Ferrania P30: curve shape and (un)coated lenses

[Scott Micciche]

I thought I understood this, but after further consideration, it is more than a bit confusing to me. If I use D-23 in a non-replenishment mode, it is essentially the first bath in Thornton's 2-bath. AIUI, Sodium metaborate in the replenisher is used to buffer the leftovers of earlier processing. What does it do all by itself in the 2nd bath after the 1st bath is gone?

Little to no development takes place in bath 1, the metaborate is the accelerator. I ended up making it for many films because HC-110 seems to be in the unobtanium category these days. I found it to work really well for the P30 as well as svema64. I'll be using it for 3 or 4 other rolls coming up. Like D23, it is very inexpensive to make.

 

[Harry Callahan]

It seems to me using problematic lenses to improve problematic film is a problematic approach. Why not just use a film without excessive contrast and virtually any lens manufactured in the last fifty years?

My intention is to find a way to get along better with P30. As i said the result will not be technically correct, trying to solve a flaw of the film by a flaw of the lens.

 

[Harry Callahan]

You are indeed no expert on this, otherwise you would not ask me this question .
It really does not matter at all which lens I have used for this test, because a different lens would not have changed the results at all.
When I am doing the evaluation of the characteristic curve I photograph the 18% grey card with even, diffuse light from behind.
And then the results are the same no matter whether you are using an uncoated, single-coated or multi-coated lens.
The characteristic curve is a film-typical characteristic.
And you cannot solve the problematic characteristics of this film by using other lenses.

Well then let me go on not being an expert :
How can you measure for shadow detail, if you just shoot a 18% grey card? And even with diffuse light from behind a multicoated lens should give higher contrast than single- or uncoated. Of course you won`t notice if shooting a grey card full frame, but with an ordinary subject you should.

 

[Film-Niko]

Well then let me go on not being an expert :
How can you measure for shadow detail, if you just shoot a 18% grey card?

I am just doing what every good BW photographer is doing: Evaluating the characteristic curve / HD curve of the film.
By exposing a complete Zone series from Zone I to Zone X. So from - 4 stops underexposure over correct exposure (Zone V) to + 5 stops overexposure (Zone X).
This curve tells you everything about real film speed, shadow detail, tonality and highlight detail.

It is just simple basic knowledge for BW film photography! And if you don't know about it, just buy a book, read and learn this essential basic knowledge. It is really worth it, and you will benefit from it very much.

And even with diffuse light from behind a multicoated lens should give higher contrast than single- or uncoated.

Again, for evaluating the HD-curve it is irrelevant whether your lens is multi-coated or single-coated. That will not change the curve shape!!!
If you are testing several film-developer combinations it is only relevant that you are using the same test procedure (including same lens) for consistency and comparison possibility.

 

[Cubao]

Again, for evaluating the HD-curve it is irrelevant whether your lens is multi-coated or single-coated. That will not change the curve shape!!!

When he‘s right, he’s right!

 

[Harry Callahan]

I am just doing what every good BW photographer is doing: Evaluating the characteristic curve / HD curve of the film.
By exposing a complete Zone series from Zone I to Zone X. So from - 4 stops underexposure over correct exposure (Zone V) to + 5 stops overexposure (Zone X).
This curve tells you everything about real film speed, shadow detail, tonality and highlight detail.

It is just simple basic knowledge for BW film photography! And if you don't know about it, just buy a book, read and learn this essential basic knowledge. It is really worth it, and you will benefit from it very much.

I see, i assumed you to use one of these test charts where there are different greys representing all the zones and you just have to take one picture to get it all.

Again, for evaluating the HD-curve it is irrelevant whether your lens is multi-coated or single-coated. That will not change the curve shape!!!
If you are testing several film-developer combinations it is only relevant that you are using the same test procedure (including same lens) for consistency and comparison possibility.

Yes, if using this method it probably is irrelevant, but when using a test chart or a normal subject coating of the lens should matter. With a test chart or a normal subject there will be brighter and less brighter areas. Especially an uncoated lens will "steal" quite some light from the bright areas and spread it onto the dark areas.
If shooting a 18% grey card full frame this cannot happen, an uncaoted lens will produce flare, but it only will "steal" light from the entire grey area - and spread it back upon it.
With a chart or a real life object things should differ. With an uncoated lens light will be taken from the bright areas and put on the dark areas. This will not change the characteristic curve of the film, but it will change the contrast the film will see during exposure. And if the film is rather too high contrast, exposing reduced contrast onto the film will help to counteract.

Consider it this way: Usually a photographer tries to match the film and the developer to the contrast of the subject - Adams made an art out of that.
Now what if you did match subject contrast to the film+dev. by using a different contrast lens? Do it the other way round?

