Tag Archives: exposure

Link Roundup 07-02-2010

Link Roundup 06-19-2010

Link Roundup 03-31-2010

I’m trying something new with the link roundups, so bear with me while I get it all figured out. This post is testing the Postalicious plugin — it basically taps into my Delicious stream and generates a link roundup based on a set of parameters. I bookmark a lot of stuff anyway, but since separating out my Twitter accounts, I’ve been much more active (and collecting many more bookmarks).

Like I said, I’m still figuring out how I want to do all this. If it goes as I hope, I’ll be sharing fewer links more often with less work.

How to Read Image Histograms

Reading histograms is an important skill to acquire in the world of digital photography. Most images from digital cameras will require some amount of post processing, particularly if you shoot raw format. And most of the processing can be done by viewing the aesthetics of the image as you go, but having the ability to read and manipulate a histogram will increase your productivity and output quality.

So what exactly is a histogram? And how the heck do you “read” one? Take this, for example:

At a glance, it doesn’t tell you much. But there are certain things that you can take from the histogram. No, it doesn’t tell you that it belongs to a photo of a deserted trailer half buried in the middle of the desert. It doesn’t tell you if the image is in focus or if your composition is good. It only tells you the tonal values of the pixels contained in the image — blacks on the left, whites on the right.

For this article, I’ll be looking at a black and white image and histogram in order to simplify things. Color histograms work on the same concepts, but with 3 channels rather than one.

MID CONTRAST AND BRIGHTNESS

This is pretty much a straight b/w conversion with no contrast or brightness adjustments. It doesn’t look too bad, but it isn’t terribly dynamic either. And if you look at the histogram, you’ll see that the pixels fall into a centered group with a little breathing room on the shadows and highlights. We’ll use this one as our baseline to compare against. The other histograms will show this in a transparent green.

LOW CONTRAST

You can visually recognize the lower contrast in this image, and that correlates to a change in the histogram distribution. The pixels near the black and white points have moved in toward a neutral gray, which gives the appearance of lower contrast. The whole thing has basically been squeezed to the center.

HIGH CONTRAST

Again, you can visually recognize the higher contrast in this image, and the histogram changed too. The pixels near center have basically migrated outward toward the blacks and whites, thus giving us more contrast. This time we’re squashing pixels from the middle outward.

LOW BRIGHTNESS

Lower brightness is just a shift of tones toward the black region. You can see that the entire histogram has been pushed to the left. Also notice that the tonal range has been decreased, as shown by a narrower histogram.

HIGH BRIGHTNESS

Higher brightness is a shift in tones toward the white region. Here you can see that the entire histogram has been pushed to the right. Also notice that the tonal range has been increased, as shown by a wider histogram.

THE FINAL IMAGE

You can see that I went with a high contrast, high brightness image for my final path. The histogram shows this with the wide tonal range and a heavy concentration of pixels in the highlights.

CAN YOU SEE IT NOW?

This chart shows a combination of contrast and brightness adjustments on the example photo. As you move from left to right (low brightness to high brightness), you can see the histograms shift to the right. As you move from bottom to top (low contrast to high contrast), you can see the histograms widen.

Click the image for a larger version

The reason I’ve posted this article is because I want to get into the topic of manipulating the histogram during post processing — using it to guide you in what adjustments to apply. So the next article will look at how some of the basic adjustments affect the histogram and the image. We’ve already covered contrast and brightness adjustments here, but there are a few others we’ll need to utilize.

In the meantime, here’s some additional reading on the topic of histograms:

Working With Image Histograms
Photoshop Tip: Understanding Histograms
Camera Histograms: Tones and Contrast
A Practical Guide to Interpreting RGB Histograms

Double Exposure Tips and Photos

In the world of artistic photography, double exposures can result in some very interesting stuff. Some can be well thought out compositions with shapes and exposures meant to compliment the other frame. Others can be happy accidents that exhibit a magic mixture of luck and randomness. In either case (and any case in between), a good double exposure catches the viewer’s attention and presents a distorted reality that would not be possible to see without a camera.

