+18 AFMA out of the box....return?

[Ewinter]

Hi all,
I got bored of waiting for a siggy 50 'A' so I bit and bought the canon 50mm 1.4 as I didn't want focus issues.
Lawl.
I've got it and it seemed really soft, and tried an afma.
It's at +18.
My question is : AFMA is supposed to be for dealing with tolerances and mishaps in the field. I know i'm not going to get a perfect 0, but if say, it gets knocked +3, i'm going to have a 1.4 I can't use.
Do I take it back or send it to CPS under warranty?

[neuroanatomist]

I'd do one or the other. If you just bought it, I'd exchange it.

[Ewinter]

Got it today.
The thing is, I have no guarantee another won't be the same. And it's not a usual item at the store, so it's probably a delay of equal time either way.

Or, do I get the store to send it to CPS for me?

[brad-man]

If you get another that requires that much correction, you should probably send both the lens and the camera to Canon.

[Luke]

Yeah, send it back..
That's what my Sigma was before I took it and the body in to Sigma

[Mt Spokane Photography]

My 35mmL was +2 on my 5D MK II and +14 on my 1D MK III.  I sent it to CPS and they calibrated the lens to their reference 1D MK III and its been nearly right on for every camera since then, including another 5D MK II, two 5D MK III's, and a 1D MK IV.
 
I think having CPS calibrate it is your best bet.

[R1-7D]

I just bought the 50mm f/1.4 yesterday and calibrated it. I got 11+.

Think I should try for a different copy of the lens too?

[killswitch]

I recently bought a used 16-3L II and it seemed soft at first. After a quick AFMA, Focal suggested +12/13 on both ends. It was tested under very good lighting conditions(+15EV) and on a stable tripod. That AFMA made it a lot better though. But do these extreme values imply something is seriously wrong with the lens and need to be checked/calibrated?

[jdramirez]

I recently bought a used 16-3L II and it seemed soft at first. After a quick AFMA, Focal suggested +12/13 on both ends. It was tested under very good lighting conditions(+15EV) and on a stable tripod. That AFMA made it a lot better though. But do these extreme values imply something is seriously wrong with the lens and need to be checked/calibrated?

 if I sell a lens, I  don't want someone with an xti  complaining I sold them a bad lens because they can't do afma. 

[victorwol]

I recently bought a used 16-3L II and it seemed soft at first. After a quick AFMA, Focal suggested +12/13 on both ends. It was tested under very good lighting conditions(+15EV) and on a stable tripod. That AFMA made it a lot better though. But do these extreme values imply something is seriously wrong with the lens and need to be checked/calibrated?

 if I sell a lens, I  don't want someone with an xti  complaining I sold them a bad lens because they can't do afma.

Very good point..... Return it.

[R1-7D]

So you guys are saying that if there's a big adjustment to the afma that a lens should be returned until one is found that doesn't require as much of an adjustment?

[neuroanatomist]

There's no problem with a big adjustment, per se, as long as it's 20 units or less.  The problem is when you change upi your gear.  If your lens needs +18 on your current body, what if you get a new body that is off in the same direction - now, 20 units of adjustment isn't enough.

[jdramirez]

I'm not really an AFMA expert, but the problem is as such.

lens is -15 and the body is +4 making the total adjustment 19 notches till AF is perfect.

Then you get a new body and the same lens.  The lens is still at -15, but the new body is at +9, so now you are at 24 notches till perfect. 

And if I'm wrong, please feel free to correct me out there.

So it is really about the lens, because let's say your body is +15 and your lens is +13, then you only have 2 in total difference.  So when you sell it to someone without AFMA, their body is -10 and the lens is +13 for a total difference of 23... which could be a real problem. 

So my presumption is that you want to make sure that you are identifying whether it is a combination of body + lens which is getting the high number or whether it is the lens itself.

[R1-7D]

There's no problem with a big adjustment, per se, as long as it's 20 units or less.  The problem is when you change upi your gear.  If your lens needs +18 on your current body, what if you get a new body that is off in the same direction - now, 20 units of adjustment isn't enough.

Thank you and jdramirez for the reply! Makes sense.

[killswitch]

I'm not really an AFMA expert, but the problem is as such.

lens is -15 and the body is +4 making the total adjustment 19 notches till AF is perfect.

Then you get a new body and the same lens.  The lens is still at -15, but the new body is at +9, so now you are at 24 notches till perfect. 

And if I'm wrong, please feel free to correct me out there.

So it is really about the lens, because let's say your body is +15 and your lens is +13, then you only have 2 in total difference.  So when you sell it to someone without AFMA, their body is -10 and the lens is +13 for a total difference of 23... which could be a real problem. 

So my presumption is that you want to make sure that you are identifying whether it is a combination of body + lens which is getting the high number or whether it is the lens itself.

Thanks jdramirez. Yeah, that made sense.