I went to the same spot again today to do some tests. Luckily the weather really sucked so I didn't have to worry about taking a "photo" but rather just experiment with focusing.
Here's what I did:
- F11 with lens set to 24mm
- According to the calculators, the hyperfocal distance is about 1.9xx metres
I took a series of images without changing the zoom / framing
1. F11 with the focusing ring set to "somewhat" 1.9m - the scale had 1.5m and 3.5m so I put it roughly in the middle (since the scale isn't linear anyway
Result: clearly nothing is in focus - front is very soft and so is the mountain
2. F11 with focusing set to almost infinity
3. F11 with focusing set to beyond infinity (basically all the way out)
4. F11 with my normal way of focusing (just focus on slightly further away to the closest object - which I noticed that the focusing ring is on near infinity - note the grass at the bottom of the image is roughly 10 metres from the camera)
The three methods above produced a similar result - everything is in focus except that it's not razor sharp, but reasonably sharp - this is before applying any sharpening but I think Lightroom applied a 'default' sharpening value of "25" which is applied to all the images including sample (1) above.
So my conclusion is that my way of focusing works for me, however maybe my lens sucks? Maybe it's a bad copy because it has fallen on to the concrete once.
How sharp is "razor sharp" for an image produced by 1ds3 or nikon d3x / d800e etc? Hard to compare different photos / scenes / lighting situation unfortunately. Is it the case that the only way to find out is to get a rental and try and shoot the same stuff with different cameras / lenses?
And here's the dirty question: will MFDB + technical camera (with tilt) totally solve the 'sharpness' issue?
The second problem as was pointed out above, was that my photo above was grossly underexposed so there is a lot of noise in the foreground grass since I had to add "Fill Light" to it.
The third problem as was also pointed out above, F20 does produce a softer image than even F16 or in this case where F11 would be just fine too. I usually take several shots at varying F stops just to cover all bases but in this instance I was too fixated over the clouds to remember doing it