Fixing Chromatic Aberration in Macro Images

May 9, 2013 by 2 Comments

Tip715 Img1 1600pxThe Lens Tool in Capture One 7 has the ability to apply automatic lens correction for a large number of cameras and lens combinations, and will automatically adjust for a number of lens artifacts like distortion, light falloff and chromatic aberration.

In order to do lens correction for a specific lens, Phase One has to measure the lens and extracted data that describes how the different lens parameters behave. These measurements are done at typical focus distances and describe very well the performance of the lens at focusing distances from normal close-ups to infinity.

However, when using a lens for macro photography the focusing distances can be quite far from those used when the lens was measured for analysis. Sometimes you can achieve better results by doing a manual chromatic aberration analysis on the individual image in the Lens Tool.

Tip715 Img2 fullIf we zoom into this macro image and look at the slightly out of focus high contrast edge, we see a strong blue color caused by the chromatic aberration in the lens.

Tip715-img3-full_arrowsBecause this is a macro image, the automatic lens corrections does not efficiently remove the chromatic aberration.

Tip715-img4-full_cirkleIn the Lens Tool you have the option to perform an individual Chromatic Aberration analysis on the selected image.  Click on the orange arrow to the right of the tool and you will access a dropdown menu with the option “Analyze”.
Tip715-img5-full_cirkleClick “Analyze” and after a few seconds a new Chromatic Aberration correction will be calculated based on the selected image. We now see that the previous strong blue color on the edge of the flower has been corrected.  If you click on the orange arrow, you will see a check mark next to the file name.  This check mark now indicates that the chromatic aberration reduction is based on data retrieved from this specific image.

So, for this macro image, it’s possible to achieve a much better chromatic aberration correction by making an analysis on the image instead of using the “Default” correction for the lens.

All the best,

Niels

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How to make the most of the High Dynamic Range Tool

April 18, 2013 by 4 Comments

Tip713 image1 fullWith the High Dynamic Range Tool (HDR Tool) in Capture One 7 you can optimize images with a high dynamic range and extract details and regain otherwise lost colors in both shadows and highlights.

The tool has individual sliders for controlling recovery of highlights and of shadow details.

If values over 70-80 are needed in one of the sliders, it can be a very good idea to use the Exposure Tool to bring in the exposure as a first step. As a second step, use the HDR Tool to extract the desired details and colors in both highlights and shadows – now with lower slider values. When lower and more similar values of the shadow and highlight slider are used, you will typically achieve a more realistic and pleasing image.

Tip713 image2 fullThe image to the left is directly out of the camera. The high dynamic range of the scene makes it difficult to see details and color in the shadows, but also the sky has lost some color. The image to the right has been optimized in Capture One 7, primarily with a combination of the Exposure Tool and the High Dynamic Range Tool. Finally the Keystone Tool has been used to correct the perspective.

To illustrate the effect of using the slider in the Exposure Tool followed by the High Dynamic Range Tool, I have shot a series of test images with different exposures.

Tip713 image4c fullThe first image is exposed with clipping of only the extreme highlights. This exposure gives a perfect definition in the bright elements in the scene, but all the shadow details are barely visible. For the last exposure, we have a reasonable amount of details in the shadows, but the highlights are overexposed and you can hardly see the large red poster on the building in the background.

Let’s start with the first image, which is exposed with good highlight details, but with very dark shadows. To bring back the shadow details, I could use the shadow slider in the High Dynamic Range Tool.

Tip713-image5-fullUsing only the shadow slider in the High Dynamic Range Tool, I need a value of 90 to open up the shadows. However by doing so, I won’t get a natural looking result.

To achieve a more natural looking result, I will use the exposure slider to open up the shadows first. This will lead to overexposure in the highlights, but this can easily be fixed with the highlight slider in the High Dynamic Range Tool.

Tip713-image6-fullThis is the same image as before, but now I am using the Exposure Tool to generally open up the image and the High Dynamic Range Tool to bring in the highlights and the shadow details. Note that I have the same value for both the highlight and the shadow slider. The image now looks much more natural.

Having this idea in mind, I will correct the last of the 4 images, which was the one exposed with EV +2.

Tip713-image7-fullInstead of only using the highlight slider in the High Dynamic Range Tool, I start out by using some negative exposure compensation in the Exposure Tool and then use the High Dynamic Range Tool. Once again I use similar values for the shadow and the highlight slider, and I achieve a natural looking image with a good balance of shadow and highlight details.

Tip713 image8b fullBy using this technique it’s possible to adjust all 4 images to give the same natural looking result. An amazing result given we have a 2 f-stop exposure variation from the left to the right image.

