Photography News issue 26

Technique 31

Photography News Issue 26 absolutephoto.com

Depth-of-field, flash and filters

F/8

F/16

Original image

With the lighting creating the glow that I wanted, I could move the subject around and shoot lots of angles

When you’re shooting with flash you can find the power of the light to be a problem, especially when using middle or wide apertures. Here I wanted to shoot at f/8 which allows some of the leaf to blur – unfortunately stopping down to f/16 kept too much in focus. But there was too much flash power so I couldn’t do it without overexposing. I first guarded against this by setting the lowest ISO sensitivity, to make the sensor as unreceptive to light as possible,

and also setting the flash power to its lowest, (1/128). But it was still overexposing. So eventually I fitted an ND filter to block more of the light and was able to set the wider aperture that I wanted and get the shallow depth-of-field I desired.

Venus Optics KX800 twin flash

bright, but I didn’t want to close the aperture because I wanted a shallow, but not too shallow, depth-of-field. I had nowhere to go in terms of lowering the ISO and increasing the shutter speed to 1/125sec would have no effect on the flash, so I dropped output to its lowest, 1/128 – but it was still over-exposing, due to the closeness of the flash to the leaf. Therefore I reached for a neutral density filter to absorb some of the light – a Cokin P neutral density with a 16x filter factor so cutting out four stops of light. This gave me what I needed, and I ended up using the main light at 1/4 power and the second flash at 1/64 to catch some of the surface details. Editing and experimentation With the lighting creating the glow that I wanted, I could move the subject around and shot lots of angles looking for nice shapes in the veins. Changing the angle of the leaf meant refocusing each time, and but with the flash and camera in consistent positions, there was no need to change the power. And with the light controlled accurately in shooting, there wasn’t much editing required; in Lightroom I did warm the colours slightly and add some saturation, also using the Adjustment Brush tool set to +20 Sharpening to add some detail to the in-focus areas. Finally I used the Spot Removal tool to clean up a few blemishes – even if you’ve got a good specimen, these will always look more prominent when magnified by a macro lens. KS

Flash (£229 from ukdigital.co.uk). Despite looking like something that’s escaped from the innards of a Dalek, this did a brilliant job. It has two articulating tentacles, at the end of which sit the flashguns, so I could bend one around under the leaf to provide the main backlighting and use the other for a little fill. There’s also a third tentacle with a powerful LED on it, I didn’t use that this time but it is handy to aid focusing. Focusing on the details With the flash in the right spot and it was easy to reposition if required, I focused on the leaf using the K-3’s live-view function and its focusing peak mode. This ‘what you see is what you get’ method I’ve found to be by far the best way of focusing for macro; you just zoom in to check sharpness is exactly where you want it, and the focus peaking highlights the sharp points making it even easier. This is all done in manual focus, and although this should keep the sharpness consistent, it’s best to keep checking between shots as even slight movements of the subject will throw the focus off. Exposure and flash power With very little natural light in the room, the flash was easy to control. I switched to manual exposure mode and started with a test shot of 1/60sec at f/8, ISO 100. Switching on the flash at the rear (the two on the Venus Optics unit can be controlled independently), I set it to a 1/4 power and fired a test shot. Thiswasway too

The Venus Optics KX800 twin macro flash proved very handy when it came to finely positioning the flash to back light the leaf in this technique. Its three flexible arms allow lots of lighting options as you can control the power of the left and right flashes, and the LED independently. It’s compatible with a wide range of DSLRs, and costs £229. You can find out more at ukdigital.co.uk.

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