depth of field

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Blending Images In Photoshop For Increased Depth of Field


One of the most intriguing tools in Photoshop is layer alignment and blending. One practical use for these is macro photography – I have been experimenting with creating images that have depth of field that is nearly impossible to get in a single frame. (this post was originally written in Jan 09; updated Dec 09)

Why? Because a 105mm macro lens on a full-frame camera has depth of field of about 0.6mm at f/16 – in other words, a very, very thin slice. Combining multiple images with different focal points gives us – voila! ….a merged macro image that should be completely in focus.

Here’s how it’s done:

Use your camera of choice, preferably with a macro lens. Create the normal setup with the camera on a tripod. Set up or manage lighting, put the camera on aperture priority, and meter. I typically use mirror-up mode as well, and shoot with a remote. Shoot in RAW format if you can. (I used a Nikon D3 digital camera, and the new Nikkor 105mm Macro VR lens).

Typical aperture on these shots ranges from f/8 to f/16 in the 35mm class – higher f/stops tend to soften the image through diffusion error. Start at f/8 or f/11.

I usually work close to the lens’s minimum focusing distance.  I shoot several frames of the subject, changing the focal point to different parts of the subject, left to right and/or top to bottom. The camera must be absolutely still so that the frames will register with one another. If we could mark the focal points, they might look something like this:

Transfer the images to a folder on your computer. Open the folder with Bridge. Select the images you’ve captured (in this case four), press Command-R to open them in Adobe Camera RAW. You’ll see this screen:

Make your adjustments to the first picture only. Be conservative. Now click “select all” in the upper left corner of the dialogue, and then click “synchronize”. All of the RAW files will be updated.

Now click “Done” (blue arrow) in the lower right hand corner. Camera RAW will close and return to Adobe Bridge.

The four images will still be highlighted in Bridge. Go up to the main menu, choose Tools>Photoshop>Load Files Into Photoshop Layers.

The images will be loaded into a single Photoshop image with, of course, four layers. Open the layers dialogue and select all the layers.

Once this is completed (may take a while) go to the main menu, and click Edit>Auto-Align Layers. You’ll see a bigger dialogue, again just click Auto.

Once this is finished, go back to the Edit menu, click Edit>Auto-Blend Layers. Click on Stack Images, and Seamless Tones and Colors. Click OK.

Photoshop will launch into an analysis of all the layers, create layer masks to use the best portions of each layer, and blend the images. You should see an amazingly sharp image with significant depth of field. This is truly something new under the sun! Here’s an example:

flower red combo 1 copy final

My good friend photographer Ted Dayton told me about this, and I should add one of his points here: “take more pictures, with more focal points, than you think you need.” He’s right – once the images are blended, you’ll see the difference.

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Medium Format Gaining on DSLRs – Part Two


I’ve received a number of emails and comments regarding changing attitudes among photographers regarding medium format digital vs. DSLRs. Seems to me, first of all, that it’s not about the equipment. My daddy used to say, “it’s not the car, it’s the nut behind the wheel”. That said, I find that I can often see the difference between medium format (MF) images I’ve created, and those taken with a DSLR. My own approach has changed quite a bit; I think it is fair to say that I use my MF cameras much more nowadays than the DSLRs.

Some of the things I notice are sharpness, resolution, acutance, dimensionality, subtleties in tone transitions, and detail in shadow/highlights. In some cases, a MF lens will also show a difference in bokeh (smoothness of out of focus areas). In all of these, excluding the last item, I feel it is a combination of factors that makes up one’s perception of “difference”. For example high acutance coupled with low resolution looks much different than a situation where both are high. (a typical look for the former is a so-called “over-sharpened” image with that crispy look with lots of edge halos).

At the end of the day, images I’ve made with my MF cameras usually look quite different than those from the DSLR world – this is particularly the case when I’ve made a large print. The image below communicates some of these in spite of the limitations of computer screens. In print, it has amazing depth and dimensionality, and impressive detail in the leaves and textures in the rocks.