All the best,

Niels

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Photography through the lens cap

April 1, 2012 by 8 Comments

A Phase One IQ back on a medium format camera has an extremely large dynamic range allowing you to open up really deep shadows while still retaining the highlight details.

This extraordinary dynamic range makes for really extraordinary photos!

No matter how skilled we are, we all make mistakes and so did I the other day. I was shooting with my favorite lens which is marked with the “focusing sweet spot” (See my tip about finding the focussing sweet spot here) and I forgot to remove the lens cap. I noticed it after the first shot, and removed the cap. When I got home, I imported all the images, including the shot with the lens cap still on, to Capture One.

Out of pure curiosity, I tried to see if anything was actually captured in the image with the lens cap. To my big surprise, the extreme IQ180 back had actually captured some information. Naturally, the colors did not look anything like the normal visual spectrum but I still managed to get a quite interesting image with colors that remind me of IR photography. Some heavy noise reductions were needed but then I got this image:

The left image is the original capture shoot with the lens cap still on. To the right is the same image after opening up the shadows in Capture One Pro 6.

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Photography Travelogues – Freeze the action with Peter Eastway

October 6, 2011 by 4 Comments

Low tide in front of the Reef View hotel on Hamilton Island, Australia is the perfect location for a run and jump. This photo was taken as part of a workshop just for fun, but it shows how useful the new leaf shutter lenses from Schneider Kreuznach can be when shooting action with flash.

Flash synchronisation shutter speeds in a darkened studio isn’t a problem because if you can’t freeze the action with the shutter speed (usually between 1/60 and 1/250 second), you can use a very short flash duration instead. The low levels of ambient light in the studio don’t significantly affect the exposure and so the flash is the only illumination exposing the moving subject.

Not so outdoors (or in a fully lit studio) because the brighter ambient light at a slow flash synchronisation speed will also illuminate the moving subject and thus the image will be blurred. The solution is a faster flash synchronisation shutter speed.

This isn’t possible with a focal plane shutter. A focal plane shutter has two blinds. The first blind opens, and then the second blind follows closing the shutter opening. At fast shutter speeds, the second blind is closing before the first blind is completely open, so at no time is the shutter completely open. If the flash fires, part of the exposure is blocked by the shutter.

Leaf shutters are different. Much smaller and sitting within the lens (as opposed to in the camera), they can open and close fully more quickly than a focal plane shutter. The new Schneider Kreuznach leaf shutter lenses for the Phase One 645DF offer flash synchronisation speeds up to 1/1600 second and so you can use flash in outdoor locations and freeze the action. It’s perfect for fashion and sport.

The way it works is that when the camera shutter is fired, the focal plane shutter in the camera opens first at a slower shutter speed. When the focal plane shutter is completely open, the leaf shutter in the lens opens, the flash is fired, and then the leaf shutter closes. Finally, the focal plane shutter closes. Fortunately, all this happens without the photographer having to be at all concerned – simply attach the Schneider Kreuznach lens and it works automatically!

For this photograph, the flash synchronisation speed was 1/1600 second using a Profoto Pro-B3 AirS battery-powered flash and the IQ180 on a Phase One 645DF.

In the set-up shot, you can see that the flash is pointed too far down, lighting the foreground as well as the subjects. Sometimes this can work as an effect, but if you want to keep the light just on your subjects, point the flash upwards so the spill doesn’t reach the ground. You can also use a local adjustment in Capture One to darken down the foreground – and sometimes a combination of techniques is required.

In Capture One, the raw file was processed to maintain detail in the highlights and produce skin tones with a natural rendition. However, most of the work was done at the time of exposure, which underexposed the background by a stop or so, giving the appearance that the photograph was taken much later in the afternoon than it was. This is achieved by setting the aperture and shutter speed so the background is underexposed, and then setting the power on the flash to correctly expose the subject. You can use a flash meter to help, but with the histogram on your camera, it won’t take you long to work out the settings with a few test frames.

If you’re interested in the photography workshops I present on Hamilton Island with David Oliver and Bruce Pottinger, or you just want an excuse to visit Australia’s tropical north, please visit http://www.hamiltonisland.com.au/photography-course/ for more details, or visit my site at http://www.betterphotography.com/. It’s a great excuse for a week on Hamilton Island!

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Tweaking Your Canon Lens Performance

September 12, 2011 by 13 Comments

Whether you’re shooting with Canon, Nikon, Pentax or Lumix DSLRs, the lenses we use have optical characteristics that are imperfect. Some of these perfections we hate, some we love – and some we love just some of the time!

Take the wide-angle lens. Most wide-angles, including the 24mm Canon TSE used to take the photo here, exhibit some light falloff towards the edges. This is only to be expected when you apply the laws of physics. Sometimes the ‘vignetting’ is a useful compositional tool, but on other occasions, you’d prefer an even exposure across the frame.

