Shadow detail & flatbeds

[Michael Heald]

Hello! I'm still confused about DMax the diffrerence between commercial flatbeds and drum scans when the final output is expected to be prints. I realize that the actual negative scans will show a large amount of difference. Will this translate into a large difference in the output print? At what size would it become apparent? This will probably even vary with the trraining of the viewer.

For example, ignoring sharpness for a moment and only considering Dmax, for a reasonably good negative that doesn't need much editing, what kinds of differences can one expect for a digital print for 8x10 through 16x20? I realize that variables need to be controlled such as paper, printer, and the skill of the operator, etc., but this applies to just about anything.

So, presuming these variables are constant (a big IF I grant you), what types of differences in the final print can be expected?

The reason I find this important for myself individually is to answer the question - how much am I willing to pay for a particular quality improvement in my photographs? This not only applies to scanning but to other equipment, training, skill development, etc. Thank you and best regards.

Mike

[Ted Harris]

Part of the problem is that I am not sure we are all using the same language throughout this thread. Bruce is absolutely correct and his statements are right on point but I am not sure that some of the questions are that absolute. I suspect that some of what Michael and Al and John are questioning is very subjective.

Michael, the variables that you note need to be controlled are huge and they start with the scan. How and where you set the white and black points for instance and whether you do it using a 'virtual' densitometer supplied with the scanning software or do it visually and how your selections would differ form someone else’s will set the amount of information in the scan at the high and low end of the tonal range ... and the way you do it can easily be very different than the way someone else does it based on a lot of externalities such as your ambient lighting and monitor or how carefully you monitor with he densitometer. It is impossible to just dismiss these variables.

Now for your second question which is the one we are all asking even if we don't say it out loud ... how much are we willing to pay for what level of quality? It's an individual decision. How do you make decisions on which lenses to buy? How your film gets processed, etc? The same sort of criteria should apply here. If you are doing this for your own enjoyment and $$ do count then the question should be how much can I afford to spend and is it enough to get me a print that I like? That answer can, of course, change over time. The differences we are talking about are similar to those you hear about a variety of different lenses of the same focal length or more to point about the differences of rigidity of various enlargers, quality of light from different light sources and differences in enlarging lenses. Just as a simple example the price range between a 'decent' older 150mm enlarging lens and the latest Apo Componon HM is probably $100 o $1500; where along this spectrum are you comfortable? I know that years ago a Componon worked fine for me and would it still be ok today now that I have seen the resolving power, etc. of the latest lenses? Personal choice. If, on the other hand, you are doing this for a living and your ability to snag the next job depends, in part, on being able to deliver images that are more compelling than those delivered by the competition you want to make sure you are not constrained by your equipment ... never forgetting that equipment will never substitute for talent and creativity.

Having said all this you might want to consider a few things: 1) take a negative that meets the 'normal' criteria for you and scan it on a 4990 or equivalent scanner then send it out to have the best scan possible made by a lab ... print from both and see if the difference matters to you; I do this all the time and know it matters to but I can also see as I keep saying that it may not matter to others for smaller prints if proper skill is exercised with the less expensive scanner. 2) From what I recall of past threads I believe you are self-taught, at least in this aspect of photography. You might want to consider some sort of training or workshop that will at least let you further develop your thinking on what you need and where you want to go. Not a semester in a University but a weekend or week. Doing this will also let you try out lots of equipment an exchange ideas and experiences (and even prints) with others. A workshop is probably the least expensive and most rewarding way to answer your questions. I'll sound my horn for a sec. For example, if you come to one of our weekend scanning/digital workflow workshops you will get to do exactly what I am talking about .... scan and print the same negative on a variety of scanners and papers and even different printers. With my new studio and workspace we will run some workshops here, in New Hampshire and that will mean that participants will have available several different consumer flatbeds and a Screen Cezanne so you will be able to do a real time comparison between the low end and high end equipment and decide for yourself on the spot if sending out for scans is worth it to you. Other workshop may also offer the same thing. You can also see if a full service printer will let you do some work there. Before I got deeply involved with digital imaging I spent literally weeks observing, working and listening to pros in three different prepress houses and labs. I got my early 'training' by bartering my skills in a traditional darkroom for their skills in the digital world. If there had been classes/seminars available then I would have taken them too.

Bottom line, others and I will keep sharing our experiences here but sooner or later you gotta hold your nose and jump in the water ... come on in, the water is warm and we will not let you drown!