Columbia River Gorge

Columbia River Gorge

Hasselblad H-series camera body, P25 back, 100mm lens, f/11, approx one second exposure. It is true that one can make a very “sellable” image using a high-end DSLR. But can one achieve that look, that feeling of a unique image or print that one can almost walk right into? Doesn’t this affect both creative approach and one’s competitive position in an environment that challenges us all? And what about client’s perceptions? Haven’t many of use had the experience of a client choosing a photographer who owns MF digital vs DSLR? Does this set one apart from the pack? Thinking back, it’s made a difference for me – I’ve made far more money with MF than I ever have with my DSLRs. I’m working right now on a tour of seven cities, teaching use of MF digital cameras, high resolution printers, fine art printmaking, and art reproduction. The interest from photographers in MF is intense – something of a wake up call, in fact. More to follow.

Here’s a recent review of the Mamiya AFD III with the Leaf Aptus digital back.

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New Series: Getting It Right In the Camera – Managing Depth of Field

We have a new guest author joining us. Ted Dayton (teddaytonphotography.com) has decades of experience as a commercial photographer, shooting celebrities, fashion, stock, product, architectural, and others with great success.

 He is one of the best photographers I know, producing work that is distinctive and meticulously crafted. He is also President of the Santa Clarita Photographer’s Association, and a graduate of Brooks Institute of Santa Barbara.

 In this article, Ted discusses Depth of Field, one of the key issues surrounding the topic of “Getting It Right In the Camera”.

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Popular Myths About Camera Lenses and Depth of Field

There is a myth that wide-angle lenses provide more depth of field than long lenses.

I would like to set things straight, as some readers may still be believers. We tend to use wide lenses and long lenses very differently and our perception of their relative Depth of Field properties is affected accordingly.

Wide lenses seem to have more Depth of Field because we tend to use them in ways that do in fact provide a lot of depth of field. We tend to back away from our subjects so we can see a wide view of things. This distance-to-subject dynamic affects Depth of Field as much as aperture setting does.

The lens is focused closer to infinity than for close-ups, and all lenses and all aperture settings provide greater Depth of Field as the plane of focus approaches infinity. We also tend to stop down when using short lenses in order to include as much information (sharpness) as possible in support of our wide view of things. So, we think of wide lenses as providing the greatest amount of Depth of Field.

With long lenses, we tend to shoot closer to a wide-open aperture for many reasons. Stopping down requires longer shutter speeds, which lead to shaky pictures if taken hand-held. Long lenses are harder to hold still and faster shutter speeds that are accessible when shooting closer to wide-open solve the problem.

And, long lenses are great for isolating distant subjects from other elements, especially if we use them, ahem, wide open. And so we think of long lenses as producing less Depth of Field than shorter lenses because most long lens photos we take do have shallow Depth of Field.

But it isn’t so!

Try this exercise on your own: put some common object like a basketball on the table in the backyard and take pictures of it with lenses of all focal lengths. Shoot all of these pictures at the very same aperture and fill the frame the same amount with the ball in every single frame.

Look closely when you edit and you will see the same amount of Depth of Field in every frame regardless of focal length, because of two things: the aperture setting didn’t change and the size of the ball in the frame didn’t change. This test is easier to understand if you use a fairly large aperture, like f/4. If you focus on the nearest part of the ball with a 28mm or a 200mm, the rest of the ball behind the plane of focus will be equally out of focus no matter which lens you use! (note: we did not provide an image example because we feel it is important for readers to perform this exercise and see this for themselves – David)

Summary

Depth of Field is a function of aperture setting PLUS the distance from the camera to the subject. You will soon discover that aperture setting is not the only reason why backgrounds are nice and soft or too much in focus.

The relationship of the distance from:

  • camera-to-subject
  • camera-to-background
  • subject-to-background

 ALL affect how in- or out- of focus the background appears.

 Backgrounds far away when the subject is close to the camera will be very out of focus and backgrounds close to the subject will be much more in focus.

 Said another way, the closer you get to the subject, the more you must stop down the aperture in order to see a given amount of Depth of Field. 

The farther the camera is from the subject in focus, the closer to wide-open you can shoot while still getting deep Depth of Field. As I said before, distance-to-subject has about the same effect on Depth of Field as aperture setting. How we use our lenses creates our perception that they don’t all behave the same way, but the laws of optics and 35 years of experience say that they do!

Ted Dayton, Valencia, CA

NOTE: NEW PHOTOSHOP WORKSHOPS TAUGHT BY DAVID SAFFIR – First session is Turbo Portrait Retouching, July 19, Santa Clarita, California. For more info, go here.