Photography News Issue 38

Photography News | Issue 38 | absolutephoto.com

Camera test 48

Imagemicroadjustments

Performance: Dual Pixel Raw

The EOS 5D Mark IV’s Dual Pixel CMOSAFsensor features 30million individual pixels. Each is made up of two photo diodes, A and B, side by side. Select Dual Pixel Raw in the menu and you get a Raw file that is twice the size of a normal Raw with image data from the combined A and B diodes but also data from the A diode only. Having this extra data means that in Canon’s DPP software, it is possible to make tiny adjustments to your images post capture.

Canon says that this technology can correct or minimise ghosting, adjust bokeh and make tiny adjustments to focusing. But this only applies to images shot in certain conditions so, for example, using a 50mm lens within a distance range of 1m to 10m, shooting at an ISO for 1600 or less and with an aperture of f/5.6 or wider. Longer lenses have the potential for a greater effect. I did try the long end of a Canon 24- 70mm and various settings on the latest Tamron 150-600mm.

Front 5, strength 10

Full-frame

Back 5, strength 10

No change

We tried this feature in a studio setting but also in practical situations too. For the studio part of the test we used the Canon EF 50mm f/1.4 and a SpyderLENSCAL with the Dual Pixel Raw files processed in Canon DPP v4.5.0. Focusing was manual using a magnified live view image for accuracy and the shutter released with the self-timer. The camera was mounted on a carbon- fibre Benro Mach3 tripod with light provided by an LED panel allowing an exposure of 1/80sec at f/1.8. The camera was positioned 1.5m from the test target, about 30x the lens’s focal length, and upright and horizontal shots taken. The largeRaws take a fewseconds to load into Canon DPP’s Raw File Optimizer. Image Microadjustment strengthsettings0to10areavailable and the focus can be adjusted using a slider, back to front, to a maximum of 5 each way. The preview image can be magnified by up to 400%, which helps to see the impact of any adjustments. Move the slider up or down and the preview takes a few seconds to refresh. Noother editingor sharpeningwas applied to the images shown here. I shot in various practical

situations and the example shown was with the Canon 35mm f/1.4L II USM focused to 0.3m. The exposure was 1/180sec at f/1.4, ISO 400. You can see – probably more clearly in the practical example – that the plane of sharp focus has been moved, albeit by a matter of millimetres. Also on our test shots, those where the focus was adjusted seemed marginally less sharp. Canon does stress that the Dual Raw option is not suitable for rescuing poor focusing technique,

but you may be able to fine-tune the look of a sharply focused shot. Whether it is worth producing Raws twice the size of normal Raws (60MB compared with 30MB) and the extra time in processing using Canon’s DPP is a decision only you can make. The thing is, you have to make the decision to use Dual Pixel Raw before you start shooting so if you shoot normal Raws and later find that you need to make focusing adjustments, you can’t.

Full-frame

No Ghosting Reduction

With Ghosting Reduction

No change

Back 5, strength 10

Front 5, strength 10

Ghosting Reduction adjustment

For this daylight picture of model Emma, I used a 35mm f/1.4 lens with of 1/125sec exposure at f/2.5 and ISO 200. The lens was focused to about 1m. In DPP and Dual Pixel Optimizer, the Bokeh Shift option was selected and three images produced, with zero adjustment and then left and right adjustments made at the strongest setting, 5. The benefit is small and it’s debatable whether it’s worth the memory consumption. With bokeh, more consideration at the time of capturewould probably be better. I shot towards the sun to get some flare and ghosting to work with. With Canon lenses and their very effective coatings this is not easy. This shot was taken with the 35mm f/1.4L II USM with an exposure of 1/180sec at f/1.4 and ISO too. In the Dual Pixel Raw Optimizer tool in Canon DPP, I selected the Ghosting Reduction option, then selected the affected area and finally converted the Raw to a JPEG. For this test, no other editing changes were applied. Bokeh Shift adjustment

The benefit? In this example, nothing discernible and the flare and ghosting in both images looked identical. I tried several different shots and found the same, although of course that is not to say it won’t work on other shots. From the evidence here, if you are getting ghosting in a shot, you could switch to Dual Raw for insurance with the (small) possibility of correction in software but you’re better off trying to combat the issue at the taking stage.

Images Look closely at the model’s mouth and the adjacent blurred leaf. Using Bokeh Shift Adjustment has changed the relationship very slightly. It didn’t help this image much but perhaps it could rescue a picture in very specific instances.

Full-frame

No Bokeh

Bokeh Shift, right 5

Bokeh Shift, left 5