That`s what i'm talking about here.

 

[Film-Niko]

Now what if you did match subject contrast to the film+dev. by using a different contrast lens? Do it the other way round?

As already explained by faberryman, Cubao and me above. That does not work!!!
You cannot change the curve shape of the film by using a different lens.
Period.
Please do yourself a favour and learn the basic essentials of BW film developing and evaluating of the characteristic curves of films.

 

[faberryman]

Now what if you did match subject contrast to the film+dev. by using a different contrast lens? Do it the other way round?

Interesting idea. Why don't you acquire lenses having different contrasts, take photographs with them in lighting of different contrasts, and let us know how that works out. To be honest, I'll probably just continue to adjust development time to control negative contrast, but often there is more than one way to accomplish a task.

 

[Harry Callahan]

As already explained by faberryman, Cubao and me above. That does not work!!!
You cannot change the curve shape of the film by using a different lens.
Period.
Please do yourself a favour and learn the basic essentials of BW film developing and evaluating of the characteristic curves of films.

You don't need to change the curve and i don't want to change it. All i want to do is to give the curve the contrast it gets along best with.

 

[Harry Callahan]

Interesting idea. Why don't you acquire lenses having different contrasts, take photographs with them in lighting of different contrasts, and let us know how that works out. To be honest, I'll probably just continue to adjust development time to control negative contrast, but often there is more than one way to accomplish a task.

I can't. I don't have the funds and i am not in shape to do it myself. But years ago i`ve taken some pictures with an old folder having an uncoated lens - and negs had fewer contrast than pictures i had taken with multicoated lenses.
I know that coating of a lens has an effect on contrast.

 

[Cubao]

I know that coating of a lens has an effect on contrast.

Yes and there are no doubts about it. You seem not to understand that this has nothing to do with the curve shape of the negative. It simply doesn’t matter as long as you use the same one lens to determine it. In fact you don’t even need a lens to do it

 

[Harry Callahan]

I`m aware that the curve is independed of the lens used - its just there because its the characteristic of the film.
But if the curve is the way it is with P30, reducing shadow detail and blowing highlights, what would happen if you don`t use a high contrast lens - but a lens brightening up shadows and reducing highlights?
The curve would remain the same, but what would the picture look like, what would happen to shadow detail and highlights? Would the picture look more correct, though the curve still is the same as with a high contrast lens?

 

[Film-Niko]

I`m aware that the curve is independed of the lens used - its just there because its the characteristic of the film.
But if the curve is the way it is with P30, reducing shadow detail and blowing highlights, what would happen if you don`t use a high contrast lens - but a lens brightening up shadows and reducing highlights?
The curve would remain the same, but what would the picture look like, what would happen to shadow detail and highlights? Would the picture look more correct, though the curve still is the same as with a high contrast lens?

No, that does not work. The lens cannot "brightening up" shadows. Only additional light can that.
And the contrast range = difference, is determined by the curve shape, which cannot be changed by the lens.

 

[Harry Callahan]

No, that does not work. The lens cannot "brightening up" shadows. Only additional light can that.
And the contrast range = difference, is determined by the curve shape, which cannot be changed by the lens.

A single- or uncoated lens will produce flare, which will be spread across the entire neg during exposure. As bright areas will be several times brighter than the flare (sometimes a 100 times brighter), you won`t notice brightening of bright areas - but with dark shadows a brightening can happen, as lens flare is additional light.
As i said several times now you don`t need to change the curve and i don't want to change the curve - all i want is to give the curve the subject-contrast it gets along best with. But, i`m afraid, you seem too focused on the curve to see my point.

 

[Harry Callahan]

That was my thought too after testing P30 with modern contrasts Zeiss glass. It seemed to me that the film might give vintage lenses a little needed punch. I was going to try it with the 120 size but it hasn’t arrived yet.

This does apply to my theory i presented a few days ago: As P30 was formulated in a time where there were no multicoated lenses, single-coated were state of the art and uncoated still in use, they maybe designed the curve to match single- and uncoated lenses by intention.
Today most use multicoated lenses and find shadows dropping and highlights blowing. Maybe P30 will give better results with single- and/or uncoated lenses.

 

[Film-Niko]

A single- or uncoated lens will produce flare, which will be spread across the entire neg during exposure.

No, that is not generally the case. You have flare only in certain conditions, but not always. In diffuse daylight or with the light source behind you you won't have any flare. I have used enough old non-coated and single coated lenses to know their characteristics.

As bright areas will be several times brighter than the flare (sometimes a 100 times brighter), you won`t notice brightening of bright areas - but with dark shadows a brightening can happen, as lens flare is additional light.

