Grain Focusing - discrepancies
I've got a problem. I was curious about my grain focuser - a Micro Sight II. I compared it to a Micromega Critical Focuser (the high end Peak ones). The two focusers were different. That was disconcerting. So I grabbed another Micromega Criticla Focuser, and a Peak Enlarging Focuser II. Guess what. All slightly different.
Truthfully, I don't really know how these things work. They're one of the few pieces of equipment in the darkroom I trust blindly. For them to all give differing information; well that is no good.
To preface: I use a glass carrier in a Durst 138s. I keep my enlarger aligned with a versalab alignment tool. I'm confident all is good on that end of things.
So here's what I did. I have one of those "test pattern" focusing negs. The one in question is made by Jobo. I loaded it into the carrier, and made a 5x7 crop from a relatively big enlargment (12x16 ish). I marked each of the four grain focusers, and made RC prints from each focusing as sharply as I could on the same spot on the neg. I also made one print where I focused by eyeballing it. I made the exposures with the lens wide open, hoping to take depth of field out of the equation as best as I could. I batch processed the prints and dried them.
I went through the 5 prints, and ranked them in order of sharpness. I gave them to my girlfriend, and she did the same.
The results? The eyeballed print was - by some margin - the sharpest. We both came to that conclusion.
This has me dumbstruck. What is the point of the grain focuser if the information it provides is not reliable? Those Micromega Critical Focuser are supposed to be high end tools. They sell for a small fortune.
The problem is, while it's easy to eyeball and focus these "test pattern" negs, it's not so easy to do the same with an overexposed shot from a Holga lets say.
I'd love your thoughts on this. Is the "test" valid? How can I remedy the situation?