Focusing Problem?

I have posted this question on another LF forum (UK), but will ask here as well to get some more advice.

I have finally had some of my 4x5 negatives enlarged onto 16x20 paper by a photographer who lives locally to me. He sent the prints back to me with a note saying that the negatives looked to be of good quality concerning exposure and processing but the image sharpness of the prints looks slightly soft overall.
The photographs were taken on 4x5 T-Max 100 using a 180mm Symmar-S on an MPP Mk VIII. I used a Toyo 3.6X focus-aid on the screen to ensure that the main part of the subject was in sharp focus, but even this is on the soft side on the enlargements. What am I doing wrong?

Which film holders (double darks in britspeak) were you using? I ask because IIRC MPPs' ground glasses are a little out of register with standard holders.

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Originally Posted by Dan Fromm

Which film holders (double darks in britspeak) were you using? I ask because IIRC MPPs' ground glasses are a little out of register with standard holders.

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Hi Dan,

I used 100TMX in a Kodak Readyload holder if that helps.

It's difficult to say without examining the negatives, but the softness could be a result of any number of issues. This includes improper spacing of the mounted lens, a poor example of the particular lens (or damage that isn't obvious), a variation in the GG position relative to your holders, or camera vibration during exposure. Note that if there's a GG position problem, something other than what you focused on should be sharp. Standards not being fully locked down might also cause a shift in the plane of sharp focus.

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Originally Posted by Ralph Barker

It's difficult to say without examining the negatives, but the softness could be a result of any number of issues. This includes improper spacing of the mounted lens, a poor example of the particular lens (or damage that isn't obvious), a variation in the GG position relative to your holders, or camera vibration during exposure. Note that if there's a GG position problem, something other than what you focused on should be sharp. Standards not being fully locked down might also cause a shift in the plane of sharp focus.

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The prints look like they are slightly out of focus and lack pin-sharp definition. I know this isn`t due the guy who enlarged them for me. The Camera was on a good tripod with very little breeze, so I don`t think Camera shake is the problem. The GG position might be the culprit, but I`m not know how to check for this.

I think I've seen a set up where you put a ruler on a table. Angle you camera down just a bit and focus on one number in the middle, numbers closer and farther will be out of focus. Shoot wide open and see what is in focus on the negative. If it matches up-great. If not you should be able to tell if your film is too close to the lens or too far away depending on where the focus point is.

Scott

Keith, according to info here http://www.mppusers.freeuk.com/ your Mk. VIII has the standard 4x5 register. Scott's advice, to find out where the actual plane of best focus is, is good.

Good luck, have fun,

Dan

If the "ruler test" indicates a problem with the GG placement (as might happen if the GG was replaced at some point), you can use a micrometer depth gage to determine how much to shim or trim the GG. Measure from the surface of the frame holding the glass, after removing the back, to the surface of a sheet of film, and then compare that to a similar measurement on standard holders.

Thanks to Dan, Scott and Ralph for the advice and suggestions. The guy who enlarged the 4x5 negatives for me uses a Technikardan and had a similar problem himself when he first used his Camera. He has offered to to take a look at the Camera for me and has some gauges and other tools for measuring alignment etc.
It wont be this week, but I will report back later and write what the problem was.

Thanks again,

Keith.

A difference between the gg position and the film plane can explain focusing problems. If that is the case, something should be in very good focus, just not where you though you had focused. Of course, if the in focus plane doesn't contain anything of interest, it may be hard to find, but it is at least worth a try looking.

Another possibility might be failure of the film to lie flat. Again there should be something exactly in focus, but it may not be in a plane or even a simple curved surface.

Finally, it may be that your standards aren't parallel. That would tilt or swing the plane of exact focus. Again, something should be in focus in the picture. He is how I check that. I use a level to make sure the gg is vertical when is the rail or bed is level, as it should be in the detent position. If it isn't, I adjust it . There is usually some play in the detent or zero position which will allow that. I then turn the camera so it is pointing downard and the gg becomes level in what was the vertical direction, and I check if it is level in the other direction. If not I adjust the swing. Using a torpedo level across the ends of lens barrel, I next check if the front standard is level in all directions and adjust its tilt and swing to make sure it is. When I'm done, I'm sure the standards are parallel.

If none of these suggestions help, and image is just fuzzy everywhere, there is something else going wrong. If you stop very far down, diffraction could cause a slight fuzziness in a large print. Otherwise, it must be something about the lens. Either it is defective or it was designed to be "soft focus" to begin with.