Tachihara Maxwell or Satinsnow

[Gem Singer]

Hello again Dan,

The Tachi focusing screens are made up of a sheet of plastic which has a ground surface facing the lens and a Fresnel grooved surface on the opposite side of the sheet. Then, there is a thin cover glass (plastic?), that has the fine black gridlines drawn on its front-facing surface. The entire viewing screen is a two piece assembly.

The frosted plastic screen with the Fresnel on the back is as fine as it gets. Since a rough ground glass surface and Fresnel grooves do not seem to be your problem, reducing the magnification of your loupe isn't really necessary. The grid lines are the problem. If you just cannot adjust to them, then I suggest replacing the cover glass to a plain one that doen not have grid lines. It's less expensive than replacing the entire focusing screen. Call, or e-mail Jim, at Midwest Photo Exchange. He will return from his trip next week.(www.mpex.com, or jim@mpex.com). He might have a plain Tachi cover glass in stock that does not have grid lines, or he may be able to order one for you.

[Dan V]

Eugene,

You are correct in your description of the Tachi focusing screen; just removed mine and checked its construction. But it's the distracting effect of the fresnel lines that I'm trying to minimize, not grid lines on the glass layer. If I decide to replace the GG, I'll report results.

[David Karp]

Brian,

Have you received and tried out your SatinSnow groundglass yet?

[kw]

Dan,

If your issue lays with the fresnel lines, then perhaps you may experience what I've gone through. When I first got my Tachihara, I was using a Peak 8X loupe, my problem is the over magnified image with fresnel lines when using the SA 90mm f8 in dim light condition (around EV 4 to 6 @ ISO 100).

So, I've changed to a 4X loupe, and it helps a little to get rid of the fresnel lines, but however, the dimmness still exist. Since then, I have learnt to live with it and although the fresnel is there, I can actually see "hot spots" on the GG when focusing under certain condition.

Even with the SatinSnow GG, hot spots still exist, so learning to get use to move around the hot spot during focusing is crucial. And I believe there's the skill that many LF photographers have been doing it in the past and most probably the future.