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Magnus W
27-Jul-2006, 11:35
All,

Apologies in advance if my question is somewhat stupid with an obvious answer to all the pros here.

I remember reading somewhere that slides/chromes are generally more sensitive to incorrect exposure than for example B&W film, where the latter would have a larger exposure latitude than the former. (please correct me if am wrong, in which case you can disregard the questions below)

1. If the paragraph above is true, does it then imply that the B&W film would have a greater tonality than a slide/chrome digitally converted into B&W?

2. Now to the real question (the answer to which might have large effects on my choice of film): Will there be a noticeable difference in tonality and exposure latitude between a scanned slide/chrome converted into B&W and a scanned B&W neg?

3. What are your recommendations? Do you regularly shoot slides and convert into B&W or is this the equivalent of a mortal sin?

Many thanks in advance.
/Magnus

Kendrick Pereira
27-Jul-2006, 12:20
Magnus,
Apologies in advance if my question is somewhat stupid but
what is "tonality"?

Exposure of slides is more critical than exposure of negatives because there is no printing stage at which any compensating for slight exposure errors can be made. With colour or monochrome negatives something can be done at the printing stage to salvage the situation, provided the negative is only slightly over- or under- exposed.
Colour slides are better slightly underexposed than overexposed but getting it just right is best and the latitude is small. Colour negatives are better slightly overexposed than underexposed -that leaves the printer a decently substantial density of negative to salvage something from.

Exposure errors also cause colour casts in colour materials, which is not much of an issue with monochrome. If the colour cast is slight something can be done to improve this also at the printing stage but if it's there in a slide it's there and there it is.

Copying i.e. re-photographing a slide or photographic print is not the same as photographing the subject in the first place. Brightly lit areas of the subject are imaged in the slide as thin areas with not much colour in them and in the print as pale areas ditto through which the backing paper shows. In the original subject the colour in these areas is just as saturated as anywhere else. Scanning digitised data into a computer presumably does not record the bright areas of the subject as "washed out" areas. Rather it would record data for the colour and data for the brightness. Photographing the original scene with a digital camera is equivalent to scanning it and should record more saturated colour in the bright areas than scanning a slide or print in which colour loss in these areas has already occurred.

I guess this mightn't answer your question but I don't quite understand your question. Sorry.

Marko
27-Jul-2006, 12:26
Hi Magnus,

Generally speaking, any conversion from analog to digital and vice versa (scanning included) introduces certain degree of degradation. Be it an image, a sound recording or anything else.

Next, negative film in general, be it b&w, chromogenic or color, has a larger exposure latitude than any slide film. There may exceptions, but I don't know of any. If there really are, I'm sure somebody here will chime in.

So, on to answering your questions:

1. You don't say what would be the output of your B&W film - conventional print or digital print after scanning it. Judging by the way you formulated the question, I assume your b&w-converted slide woud be printed digitally. If you'd print the b&w conventionally, I would wager on it showing a very visible difference.

2. If it were scanned as well, all bets would be off, depending on the skill factor of the operator. Again, in principle, any difference in analog should carry over and even be exaggerated after converting to digital, due to the inevitable losses introduced by the conversion process.

Since slide films have narrower lattitude, they should come out of the scanner containing significantly less detail than any negative film. On the other hand, silver b&w emulsions (as opposed to chromogenic ones) are more difficult to scan than any regular color film because the scanner CCDs "see" them differently.

Once scanned, the actual conversion from color to b&w should not introduce significant degradation, provided it is done competently.

3. Photography is an art, not a religion. Therefore, everything's allowed, just like in love or wars. If it works for you, then there's no reason you shouldn't be doing it. For me, discovering what works and what doesn't and how does it work when it does and why not when it doesn't is the best part.

But I bet some here will disagree and I'm sure we'll hear from them too. :D Which is great, because we'll both learn something from it. You'll find out the answers to your questions, and I'll get to test my understanding of the process...

reellis67
27-Jul-2006, 12:32
1) That is true because you only have what is there to begin with, and if the scan does not capture %100 of that information, then you will end up with even less.

2) If you are planning on scanning, I would suggest black and white print film. Others may disagree, but for me, having the most detail recorded would be the best option unless you have a specific need for a transparency.

3) I use black and white negative film, print it, and scan the print if I want to display it online. As for sin, it's a personal choice, there is no right or wrong as long as you are doing what you want to do for a reason that makes sense to you.

- Randy

Marko
27-Jul-2006, 12:48
2) If you are planning on scanning, I would suggest black and white print film. Others may disagree, but for me, having the most detail recorded would be the best option unless you have a specific need for a transparency.

Makes sense. But, on the other hand, starting with color film, either negative or transparency, would allow him to have both options and also to have more lattitude in conversion to b&w. E.g. play with filters, amplify certain colors or subdue the others, etc.

