If you haven't had the chance to read Part 1 of this series, that post can be found here.
Hurdle #2: Focus
The images I have been making involve isolating small areas of stone that have interesting abstract patterns. This obviously calls for using a macro lens, and I have been using a Canon 180mm macro with a 1.4 teleconvertor. Because the magnification is so great, the depth of field is quite shallow, and, in my opinion, the toughest part of making images like this (aside from finding a great composition) is assuring edge to edge sharpness across the photo. In this post I thought I would share some of the aspects of achieving sharpness that I have worked out thus far.
There are two planes that should optimally be perfectly parallel to each other. These are the plane of the rock slab surface and the film or sensor plane. In addition, while the surface of the sensor is, for all intents and purposes, perfectly flat, the plane of the rock surface will not be. So where does one start?
My first step has been to make the back of the camera itself perfectly level to the ground while the lens is pointed downwards. This must be done in both the north/south and east/west planes. I check the 'levelness' with a short bubble level by placing the bottom of the level flat on the lcd sensor screen in both the north/south and east/west orientations.
I quickly found out that making such adjustments in two planes with a ballhead while the camera is pointed straight down is quite difficult. This is because when the ballhead is loosened the camera can move freely in both planes and thus it is very hard to adjust the camera's position in one direction only. My solution (without buying any fancy new equipment) is to separate the two plane adjustments. I do this by dropping the camera (mounted on a focusing rail which ultimately makes life much, much simpler) as far down as it will go into one of the ballhead slots. As long as the camera is as far down into the slot as it can go, the 'levelness' of the north to south plane will not change. That plane can now be made level by putting some cardboard underneath a tripod leg (or legs) to make the back of the camera parallel to the ground. Now the ballhead lock can be loosened and the camera rotated in the east/west direction until it is level in that plane as well. You can recheck the position in the north/south direction, but as long as you maintained some gentle downward force on the camera so that it is down in the bottom of the ballhead slot while rotating it east/west, the north/south leveling should remain intact.
Stone Trees
Copyright Howard Grill
The next step is to level the rock slab. Find a heavy flat object that will serve as the surface on which the rock slab to be photographed will sit. This surface now needs to be leveled in the north/south and east/west directions using the same level as for the camera and adjusted as needed by putting some paper or cardboard under the ends that need to be raised or lowered (when you live in a very old house the floors tend to not be truly flat!)
Now comes the part that ruins the perfection. I find that the rock slabs themselves, even if cut nicely, rarely are perfectly flat. In addition, the edges of the rock slab frequently have a ridge or ledge that lifts it off the surface on which it rests in an uneven fashion. This can sometimes be remedied by using a level and slipping a few pieces of paper underneath an edge of the slab where needed. Also, if the ridge on one edge is particularly prominent, I may let that edge extend off the surface it is resting on. Ultimately this can be a bit of an exercise in futility because I end up moving the rock around to get different compositions. I simply do the best I can with a reasonable effort. Even with these uncontrollable imperfections in the rock slab, the better you have leveled your camera and the surface on which the rock slab to be photographed sits, the better off you will be.
If anyone has any further recommendations as to how to ensure that the plane of the rock and the plane of the sensor or film are parallel to each other, please chime in!
, which is absolutely gorgeous. After several sessions of trying, I have learned several tricks that have worked for me without buying any new equipment and thought it might be of interest to share them in a few blog posts....if I have time to process some images more fully I will display some of them as well.
