An extra pane on my Tachihara
As one who likes to know his equipment well, I can only excuse the following oversight by noting that my Tachihara 4x5, purchased used several years ago, was my first field view and that I had been away from photography for more than a decade.
Anyway, in the course of pursuing something entirely different earlier today, I was astounded to find, in a belt pack hanging in the closet, the Wista loupe I had been convinced I had lost while gathering equipment from the car on a field trip more than three years ago with my monorail at Great Falls Park (the trip that "inspired" my replacing that 26-lb camera+tripod lug-bundle with an 11-lb pair including the Tachi).
I had eventually replaced the loupe with an identical, used one, but found that I needed to make an extension collar to focus on the ground surface of the glass. (In fact, I mentioned this at the time here, and I believe it was Bob Solomon who asked, reasonably enough, if I was really sure of my focus.)
Today, comparing the two led with this in mind led me to discover my cited oversight: that between loupe and GG is another pane, entirely clear. I have trouble ascertaining whether it is some kind of acrylic or special, perhaps shatter-resistant glass. I assume it to be a GG protector and not original equipment. In any case, I then discovered that the ground surface of the GG faces rearward. This make sense, I guess; better to focus through as little thickness as possible.
Now I'm curious: Is this a common configuration? Your experience or thoughts?
On my Omega monorail, I had a Fresnel lensward of the GG, cut side in contact with the ground surface, which is pretty standard -- though I have seen debate here (imagine that!).
Once I clean both, and double check my loupe focus, again, I'll probably put them back as they were. Perhaps I'll try with and without (reversing the G for the latter, of course) to see if significant flare or other issues arise with the clear pane.
Re: An extra pane on my Tachihara
Quote:
Originally Posted by
Ulophot
As one who likes to know his equipment well, I can only excuse the following oversight by noting that my Tachihara 4x5, purchased used several years ago, was my first field view and that I had been away from photography for more than a decade.
Anyway, in the course of pursuing something entirely different earlier today, I was astounded to find, in a belt pack hanging in the closet, the Wista loupe I had been convinced I had lost while gathering equipment from the car on a field trip more than three years ago with my monorail at Great Falls Park (the trip that "inspired" my replacing that 26-lb camera+tripod lug-bundle with an 11-lb pair including the Tachi).
I had eventually replaced the loupe with an identical, used one, but found that I needed to make an extension collar to focus on the ground surface of the glass. (In fact, I mentioned this at the time here, and I believe it was Bob Solomon who asked, reasonably enough, if I was really sure of my focus.)
Today, comparing the two led with this in mind led me to discover my cited oversight: that between loupe and GG is another pane, entirely clear. I have trouble ascertaining whether it is some kind of acrylic or special, perhaps shatter-resistant glass. I assume it to be a GG protector and not original equipment. In any case, I then discovered that the ground surface of the GG faces rearward. This make sense, I guess; better to focus through as little thickness as possible.
Now I'm curious: Is this a common configuration? Your experience or thoughts?
On my Omega monorail, I had a Fresnel lensward of the GG, cut side in contact with the ground surface, which is pretty standard -- though I have seen debate here (imagine that!).
Once I clean both, and double check my loupe focus, again, I'll probably put them back as they were. Perhaps I'll try with and without (reversing the G for the latter, of course) to see if significant flare or other issues arise with the clear pane.
Normal gg positioning is the ground side faces the lens. Are you saying that yours faces the film.
If so you are probably always out of focus by the thickness of your gg unless your camera’s gg position was adjusted for this anomaly.
Even if you adjusted your loupe to the grain side of your gg.
Re: An extra pane on my Tachihara
Quote:
Originally Posted by
Bob Salomon
Normal gg positioning is the ground side faces the lens. Are you saying that yours faces the film.
If so you are probably always out of focus by the thickness of your gg unless your camera’s gg position was adjusted for this anomaly.
Even if you adjusted your loupe to the grain side of your gg.
And if that "protector" that you found in place is not supposed to be there, it too will throw the focus off even if the ground glass is facing the right way.
Re: An extra pane on my Tachihara
Quote:
Originally Posted by
Neal Chaves
And if that "protector" that you found in place is not supposed to be there, it too will throw the focus off even if the ground glass is facing the right way.
Not if it is closest to your eye. It’s just a protective glass. If it was under the gg, and the gg has not been adjusted for it, then it will displace the gg plane.
Re: An extra pane on my Tachihara
As usual, Bob, an important point, and certainly something I should have already considered when I thought about removing the clear cover and reorienting the GG with the ground surface forward. Thank you.
In this case, I had sent the camera to Richard Ritter soon after getting it, to fix the very stiff bed-extension and double-check focus, so I have not had the focus-discrepancy issue that might otherwise have obtained.
Re: An extra pane on my Tachihara
“ On my Omega monorail, I had a Fresnel lensward of the GG, cut side in contact with the ground surface, which is pretty standard -- though I have seen debate here (imagine that!). ”
Having a fresnel between the lens and ground side of the ground glass is common for Graphics, but I’m not sure who else does it that way. I think few, if any, others...
Re: An extra pane on my Tachihara
Quote:
Originally Posted by
BrianShaw
“ On my Omega monorail, I had a Fresnel lensward of the GG, cut side in contact with the ground surface, which is pretty standard -- though I have seen debate here (imagine that!). ”
Having a fresnel between the lens and ground side of the ground glass is common for Graphics, but I’m not sure who else does it that way. I think few, if any, others...
LInhof used to with old models but stopped doing that decades ago. I think that the inside position had more to do with how easily old fresnel screens could scratch compared to modern ones.
Most current cameras have the fresnel positioned on top of the gg with the grain side of the gg facing the lens.
Re: An extra pane on my Tachihara
Focus screen assemblies come in many styles, but I agree with Bob, ground side of the glass should be toward the lens.
