The Aero Ektar has a very nice look to it.
However shooting such a shallow depth of field with a 4x5 range finder can be very difficult.
The main problem is that the rangefinder will only help you focus on a feature that is in the very center of the frame.
Recomposing for your shot will throw your focus off.
I have shot for years on large format 8x10 film and polaroid. Fashion editorial and advertising. I found that you really have to focus
with your composition already established and on the ground glass.
However I did do some hand held 4x5 using what I call the string technique.
I would run a string from the lens to the subjects eye. I had it on a retracting thingy like a small dogs retractable leash.
Either I would man the camera or my assistant.
IF I was at the lens I would set up the shot indicating to the assistant where I wanted the framing. I would then pose the model and pull the string upto
up to just beside the eye of the model. The line had markings that corresponded to marking on the focus rail.
With this method I could shoot wide open and with a very high focus hit rate. The method also let me keep close to the subject and concentrate on mood and expression.
However it is a two man job.
I have had the model be the second "man" a few times. I ask them to hold up the line and then drop bring it down just before the shot.
If you are interested in 4x5 portraiture with rangefinders you should check out these two friends of mine..http://www.twinlenslife.com/search/label/The%20Life