See explanation above. And please don't ignore the physical fact that lens coating is increasing and improving light transmission through the lens.
Your statement that uncoated lenses will give you "additional light" is not true.

As i said several times now you don`t need to change the curve and i don't want to change the curve - all i want is to give the curve the subject-contrast it gets along best with. But, i`m afraid, you seem too focused on the curve to see my point.

No, your problem is that you don't understand that uncoated lenses cannot solve the original problem with this film. And that you unfortunately don't know what a characteristic curve really is and what it is showing. And your object contrast / subject contrast is determined by the lighting conditions on that object, and not by the lens.
If you could significantly influence object contrast by lens choice our photography techniques would be very, very different to what we are using for decades!

 

[koraks]

@Film-Niko please keep it polite. Debate the issue, not the person. Thanks.

 

[Film-Niko]

This does apply to my theory i presented a few days ago: As P30 was formulated in a time where there were no multicoated lenses, single-coated were state of the art and uncoated still in use, they maybe designed the curve to match single- and uncoated lenses by intention.
Today most use multicoated lenses and find shadows dropping and highlights blowing. Maybe P30 will give better results with single- and/or uncoated lenses.

Sorry, but that is really esoteric wishful thinking. And ignoring physics: E.g. Because of the better light transmission multi-coated lenses have better shadow tone separation, and not "shadows dropping".

As you are so extremely convinced of your "theory", then go, buy some uncoated lenses, make comparison tests with modern multi-coated lenses and evaluate the characteristic curves, show the results and give evidence that you are right.
But I can guarantee you: It will be a total waste of time, and you will fail. Because you are ignoring physics.

 

[Harry Callahan]

No, that is not generally the case. You have flare only in certain conditions, but not always. In diffuse daylight or with the light source behind you you won't have any flare. I have used enough old non-coated and single coated lenses to know their characteristics.




See explanation above. And please don't ignore the physical fact that lens coating is increasing and improving light transmission through the lens.
Your statement that uncoated lenses will give you "additional light" is not true.



No, your problem is that you don't understand that uncoated lenses cannot solve the original problem with this film. And that you unfortunately don't know what a characteristic curve really is and what it is showing. And your object contrast / subject contrast is determined by the lighting conditions on that object, and not by the lens.
If you could significantly influence object contrast by lens choice our photography techniques would be very, very different to what we are using for decades!

Glass does reflect light, if you`re outside looking at a window pane you will find the environment to be visible in the window - though windows are intended to let light into the house and not reflect it back. But as you also don`t want everybody to be able to look inside your house, windows reflecting some light are not a real problem.
But with lens elements it is problematic, if there are too strong reflections. That's why they use optical glass which does reflect fewer light than window glass - while window glass does reflect about 20-30% of incomming light, optical glass does reflect only about 6-12% - let`s take the average value and say its about 9%.
9% is what each element of a uncoated lens does reflect, with single-coating did reduce reflections to about 3% and multi-coated is about 1% per lens element.

This means as soon as there is light passing through the lens, there will be reflections, no matter what light or light source there is - even with a multicoated lens. If a light source does shine directly into the lens, there will be visible artifacts which usually are called lens flare, but there also is a different kind of flare which could be described as an even fog laying above the entire picture - and because of that isn`t that obvious or not obvious at all.
This is what i mean when i was talking about flare, not obvious reflections of the aperture or multiple images of light sources. Think of it as a fogged lens, it will produce flare even if there is diffuse light comming from behind.

Now as a single coated or uncoated lens does produce flare (fog) any time, there will be additional light be shed on the shadows during exposure. Light that would not be shed (respectively much less) onto the shadows with a multicoated lens, as this does produce way fewer flare (fog).
This additional light on the shadows of course is not comming out of nowhere. A single- or uncoated lens does not have higher light-transmission and there are no extra openings in the lens barrel to let in additional light, no this flare (fog) is created by the lens elements reflecting light. That's what i meant by "stealing light from the bright areas of the subject". Light of the bright areas will be reflected between the single elements, it will be converted to flare (fog) and spread even above the entire neg.

If we now only take a triplet, a single-coated lens will produce 3x3%=9% flare (fog) of the light passing the lens, while an uncoated triplet will produce 3x9%=27% flare (fog) of the light passing the lens.
That`s quite some flare and this should be able to brighten up shadows on the neg inside the camera.

And if shadows are brightened up, there is fewer contrast on the neg. Therefore a lens is able to influence subject contrast, any lens does reduce subject contrast as there is no lossless lens - the question is how much the lens does reduce contrast. And a multicoated lens does reduce contrast a lot less than an uncoated lens.
...

