(yet another) Film scanning post

[jimeca]

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What interests me is the sharpness of the negative. Some images are beautiful and others are soft. As if the lens was a "bottle ass", with fog. 
The Leica 50 APO is not but a "bottle ass" 

That’s why I wonder if it’s because of the scan process.

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[hansvons]

Asses the sharpness of the negative by its grain. It should be fairly sharp from corner to corner. If not, there's an issue with the scanning process.

[Einst_Stein]

This is where I find the drawback of the non-native AF lens such as Apo-Rodagon enlarger lens. 

Before I settled on this lens, I tried native AF lens with macro filter, and used AF and auto exposure. This way I got the first base line. All other method or lens has to exceed this base line.

Then I use the focus peak to check the manual focus accuracy. The bellow or the focus/rail adjustment has to be fine enough so that I can get to the best focus point.  To check focus accuracy, I can't rely on the grain (like doing the darkroom exposure). The grain is too small to be useful. Instead I use the text on the film edge. 

The other preoblem that mightb cause focus error is the leveling.  Here I use spirit on both the film plane and the camera hotshoe. 

[250swb]

16 hours ago, jimeca said:

The Leica 50 APO is not but a "bottle ass" 

 

It's also not an enlarger lens designed to project from a flat field onto a flat field (in this case film onto sensor), and it's also not a highly corrected macro lens designed with a 1:1 reproduction ratio. Macro lenses are also designed to minimise diffraction as much as possible so they can be stopped down just a bit more than an ordinary lens, meaning you can use a smaller aperture and use DOF to overcome focus inaccuracy, or indeed trade off some diffraction at even smaller apertures for even more DOF to overcome a curly negative if your neg holder can't keep them perfectly flat. For example test charts show my 105mm Nikon Z micro lens starts to show diffraction affecting the chart at f/14, where a standard lens would be f/8. This allows me to set the lens at f/11 and well within it's diffraction limit (or my own personal tolerance for a diffraction limit) and use the DOF to counter any slight warp in the negative or inaccuracy in the level of the copying rig.

Edited May 24, 2024 by 250swb

[jimeca]

Thank you all for your answers.

 

I don’t use the 50APO for scans. I use it for photographs. 

For the scans I used the 105mm Sigma Macro on Nikon D850.

I have always been careful to level the DSLR and support negative.

I have often noticed that the negative is never 100% flat in the Essential Film holder.

 

[250swb]

2 hours ago, jimeca said:

Thank you all for your answers.

 

I don’t use the 50APO for scans. I use it for photographs. 

For the scans I used the 105mm Sigma Macro on Nikon D850.

I have always been careful to level the DSLR and support negative.

I have often noticed that the negative is never 100% flat in the Essential Film holder.

 

I see, I thought you were talking about what lens you used to scan with. So it seems it is the scanning process that's introducing unreliable scans but if it's hit and miss the only thing that can change between negatives is the focus accuracy. Just a thought, if you are using focus peaking ensure you are doing it at maximum aperture and not stopped down.

[hansvons]

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3 hours ago, 250swb said:

Just a thought, if you are using focus peaking ensure you are doing it at maximum aperture and not stopped down.

This may introduce focus shift, which I experienced with my macro lenses. Perfect macro photography isn't easy. 

 

[250swb]

12 minutes ago, hansvons said:

This may introduce focus shift, which I experienced with my macro lenses. Perfect macro photography isn't easy. 

 

Agreed.

[jimeca]

With what type of lens I can get the best results: an enlarger lens or a macro lens?

Thanks for your feedback 

[BernardC]

3 hours ago, jimeca said:

With what type of lens I can get the best results: an enlarger lens or a macro lens?

In theory, enlarging lenses are optimized for magnifications around 5x-15x (printing on 5x7 inch to 16x20 inch paper for 35mm film), with a few notable exceptions. The APO-Rodagon-D series of lenses are meant for 1:1 reproduction, as are most classic "repro" lenses (although those are meant for large format, up-to newspaper size).

Macro lenses may be optimized for 1:1, but this will be different for each make and model, and maybe each version of that model.

I don't think it will make a huge difference in the end. You should worry more about film flatness, parallelism, and rigidity. I've been getting great results with an old Hasselblad bellows and an enlarging lens mounted on an L-39 adapter. The main reason why I ended-up with that system is because I already owned most of the pieces. Frankly, a modern macro-lens system, like the Valoi offerings, would be just as good.