Here are a few tips to get you started with double exposures.

  • Pay attention to shadows and highlights in each exposure. You’ll notice that large areas of shadow on one exposure will allow the highlights to show through from the other exposure. If you line up shadows on both exposures, you’ll get little detail due to underexposure. If you line up highlights from both exposures, you’ll get a faded looking image with low contrast.
  • Try to keep at least one of the exposures rather simple. Two busy exposures will typically result in chaos and make everything harder to see (unless chaos is what you’re going for).
  • To create a “ghost”, put the camera on a tripod and take the first exposure. Then remove or add objects or people and take the second exposure without moving the camera.
  • If you wan to go the film route, don’t forget to underexpose by one stop for a double exposure (2 stops for 4 exposures, etc). And make sure you know how to double expose with your specific camera.
  • If you want to go the digital route, one method is to underexpose as you would with film (or do so with post processing) and apply a screen layer blend (which essentially mimics the process of projecting two slides onto one screen). More details on the digital process in this article: Digital Multiple Exposure.
  • And most of all, experiment and have fun with it. Over time, you’ll get a sense for how the two exposures work with each other and you can really start to form the final image to your intent.

And here are some pretty awesome multiple exposures from Flickr. Most (if not all) of these were done with film. If you have some double exposures of your own (and/or tips for double exposing), drop them in the comment section below the article.

I am what I have found
Creative Commons License photo credit: FilmNut

raina
Creative Commons License photo credit: cx33000

Alien Sunset
Creative Commons License photo credit: Brian Auer

Some Time on Earth
Creative Commons License photo credit: *it’s not a cabaret

Britain in Bloom
Creative Commons License photo credit: slimmer_jimmer


Creative Commons License photo credit: moominsean

Office building
Creative Commons License photo credit: Andrea [bah! la realtà!]

double exposure
Creative Commons License photo credit: depinniped

Church of St. Thomas the Martyr
Creative Commons License photo credit: teotwawki

Towers over Tribeca
Creative Commons License photo credit: gaspi *your guide

ghosts
Creative Commons License photo credit: twinleaves

Bursting WindMill
Creative Commons License photo credit: FilmNut

Exposure-Blend and Shine-Be-Reduced Photoshop Actions

This article and project entry comes from Martin Kimeldorf. The content in this post comes from the PDF documents that Martin put together for his actions.

EXPOSURE BLEND

Exposure Blend Example, by Brian Auer

Photo by Brian Auer showing (L) under exposed, (M) over exposed, and (R) exposure blended image using Martin’s action.

Most people find the outcome of my little action to be very similar to Photomatix… certainly cheaper… and I think a bit easier since you just mouse click away. I don’t charge for this action as re-payment for all the people who helped me along the way.

Put the camera in Aperture Priority or Manual and set to your preferred f-stop and ISO. Use auto-bracketing to take three frames with different exposures: normal, under exposed, and over exposed. Make sure the auto-bracket is set so the images are at least 1.5 stops apart from normal.

The following notes are also embedded in the action to prompt you.

Prepare a file with two images labeled as Under and Over Exposed. Place both the under exposed and over exposed image in a new Photoshop file. Neither file should be locked as a background layers, so unlock any background layer by double clicking on them. Make sure the over exposed layer is labeled as such and sits on top of the under exposed file.

In the end you will get 3 image version to choose from:

1) The basic Composite or exposure blend
2) the same composite with shadow recovery applied
3) The shadow recovery image with soft light blend applied for more contrast.

You then take your final image and apply noise reduction if needed and then sharpen.

DOWNLOAD THE ACTION
DOWNLOAD THE PDF FOR MORE INFO

SHINE-BE-REDUCED

Install this Action in your Photoshop program (see sample at the end). Run the action, and then “paint away” the shine from the areas that offend your sensibilities. Paint away distracting shines from flash on nose, cheeks, foreheads.

