How Many Exposures Do You Need For HDR ?

Condensation X - Prelude

1 exposure

scenes like this won’t benefit from HDR

Incubation II

 3 exposures

scenes like this may be made with 1 exposure but benefit from more

Antarctica CXXX

5 exposures

scenes like this require HDR

How many exposures do you need for HDR images?

It depends.

It depends on the contrast ratio of the scene you’re photographing.

And, it depends on how many corners you’re willing to cut.

There is a case to be made for rendering all images with bracketed exposures. If the best data in a file is in the top stop of the dynamic range of a camera, then making one exposure per stop of dynamic range in the scene, each weighted to the top stop pf the camera (ETTR), will give you ideal data in every stop of the rendered scene, once the exposures are merged. So, ideally, you’d make one exposure per stop of dynamic range in the scene. In your first exposure place the shadows in the top stop of the histogram (to the right), without clipping. Then in subsequent exposures reduce exposure in one stop increments, making a new exposure each time, until the highlights are placed in the top stop without any clipping. Then stop.


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Paper / Substrate

Epson K3 ink on Luster and Watercolor compared

 

There’s an art to making paper. Since its invention, thousands of years ago, paper has had a long and interesting history. There are many ways to make paper and many kinds of paper. We’ve found many ways to use paper – architecture, furniture, crockery, fashion, sculpture, and of course the display of text and images in a variety of forms. Contemporary printmakers don’t print exclusively on paper. There’s also canvas, wood, metal, and plastic too. Anything you print on could be considered a substrate.

Substrate dramatically impacts print quality.

Substrate determines white – ISO brightness. The white of the substrate determines the brightest values achievable and the quality of the highlights in a print. Some substrates have bright cool whites, while others have duller warmer whites, some are so dull they look antique. Short of bleaching or coating a substrate with a brighter substance, this is something you can’t change about the substrate.

Substrate has a dramatic impact on ink limit, how much ink can be put down before detail begins to be lost. Droplets of ink spread when they come in contact with paper and dry. Dot gain specifies how much a dot spreads. A dot spreads more on an uncoated paper than it does on a coated paper. A dot spreads more on a matte paper than it does on a glossy paper. Consequently, fine detail is more precisely rendered on coated glossy surfaces. In addition, very smooth surfaces render subtler gradations, without interference from ink spattering or textured surfaces.

Ink limit has a dramatic impact on black – dmax. More ink, blacker black, higher dmax ratings. Using Epson UltraChrome II ink, dmax on glossy papers is approximately 2.4, 1.8 on matte papers. 

Ink limit has a dramatic impact on saturation – gamut. More ink, more saturated color, wider gamut. It’s important to understand where gamut is extended. The dmax and gamut on glossy papers is greatly expanded in the shadows and minimally reduced in the highlights. Put another way, glossy papers render significantly more saturated shadows and slightly less saturated highlights. 

Most inkjet substrates are coated. Coatings involve complex chemistry. Coatings reduce the spread of ink, allowing less of it to sink into the base and more of it to sit up on the surface. Most coatings contain drying agents to increase drying time and reduce dot gain. Many coatings contain optical brighteners to render brighter, cooler whites and more saturated colors. Some optical brighteners actually fluoresce, emitting more light than they receive. You can tell if there are a lot of optical brighteners on a substrate if you view it under a black light and it glows. Many optical brighteners are not stable and prints made with them typically display reduced longevity ratings. If print permanence is a significant concern avoid them.

Substrate has a dramatic impact on longevity. Different substrates yield different longevity ratings. If longevity is a significant concern, research the most current data. Visit Wilhelm-research.com for a wealth of information from one of the most definitive and respected resources. Remember, when comparing data on longevity from a variety of sources, testing conditions must be comparable for comparisons to be valid.

For best results, print on the coated side of a substrate. How can you tell? If you can’t tell from the orientation in the manufacturer’s packaging and you can’t see a manufacturer’s logo on the back of the paper, wet your lips and press the paper in between them, the side that sticks most is coated. A few papers are coated on both sides. Printing on the uncoated side typically yields soft under-saturated results. Printing on uncoated papers yields similar results. You can coat your own custom substrates with products like Ink Aid. (See my review at www.johnpaulcaponigro.com.)

