Can you really fix bad focus?

I managed to capture a couple of parrots in flight, but they where very close and the light in the forest wasn’t great. I was panning ok but the speed of the bird and the slowness of the shutter and not to mention autofocus cranking away. Ok The birds swooped in and I had little time other than your pick up the camera follow the bird and push the shutter. The result was clearly out of focus birds, yet the composition and action was interesting.
Can I recover the focus? My experience has always been I Can Not! Normally such photos get culled as they are first uploaded.

It just happens that Corel are promoting their registration and support with a link to their new 64 bit add-ins and two of the add-ins caught my eye. The first was Wavelet Sharpen 3, which use a larger radius Unshapen Mask (USM) as well as the wavelet sharpening algorithm popular in GIMP. But such sharpening usually enhances the noise, so Wavelet Denoise also looked interesting. It brings the common controls over both luminance and colour noise filtering. With a little back and forth adjustment between these two add-ins and I was able to bring the images to a better “not quiet in focused” state albeit with some grainy artifacts in the background and some haloing. Definitely not in focus but more acceptable. However I can see there is a lot of power in these tools.

Big Hint: Normally I would recommend using manual focus when panning after birds in flight and have any anti-shake of stability adjustment turned off. Of course you need to pre-set the focus to roughly the distance you expect the bird to be and there is a limit on to how slow you can let the shutter exposure be. (for most of us the limit is something like 1/60th. second) so in low light that means a higher ISO (eg 800)

PhotoProject :: Focus Stacking

This month theme for the 12 Months with Matt Kloskowski group on flickr (its a private group for those that have upgraded or purchased OnOne’s Perfect Photo Suite 9) is photo stacking, something I have never tried. I was have lunch at a favorite stopping point and could see a perfect place to try out the technique. I opened up the aperture as far as it would go (just f 5.6 on this kit zoom lens, my good lens has a broken mount), in the mistaken thinking I could challenge myself. (opening up the aperture reduces the depth of field)


The first spot I picked to try out the focus stacking series had some good point of interest from the bluff in the background the beach and waves an the foreshore vegetation and then the fence. Trouble was the stiff breeze (aka gale) was straight from Antarctica. So the reeds in the foreground here dancing around and the waves are pounding in. Not to mention my fingers where freezing. (the google photo auto-gif doesn’t record how cold it was). The other important issue I realised as I took these photos was I realised I was taking the series hand held in the wind, which was likely to make merging the photos a challenge. I walked along a bit further and found another overgrown fence post with a view down to the beach. Having warmed my hand in my pockets and braced myself against the wind I took another three set. Firstly focussed on the distance, then focused on the near beach and finally the vegetation on the post.

Distance Focus	Near Beach Focus	Vegetation on Fence Focus

These are not the only photos I took but they appealed to me most to bring together a number of points of interest at different distance and still have an interesting composition. The photo still bounce around a bit (compare the horizon and exposure of the sky) and I did have to be patience adjusting the images to fit (this is because I hand held the camera) using the Transform Tool in Perfect Layers. Would have been a lot easy if I’d used a Tripod. The actual blending of the layers was easy, even though the images have noticeably different exposure. I use 50-75% feathering between the distant and near beach layers but only 25% feather and a smaller brush to lift out the fence and vegetation. While I was at it I used the magic eraser to remove the fencing wire. None of the photo really has the top of the fence post in crisp focus so I had the feather between the close up and near beach focus to fudge the weathered post end. I probably should have taken a fourth exposure (or more sensibly used a smaller aperture (like f8 or f11). All that remained to do was use Perfect effect to finish the photo using the Dynamic Contrast Natural filter, but moving the medium detail slide a fair way to the right and the Big softy vignette.>

So what did I learn?

1. Use a solid tripod! (especially in the wind)
2. Don’t go crazy with a trying to use a low F-stop (ie don’t try and show off)
3. Take extra intermediate focus points, when in doubt.
4. Its a fun way to maximize your depth of field.

Rethinking the Sketch Approach for a Photographer

I haven’t actually used my camera this week (a very unusual situation) but I have been thinking about the different way an artist might approach an image via a sketch and a photographer that just needs to press the shutter. They are quiet different approaches yet they are both about being able to “see” the final work.

This is a photo of my small sketchbook and sketching gear. I have drawn a quick watercolour sketch of my own eye. It is in fact the small A7 sketchbook that I carry in my camera bag, taken last weekend as I was waiting for the sketch to dry. It is a nice example to explain the difference in an artist’s approach to seeing via line, tone and colour. It is also a nice bit of artistic self reference as I have long used such an image as my blogger and more recently google+ profile photo. I am also going to use Paint.NET, which is still free to download, (donations are appreciated) and a wonderfully simple yet powerful and intuitive photo editor for this demonstration. See also my post on the anatomy of Paint.NET Workspace

1. Line

It is very common for an artist to begin with lines. Our eye love lines and edges, they quickly follow these subconsciously. Eye tracking is a relatively new high tech applied science with lots of applications, and it demonstrates that our eyes tend to follow lines almost involuntarily. Artist have traditionally realised this intuitively and they selectively lay down the lines they need to build their image, so as to capture the viewers gaze. Often these lines are edges, something that is the boundary between light and dark or just a thin change of contrast. Whilst an artist will probably use a pen or pencil a photographer can easily find the strongest lines by converting their image to just black or white. Some software give this as a separate tools with a threshold slider that changes the point an image changes from black to white. Another common way to achieve this is using the “curves” (tone curves). These are a very mathematical looking tool but they just allow you to remaps given luminosity (light intensity or tone) and often colours with considerable precision. In this example, using Paint.NET the horizon axis represents the input intensity and the vertical axis represent how this intensity is to be output. The upper right is the lightest tones (the whites) and the lower left is the darks (the blacks) So if I grabbed just the luminosity curve and move that point up to the top of the graph suddenly and tones this shade and lighter become white. If I then grab a nearby point just to the left and take it down to the base of the graph, suddenly all these tones and darker become black. If I moved these points horizontally the threshold of the black to white change moves through the tones. I’ve chosen a threshold that avoids focussing on the eye sketch itself. What is created is a black and white silhouette that highlights all those strong lines that out eyes like to follow. This is very useful in understanding our eye flow and establishing points of interest. An artist “trick” is look at their sketch upside down (in this case I’ve simply done a flip vertically) as this tends to let them see the shapes in a more abstract way rather and interpret the objects they represent.