Most people leave shines on hair and lips and pupils. This will be done by creating a second duplicate layer over your original layer. Then you can brush in the amount of “shine removal” that you want. Here are the steps to follow for removing the shine, AFTER the action is run.

1) A new adjusted layer is placed above your original, and is masked (blacked) out.
2) While viewing at 100%, select a soft WHITE brush, Set the brush so it is slightly larger than the shine area, and Set brush opacity to 30% opacity
3) Then paint over the shine…on the black layer mask.
4) For real finesse, select the layer mask by holding down the Command Key and click on the layer MASK. This will make the selection come alive with marching ants. Then apply a Gaussian blur of about 4 to this mask to soften the edges.

DOWNLOAD THE ACTION
DOWNLOAD THE PDF FOR MORE INFO

Cross Processing Tips and Suggestions

XPRO

It’s no secret… I love film photography. But if there’s one thing I love more than film, it’s cross processed film. There’s something so intriguing about it — adding a touch of unpredictable to the imperfect nature of film. Many photographers tend to either hate it or love it. Some love it so much that they attempt to recreate the look with Photoshop.

I’ve had this article on the half-finished backburner for a while. I figure we’ll take a slight detour from the photo backup series and get this one out there. One reader recently commented on another cross processing article, asking some questions about it. So I’m guessing that at least one person will find some of this useful.

Here are some tips for choosing films to cross process, exposing the film, getting it developed, and color correcting it. So grab a cheap film camera start cross processing!

WHAT THE HECK IS CROSS PROCESSING?

It’s a beautiful thing… simply put, you shoot a roll of film (most commonly slide film, or E-6) and develop it as if it were something different (most commonly color negative film, or C-41). Intentionally processing a film in the wrong chemicals. Doing this with slide film works out well for several reasons: the results are very cool and C-41 processing is much more available than E-6.

DIFFERENT FILMS = DIFFERENT RESULTS

Darkness Creeps InWe Have LiftoffThe Wind CatcheruntitledjesusLanterns

The largest differences in the outcome of your cross processed photos have to do with the film you’re using. Each film has it’s own unique look, and they can vary drastically. The most obvious difference is the color cast produced during development. Here are some results from those that I’m most familiar with:

Kodak EktaChrome (or EliteChrome) = very green
Fujifilm Velvia 50 = green + some blue
Fujifilm Velvia 100 = very red + some magenta or yellow

And here are some others that I have yet to try:

Fujifilm Sensia 400 = blue + green
Fujifilm Sensia 100 = red
Fujifilm Provia 400 = green + yellow
Konica Centuria 100 = little color cast

It’s also worth noting that different developer solutions will have slightly different effects on the outcome of the film. For any given slide film that can be cross processed, I’ve seen a vast array of colors show up from different photographers.

UNDER-EXPOSE BY ONE STOP

Color slide film has a lower dynamic range than color negative film. On top of that, cross processing tends to boost the contrast between highlights and shadows, thus requiring that you properly expose your shots. But cross processing (in my experience so far), tends to over-expose the film by about one stop. The first few rolls I got back were overexposed — some being unusable. So I figured out that if I underexpose the shots by one stop, I got better results with the exposure of the developed film.

To underexpose by one stop, you just have to set your ASA/ISO value to double what it should be (assuming that you have a light meter on your camera). So if you’re shooting with ASA100 film, set the camera to ASA200. This makes the camera “think” that you have a faster film loaded, so it lets in less light.

FIND A GOOD PHOTO LAB

Cross processing requires the C-41 process, and most of us aren’t equipped to do this ourselves. However, just about any lab that develops film will have this capability (since it’s the most common process for consumer film). The tricky part is finding somebody who will cross process your E-6 film as C-41 film.

When film is developed, a lot of chemical reactions are taking place. The end result is a stable piece of film with an image on it and a bunch of extra “stuff” that gets left in the developer solution. Developer solutions have to be changed out on a regular basis to continue to work properly.

