TS-E 17mm focusing issue

[Rajan Parrikar]

In the field, I almost always focus my TS-E 17 lens using Live View.

However, when I use the viewfinder and rely on the blinking focus lights to confirm focus, I find that the focus is a little off. Has anyone had this issue? I am thinking of sending my bodies and the lens to Canon service to get this calibrated. This is not really a problem since (as I indicated above) I use Live View for this lens, but still, I would like the alternative focus procedure to be be available, too.

[Bart_van_der_Wolf]

In the field, I almost always focus my TS-E 17 lens using Live View.

However, when I use the viewfinder and rely on the blinking focus lights to confirm focus, I find that the focus is a little off. Has anyone had this issue? I am thinking of sending my bodies and the lens to Canon service to get this calibrated. This is not really a problem since (as I indicated above) I use Live View for this lens, but still, I would like the alternative focus procedure to be be available, too.

You mention Live View, but you don't mention the camera model, so I have to assume you can also use AF microadjust. Try it, it also works on manual focus lenses by adjusting the focus confirmation feedback.

Cheers,
Bart

[tokengirl]

The AF confirmation only works if you have no tilt or shift.  Once you introduce any of either, the AF confirmation will not work properly.  That's just the nature of the beast.

[Bart_van_der_Wolf]

The AF confirmation only works if you have no tilt or shift.  Once you introduce any of either, the AF confirmation will not work properly.  That's just the nature of the beast.

Could you quantify "does not work properly"? Also, how much tilt or shift do you use with the 17mm before it stops "working properly"?

I don't have the 17mm so I can't tell you, but with my TS-E 24mm II I can use 7 degrees of tilt, and the most outer horizontal focus sensor still reponds accurately when using my 1DS3 in portrait mode. Only at an extreme 7.5 degrees does it start to suggest front-focusing, and 8 degrrees no longer gives a response.

Cheers,
Bart

[Rajan Parrikar]

Could you quantify "does not work properly"? Also, how much tilt or shift do you use with the 17mm before it stops "working properly"?

I don't have the 17mm so I can't tell you, but with my TS-E 24mm II I can use 7 degrees of tilt, and the most outer horizontal focus sensor still reponds accurately when using my 1DS3 in portrait mode. Only at an extreme 7.5 degrees does it start to suggest front-focusing, and 8 degrrees no longer gives a response.

Cheers,
Bart

The TSE 17 goes 'rogue' at much less extreme shift/tilt positions.  At any rate, this has little practical impact since I use Live View (on 5D Mark II) in the field.

[Bart_van_der_Wolf]

The TSE 17 goes 'rogue' at much less extreme shift/tilt positions.

That's what I would expect (perhaps from ~4 degrees?), but it's also much (>40%) more effective at small amounts of tilt/shift due to the short focal length, so less is needed for the same effect. Besides, the large DOF also makes it more difficult for the AF sensors to pinpoint an optimum, so Live View is of paramount importance anyway when using a TS lens.

Cheers,
Bart