[Michael Heald]

Hello! Ted, I'm hoping to attend one of your upcoming scanning workshops and I appreciate your input and guidance that I'ce received in this forum.

I amstill puzzled by the math, and it may be that the math is tripping me up. If a drum scan has a Dmax of 4, for a B&W image, that would yield 10 to the 4th power levels of gray, or 10,000.

If printing paper has Dmax of 2.4, then only 256 levels an be discerned on a print. If this is so, then does this mean that the 10,000 gray levels from the scan have to be condensed to the 256levels for the final print?

If I'm understanding this correctly (which I question), then the reason that a drum scan would produce a better print (or much better) compared to, say an Epson 4990, wouldn't have to do with the difference in Dmax between the two scanners (4.0 and 2.4), since they both would condense the gray scales down to the final paper DMax of 2.4 (unless a lot of editing is anticipated - the same reason to scan in 16 bit rather than 8bit?).

The reason to use a drum scan (of high end flatbed) would be the other factors that affect a scan, such as optical quality and the sharpness of a scan, mechanical quality to minimize vibration, and software quality for processing the raw images?

In other words, given a negative that doesn't require much editing, once the true DMax (not claimed/stated) of a scanner exceeds that of the output paper/medium, does this mean that Dmax becomes relatively unimportant and that the other variables then become much more important in evaluating a scanner's performance - such as optical and mechanical build quality? Best regards.

Mike

[Bruce Watson]

...presuming these variables are constant (a big IF I grant you), what types of differences in the final print can be expected?

You'll have to try it and make that decision for yourself.

The metaphor I sometimes use to descibe the differences is that of a window between you and scene. Think about the glazing you would use in framing. You can use hardware store plexiglas, Tru Vue Museum Glass, or something in between. At the low end is less than perfect optical performance (distortions, haze, glare, color shifts) while at the high end you get excellent optical performance. You can go to most framers and hold samples of the various glazing options in your hands and evaluate them yourself.

This is more or less what you are talking about as you go from low quality scans to high quality scans.

Remember too that the scan is the front end of the workflow leading to the print. Everything builds on it.

[robc]

I am still puzzled by the math, and it may be that the math is tripping me up. If a drum scan has a Dmax of 4, for a B&W image, that would yield 10 to the 4th power levels of gray, or 10,000.

Wrong! dmax 4 refers to density range and is expressed in logarithms. Dmax 4 means the the scanner can handle a neg/pos of density range 4 which is 12.3333 stops, each stop being 0.3 logD. A typical B+W neg usually has a density around 1.5logD i.e. 5 stops. A tranny has ??? someone will enlighten us but it is likely less than 4logD.

So scanner Dmax 4 means simply that a scanner is capable of pulling detail from something which has a density of 4logD.

Dmax has nothing to do with levels of gray. That is simply colour depth which is a function of the hardware and software and not the neg/pos

[robc]

Just to add:

the figure of 10000 which you calculated is the "opacity" of the neg/pos expressed as a relative term. i.e. it passes 10000 times less light than the clear part of the neg/pos.

4 is the base 10 logarithm of 10000.

Appendix 5 of AA's The negative explains all this in simple terms.

[Michael Heald]

Hello! I thought Dmax was the highest or whitest level that the scanner could detect a difference between adjacent light levels and Dmin was the darkest? For a Dmax of 4, the highest or whitest level would be 10,000 times more intense than the blackest? In this regard, I am using tone or white level only with regard to intensity or amount of light, and not to color or chroma.

With silver B&W, different tone is achieved by the build-up of silver. For a negative, the more silver, the darker the area and the less light is transmitted. For a print, the darker area, the less light is reflected.

For a B&W negative, if Dmin is 0.3 above base+fog, does this mean that that amount of light is 10 raised to the 0.3 less than the amount transmitted for the base +fog, or that one-half the amount of light is transmitted in thsi zone as is transmitted for base + fog? From what I've read, folks place this value on Zone 1 of the Zone System, so Zone 1 would darker than zone 0 which would be film base + fog. Is this correct?

Similarly, if DMax is 2.4, does this mean that that darkest area of a negative transmits less light than zone 0 by a factor of 10 raised to 2.4 or 256 times?