From what I understand, developing slide film in C-41 chemicals can leave behind stuff that normally isn’t left behind. I don’t think this does a great harm to the solution or to the other film being processed in the developer, but shops with less-experienced technicians will shy away from cross processing because of this. You’re better off finding somebody who knows their stuff.

It’s also recommended that you find a shop with a higher volume. Developers that are used more often have their solutions changed out more often. For example, I’ve got a place downtown that changes the solution every day, and they have no problem cross processing as much as I want. But my local place has a lower volume and they only change out the solution once per week. They’ll cross process for me, but they ask that I don’t bring in more than a couple rolls at a time.

CORRECT THE COLORS WITH WHITE BALANCE

As I mentioned above, cross processing can produce some very strong color shifts in addition to other things. Sometimes these color shifts work really well with the subject and you’ll want to keep them. But other times, it’ll be too much an you’ll want to back it off a bit. This section is aimed at those of you scanning your film and processing the digital files (but this can also be done in the darkroom).

The best tool that I’ve found for this is the white balance adjustment found in software such as Adobe Camera Raw or Lightroom. A color curves adjustment in Photoshop might be slightly better, but the white balance is so quick and easy in comparison.

For photos with a strong green color shift, increase your “tint” into the magenta region (or away from green). Depending on the film and the specific color shift, you may also need to adjust the “temperature” toward yellow or blue to take care of secondary color shifts left behind.

For photos with a strong red shift, move your “tint” into the green region (away from the magenta). Again, you may have to adjust the “temperature” to clean up the rest of the colors.

The same rules apply with yellow and blue color shifts — just move adjust the white balance in the opposite direction. So basically, you’re just evaluating the color shift of the photo, finding that color or combination of colors in your white balance adjustment, and compensating for it by negating the colors.

Another thing that works well with Adobe’s raw processor is the White Balance Tool even with cross processed film scans. Just find something in the photo that “should” be a neutral gray and sample it with the tool. This will adjust the white balance for you, then you can fine-tune it from there. I usually like to leave a bit of color shift in my photos (and sometimes all of it) — if you go too far with the white balance adjustments, you’ll start to see weird colors showing up in those neutral gray or white areas.

JOIN AN XPRO FLICKR GROUP

If you’re on Flickr, one of the best ways to get excited about a topic is to join a group dedicated to that topic. Seeing the photos and reading the discussions is a great way to get inspired and educated. Here are a few cross processing groups:

XPRO CROSS PROCESSING
Cross Processing – XP – XPRO
Kodak Xpro
Cross Process Masterpieces
Cross Processing Anonymous

Other than that, all I can do is suggest that you get out there and try things out for yourself. Try different films, different cameras, different developers, etc. Cross processing can be quite interesting, as it adds to the “unknown” factor already inherent in film photography.

For you seasoned cross processing film photographers out there, what other advice would you give to photographers just getting into this stuff?

