On several occasions recently, I have needed to pre-set my focus to specific distances to achieve certain focus requirements - like focusing at the hyper focal point or focusing within a certain depth of field range. I do this using the iPhone app ‘Field Tools’ and pre-setting my focus by focusing on something I can easily estimate the distance to. This methodology works well enough but it is not precise nor does it work well if you need multiple focusing points as in a medium distance focus stack.
Several Panasonic users, on this and other camera forums, have lamented the lack of a scale on the manual focus guide. (Bar with mountain/flowers in the display panel.) Without a scale, the focus guide is of little value and it does not appear that Panasonic is going to cook up a software revision that would add a scale.
One option to solve this issue would be to purchase a digital laser tape measure. Point it to the distance you need to set and focus on the laser dot with the camera. But, this would mean purchasing a fairly expensive tool and keeping it in your camera kit.
So what about adding your own guide to the camera’s screen? I did some preliminary checking and I think this is feasible. The guide always displays in the same place and in the same size regardless of screen settings, lens model or framing format. Therefore, it is possible to calibrate the guide and place marks on the screen for critical focusing distances. There are some obvious issues.
First, you shouldn't mark directly on your screen. A soft lead pencil will not write on it. But, you can get screen protectors that could be written on using a fine permanent marker.
Second, different lenses will have different calibration. I initially tested the Panasonic X 2.8/12-35 and did find that the lens focuses at the same points throughout its zoom range. This important, because if it changed, a simple scale would not be sufficient. The Panasonic f1.7/20 seemed to have similar focusing points, but not exactly. I did not test my f4.0/14-140. This may mean that you would need multiple screen covers or it may mean that you pick one lens that is most commonly used in these situations and only use it. In my case, I’m sure the 12-35 would be sufficient for most of my needs.
Third, what is the best scale to use? The focus guide uses more than half its range just to get to a foot of focus. Focusing at less than a foot is so precise that it is doubtful a scale would be of much use. The distance on the scale from 1’ to 2’ is large – about 12mm, but the distance between 3’ and 4’ is less than 2mm. Above 10’ the scale becomes too tight to mark with any kind of normal writing device. At best you might be able to mark 10’, 25’ and 50’. Of course, with a M43 camera the need for critical depth of field beyond 10’ is slight. Hyper focus, at f11 and 25mm focal length, is 12.2’ with a depth of field of 6’ to infinity. At f11 and 12mm, the hyper focus distance is only 2.8’.
My thinking is that it would be worth the small investment to purchase some screen covers, preferably with a matte surface, and try this out. It’s an alternative to a problem that won’t get solved by Panasonic and it might just work – possibly very well. If anyone can recommend a good brand of screen covers, I’ll obtain some and try this out.