Negative film would still be more flexible, I think, except that slides tend to have finer resolution.

It also sounds like a good case for digital... Large format digital, of course, just so I don't test the tolerance limits here. ;-)

Kendrick Pereira
27-Jul-2006, 21:18
"Negative film would still be more flexible, I think, except that slides tend to have finer resolution."

I have often heard this said but have yet to be convinced that it is so. I have recently been projecting our 35 mm slides and also have a project going to scan a large selection and have 4"x6" prints made for our kids' photo albums. Ditto with colour and b&w negatives. The slides do not seem to my eyes to have finer detail.

By the way, Magnus are we talking of small slides [35mm or 2 1/4square] or large format transparencies?

Marko
27-Jul-2006, 21:48
"Negative film would still be more flexible, I think, except that slides tend to have finer resolution."

I have often heard this said but have yet to be convinced that it is so. I have recently been projecting our 35 mm slides and also have a project going to scan a large selection and have 4"x6" prints made for our kids' photo albums. Ditto with colour and b&w negatives. The slides do not seem to my eyes to have finer detail.

I'm not sure myself, that's why I said "I think". But on the other hand, I'm not sure you'd be able to see much of a difference on 4x6 either...

Myself, I prefer to go digital for projects like that anyway. :)

When I want to enjoy the process itself, I turn to 4x5.

Magnus W
28-Jul-2006, 01:59
Thank you all for taking the time to answer.

To clarify; I have no access to a wet darkroom so any prints would have to be made by way of digital.

Shooting in colour (I prefer slides) would allow me to have a colour image which can be converted to B&W in Photoshop (added flexibility). The basic question is whether this method would generate B&W prints of lesser quality than those from a B&W neg when the differences in film characteristics are taken into consideration.

Marko/reellis: I think you are hitting the nail on the head, at least as far as my limited knowledge goes.

Kendrick: The question is more of a general one, and I assume there would be no difference in outcome for different formats. Please correct me if I am wrong.

Marko: I agree this is a good case for digital (LF of course) as the final image would have been reproduced the least amount of times. There are of course other factors that detract from the digital systems that are currently available (price, resolution, iso, noise etc.)

/Magnus

Chan Tran
28-Jul-2006, 05:51
Most of the latitude you get from either B&W or color negative film comes from the fact that the film captures a much wider dynamic range than you can possibly put on photographic paper.

Kendrick Pereira
28-Jul-2006, 07:56
Magnus: I was just wondering if the comparison was between results obtained by scanning, say, 35mm colour slides and 4"x5" b&w negatives. I think the latter could be expected to deliver better image quality when you print from your computer. If your only concern is exposure latitude I think you are right about the same principles applying the same way to different formats: but you also ask, "Do you regularly shoot slides and convert into B&W or is this the equivalent of a mortal sin?" Exposure latitude is not the only consideration which bears on this choice though of course it might be the only aspect you are inviting attention to here.

Kendrick Pereira
28-Jul-2006, 08:30
Marko, My comment was not very well worded. It is only the greater fineness of resolution of slides that I am not convinced of. I agree that negatives afford more flexibility than slides.

The slides and colour negatives I refer to were taken 10 to 35 years ago. They are the records we have of that period, when we were bringing up our children. Of course we use digital for the equivalent of those snapshots now.

My impression that slides are no sharper than negatives is not based only on 4"x6" prints but also on larger prints of selected photos up to A4 from scan files from both slides and negatives as well as impressions formed by conventional projection of the slides [using a Leitz Prado with tungsten lamp and 120mm f/2.5 Hektor].

darr
28-Jul-2006, 09:17
Magnus: I shoot strictly color slide film with my walk-around medium and small format cameras for convenience. I will not get into all of my personal choices that led me to this over 30+ years of shooting, but I have them. Post processing to black & white via the digital darkroom is not terribly difficult if you have the proper software and went through the necessary learning curves on scanning and Photoshop. It can also be a personal taste issue.

When I shoot large format it is a different story. I pre select my composition and select the best film for the job. If I know that I want a black & white negative only, I will use black & white film, if I want more options, I'll shoot color slide film. I also shoot Polaroid 55 P/N for its own characteristics.

My job experience lies mainly in the composition of the thing photographed so someone that is a professional black & white printer may have a totally different take on the film from the start. For the work that I have produced, my technique has always worked and I guess that is why it is what it is. I will continue to shoot color slide film and post process to black & white if the composition looks better and my equipment at the time of shooting required a quick zoom lens or quiet rangefinder.

Here is a snapshot of a recent quick zoom shot I post processed to black & white because what I imagined at the time of shooting was more on the black & white look. Hope this post has been helpful in some way.