My main question regarding Dmax of scanners, however, is how much the expanded dynamic range is seen on the final print. Ink jet papers have about the same range is traditional silver based papers, am I correct? Once all editing is finished and the file is sent to be printed, the dynamic range of the file will still be compressed to what the paper can handle. Is this true?

Or am I confusing apples and oranges. Does the dynamic range of scanners refer to the same thing as for prints and negatives - the difference in the intensity of light from the darkest part of an image to the brightest expressed logarithmically? Thank you and best regards.

Mike

[tim atherton]

Hello! I thought Dmax was the highest or whitest level that the scanner could detect a difference between adjacent light levels and Dmin was the darkest? For a Dmax of 4, the highest or whitest level would be 10,000 times more intense than the blackest? In this regard, I am using tone or white level only with regard to intensity or amount of light, and not to color or chroma....

Or am I confusing apples and oranges. Does the dynamic range of scanners refer to the same thing as for prints and negatives - the difference in the intensity of light from the darkest part of an image to the brightest expressed logarithmically? Thank you and best regards.

Mike

This is from an old post - never sure if I get this exactly correct, but it goes something like this:

Unfortunate confusion of terms - use of the same or similar term to mean something very different. The "D" in DMax when used with regard to scanning isn't referring to dynamic range but density. Here is a definition I keep around to help me make sense of it...:

"First dRange... The "d" means density (and doesn't really have anything to do with dynamic range as such), and when measuring density that film records (as in contains valid image data), there is a minimum value (dMin), and a maximum value (dMax). The range between these two density points is the density "range", or dRange.

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.

Well, let's say the dMax (blackest part) of both films can be measured at 3.6...and the positive films dMin is .2; and the negative films dMin is .8... That gives a dRange for the positive film of 3.6 - .2 or 3.4, and for the positive film 3.6 - .8 or 2.8.

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)

For another discussion let's say that the same range of image tonality could be recorded on either film...just that negative film would have the range compressed, film density wise that is, compared to positive film. Also, the "dynamic range" of the film is not the same as the density range...and the term dynamic range is often misused when talking about density range."

any clearer... :-)

[Brian Ellis]

"Ink jet papers have about the same range is traditional silver based papers, am I correct?"

No, I don't think that's correct. According to Ctein (in his book "Post Exposure") traditional darkroom papers had a range on average of about 2.0 log units or roughly 7 stops. I've seen the results of tests performed by various people in the Yahoo digital black and white print group using a variety of different printers, inks, and papers and the best they're getting from ink jet is about 1.7 log units IIRC. So there's about a stop difference. However, I've always liked Dick Arentz' saying, which is something along the lines of "you don't need the blackest black, you just need a convincing black." Which is why I don't think the one stop difference is important, the black I get from my ink jet prints is plenty convincing (at least to me : - )).

[Helen Bach]

There are a few different questions in your post. I'll start with an attempt to answer

"My main question regarding Dmax of scanners, however, is how much the expanded dynamic range is seen on the final print. Ink jet papers have about the same range is traditional silver based papers, am I correct? Once all editing is finished and the file is sent to be printed, the dynamic range of the file will still be compressed to what the paper can handle. Is this true?"

Ink jet prints can have a wide spread of density ranges - from about 1.5 to 2.6, ie from less than most silver gelatin to noticeably more than silver gelatin. That's a quantitative comparison. The visual appearance of the tonal range depends on the image itself. A print with shadow detail in densities between 2.3 to 2.7 needs quite bright light to be fully appreciated, and wide density range prints are quite demanding technically because they show imperfections quite well.

When a file is printed nothing can be brighter than the paper base, and nothing can be darker than the D-max produced by the paper/ink combination. That can result in a compression or expansion from the original scene brightness range, just as it can be a compression or expansion from the density range of the film original.

If you consider a film with a very wide dynamic range, say Fuji Pro 160S, it can record about twelve stops of scene brightness range. This results in a density range on the film of about 1.6 for each channel (the overall density range is about 2.5 because of the density in the blue channel of of the orange mask).

As an aside: Typical colour neg films have a D-min of about 0.2 in the red channel and 1.0 in the blue channel, because of the ‘orange’ mask. D-max might be around 1.8 in the red channel and 2.6 in the blue channel.

The full density range of the film could be scanned then printed on paper with a density range of 2.3 (for example).

Twelve stops of scene brightness range has been converted to five and a bit stops of film density range then a print made with a density range of about seven and a half stops. In most cases, that 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).

Best, Helen