Strange fruit : focus problems on Norma

[Axel]

While doing tests to check on basic functions and film planeity of a DaYi rollfilm back (which I had to return : not plane at all, random view-spacing), I've been experiencing a very strange problem : what I focus on while shooting isn't what ends up being in focus on the film !

Never happened to me in 25 years : 4x5", 8x10", field, studio, portrait, still-life, whatever. Never.


The Sinar is straight : no tilts, no shifts.

My first option was to blame the new lens (Sinaron 55/4,5) - silly, I know. But the problem did happen whichever lens I used : 55 / 75 / 90 / 150 / 180 / 240 / 300 - same. I use the most open diaphragm so I can check exactly where the focus should be.

Even more strangely, the problem is more pronounced when I use wide lenses (55>90) rather than the longer ones.

Second option... my own eyes ! But it is out : did some shoots with a Yashica MAT-124G and they are are sharp as can be (great lens btw).

The problem is that whatever I focus on, the actual focus ends up in front of the desired (and dialed) focus point, closer to the camera. I am as sharp as can be on the ground glass and I even use my three different Norma backs to be sure.
Focus is (re)checked just before taking the image and after as well with a variety of loupes and eyepieces.

Whether I use a 4x5" chassis or the 6x9cm Horseman rollfilm back - don't matter, same problem. Still have to check my old 6x7cm Calumet C2 (just so I can say I've covered all the possibilities !).

I've uploaded a quickie sample made with the DaYi before returning it here and the Horseman back yesterday here (zoom in on both).


Simply put : whatever I focus on while making the shot should be the sharpest point on film. Even if the two Norma bodies are acrobatically spread, the focus point I choose becomes the film's sharp(est) spot - right ?

But isn't !

...any ideas ?

[E. von Hoegh]

There's something caught between the GG frame and the back of your camera? Something is moving the film plane farther from the lens than the GG you focus on.

If the GG is properly placed, and if the film takes up the same position as the GG, then whatever you focus on will be sharp.

How do you focus?

[Tobias Key]

The only thing I can suggest is to use a micrometer to check that the ground glass is in the right place. If the error is consistent across everything the ground glass must be to blame.

[Sevo]

Across three backs and five lenses, we can probably rule out the camera. Maybe the onset of presbyopia? The Yashica being immune might merely mean its finder is infinity adjusted whereas your loupes are set for a meter apparent viewing distance (as common). Can/do you see the screen grain and the focused image at the same time? If not, try to adjust your loupes until you can - but many adjustable ones will only adjust the wrong way, towards myopia values, so it might be time to see an optician for glasses and/or corrective eyepieces...

[Axel]

Thanks for suggestions all !

I must add that the Norma hasn't changed a bit since doing the Nouvel and Perrault images last year : same old Norma back I've been using since... 1990. Very tired fresnel, scratched GG but always fine.
The other viewing backs acquired since don't change a thing : sharp on all at the very same spot.

The DaYi required removing the GG and so does the Horseman ; the Calumet, like the 4x5" Fidelity chassis, are slide-in. But that makes no differences, either.

For critical focus, I do not use the Sinar mirror/binoculars so I focus with the same Nikon loupe I've been using all these years which I also use on the GG of the Yashica to check a bit closer (quirky slide in but it works and does help :)
I've never adjusted it ; I put it directly on the GG (or the Fresnel for the backs that have the Fresnel up front) and focus ; I see everything.

Perhaps Sevo has it right. Will try to toy/adjust it tomorrow. And then see an optician :(?((

[Tobias Key]

Have you thought of having a friend or assistant check your focussing?

[Axel]

@ Sevo
Just tested on my main Norma back with the 150mm and toying with the loupe's top piece don't change nothing either : same sharpness to my eyes (and that old 1963 Symmar is a killer, too).

The Nikon I use for focus, the old battered Sinar mainly for wider viewing and composition but also for focus : it "feels" right in it when I am spot-on in focus...

[Axel]

@ Tobias Key
Ah - I work alone now but the last time I did have an assistant was last june ; he did the fine focus which I naturally checked and it was as if I had done it myself : crystal sharp.

If eyesight it is, can it fail so... suddenly, in a matter of weeks ?

[Sevo]

If eyesight it is, can it fail so... suddenly, in a matter of weeks ?

It won't actually fail in a matter of weeks, but it will appear to suddenly go past the threshold where it affects some particular task - the very moment the screen drifts out of your eyes focal range, you start to focus on the aerial image in front of the screen, and for that purpose, millimetres are critical.

[Axel]

... then I guess a visit to an optician will have to be scheduled for tomorrow :(