4 x 5 focus problem

[LotusEsp]

Hi
I'm having a bit of trouble with soft images.

I'm using a Shen Hao 4 x5 with a 90mm rodenstock lens. I have a good solid tripod and am focusing with a loupe on the standard GG

I focus with the aperture wide open, and then stop down (f32) for the shot I want. When I develop and scan in my slides, they are all slightly out of focus, across the entire frame (landscape images) near-far-middle, all slightly soft. There is no sharpness anywhere

I am shooting on Kodak Ektar 100 and developing myself with unicolor C-41 kit

I am troubled by what I think is sharpness on the GG glass not transferring to the negative. Is it a shooting thing or a developing issue at play here?

Any thoughts gratefully received

Thanks
Simon

[Jim Jones]

Perhaps the lens is flawed. Is there a problem with any other lens? At very small apertures, diffraction limits sharpness. However, f/32 shouldn't be quite that small an aperture on a 4x5 camera. A more likely problem is the position of the focusing screen. Sometimes Fresnel lenses have been added or removed between the focusing screen and the camera lens, throwing the focus off by about 2/3 the thickness of the Fresnel. In a 4x5 film holder, the distance from the face of the holder to the back of the film should be 0.197 =/_0.007 inches. The distance from the face of a plain ground glass frame to the ground glass should be slightly less to allow for the thickness of the film. This distance must be adjusted if a Fresnel lens is mounted between the ground glass and camera lens. To check for this, photograph a ruler at an angle. If the image is sharpest at a different mark on the ruler than you focused on, the problem is likely the positioning of the ground glass in its frame. By using standard lens formulae or online calculators, the displacement of the ground glass can be calculated. Remotely possible is a defective film holder.

[David Lobato]

You didn't say if you examined the negatives with a loupe. Are they sharp?

[Robert Oliver]

Using a Cable release?

F32 should compensate for any minor film plane issues.

Is it possible it's a scanning issue? You didn't say if you looked at the negatives with a good loupe.

Can you post a scan?

[Bob Salomon]

Using a Cable release?

F32 should compensate for any minor film plane issues.

Is it possible it's a scanning issue? You didn't say if you looked at the negatives with a good loupe.

Can you post a scan?

F 32 is in diffraction and can't compensate for film plane issues. That would be the depth of focus of the lens. Which is behind the lens and determines where the film plane is. Depth of field changes with aperture and is what appears in apparent sharp focus depending on the chosen CofC and the magnification and the viewing distance.

What kind of loupe are you using to determine focus? Have you adjusted its eyepiece so it is adjusted to focus other grain of the gg?

[LotusEsp]

The loupe is pretty cheap/basic

http://www.bhphotovideo.com/c/produc...yle_Loupe.html

[Jac@stafford.net]

The loupe is pretty cheap/basic

http://www.bhphotovideo.com/c/produc...yle_Loupe.html

I used to use those. I have two and each focuses differently. I had to use it backwards to focus upon the ground glass texture. Could that be an issue? Can you see the GG texture?

[Doremus Scudder]

Several things could be going on here.

First, check the negative with a good loupe (even your Agfa 8x loupe should be sharp in the center) and see if, indeed, the flaw is with the negative.

If it is not, then it is a scanning problem. I don't scan, so no help from me here

If the neg is soft, then look for focus issues. Although Bob is technically correct that f/32 introduces a bit of diffraction, I use that aperture all the time and can make razor sharp 16x20 prints from it. That's not your problem. Camera movement should be obvious under magnification; you will see directional blur, or a double image. If the image is unfocused, than you may have a ground glass misalignment, Fresnel positioning problem or filmholder seating problem, all of which result in the film being in a different place than where you focused.

Check this with the following test: With the camera in zero position, set up a ruler at a 45° angle to it. Focus wide open on a specific marking (say the 10cm mark). Shoot wide open, develop the negative and see where on the ruler is sharp. If the 10cm part is the sharpest, then no problems. If that's not the case then start checking things. First check if your filmholders are seating correctly. Any gunk or added light-trap material in the seat can cause the film to be positioned incorrectly. If you have a Fresnel screen, make sure it is installed correctly. If it is between ground glass and lens, it may well be the culprit unless it is an OEM screen. If your Fresnel can be removed, take it out and place it behind the ground glass and do the test again.

If none of these are the problem, then the ground glass is likely misaligned. If the sharp focus in your test is at a point farther from the camera, then the ground glass needs to be shimmed back. If a point closer is in focus, the ground glass needs to be unshimmed or moved forward (this latter is rare).

Good luck finding your problem,

Doremus

[Bob Salomon]

The loupe is pretty cheap/basic

http://www.bhphotovideo.com/c/produc...yle_Loupe.html

That's your first problem. Invest in a proper, adjustable, opaque barrel focusing loupe.

[LotusEsp]

any suggestions on a good loupe?