50L - taming the beast!?!

[te1973]

Dear all,

this one is for the advanced users only - and ONLY about the 50L - and only about close
subjects and only about wide apertures...
I am interested in your experiences with this special one, best 50L with 5DIII or 1Dx.

I know that this is the trickiest Canon lens.
And this was and sometimes still is giving me headaches.

It is absolutely tricky to nail the focus with this one.
And I still have a lot of misses.

Please don't give me hints like the DOF is very thin... or be aware of moving the thin focus pane etc.
Believe me - I can exclude subject movement and camera movement.

I have multiple calibrated bodies and calibrated lenses as well - all calibrated separately to neutral 0
by Canon. I did have multiple copies - all behaved very similar.The current 50L was calibrated twice.

I think I have learned the following:

a)
Shooting portraits I always use the center focus point aiming on the eye with ONE SHOT or SERVO, even with 5DIII I do avoid outer focus points because they behave differently and may cause trouble.

b)
This lens can't be properly calibrated by Canon or via MA at all because of the focus shift issue.
It can be calibrated on distances greater than approx. 2m, there you might have no issues.

c)
On closer distances we must face focus shift. Focus shift depends on aperture and subject distance,
this is why you can't get a unique calibration which always does fit.

d)
I had two copies, both behaved like this:

On close distance (approx. 1m) I have to use micro adjustment around -10 for f/1.2.
On close distance (approx. 1m) I have to use micro adjustment around -15 for f/2.
On close distance (approx. 1m) I have to use micro adjustment around -20 for f/2.8

I am not much interested in other apertures at this distance.

On distances > 2m I use MA = 0. No issues.

Makes sense to me because the lens always uses f/1.2 for focussing. For other
apertures focus shift kicks in when taking the picture. (Does not explain why I have
to start with -10 right at f/1.2 - maybe otherwise the lens does not perform in other scenarios?)

e)
Anyway the lens is inconsistent, keeper rate is still only around 60% even using the technique above.


So I am interested in you experts how do you deal with this lens?
Do you have the same findings?
Is there someone having no issues and who does not need MA for apertures < f2.8 at close distances?
(I read a post somewhere where someone was stating having no problems and did show totally
blurred pictures to prove is flawless equipmentt ;-) )

No - I am interested in you pixel peepers - accepting nothing but crisp sharp pictures where the focus
is spot on.

Please concentrate on just the 50L.. all the others (85L, 135L, 35L, 50 1.4) are all easy stuff compared
to this one.

Tell me - how do YOU tame the 50L beast?
How do you take crisp sharp images?

Regards, Tom

 

[mackguyver]

Tom,

I'm on copy #2, having sold the first one to fund other gear, then buying another. I use it almost exclusively to shoot portraits between f/1.2 and f/2 in the range of 5-15 feet. Both copies were AFMA calibrated with FoCal at a distance of about 6 feet. The AFMA values have been around +2 to +6, I think, but don't have it in front of me. I have used the lens on the 5DII, 5DIII, and 1D X. I have never sent one to Canon for calibration. I have also found that a good FoCal calibration helps a lot to reduce the CA with this lens.

I have not experienced the infamous focus shift, possibly because I don't shoot too close or above f/2. I don't focus and recompose, unless it's very slight. I use all AF points, except the very outer ones to lock on the eye and my correctly-focused shot rate is probably 70-80%, mostly because it's handheld in low light. In good light, it's probably upwards of 90%. The key for me has been to make sure that I and the person I'm shooting hold still.

 

[jman]

I purchased this lens from the Canon Refurbished store about a year ago and use it frequently on a 1Dx for taking pictures of my 3 year old son at the park and really enjoy the pictures I get with it. I usually shoot around f2, within 6 feet, a subject that doesn't sit still for very long. This is a huge test for autofocus on any camera and lens combination. My autofocus set up is only cross type sensors, single point, servo case 1. I will use the inner or outer focus points depending on the framing for my subject. I usually will shoot a short burst of images to aid in getting at least one in focus. I estimate that my keeper rate is around 30-40% when taking pictures of my son in this environment. That is mostly due to his movement and my success rate is much higher when shooting a more static subject.

When shooting at wide apertures I am always in single point, servo mode and focus on the closest eye to the camera. I have found that this helps me to increase focus accuracy because the camera is constantly adjusting for any slight distance changes between the subject and camera. I have been using these setting for a couple of years so it is very comfortable for me compared to one shot focus. I also have not noticed any focus shift with this lens. This maybe due to using servo mode with this lens.

I have not done any AMFA for this lens or any of my other lenses. It is something I have looked into but I have not done yet. I have also used this lens on with my 5D3 and have had similar results. The main difference is the 1Dx keeps up with a moving subject and acquires focus much faster which is why I use it exclusively when taking pictures of my son. Here a couple of examples of the 1Dx and 50L combo where the eyes are tack sharp. He only held the pose for about 1-2 seconds before turning his head or getting up to do something other than pose for me.