Canon 24-70mm Version: 1... Worthy or Unworthy?

Quote:

---

Originally Posted by Donald

Not sure that I'd know whether the lens was in need of re-calibration. How do you actually determine this?

---

Basically, when focusing on say, a ruler which is slanted, I would set the center AF point on the 5cm mark on the ruler and focus, if the lens is calibrated properly, the 5cm mark would be in sharp focus.. If the lens wasn't calibrated properly, then instead of the 5cm mark being in focus, the 8cm mark or maybe the 2.3cm mark on the ruler would be in sharp focus.

Quote:

---

Originally Posted by Traingineer

To make everything clear, the lens was never calibrated, I tested it and then calibrated it to -15, then a few weeks later, i set it to -6, and recently, I set it to -7.

---

It occurs to me that you are confusing Lens Calibration (which is done by a service technician) and Auto Focus Micro Adjustment (which is offered as a User Function on some EOS Cameras).

The two functions are related, but are quite different.

The lens you had MUST have been calibrated as it left the production line and should (would) have left that production line within Canon's calibration specifications. IF the lens subsequently required "occasional recalibration", that would very odd: and that is why you have responses, that you have.

It can be that some Photographers have their lens (re)-calibrated upon purchase such that lens's calibration tolerance sits better within ONE SPECIFIC camera the Photographer will use. This service is offered by Canon and (I think) is still free for CPN Members.

Auto Focus Micro Adjustment (AFMA) is a USER FUNCTION which is offered on many of the newer EOS cameras; (for examples: 5DMkII / MkIII; 50D; 7D; 1D Mark III, 1D Mark IV; 1Ds Mark III, and 1D X). AFMA allows the user to correct for small errors of front-focusing or back-focusing and has a quantifiable benefit for lenses with fast apertures, because the shallow depth of field at wide apertures makes even small focus errors more evident.

It is possible that you are applying AFMA in not the best manner possible and it is also likely that micro focussing adjustment (if used) will vary dependent upon the Focal Length at which the lens is set.

WW

I might add to Bill's thorough post that micro adjustment can be very hit and miss; autofocus isn't 100% repeatable and additionally, the micro-adjustment required is usually different for each end of the zoom range (and yet only recently have they added support for 2 micro adjustments (one for each end).

Normally I'll only change micro adjustment in lots of 5 - anything less is impossible to see (and even lots of 5 is darn difficult). In all the times I've played with it I've ended up concluding that it just wasn't worth it as the AF just wasn't repeatable enough.

Sorry about that, I meant AFMA. While my way may not be 100% accurate, it did still make a difference.

Only problem I have found is that the lens hood reversed on the lens makes holding the lens to fit on the camera quite difficult. My grip is not good when twisting my wrist. Having to be careful as nearly dropped it a couple of times.

Quote:

---

Originally Posted by loosecanon

Only problem I have found is that the lens hood reversed on the lens makes holding the lens to fit on the camera quite difficult. My grip is not good when twisting my wrist. Having to be careful as nearly dropped it a couple of times.

---

Not sure I'm understanding this??? Why wouldn't you take off the hood before mounting the lens?

I tend to have lens hoods on to protect them. Reversed when in bag. To pick up the lens there is little to hold on to, almost only the mount cap. Usually I mount lens then take lens cap off then reverse the hood. Holding camera in one hand and lens in other to mount.