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Hi Ted and Bob,
Many thanks for your time spent considering this problem it's really appreciated!
I've conducted a few more tests this morning in the office as you both suggested. Before I did anything I re-double checked back focus on the Fujinon. Its absolutely spot on.
I found that to achieve sharp focus on the grain (without macro or infinity focus) I had to slide the Letus 26mm away from the front of the Fujinon. This, however, then gave conflicting focal distances as marked on the 35mm lenses. If I'm right then all focal distances should include the difference of 26mm from what's marked on the lens, as the focal plane position has effectively been shifted 26mm. So a true distance of 474mm from the Letus focal plane shows as 500mm on the lens. I tested this and it was consistent. I don't really want to be sharpening my maths skills on every shoot as well! However, this does achieve the sharpest image of all my testing so far, but not still not great.
So, I went back to Ted's method and found the best focus I could with all focal distances correct and Letus fitted as it should be. See attachment for the best focus.
Settings: Infinity focus, 22mm zoom, macro mid way and marked.
50mm lens f4, Fujinon also at f4. I've tried various other aperture configurations, but you start to get aberrations elsewhere, which appear very quickly! etc.
(Ted I tried your method for measuring the image plane on the ground glass, but I'm not sure I follow where you measured. Did you disassemble the Letus to see the ground glass? It's not possible to take a measurement from the anchromat end or have I plainly misunderstood?)
Unfortunately this is still soft, although its the absolute best I could achieve. I thought I would double check again on the Letus instructed method and had the same results. Unable to focus on ground glass without using macro. I decided to try with the GG soft, but obviously all shots are also soft too.
I've since had an email from the manufacturer who suggested that many people use macro to obtain focus, and that doesn't seem to be unusual. However, I truly don't believe using macro gives you the sharpest image so I am awaiting my next reply.
Bob, I've attached an image of the rails and support. I purchased the rails and Letus from Zacuto together for this camera. The quality of the Zacuto gear is extremely good and the support system is as stable as it gets. I've tried the Letus support and found them fragile, wobbly and not stable enough for a shoot with the JVC. I've also tried Cavision and another one who's name escapes me. Zacuto is by far the best. It offers adjustment on all planes and I have set it up so it lines up with the Letus exactly. The base plate, wedge and tripod plate all stay together as a single unit now so its very quick to set up.
Well this is now 3 mornings or 12 hours I've spent trying to get a sharp image from this unit. From the point of view of my business this is more than unacceptable. I'm wasting time on this unit when I have a thousand other things to do as it is. Am I not entitled to buy something and have it work without all this effort? Needless to say I'm a little frustrated! I'm really hoping this is something really daft on my part that I'm overlooking (which I'm always willing to accept as a possibility) and that one simple thing will get it working, but.....I'm really beginning to doubt that now!
Your efforts are really appreciated guys. Many thanks.
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