So i`m comming back to my theory: If a film like P30 does drop shadows, what would happen if you did not use a multicoated lens, but a lens producing more flare (fog) which does brighten up shadows?

 

[Harry Callahan]

Sorry, but that is really esoteric wishful thinking. And ignoring physics: E.g. Because of the better light transmission multi-coated lenses have better shadow tone separation, and not "shadows dropping".

As you are so extremely convinced of your "theory", then go, buy some uncoated lenses, make comparison tests with modern multi-coated lenses and evaluate the characteristic curves, show the results and give evidence that you are right.
But I can guarantee you: It will be a total waste of time, and you will fail. Because you are ignoring physics.

But why have multicoated lenses better shadow tone separation?

Because there is fewer flare brightening up the shadows.

 

[Film-Niko]

This means as soon as there is light passing through the lens, there will be reflections, no matter what light or light source there is - even with a multicoated lens. If a light source does shine directly into the lens, there will be visible artifacts which usually are called lens flare, but there also is a different kind of flare which could be described as an even fog laying above the entire picture - and because of that isn`t that obvious or not obvious at all.
This is what i mean when i was talking about flare, not obvious reflections of the aperture or multiple images of light sources. Think of it as a fogged lens, it will produce flare even if there is diffuse light comming from behind.

O.k., the correct technical term for that is light transmission, and not flare.
That is also measured by the T-stop value (in addition to f-stop), which gives you the real "light-power" of a lens.
Uncoated or single-coated lenses have lower / worse light transmission than multi-coated lenses, and therefore also a worse T-stop.

Now as a single coated or uncoated lens does produce flare (fog) any time, there will be additional light be shed on the shadows during exposure. Light that would not be shed (respectively much less) onto the shadows with a multicoated lens, as this does produce way fewer flare (fog).

No, there will not be any additional light!! See above, the light transmission / T-stop value of an uncoated or single coated lens is lower than of a multicoated lens.
Less light is going through the lens.

This additional light on the shadows of course is not comming out of nowhere. A single- or uncoated lens does not have higher light-transmission and there are no extra openings in the lens barrel to let in additional light, no this flare (fog) is created by the lens elements reflecting light. That's what i meant by "stealing light from the bright areas of the subject". Light of the bright areas will be reflected between the single elements, it will be converted to flare (fog) and spread even above the entire neg.

No, no, no.
That is not happening. There is no magic "stealing light from the bright areas and transferring them to shadows" made internally by an uncoated or single coated lens.
Because the worse light transmission affects the whole picture.
And because if that would really be the case, then logically two other things would happen:
1. The characteristic curve of the film would change with higher density in the shadows and lower density in the highlight zones.
2. Your film speed would be increased.

But as we all know, that two things do not happen: Neither is the curve shape changed with a worse-coated lens, nor do you get higher real speed with such a lens (just the opposite, because of the worse T-stop / worse light transmission you loose real speed).

Therefore you cannot solve the inherent problems of P30 by using worse lenses.
Of course, if you don't trust physical laws just buy several old lenses, lots of P30 and chemistry and try it.
But be assured, it will be a huge waste of time and money (and I just want to protect you from that mistake).

 

[koraks]

O.k., the correct technical term for that is light transmission, and not flare.

I think you may be referring to something else. AFAIK @Harry Callahan is talking about flare, in the sense of 'veiling glare', which does indeed reduce overall contrast by illuminating shadows that would otherwise remain darker. See e.g. this explanation by Imatest: https://www.imatest.com/docs/veilingglare/

What veiling glare will do is create density (on a negative image forming medium) in shadows. As such, it will also interact with the toe behavior of the medium as there's a point where this additional shadow exposure sensitizes the medium in the same way a preflash does, so it will allow the capture of some shadow detail that would not be recorded when using an optical stack with less glare. Note that this only happens in a select part of the toe region of the film.
What veiling glare will not do is create detail/contrast in those shadows, or significantly affect straight-line or shoulder behavior of the medium, since there is no significant decrease in exposure happening in those parts of the curve.

All combined, an optical system with a large amount of veiling glare will reduce overall contrast by making shadows lighter, possibly capturing marginal detail in those areas (albeit still with low contrast/poor separation). The severity of the effect changes with the amount of glare. As such, the effect is relatively easy to reconstruct by a simple A/B test with a glare-prone lens with and without hood and a light source just outside the image frame, and then comparing the captures.