413 412

Kendrick Pereira
30-Jul-2006, 02:27
Magnus, you may have found the thread in this forum titled “Re: Shadow detail & flatbeds”. If not, what follows indicates some of the material in posts on it which I think might interest you.

In what follows the more widely spaced sequences of dots indicate passages of text omitted. The more closely spaced sequences of dots are as in the original post. Square brackets indicate an addition or emendation of my own which the author might not own - I suggest accessing the thread and reading the whole post.

Abstracted from a post by Tim Atherton: “The "d" means density. . . . and when measuring density that film records (as in contains valid image data), there is a minimum value (dMin), and a maximum value (dMax) . . . . Positive (transparency) film has a clear base...so the dMin for it is going to be quite low...as compared to negative film, which has a cloudy base...so the dMin for negative film will be quite a bit higher than positive film. Both films will pretty much have the same max density, black is still black, whether it's positive or negative film . . . . It's purely the film base "offset" that creates the difference in density range.. . . .(and so you don't need the same density range to get the info out of a negative film as you do from a transparency film) . . . . the same range . .[of subject brightness] . . could be recorded on either film...just that negative film would have the range compressed, film density wise that is, compared to positive film”

You might also find the contents of a post by Helen Bach on the same thread illuminating. Citing an example of a negative film “with a very wide dynamic range” Helen tells us it “can record about twelve stops of scene brightness range” and then gives some estimates of the density range on the film itselfwhich would result from this scene brightness range. She goes on to remark that if, when the film has been scanned, the full density range of the film is printed on paper (paper with a density range which she specifies), then twelve stops of scene brightness range will have been compressed to five and a bit stops of film density range and then expanded to about seven and a half stops of print density range.

I am not concerned with the specific figures Helen gives, though I have no reason to doubt them. My point is simply that this sort of compression and expansion does occur when transfers are made from one medium to another (O.K., the original subject is not a medium but I am sure you see what I’m driving at). The degree of compression from subject to film varies from one negative film emulsion to another and from one positive film emulsion to another depending on the chemical formulation. The exposure latitude of a film is intimately tied up with the subject to film compression of that particular emulsion. It is not the only factor involved but other things being equal or indifferent the greater the degree of compression the greater the exposure latitude i.e. the "softer" = less contrasty the film the greater the latitude.

We have therefore to put forward a third* consideration bearing on your original enquiry. Recognising that some negative films are more contrasty than others and the same with positive films the question arises whether, taking one film with another in each category, the chemists at Kodak &al tend to formulate positive film emulsions to be more contrasty than negative film emulsions.

The impression certainly used to be widespread in the amateur photographic fraternity that this is in fact the case. I have not heard it mentioned recently so I hesitated to put it forward in my first post.

The safest bet would be to expose colour negative film, choosing a soft film which can record a wide subject brightness range. Scan it. Adjust the contrast in the digitized image using your photo-editing software and print the desired density range# on the paper of choice.

This cautious policy should yield good or better than good quality almost all the time: but it is inherent in this practice of greater compression with consequent subsequent greater expansion that there could be very subtle low-contrast detail which is so thoroughly suppressed in the compression phase that it is no longer separable from the “surface noise” arising from the inefficiency of the equipment and so is not recoverable in the expansion phase. If you must have the best, the very best, quality there is nothing for it but to live dangerously on the edge.

*1) The possibility of correcting at printing stage affords the photographer using negative film a little extra latitude. I raised this when I was not quite sure what you were asking. I doubt if in the end it is of relevance to you. 2) By raising the density threshold without raising the density ceiling the relative opacity of the support reduces the density range of colour negative film. So what? Such compression of the density range as arises from this factor does not increase the exposure latitude of the film. If anything, it would tend to marginally impair it inasmuch as the density that your scanner cannot penetrate will be reached a little sooner due to the augmentation of the emulsion density by the relative opacity of the support. 3) A "softer" = less contrasty emulsion could give you a real increase in exposure latitude, other factors being indifferent (and why should they not be?).

#Helen Bach writes, “In most cases . . [the full density range of the film] . . would look rather dull. However, there is no need to print the full density range of the film. Typical colour wet print systems are designed to produce a print from the equivalent of seven stops of scene brightness range (depends on the film contrast and the paper contrast).”

Magnus W
31-Jul-2006, 01:54
Kendrick,

Thanks for the informative reply, I will re-read a couple of times to let it all sink in. Thanks also for pointing to previous threads, which I will dig out of the archives.

/Magnus

Kendrick Pereira
31-Jul-2006, 04:51
Magnus,
The thread “Re: Shadow detail & flatbeds” is a pretty current thread. In fact I wonder if Bruce Watson's post of 28th instant doesn't address your question head-on. I hadn't seen that post when I typed in mine.