Hi Warren,
I do use focus peaking. If the whole scene is well lit so the back sees enough contrast it works fine. It would be nice if the whole scene lit up like a green Christmas Tree, but it usually doesn't. In this case, the rocks were just too dark. Usually it appears in small parts of the scene. When it appears in spots all over I know I am close. Maybe a blade of grass up front, one of the rocks and then trees in the distance. I then zoom into 100% at various places to see how everything looks. Zoomed in I will move focus a little. If the distant areas get sharper as I rotate focus farther out, I know I need more tilt. If they get sharper as I rotate focus closer in, I have too much tilt. Same with things up close but reversed. So in detail it goes like this:
- Open to f/5.6
- Dial in 1 degree of tilt.
- Zoom in to middle distance and focus.
- Zoom back out. If everything has peaking, then I'm done.
- If not, zoom in to a far distance and rotate the helical to a farther distance and rotate back. If things got sharper when doing that helical rotation test, add a little more tilt and try again. If things got more out of focus, use a little less tilt and try again.
- Then zoom in up front to see if everything is sharp. Usually at this point everything is really good. If not, I try again using the close focus point. For a close point, I dial focus closer and back out. If it got sharper, I add more tilt. If not, less tilt.
- I don't expect everything to be tack sharp because I'm still at f/5.6. But it should be uniform throughout the image.
- Close down to f/11 or f/12, adjust shutter speed and shoot.
Sometimes I do the helical rotation up front first, it just depends on where things are in the frame. The tricky thing with tilt is that as you dial in more tilt, the DoF wedge gets narrower. In this case, I had the whole camera tilted forward. So even though the camera was pretty close to the ground I didn't need too much tilt. The less tilt you need the easier it is.
@Greg Haag started a post a while back about tilt and there is a lot of info there. Can't seem to find it right now [edit -
here it is]. On an Alpa, 1 degree is about 1.5 rotations of the dial. I have a white mark on the dial so I can keep track of where it is. The adapter has degree marks, but they are hard to see in the dark.
Dave