Edge to edge sharp L macro lens

[dpitt]

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On 1/27/2023 at 3:29 PM, BernardC said:

It's counterintuitive, but all lenses have the same theoretical depth of field at 1:1. Depth of field is based on magnification. This makes sense when you consider that a wide angle has lower magnification than a telephoto, and therefore more depth of field.

In other words, the focal length of a macro lens should be selected based on working distance. The angle of view doesn't matter if you are copying flat art.

The only difference you can make is reduce your sensor size. This would be the only benefit of going for APS-C crop. It will 'increase' the DOF for the same magnification relative to the sensor size. It might be the reason for Camera West to use the 60mm and crop the results. I use a MFT for macro (1:2 or so mostly) and this effect is very helpful compared to FF and the same magnification.

[Babylonia]

Hello, I just "hop in" to this topic.  (I am a new forum member).
Interesting subject, as I am looking to similar reproduction methods for "digitising" old  "film" made photographs.
(35mm   -   6x7cm roll   -   4x5"   &   8x10" sheet film).
 

On 2/3/2023 at 6:06 PM, Photoworks said:

I use flash instead of the Lightbox , no problem with the strongest window light or artificial. 1/250 f13 ISO 100

Why using f13 ??
When using e.g. a Leica S2 (47 megapixel), using this aperture value, diffraction has already heavily negative influence to sharpness.
Especially in strong close reproduction macro used distances, the actual relative aperture value, taking into account the "tube" focus distance extension,
the "real" aperture opening even is far more closed. So diffraction even shall be more severe.

I do understand that by using a smaller aperture value, you have a bit more "spare" in terms of DOF variation if the film flatness is not properly guaranteed.
But I think by using this "small" aperture value, the balance by DOF variation versus real optical system / image sensor sharpness,
is tipped too far into a negative sense.

I think that you should not be using an aperture value above F 5.6  -  maybe F 8 maximum, (or better "between")
as a balance between DOF variations and general sharpness.

[Stuart Richardson]

9 minutes ago, Babylonia said:

Hello, I just "hop in" to this topic.  (I am a new forum member).
Interesting subject, as I am looking to similar reproduction methods for "digitising" old  "film" made photographs.
(35mm   -   6x7cm roll   -   4x5"   &   8x10" sheet film).
 

Why using f13 ??
When using e.g. a Leica S2 (47 megapixel), using this aperture value, diffraction has already heavily negative influence to sharpness.
Especially in strong close reproduction macro used distances, the actual relative aperture value, taking into account the "tube" focus distance extension,
the "real" aperture opening even is far more closed. So diffraction even shall be more severe.

I do understand that by using a smaller aperture value, you have a bit more "spare" in terms of DOF variation if the film flatness is not properly guaranteed.
But I think by using this "small" aperture value, the balance by DOF variation versus real optical system / image sensor sharpness,
is tipped too far into a negative sense.

I think that you should not be using an aperture value above F 5.6  -  maybe F 8 maximum, (or better "between")
as a balance between DOF variations and general sharpness.

Agreed! This was a lesson I learned once when doing film scanning with the Leica S006 and 120mm Macro. I had been shooting at f8 when reproducing an 8x10 sheet, so it was not a high reproduction ratio, but still. I mistakenly took a photo at f2.5 instead of f8, and the image was actually sharper at 2.5 than f8. That was a function of diffraction, even in an medium format camera with the relatively conservative sensor resolution of 37mp. Of course it was also because the 120mm APO is such a fantastic lens. This phenomenon is also why true microscopic lenses and high reproduction ratio lenses tend to be extremely fast...the smaller the f stop, the more diffraction. Obviously there is a trade off in image quality, but most macro lenses for L mount are going to reach their peak performance closer to f4 or f5.6 than at f11 or f16. This is a case where wet mounting or having an anti-newton and plane glass sandwich is probably required to get the absolute maximum out of the film.

Edited February 5, 2023 by Stuart Richardson

[Babylonia]

On 2/3/2023 at 1:26 PM, Stuart Richardson said:

I think the camera scanning product I am truly waiting for is something to automatically do stitching. That would solve the resolution problem for larger formats like 4x5 and 8x10, and then we could probably finally let go of the old pro flatbeds and drum scanners. Stitching based on the photoshop algorithms has not really worked well for me with film scanning...typically if there is an area of sky the programs get confused.

If there was a dedicated program and a standardized stitching amount, I am sure it would work much better. I think that is what Kodak did with the Eversmart line in the 90s, so clearly it is technically possible, just no one seems to have done it with modern tech (other than a few very skilled DIYers).

Check if you can have better results and advantage by using:    https://ptgui.com/

Used for stitching Gigapixel panorama's and correcting every tiny distortion of lenses to "pixel" amount.
The behind resources based to professor "Helmut Dersch" Panorama Tools IMO are the best scientific algorithms for stitching images.

https://wiki.panotools.org

https://hugin.sourceforge.io/

https://hugin.sourceforge.io/docs/manual/Panorama_tools.html

[Stuart Richardson]

Great, thank you!

[BernardC]

You can also run into issues if the scanning resolution is too close to the frequency of your film grain. I ran into this with a 16mm B&W film project, years ago. The grain looked like bubbling gruel at 2K, but it was OK at 4K (and in a test SD scan we tried). In that case, stopping-down to get more diffraction would have helped, but it wasn't an option with the type of telecine scanner we were using.

Long story short: run lots of tests until you find the right settings.