Today, you have an amazing array of substrates to choose from. The astonishing array of choices available for inkjet printers today should suit almost every need. With a single printer, you can print on surfaces that span the gamut, from matte to glossy. You’ll find fiber, plastic, and metal. Uncoated, hand-coated, mechanically-coated. Machine-made or hand-made. Silk, canvas, foil, and transparent mylar don’t seem exotic in comparison to the most unusual substrates people have tried to feed through their printers. I encourage you to experiment. Use some caution in your explorations as very fibrous substrates may clog print nozzles and you can damage print feed mechanisms with very thick substrates. While I don’t recommend you use third-party inksets, I do recommend you test third-party substrates. Because of the enormous industrial infrastructure required to mass-produce paper, most printer manufacturers don’t make their own substrates but instead partner with paper manufacturers to produce materials to their specifications. There are many fine companies that make papers specifically for inkjet printing; Arches, Cranes, Hahnemuele, Ilford, Innova, Legion, Moab, Museo, and Pictorico are just a few. New materials are being released every year. Some have unique characteristics. My recommendation is that you test many substrates. Make test prints using a representative image that contains the full spectrum and includes a neutral step wedge with specific values that will help you determine minimum and maximum printable densities. There’s only one way to truly find out how the look and feel of a substrate will impact your work – use it.

Above all, remember that looking is a sensual act. Aesthetics may win out over technical considerations. While it’s useful to identify quantitative criteria (such as ISO brightness, dmax, gamut, ink limit, and dot gain) other qualitative aspects of a substrate may be as or more important. Substrates come in various weights; some are so thick they don’t need mounting while some are so thin you can see through them. Substrates have different textures; some are wavy or ridged, some are woven or cratered, some are fibrous or fuzzy, some are very smooth. Some substrates have distinctive edges, such as deckling or excess fiber. Substrates have different reflectivities; some are so glossy they are mirror-like reflecting everything in front of them as well as within them, while others are extremely matte exhibiting no surface reflections. The material characteristics of a substrate may carry specific connotations; one may look synthetic while another looks organic, one may seem commercial while another seems artistic. These qualities, in combination with one another, may be extremely useful for enhancing the expressive characteristics of your prints.

Research your options thoroughly to help you make more informed decisions before you commit your images to print. It will be time very well spent.

Read more on digital Printing here.

Learn more in my digital photography and digital printing workshops.

Ink

It’s complex chemistry

The science of ink formulation is one of the most significant, if not the most significant, factors driving the current inkjet revolution. Ink is complex chemistry. It’s colorants (dye or pigment varying in type and density), resins (protecting colorants and reduce metamerism), mediums (suspending the colorants), solvents (increasing viscosity to deliver it through tiny nozzles), and drying agents (decreasing drying time and reducing dot gain).

Consider the currently reigning inkset for professional photographic inkjet printing – Epson’s UltraChrome HDR. Epson UltraChrome HDR ink’s exceptional pigment density delivers supersaturated colors and dense blacks unprecedented in photographic output, able to be delivered in small droplet sizes (2-6 picoliters – a picoliter is one billionth of a billionth of a liter), smaller than the width of a human hair, so quick drying that droplets form a precise dot and prints emerge from printers essentially dry, water and ozone resistant pigment is encapsulated to reduce light refraction and abrasion. High Gloss Microcrystal Encapsulation Technology is formulated into the inkset’s suspension technology to make the print surface more uniformly reflective despite dramatic variances in ink density throughout a print. While counteracting the tendency for gloss to reduce as pigment content increases, gloss-optimizing additives also increase translucency allowing higher ink density and chroma.

Epson still leads the inkjet revolution. Recently, there are competitors whose newest solutions and their immanent evolutions deserve serious consideration and monitoring – Canon’s Lucia inkset and HP’s Vivera inkset.

Epson K3 on matte and luster

Dye vs pigment

While there are profound differences between dye-based and pigmented inks, the differences in image quality are frequently overstated and sometimes misstated. Years ago, pigmented inks suffered from reduced gamut (saturation) and dmax (maximum density or black) and increased metamerism. Today the differences lie largely in the areas of longevity and durability, where pigment still reigns supreme. (Cost may also be impacted, as dye inks are typically less expensive to manufacture.)

