Photo Answers
Exasperated by exposure settings? Nonplussed by ND filters? Send your technique and camera questions to digitalcamera@futurenet.com
Our expert answers your questions, plus Tech Check and Image Rescue
Back up to get sharp
Q
Can you explain the difference between back-button focusing and continuous focus tracking (including eye-detection AF) on my Nikon Z 7? Iain Smyth A
Back-button focusing is a way to divorce the act of focusing from the traditional top-of-the-camera shutter button that focuses when half-pressed and fires the shot when fully pressed. Your camera doesn’t come with back-button focus set up so you need to assign it to a specific rear button, such as the AF-On button.
There are some good reasons why you might want to switch to back-button focusing: the most obvious is that you can press the back button once to lock focus on a static subject, then simply fire the shot when you are ready via the shutter button, even if you’ve needed to recompose your scene a bit. Whichever control method you choose, do it exclusively so your brain can react quickly and intuitively to how you work.
Continuous focus mode allows you to track a moving subject, such as a cyclist, and keep it in focus as long as you have the back button pressed or the shutter button half-pressed. As a rule, if your subject has any kind of movement you can’t control, you want to use continuous focus (AF-C on your Z 7) – whether that’s with back-button focusing set up or not.
You’ll find photographers who love back-button focus, and others who prefer the traditional way. Neither is right or wrong: they are just alternative ways of doing the same thing – getting your shot in sharp focus where you want it to be.
Eye-detection AF is a clever function that will detect eyes using the Auto-Area AF mode when you work in both Continuous Focus or Single Shot (AF-S). It’s useful for portraits. However, if you have lots of eyes in the frame, you will still have to guide it to the eyes you want to focus on, via the AF-control pad you use to move the active AF points around.
Moving parts
Q
I’ve been trying out intentional camera movement, with mixed results. Can you give me any tips for a better success rate? Jon Roland A
When you shoot using intentional camera movement, part of its attraction is the element of the unknown: to a degree you are always going to get mixed results. There are several ways in which you can inject ICM into an image, including moving a telephoto lens through its focal range during the exposure, tilting the camera up and down vertically, jiggling it from side to side or sweeping it around in an exaggerated fashion.
The key is having a slow enough exposure for the movement to affect your image in a visually pleasing way. Unless you’re shooting in low light, you’ll need to use a filter such as a six-stop ND to hold the light back and set shutter speeds of 1/15 sec or slower.
If there’s one thing that makes the biggest difference to your results, it’s to take your camera out with the intention of shooting ICM rather than doing it as an afterthought, a technique you’re trying just because the light is poor. Good ICM really needs strong shapes – even if the image is relatively abstract – and shapes are created by contrast between light and shade. That means shooting in good light.
There is no doubt that intentional camera movement can result in interesting images that occupy a space between conventional photography and fine art, so it’s definitely worth persevering with.
Highlight detail
Q
After processing my raw files in Lightroom, some of my landscapes look too bright in some areas. How can I avoid this? Casey Rollinson A
Assuming you have captured a full tonal range between pure white and pure black, without any overexposure, it’s relatively easy to keep the final image within those parameters – but equally easy to stray on the wrong side of what’s ‘acceptable’ in the highlight areas. In this scenario, the brightest part of your tonal range is close to the far right of the Histogram, so as soon as you add additional contrast, you can run into problems. Having your Highlight Clipping Warning switched on is one good way to make sure you don’t stray to pure white but sometimes you don’t have to get to pure white to lose visible detail, and this won’t be picked up by the clipping warning.
In the example shot above, there’s quite a difference between the highlights in the base of the large lump of ice on the left and the darker foreground. The Histogram shows the brighter area in the ice isn’t overexposed, but I know that adding some contrast will lose highlight detail, which will jar slightly when I look at the image.
In cases like this, I’ll run an Adjustment Brush over the lightest area and darken it slightly using the Highlights slider and possibly the Exposure slider. This way, when I add contrast across the whole image, either within Lightroom or by using a thrid-party plug-in such as Topaz, I can worry less about that action losing detail from the lighter zones.
Obviously, you still need to keep an eye on the brightest parts of the scene but, having identified them and based some of your workflow around them, you should end up with a great finished photo.
Sony glass for wildlife
Q
Should I go for the Sony 100-400mm f/4.5-5.6 or the 200-600mm f/5.6-6.3 for wildlife photography on my Sony A7R IV? Gary Treasure A
There are many variables within a question like this – such as budget, what other type of photography you might use the lens for, and how happy you are carrying and using a heavy telephoto lens. Assuming you can afford either lens, the weight factor is reasonably significant, with the 200-400mm weighing (complete with collars, hoods and so on) 26 grammes more. This is not an issue if it’s on a tripod, but if you are walking around with it all day, it can start to feel heavy!
That said, I’d still opt for the 200-600mm lens. It only has a maximum aperture of f/6.3 at 600mm, but I feel the added focal-length power is probably more important for the type of photography you are talking about than the slightly wider f/5.6 maximum aperture of the 100-400mm lens at 400mm. While I’m a great believer in shooting wide to include some of the environment, the 600mm will definitely come in useful, especially for bird photography; and if you take the zoom back to 200mm, you still have a medium telephoto option for environmental shots. The good news is that the 200-600mm is the cheaper of the two, presumably because its aperture is wider.
If you really want to push the boat out, you couldn take a look at the Sony FE 600mm f/4. It doesn’t have the flexibility of the zoom option, but it does have a much wider maximum aperture, which can be useful for creative reasons and in low light. I’m not going to tell you the cost, though: it might come as a bit of a shock!
Cold cards
Q
I’m hoping to head to Antarctica in 2022. How will the extreme cold affect my CompactFlash cards? June Maloney A
CF cards are quite robust: while there will be variances between cards from different manufacturers, they’ll generally operate fine in sub-zero temperatures. I keep my spare cards in a pouch zipped in an inside jacket pocket so they are ready for action if I need to change cards. Having worked in both Antarctica and the Arctic several times, I’ve never had any issues with my memory cards.
Good housekeeping
Q
Can I delete old versions of Photoshop that are still on my system, or do I need to keep them? Keith Harper A
Unless you like a way an old version of Photoshop did a particular thing or just like to have a record of the differences between the various versions, there is no reason to keep the older versions; they are just taking up space on your computer. You need to go into your Creative Cloud App and select Uninstall to delete them.
Solar power
Q
I saw some images in a photo club competition that I was told were ‘solarised’. What does that mean? Joseph Peters A
It’s a traditional darkroom technique where you re-expose a partially developed print to light to create a stylised look to the finished image. It’s easy to mimic in the digital era [seep48]. Photoshop actually has a Solarize filter found via Filter > Stylize that can be applied to both black-and-white and colour images. You can get the same effect, but in a more controllable way, by reversing the tones using a Curves Adjustment Layer, as you can see above.