Although I am not an expert I will provide the following.
Most lens are sharpest at 2 stops down from wide open. f8 in this case is about sharpest. I have tested this on thedigitalpicture and confirmed. So the go to fstop is f8 unless you have some other need. And keep in mind that f4 is less sharp than f8 so why use it unless you have to.
24mm focussed at infinity, straight on will have depth of field of 8\' to infinity according to the standard definition of dept of field. On full frame. Being convservative, say 20\' to infinity because I am fussier than a standard person. At f11, there is not much loss in iq and this shrinks to 10\' again with my conservatism. At f16, defraction starts to kick in and I am tempted to tilt.
Thus in the majority of cases the tilt is not necessary and will yield a softer picture, and it is only necessary where there is a item in the foreground closer than 10\'.
So when would you need tilt. Either closer than 10\' or if you need a faster shutter. I have used tilt for northern lights for this reason. Tilting permits focus from close to infinity at f4 - which permits a 15s shot at ISO 800. So night shots or fast moving clouds or night shots.
I have played with my ts17 and concluded the focus is very sensitive to tilt and most of the time a tilt of between 1 and 3 is appropriate at eye level. Beyond 3 it you will cause some wild things to happen where you either have to choose foreground or background in focus for a pretty flat plain.
I have also tried to focus at sunset and sunrise and conluded that focussing is very difficult in liveview in the dark
All of that has brought me to a simple path of - focus near infinity (which I have found by experiment with live view to be a little to the right of the sideways L not at the right end) and set it at about 1.5 down and fire away.
[I find the shift is far more useful than the tilt. Shift helps fix perspective and is fantastic for pano\'s. ]
So the summary is on TS17, 99% of shots are with shift not tilt to maximize iq. Tilt should be small and only used where items are close (rare) or much faster shutter is needed (night time). You are better to figure out a rule of thumb than trying to focus with a formula unless you are smarter than me in real time, because in real time it too complicated. The rule of thumb is at eye level 2 marks down and focus at infintity and at 1\' above ground 7 (guess) marks down.
Of course this logic is not appropriate at ts45 or ts90 where depth drops considerably.
I am new to my lens so if I am wrong please let me know.
Fred Miranda is much more experience in this area. PM him and get him to provide advice.
Jun 06, 2012 at 02:31 PM
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