Hi Ron,

Quote Originally Posted by Photo Engineer View Post
Well, the method you used is excellent and just fine for comparing 2 optical trains with 1 film, or one train with 2 or more slide films with identical contrasts, but in this case you are comparing a slide film with a contrast of about 1.8 and a negative film with a contrast of about 0.6, so how do you normalize the results?
all BW films were developed to the same contrast.

Colour films: All slide films were developed in standard E6 process, professional lab (Kodak Q-Lab).
All CN films in standard C-41, the same professional lab.

The reasons for this workflow:
1. Normalizing of the overall, global contrast would make no sense, because we want results relevant for real, daily photography, real pictures, and not for pure lab comparisons.
In daily photography no photographer would increase the contrast of his color negs from 0.6 to to 1.8, and no photographer would decrease the contrast of his slide film down to 0.6. The films are not designed for this 'abuse'.
Negative film works best with the lower contrast, and slide film with its higher contrast, that's why it is used in that way. Including all pros and cons.
If you now change the contrast dramatically you would loose the strengts of films in both cases, and you would gain nothing.

And our interest was to see the results the films deliver when they are used in the way all photographers use it.
When you print optically you have the differences between neg and positive film, and when you scan as well (of course also when you project it, but that makes seldom sense with negatives; nevertheless we've done it with high resolution films with extremely interesting results, but that is another story).
That is what we are doing in our daily photography, and are confronted with the (different) results.
To analyse these results was our interest.

In general you have the higher global contrast with slide film, and of course resolution benefits from that. That is an essential characteristic of slide film.
But you have to pay for it with less dynamic range because of the higher contrast.
And the other way round with negative film. Less resolution, but higher d.r..
There is no free lunch.

2. Global contrast is not the major factor for resolution of higher spatial frequencies. Here microcontrast is important, the contrast of the extremely fine black and white lines. And the difference in microcontrast between slide film and negative film at these high spatial frequencies is much much lower than the global contrast. You even see this clearly with the eye under the microscope, and you get that confirmed with densitometric tests (what we did).

Quote Originally Posted by Photo Engineer View Post
And, even though you get a difference, how do you explain the data presented by Kodak and others which says that the Ektar is sharper than the Ektachrome?
I guess you refer to the MTF chart, and not to Kodaks marketing statement.....

Our experience with doing such tests for more than 20 years now is that MTF data has very little relevance for real life shooting under normal photography conditions. MTF data is generated under completely different conditions, e.g. with much higher object contrast.
Our contrast is lower, because most details in scenes have low(er) object contrast. And our interest is daily photography.
And with lower object contrast slide film performs better.
And there are differences in MTF data from manufacturer to manufacturer (different test conditions).
For example we have made the experience that the MTF data of Fuji is quite conservative. It is relatively easy to reach their resolution values.
A friend of mine, using the same method, but only with littler higher contrast (1:8) and a different lens has even achieved slightly higher resolution with Pro 160C than Fuji data gives for 1:1000 contrast.
These differences between MTF data and test results with real shots (higher as expected resolution in real shooting conditions) was also confirmed by Zeiss.

Therefore the result from our experience: If you want to see the real resolution, sharpness, grain, dynamic range, than take photographs with your equipment, your lenses, your films, your needed object contrast etc.
MTF data is not the answer of your questions concerning your equipment and your individual shooting conditions. Look at your pictures, not at curves from someone else.

Best regards,
Henning