is not all manual anyway.

Well, I feel silly now. For some reason I had it my mind that Bracetty was the OP. My apologies, must be time to sleep.

BenjaminMH wrote in post #16842276
Well, I feel silly now. For some reason I had it my mind that Bracetty was the OP. My apologies, must be time to sleep.

My apologies didn't mean to take up the thread, I just had a very similar question and didn't think it would be appropriate to start a new one.

No, I was careless and wasn't paying enough attention. Not your fault at all. I do think that my advice above could really help you though. ML makes these lenses shine.