Multiple inks

To improve gamut and dmax manufacturers have been adding more inks to inksets; alternate colors (variants of offset’s high-fi orange and green, light cyan and magenta, or red, green, and blue) and additional blacks (blacks optimized for matte and glossy surfaces, light and medium blacks or grays) are used in combination with CMYK.

Do more inks yield better image quality? Typically. But not necessarily. Image quality is the result of a combination of a number of factors. To assess print quality, you have to assess the total printing solution – ink, profile, rendering intent, driver, screening algorithm, ink limit and substrate. Compare gamut, dmax, ISO brightness, neutrality, graybalance, metamerism, gloss differential, bronzing, gradation, fine line detail, longevity and durability. Both the physical makeup of ink and its application are important.

Gamut and dmax

The impacts of increased gamut and dmax are both easily seen. Gamut has a dramatic impact on color but not black-and-white print quality – more saturated color. Dmax has a tremendous impact on both color and black-and-white print quality – blacker blacks.

What is not obvious is that greater dmax extends gamut by increasing the saturation of dark colors.

Dmax and gamut figures for inkjet prints are at a photographic all time high. Both significantly exceed traditional print materials. (Dmax – silver gelatin 2.35, Epson UltraChrome HDR 2.45, Canon 2.5.)

Neutrality and graybalance

Inksets with multiple black inks not only deliver the best dmax, they also deliver the best neutrality and graybalance (consistent tint throughout the tonal scale). Producing truly neutral and consistently neutral colors with supersaturated inks is quite challenging; black ink becomes a stabilizing factor. While ink is an essential factor, it is not the only factor – driver’s and profiles play a significant role.

Highlight detail

Light inks, including light black inks, aid in the reproduction of highlight detail. They hold detail with not just smaller but also less visible dots.

Metamerism 

 Metamerism can be reduced with multiple black inks and heavier black plate generations (using more black ink to reproduce the image). Metamerism can be minimized by reducing the use more metameric saturated inks and increasing the use of less metameric neutral inks. Metamerism can also be subdued by coating irregularly shaped pigment particles with polymers, making surfaces more uniform and reducing light refraction. 

Gloss differential 

Gloss differential is an uneven sheen due to varying ink densities in highlights and shadows that affects glossy surfaces significantly more than matte surfaces. Gloss optimizing additives are incorporated into ink formulation to dramatically reduce gloss differential. It goes where ink doesn’t. It also counteracts the tendency for gloss to reduce as pigment content increases. It goes where ink doesn’t.

Sprays, coatings, and varnishes applied after printing can also help reduce gloss differential. When using these types of non-native chemistry guard against staining and poor adherence, the tendency towards additive failure (reduction of gloss, dmax, or gamut), and possible reductions of longevity. (Download a free PDF review of PremierArt’s PrintShield sprays at www.johnpaulcaponigro.com.)

Bronzing 

Inkjet prints may display bronzing (an iridescent flash of colors seen at different viewing angles particularly noticeable in neutral areas). Heavier black plate generation and alternate screening frequencies (dot placement) dramatically reduce this. 

Longevity

Dye ink achieves significant lightfastness and ozone resistance only with a limited choice of swellable papers, which are not water-resistant and prone to running in high levels of humidity. (Epson’s new Claria ink is an exception whose longevity ratings approach 100 years on a wide variety of substrates.) Pigmented ink offers superior longevity and durability with lightfastness, water and humidity resistance, and ozone resistance on all media (swellable, porous, rag). Inkjet longevity ratings are reaching new highs in photography (for color108 years, 166 years with PremierArt Spray – for black-and-white 284 years and 312 years with PremierArt Spray). (See wilhelm-research.com for more information.) Longevity is derived from a complex set of factors chemistry, adherence, lightfastness, and exposure are a few of the key elements. Where longevity is a concern, use tested materials whenever possible.

Durability 

Durability can be seen as separate from longevity or an extension of it. Ink plays a role. Pigmented inks are prone to scuffing and burnishing. Sprays can reduce this tendency somewhat. Related issues such as scratching, cracking, flaking involve ink but are often more attributable to substrate. Handle with care.