The pink lines show the likely flow of the eye. Those that bringing the eye into a center of interest, such as my eye sketch in this case, will be keys to help the artist build his composition.  A photographer should also study these lines and help in the composition because they might need to be enhanced during post processing. Unfortunately strong lines at the boundary (the red dotted arrows) will tend to draw the eye out to the edge and possible away from the image. An artist would probably not even drawn these, however it will be important for a photographer to see these and perhaps dampen them in the post processing, by using a vignette or central focus that blurs the edges, or even a gradation mask and Gaussian blur.

It is probably unnecessary to keep this liner version of your image, so just Undo these “enhancement” with a couple of  <Ctrl> <Z> or clicks on the big blue back arrow icon on the menu bar.

2. Tone

Most artist know that half squinting their eyes tends to desaturate the image and allows them to better judge the tone of the subject. Tone is “king” in realistic painting/sketching and it is important to understand how that tone maps onto lines and shade on the page. Where are the darkest darks and lightest lights? There are lots of ways to convert a colour image to black and white, edit tools, presets, filters and plugins. However for the tonal sketch aspect the simplest and best way is just to remove the saturation by moving that slider to the right. in this example I have moved the slider all the way to the right.

Half closing the eyes has a slight disadvantage in that it also lowers the light entering your eyes and thus darkens the image a little. There is no need to replicate this.

This black and white (actually its a greyscale) image should really help you understand the distribution of tone. Where the darkest tones are, where the lightest tones are and how these tonal areas connect. Often it is the areas of greatest contrast that interest our eyes and make for natural centers of interest. I find this greyscale images is also very helpful in guiding composition, ie the best way to crop the image. Notice I’m not trying to follow the rule of thirds I’m just trying to balance line, form & tone.

Once again it is time to hit <Ctrl><Z> and undo any changes and get back to the original image.

3. Colour

Another trick some artist know about is “defocusing” your gaze. This is a bit of a challenge if you haven’t done it before. The idea is to deliberately make yourself cross eyed and your eyes will no longer be well focused. What you hopefully see is really the dominant areas of colour. To train yourself to do it hold up your finger, or better still your pencil, focus on just its tip and bring it closer to your nose. With a little practise you should be able to remove the pencil and take in the whole defocussed view. Of course this is much easy to do with your camera (for example on a DLSR you just grab the focus ring and crank the lens out of focus while looking through the viewfinder). You will be surprised how much of the detail is gone from the image but you will still be able to make out the dominant colours.

The green to blue (harmony), then to blue against strong ochre (yellow) contrast works well, but the red of the rubber band distracts from this. A photographer might reach in and remove the rubber band (if the defocussing was done in the camera before the photo was taken). Alternatively this could be masked and selectively desaturated in post processing.

Time for <Ctrl> <Z> again, to Undo. You may or may not have saved these versions but you should have seen a few extra things in your photo that will probably help you enhance the photo during post processing, much like an artist referring back to his sketch book.

Can you really refocus in post process?

I came a cross a very interesting little program, when updating what's on my USB darkroom. Its called Smart Deblur, and it promises the restoration of defocussed and blurred photo. Quite a claim! The example is quiet impressive, you can practise with the blur sliders on a deliberately out of focus image of text, which comes op as you start the software.

Ok how does it perform on real photos?. Just after the big storm on thursday last week I found myself in a taxi going over the Bolte bridge just as a double rainbow formed over the city. I grabbed my camera but i was taking the photo through a wet droplets covering the taxi window in rapidly darkening condition. The auto focus was tracking in and out, presumably confused by the contrast on the rain drops on the window. So I turned off the autofocus and had enough time to get two photos before a truck in the next lane blocked the view for long enough for the rainbow to fade, Damn! Trouble was my focus was not quiet right and/or the movement softened the detail too much. So I figured these where perfect images to test the deblur utility! With a fair bit of fiddling and a long wait or two I did get a serviceable improvement, albeit with more noise. which a little tweaking in lightroom calmed down. The results being better than I could achieve in lightroom alone, but in reality don’t expect magic.

PhotoFriday :: Flaming Sharp Focus

This set of amazing ripple patterns in the shallows behind a sand bar reminds me of flames, frozen in time in their best and most intricate detail.

Normally photographing a very monochrome and evenly lit subjects, like a pattern in beach sand is very difficult to focus, even manually, and would normally send my camera’s autofocus tracking back and forth in a rather futile effort to find a sharp image. Being winter the sun was low enough to throw a shadow and it was just a case moving around  to get the direction that had the shadows maximised and darkest. Thus giving some good contrast in the area on which I was focusing.

For PhotoFriday‘s Topic Sharp Focus

After the rain II

 
Things around my garden have been enjoying the recent rains, and the lighting this morning was perfect.

I still prefer to use manual focus when taking macro (close up) photos of plants, their intricate shadows and patterns can often fool the autofocus into blurring your subject while bringing a leaf or twig off to the side into sharp focus. Autofocus can be particularly difficult when you subject is light (a white flower) and your background dark (in shadow)