How do you know exposure time for paper when making print

[interneg]

interneg, if the color clouds of the different layers are not overlaping this ends in noise when scanning at high resolution, the popularization of digital minilabs led to larger clouds in CN films.

The PORTRA 160 datasheet says "Film features a significantly finer grain structure for improved scanning and enlargement capability in today's workflow"

Well, first is that CN films have clouds and no grain... second is that manufacturers never want to say "larger color clouds"

Very simply, the designers don't want to get larger dye clouds from finer grain. It would impact sharpness massively, in fact most of the things that are done in terms of specialised couplers etc are to ensure higher sharpness intra- & inter-layer from what are essentially oily clouds (couplers) forming around the grain. Scavengers, acutance dyes etc also play roles in this.
The couplers use a form of controlled starvation to ensure that as more silver forms (overexposure), there is not a major rise in dye formation or coarser 'granularity'.
Aliasing etc is best combatted by smaller, more tightly packed grains - which is why modern C-41 films are harder to bleach & fix & need specific integrated components (in the case of the former) & a fix with thiocyanate etc for the latter.

[Cor]

Many roads to Rome..

What works for me is a F-stop timer (in my case a RH deign)

And the test strip printer from the Way beyond monochrome book of Lambrecht (great book !)

Good luck,

Cor

[Pere Casals]

Very simply, the designers don't want to get larger dye clouds from finer grain. It would impact sharpness massively, in fact most of the things that are done in terms of specialised couplers etc are to ensure higher sharpness intra- & inter-layer from what are essentially oily clouds (couplers) forming around the grain. Scavengers, acutance dyes etc also play roles in this.
The couplers use a form of controlled starvation to ensure that as more silver forms (overexposure), there is not a major rise in dye formation or coarser 'granularity'.
Aliasing etc is best combatted by smaller, more tightly packed grains - which is why modern C-41 films are harder to bleach & fix & need specific integrated components (in the case of the former) & a fix with thiocyanate etc for the latter.

Interneg, take a competent microscope and observe the developed film with it, at aprox. x600, and just compare Velvia/Provia with Fuji 160 (or Portra) clouds.

This will tell you why velvia is sharper than portra and why Portra scans better. Then, if you want, you can also observe a color negative pre-dating the digital minilab era, then you will have all information about that, and you will know what was changed in negative color films and why.

[interneg]

Interneg, take a competent microscope and observe the developed film with it, at aprox. x600, and just compare Velvia/Provia with Fuji 160 (or Portra) clouds.

This will tell you why velvia is sharper than portra and why Portra scans better. Then, if you want, you can also observe a color negative pre-dating the digital minilab era, then you will have all information about that, and you will know what was changed in negative color films and why.

This is not the case at all - as you'd be able to observe (for example) if you've scanned VPS III, the various generations of 160NC & VC & current 160 side by side on the same high end scanner with no in scanner sharpening. Or for that matter made optical chromogenic prints of reasonable size. Only significant changes for scanning related to the supercoat & retouching surfaces. VPS III has a print grain index equivalent to current Portra 400 according to the available data & my own experience would generally agree. The sharpness jump of the Portras is significant & it is clear that they are using much finer grain structures & tighter control of coupler cloud growth in exposure & processing. This should not be surprising given that films like TMY-II clearly display grain growth technology learnt from manufacturing C-41 films etc - indeed it would not be hugely surprising if the r,g,b sensitised layer groups each had a remarkable resemblance to the layers & grain shapes of TMY-II.

For that matter, a transparency made on a print film from a colour negative will outperform Velvia & other transparency films. Which is at least a large part of why professional filmmaking adopted a pos/neg process rather than pos/pos - and beyond that, it gets deeply mathematical. What a transparency looks like on a light table is not necessarily a good indication of how well (more accurately, how painful it'll be) to translate to a print or reproduction.

Finally, you might want to look much more carefully at how minilab scanners actually work to achieve their resolutions relative to aliasing - your suppositions are wrong, at least on the Fuji Frontier. Suffice to say, a low resolution sensor (1500ppi), pixel shifting & supersampling all seem to be working together 'under-the-hood' to balance resolution & aliasing long before the (often heavy-handed) sharpening options in the software.

Again, most of this is not complicated stuff at the end user point (and is arguably largely irrelevant if you have half an idea about the real-world behaviour of your materials), unless you believe you know more than the engineers who designed the films.

[Steven Ruttenberg]

Wow, and here I tbought taking a picture was straight forward. Digital technology is rather simple compared to this and now my head hurts.

[Bernice Loui]

Most important relative to the recent posts on this topic. Unless the viewer has DECADES of experience with negative-positive color films and related prints coupled with as much experience with lens personalities, lighting and a LOT more, what metric does one use for a point reference?

Keep in mind there are numerous individual bias and more mixed into visual and emotional perception of images that will result in a variety of outcomes.


Bernice

[interneg]

Wow, and here I tbought taking a picture was straight forward. Digital technology is rather simple compared to this and now my head hurts.

Main thing is that to a large extent you don't need to understand too much of what's going on under the surface with analogue processes to make good prints - and in fact many of the claims & 'special procedures' and developers that have gained traction over the years have very little advantage (and often the opposite) over basic technique competently applied. It largely boils down to sufficient exposure & adequate processing. The rest is largely commentary.

Most important relative to the recent posts on this topic. Unless the viewer has DECADES of experience with negative-positive color films and related prints coupled with as much experience with lens personalities, lighting and a LOT more, what metric does one use for a point reference?

Keep in mind there are numerous individual bias and more mixed into visual and emotional perception of images that will result in a variety of outcomes.


Bernice

I'd essentially agree - and it gets deeply technical & far away from what can be observed with a basic microscope very, very fast, not least because of the number of optical, mechanical & chemical interactions that need to be controlled for. I go by what the finished print looks like - though it is somewhat reassuring to discover that there is a correlation between what you can observe in day-to-day printmaking work & the conclusions that the product researchers arrived at.

[Bernice Loui]

There is currently an entire group of image makers who have not had the real world experience of film and film based prints to projected or similar transmitted light images. Many have grown up with digital based, display screen based images which are inherently different than film based images. Once the point of reference has been set by either metrics, individuals can develop an emotional attachment to that metric which can bias their preferences. This is neither good or bad, it is one of the host of factors that must be considered when a point of reference is used.

One can go deep into the technical and theoretical aspects of image making, being technically and theoretically ideal is often simply not good enough to result in emotionally expressive images. To achieve this requires far more than the technical and theoretical aspects, there is a human and artistic aspect that can impart that special quality of emotionally expressive images.

And yes, if one were to make technical assessments of film image quality, use a high quality microscope with the proper lighting system.



Bernice

[Pere Casals]

This is neither good or bad, it is one of the host of factors that must be considered when a point of reference is used.

Of course. At the end it's about a cultural development, new artists will create with the resources what they have at hand, and this has been seen in how digital image edition has evolved.

But darkroom printing process has also an amazing cultural heritage that cannot be overlooked. Some times cultural evolution looks back to find what was lost.