120 film scanning - am I getting correct sharpness results?

cedric07 · Feb 25, 2015

Hi everyone,

I recently made the acquisition of a Mamiya 7ii with a 80mm lens. I then went on a trip and shot 10 rolls of Kodak Ektar 100 (known for their fine grain), opening at f22 and using a tripod and a cable release most of the time, looking for maximum depth of field, sharpness and accuracy. I then when to a pro lab and had them developed and scanned. I was expecting a wonder of sharpness and details (such as ken rockwell mamiya7 scans : How to Shoot Film but I'm quite displeased with the results.

I'm attaching one of the pictures, with different levels of zoom.

Can you tell me what i'm doing wrong?
- Am I right to expect more details?
- Am I doing something wrong with the camera, that the lab maybe tried to compensate? (poor exposure, shaking...)
- Did the lab do a poor job? Or should simply pick one that offers a better resolution?
- What should the file size of a "high res" 120 film scan be? Does that question even makes sense?

Thanks a lot for your help!
Cedric

gsgary · Feb 25, 2015

Shooting at F22 was probably your problem, what is the maximum aperture of that lens ?

cedric07 · Feb 25, 2015

Max is F22. But i had checked online prior and my understanding was that this lens being of exceptional quality, it was totally OK (even though not optimal) to shoot at F22.

Alexr25 · Feb 25, 2015

Part of the problem is that shooting at f22 is going to give you good depth of field but the resolution will be rubbish due to diffraction. I'd aim for f/5.6 to f/11 to get the best resolution.
Also the focus a seems bit off as the plants nearest the wall are just coming into focus so either you got the focus wrong or the range finder needs alignment. Probably the latter as this does seem a rather common problem with the Mamiya 7.

compur · Feb 25, 2015

A general rule of thumb is that best sharpness is usually at one or two stops down from wide open and the middle apertures should provide plenty of depth of field for most scenes.

Smallest aperture should only be used when you must, that is, due to extreme lighting or for maximum macro depth of field.

Another rule of thumb is don't believe everything you read on the internet.

MarkF48 · Feb 25, 2015

Alexr25 said:
Part of the problem is that shooting at f22 is going to give you good depth of field but the resolution will be rubbish due to diffraction. I'd aim for f/5.6 to f/11 to get the best resolution.
Also the focus a seems bit off as the plants nearest the wall are just coming into focus so either you got the focus wrong or the range finder needs alignment. Probably the latter as this does seem a rather common problem with the Mamiya 7.

My understanding of diffraction limiting is that the larger the format, the less of an effect will occur at a given aperture. The 6x7 format of the Mamiya 7ii should be good at least out to f/22. The f/5.6 - f/11 would likely be a good recommendation for an APS-C format digital sensor.

Scroll down the page below to "Diffraction Limit Calculator"
Diffraction Limited Photography Pixel Size Aperture and Airy Disks

Ysarex · Feb 25, 2015

MarkF48 said:
Alexr25 said:

Part of the problem is that shooting at f22 is going to give you good depth of field but the resolution will be rubbish due to diffraction. I'd aim for f/5.6 to f/11 to get the best resolution.
Also the focus a seems bit off as the plants nearest the wall are just coming into focus so either you got the focus wrong or the range finder needs alignment. Probably the latter as this does seem a rather common problem with the Mamiya 7.

Click to expand...

My understanding of diffraction limiting is that the larger the format, the less of an effect will occur at a given aperture. The 6x7 format of the Mamiya 7ii should be good at least out to f/22. The f/5.6 - f/11 would likely be a good recommendation for an APS-C format digital sensor.

Scroll down the page below to "Diffraction Limit Calculator"
Diffraction Limited Photography Pixel Size Aperture and Airy Disks

Correct. There is no diffraction problem with f/22 and a 6x7 film camera.

Joe

Gary A. · Feb 25, 2015

That looks extremely bad. It looks as if the lens wasn't focused on the subject. Maybe a bad scan, check the negative with a loupe for sharpness (the lab can't screw up sharpness in development). On the plus side ... nicely exposed, so the aperture is working.

480sparky · Feb 25, 2015

My first question would be, are ALL the frames soft?

Alexr25 · Feb 25, 2015

Ysarex said:
Correct. There is no diffraction problem with f/22 and a 6x7 film camera.

Perfectly true if you are making a print from the negative, the circle of confusion is going to be greater than any degradation due to diffraction, but if you are pixel peeping at 100% then you will in all likelihood see the effects of diffraction. In any case while you are chasing the cause of the poor resolution using a larger aperture rules out one possible variable and narrows the plane of focus so that any range finder problems are easier to see.

Derrel · Feb 25, 2015

I looked at the sample image...there looks to me like a small amount of movement to the shot, like there might have been a very slight bit of wind, or a small amount of tripod vibration, something. It is difficult to describe, but after you've looked at a few thousand negatives and slides, you will see that MANY times, when seen at very high magnification and examined very critcally, pictures made at speeds like 1/100 or 1/60 second are often not quite rock-steady, and that there is a very small bit of movement, or vibration, or subject movement, that makes the high-magnification view just ever-so-slightly not 100 percent as clear as is possible.

I would like to introduce the idea that this could also be a SCANNER-created fault!

I never really noticed how critical shutter speed can be until I spent one full week shooting everything with my same,exact equipment, but shooting all images at 1/500 second: the difference is very real.

Keep in mind though that at smaller sizes, or normal-sized image viewing, a small amount of shake or blurring is often not that noticeable! All is not lost!