Link Roundup 06-28-2008

  • the Nuts and Bolts of off-camera flash – part 2, manual flash
    F/1.0
    A really great review of the methods for firing an off-camera flash unit: various connectors, wireless, etc.
  • Understanding Camera Exposure Modes
    Beyond Megapixels
    Although your camera may have a light meter built right into it, you still have some options for how that meter reacts to different situations. Here are some of the basic modes for exposure.
  • Jowling – Photography Fun For a Rainy Day
    digital Photography School
    It’s both funny and frightening what we can do with a human face and a camera.
  • Thomas Hawk’s Photography Workflow
    Thomas Hawk’s Digital Connection
    Thomas offers up some insight to his photography workflow using Bridge, ACR, and Photoshop. Definitely some good tips and insights — especially coming from a guy who posts around 30 new photos each day.
  • My new geotagging workflow
    All Narfed Up
    Bryan guides us through his new geotagging workflow using the Amod AGL3080 and Lightroom on Windows. If you’re thinking about adding geotagging capabilities to your workflow, definitely check this out.
  • 10 Steps to Maintain Your Camera
    HyperPhocal
    Cleaning our gear is something we should all consider making a part of our recurring activities. Here are 10 tips for keeping your equipment clean and clear of problems.
  • Matt Kloskowski Shares His Wishlist for Photoshop Features
    Photoshop Insider
    Matt does an awesome job at laying out some useful features that Photoshop could possibly have in the future. He even goes so far as to mock up the dialogs and layouts of the tools he’s dreamed up.
  • Do High-End Cameras Make You A Better Photographer?
    JMG-Galleries
    A philosphical discussion about the age-old question “is it the photographer or the camera?” Definitely some good insights shared in this post and comments.
  • 10 Tips on Getting Your Photos Into a Gallery Show
    HyperPhocal
    Getting started with gallery shows can seem impossible for a beginner, but here are some tips and methods for getting your work on the public wall.
  • 10 things I hate about Flickr (and its users)
    Neil Creek
    Neil posted a very interesting article about Flickr, Flickr comments, and Flickr users in general. Though he mentions the things that he “hates”, the article is intended to point out some of the flaws in the system and the way people use that system.
  • And here’s a fun theme slideshow that I found to be extremely creative. Found via Photojojo.


looking down. from hrrrthrrr on Vimeo.

Brushing Up on the Sunny 16 Rule

Wait .. Don't go !!
Creative Commons License photo credit: Kuw_Son

With digital cameras today, there’s almost never a need to “guess” or estimate exposure settings. Even so, you may eventually find yourself having to ignore your light meter and take the situation into your own hands. Or perhaps you’ll end up falling for film and buying an old camera without a light meter. Either way, having the ability to set exposure without the assistance of a meter is a good skill to acquire.

USING THE SUNNY 16 RULE

  1. Gauge Your Light
    For the Sunny 16 Rule to work, you’ll first need a sunny day. The rule can also work with other lighting situations such as cloudy and overcast — take a look at the next list for those.
  2. Set Your F-Number
    Set your f-number to f/16. If you don’t have strong sunlight, use the next list to determine your starting f-number.
  3. Set Your Shutter Speed
    Take note of your ISO or film speed (let’s call it “X”). Now set your shutter speed to 1/X. So at ISO 400, you’d use a shutter speed of 1/400 seconds.
  4. Adjust With Reciprocals
    You may want to use different shutter speeds or f-numbers. You can adjust one as long as you adjust the other accordingly. Opening up by one full f-number requires cutting your shutter speed in half (and visa versa).

VARIATIONS ON SUNNY 16

  1. f/16 for Sunny
  2. f/11 for Slight Overcast
  3. f/8 for Overcast
  4. f/5.6 for Heavy Overcast
  5. f/4 for Sunset

F-STOP GUIDE

Since most cameras offer full stops, half stops, and third stops, you’ll need to have a handle on which ones are full stops so you can use the rule of reciprocals to change your f-number and shutter speed. Here’s a list of full f-stops.

f/1 – f/1.4 – f/2 – f/2.8 – f/4 – f/5.6 – f/8 – f/11 – f/16 – f/22 – f/32 – f/45

But you don’t need to memorize these numbers — there’s an easy little trick to them. You actually just need to remember two numbers: 1 and 1.4. These are the first two full stops in the list. Double them and you get the next two in the list. Double those and you get the next two numbers. Check it out:

1.0 – 2.0 – 4.0 – 8.0 – 16 – 32
– 1.4 – 2.8 – 5.6 – 11 – 22 – 45

You’ll notice that twice 5.6 isn’t exactly 11 and twice 22 isn’t 45. This is because the bigger numbers are rounded and the starting number isn’t exactly 1.4 — it’s 1.41421356… or the square root of 2.

Further Reading

Here are some additional resources having to do with Sunny 16 Rule and exposure.

The rule really works — if you don’t believe it, go try it out with any camera that has manual controls. I’ve been using the rule with my 1956 Minolta Autocord Twin Lens Reflex (no light meter) and it performs flawlessly.