Whether it is an effective strategy to use a lens that is particularly prone to glare as a means to compensate for undesired film curve behavior (or vice versa) is up to the individual photographer or cinematographer to decide. Personally, I think it's a tricky strategy since it is very prone to per-shot conditions, specific glare behavior of the lens and the specific characteristics of the film that need to be addressed. That makes it a rather difficult to predict set of interactions. I'm sure high-end cinematographers could expound lengthily on how to make thos controllable, as it's a phenomenon that can indeed be exploited deliberately for creative purposes.
For the still photographer and especially amateurs, I can imagine that it can simply be a fun and somewhat effective 'workaround' to combine a flare-prone lens with a film that has a pronounced S-curve behavior and get pleasing (albeit somewhat unpredictable) results. Personally, I'd rather choose to use a properly coated lens with decent optical characteristics and avoid the toe of the curve in those cases where it's needed by simply adding some exposure, perhaps combined with some reduced development.

 

[flavio81]

A single- or uncoated lens will produce flare, which will be spread across the entire neg during exposure.

You should not mix "single-coated" with "uncoated" lenses in the same basket. There are single-coated lenses that are very contrasty.

Single-coating has the same effectivity than multi-coating at a specific wavelength (i.e. green color). Some older lenses (i.e. Nikkors) had all their single-coatings optimized for maximum transmission of a specific wavelength. They are very contrasty at the expense of a suboptimal color balance. Additionally, what is often called a "single-coated" lens colloqially, might have dual-layer coatings, which are highly effective. Yet additionally, a so-called "multicoated" lens might have many single-coated surfaces.

Lenses with few group (i.e. Tessar, 6/4 gauss types) don't really need multicoating to give excellent contrast. One can compare the results, for example, of a single-coated Nikkor-H 50/2 with the multicoated Nikkor-H-C 50/2 of identical optical design. The contrast is the same, the multicoated lens has a litle bit more resistance to ghosting (which is not the same as "flare")

Today most use multicoated lenses and find shadows dropping

Sorry, this makes no sense.

See explanation above. And please don't ignore the physical fact that lens coating is increasing and improving light transmission through the lens.

Correct.

Because of the better light transmission multi-coated lenses have better shadow tone separation, and not "shadows dropping".

Correct

9% is what each element of a uncoated lens does reflect, with single-coating did reduce reflections to about 3% and multi-coated is about 1% per lens element.

Sorry, your figures are not correct (and are far higher than actual values). First of all, there's not only one "figure" but a curve. Because transmission will change with wavelength. Second, it will depend on the refraction index of the glass and of the coating(s) themselves.

The light transmission of the complete lens system will depend on how the lens designer has designed to apply the coatings (either single- or multi-coatings): to get maximum transmission OR to get perfect color balance. Often it's a compromise, to get good (pro-quality) color reproduction and sufficiently high transmission.

Additionally, if we're speaking about old "single-coated" lenses, since the late 1950s there are different single-coating techniques, with dramatically different effectivity at light transmissions.

O.k., the correct technical term for that is light transmission, and not flare.
That is also measured by the T-stop value (in addition to f-stop), which gives you the real "light-power" of a lens.
Uncoated or single-coated lenses have lower / worse light transmission than multi-coated lenses, and therefore also a worse T-stop.

Correct if we consider the light transmission at all wavelengths (i.e. measuring red, green, blue).

 

[flavio81]

To summarize my previous post, let's see this graphic:

Light transmission of the 1960 Nikkor-S 58/1.4 (single-coated)
versus the circa-2010 Nikkor AF-S 50/1.4G (nikon modern super integrated coating)

More than 50 years of diffference... Yet the light transmission is the same at the 500nm wavelength (see my previous post), and even better in the older lens from 800nm onwards.

The modern lens seems to have been optimized for max performance at the green spectrum (again, see my previous post), and to try to supress infrared radiation.

BTW 91-93% of light transmission for a normal lens is pretty similar to what many multicoated lenses in the 1970s would achieve. See 2nd picture for an example.

Source:lenstip.com


Late 1970s test, Pop photo. See "transmittance". Multcoated lens.

 

[Film-Niko]

I think you may be referring to something else. AFAIK @Harry Callahan is talking about flare, in the sense of 'veiling glare', which does indeed reduce overall contrast by illuminating shadows that would otherwise remain darker.

As I have explained the physical background several times above, I will keep my answer short:
If Harry Callahan is talking about flare in the sense of 'veiling glare' he really should make a direct comparison of a lens showing such flare, and one which does not have that problem.
Flare is reducing detail. You see less details with a 'flaring' lens compared to a non-flaring lens. That is the reason why lens designers do all possible to avoid that technical flaw.
Therefore you cannot solve the inherent P30 problems with a lens showing flare. You will not see more real details in the shadows.