You can also find some barrel or pin-cushion distortion (curvature) in most wide-angles, especially zoom wide-angle lenses.

 Image with no Lens Correction

Neither of these ailments are difficult to fix. In fact, in Capture One they are extremely easy to fix – simply visit the Lens Correction Tab and slide the Distortion and Light Falloff controls until the image appears correct.

Image with Lens Correction

It doesn’t take much to make the correction, but given that every photograph shot with this lens will have the same light falloff and distortion, it would be great to have an easier way to fix it.

And there is. For your Canon DSLR (or any DSLR, actually), you can make a series of lens adjustments and save them as a user preset. In addition to Distortion and Light Falloff, you can correct Purple Fringing, Sharpness and Chromatic Aberration, and all these adjustments can be saved into a single preset.

Image with Capture One Lens Correction Preset

Once you’ve made the adjustments to one photograph, go to the presets icon at the top of the Lens Correction tab (second from the right). When you click it, a list of presets is displayed. At the top of this drop down menu is the option to Save User Preset… Click on this menu item and give your preset a name – I used ‘Canon24mmTSE’ for this lens so it’s easy to recognise. No point being too tricky with your names!

Now when I open a photo taken with my 24mm Canon TSE, I can simply click on the preset and my adjustments are made automatically. And, if I have taken an entire shoot with the one lens, I can apply my preset automatically to every image as I import the files into Capture One 6.

There really is a lot of power and automation built into Capture One 6 for the DSLR user.

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Special Curves For Nikon DSLRs

September 3, 2011 by 5 Comments

If you use a raw converter like Capture One, you obviously have an interest in achieving the best quality possible. You’re not one of the photographers who presses the button and simply expects the JPEG file to be as good as it gets!

The advantages of shooting in raw and processing your files in an application like Capture One are well-known, but perhaps not so well-known is the range of processing methods at your disposal in Capture One.

Tonal Curves

Take tonal curves, for example. Most people accept the default curve when processing their files, but the engineers at Phase One realise you can get so much more out of files if you apply a curve that is better suited to the subject.

For instance, Nikon users have a choice of six curves when processing their files in Capture One: Film Standard, Film Standard V2 (an improved standard curve), Film Extra Shadow, Film High Contrast, Portrait and Linear Response.

Capture One includes a range of specially designed tonal curves for Nikon D3s, D3x, D3, D2x, D700, D300, D300s and D90 DSLRs. To apply the curve, go to the Base Characteristics menu in the Quick Menu tab and click on the Curve selection box.

In this screen grab, the image is shown with two identical variants, but with different curves attached. You can see slight differences.

Film Standard V2

The first image has been processed with the Film Standard V2 Nikon curve. The image has a good range of tones, but the background is quite dark in places and the highlight on the girl’s skin and t-shirt is a little strong. It’s a good ‘overall’ curve, but perhaps not the best match for what is quite a high contrast lighting situation.

Film High Contrast

Talking of high contrast, one of the curves provided by Capture One for Nikon DSLRs adds in contrast and is ideal for photographs in soft lighting. However, in this situation, you can see that applying the Film High Contrast curve has simply made the dark shadows darker and has done little to improve the highlights.

Portrait

The best two curves for a photograph like this are the Film Extra Shadow, which lightens up the shadow areas, and Portrait. Portrait also lightens up the shadows, but not as much as Film Extra Shadow. It also smooths off the transitions between highlights and shadows, which is exactly what you want for portraiture. Notice how the sunlight wrapping around the girl’s shoulder and legs is much smoother and better rendered. This has been achieved by applying a suitable curve to the raw file.

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Playing With ICC Profiles in Capture One

August 30, 2011 by Leave a comment

We spend a lot of time ensuring our cameras and our software reproduce accurate, natural colour, but sometimes we should leave this to the men in white lab coats and use our tools simply to create the best result aesthetically. Accurate colour might not look as good as colour that is enhanced.

Outdoor Daylight ICC profile

Take this photo exposed under late evening light at Joffre Falls, Karijini, Western Australia. When processed using the ‘correct’ ICC profile setting in Capture One (Outdoor Daylight), the result is magnificent with the strong colours beautifully reproduced.

Portrait ICC Profile:

Now take a look at the same file with the ICC Profile in Capture One set to Portrait. The Portrait profile for the Phase One P 65+ back has been designed to give reds and yellows a bit of a lift, and these characteristics also work brilliantly well with many landscape photos.

Note how the reds in the Portrait ICC profile have been strengthened compared to the Outdoor Daylight ICC profile and a little more detail added into the shadows!

Depending on your camera, look at both the ICC Profile and Curve settings in the Base Characteristics tool and test various settings – you may be surprised at what works!

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