Switching inksets

Choosing an inkset limits or determines your choice of printer model. While some printer models can accommodate more than one inkset (generally not simultaneously), printers are usually designed for a specific inkset.

Avoid switching inksets in the same printer, such as dye with pigmented or the printer manufacturer’s inkset with a third-party manufacturer’s inkset. Don’t confuse this with swapping inks within the same inkset, such as different ink cartridges of the same ink or different black inks designed for specific substrates, such as matte and glossy. Different inksets inevitably contaminate one another producing unreliable results and frequent clogging. If you do switch inksets, be sure to thoroughly flush a printer of all residual ink before installing a new ink type.

Epson K3 verus Canon Lucia

Third party inks

There are a number of third-party manufacturers who produce both dye-based and pigment-based inks – Lyson, MIS, Generations, ConeTech, etc. It’s nice to have a choice. Many users are happy with them. While these inksets often offer significant savings over the printer manufacturer’s inksets, I’ve never been as impressed with the quality they deliver. Third-party inks are prone to clogging. Longevity is often questionable. Using them sometimes voids the warranty on your printer. Buyer beware.

The bottom line

While it is only one factor you should consider when evaluating print quality, ink is of paramount importance. Choosing an inkset is one of the most important decisions you can make when selecting tools and materials to make fine prints with. Research your options thoroughly and explore all the related variables carefully before committing your images to print. Continue monitoring this rapidly evolving field. Its arc has been so stunning that in less than a decade, inkjet printing has changed the nature of the photographic print.

Read more on digital Printing here.

Learn more in my digital photography and digital printing workshops.

Save 10% On Black & White Mastery Workshop / Dec 12-16

Suffusion XV

 Workshop

Black & White Mastery

December 12-16, 2016

Find out more here.

Test the latest Epson printers, inks, and papers. They’re the best ever!
Learn the heart of Adobe Lightroom & Photoshop including the latest advances.
This workshop closely follows the content of my most popular workshop, The Fine Digital Print Intermediate, diving more deeply into black and white imagery.
The Fine Art Digital Printing workshop series offers the most advanced digital printing workshops available anywhere. You’ll learn more in one week than you learn in a semester in college.

Register Now!

Save 10% / $160 – Register By Nov 18

Alumni, save an extra 10% / $160

25 Great Quotes On Visualization

quotes_visualization
Enjoy this collection of quotes on visualization.
“Visualization is daydreaming with a purpose.” – Bo Bennett
“Visualization and belief in a pattern of reality activates the creative power of realization.” – A. L. Linall, Jr.
“Try out your ideas by visualizing them in action.” – David Seabury
“Visualize this thing that you want, see it, feel it, believe in it. Make your mental blue print, and begin to build.” – Robert Collier
“Having a mental snapshot of where you are, where you are going, and what you are moving toward is incredibly powerful.” – Sara Blakely
“The harder you work… and visualize something, the luckier you get.” – Seal
Read More

Support Maine Contemporary Art – CMCA's 39th Annual Art Auction

2016-cmca-auction-1

Don’t miss out! Browse + Bid on exceptional works by 36 leading and emerging artists. A great way to support The Center For Maine Contemporary Art / CMCA and contemporary art in Maine. Auction online through Paddle8. All proceeds directly support CMCA.

Participating artists include …
Bo Bartlett, John Bisbee, Katherine Bradford, Emily Brown, Tom Burckhardt, Tom Butler, John Paul Caponigro, Caleb Charland, Ann Craven, David Dewey, Lois Dodd, David Driskell, Betsy Eby, Inka Essenhigh, Linden Frederick, John Goodman, Ken Greenleaf, Peter Halley, Charlie Hewitt, Tanja Hollander, Yvonne Jacquette, Alex Katz, Rollin Leonard, Amy Lowry, Kayla Mohammadi, John Moore, Paul Oberst, Winston Roeth, Kate Russo, Peter Soriano, Aaron Stephan, Joyce Tenneson, Don Voisine, Todd Watts, William Wegman, Dudley Zopp

View the art works here.