Understanding Depth of Field
Derek Smith • 15 December 2020
Depth of field when taking photographs can be a help or a hindrance, dependent on the type of image required. The definition of depth of field can be best described as; “the area of an image that is in sharp focus.”
When taking portraits, a lot of photographers will try and blur the background, limiting the depth of field from the tip of the nose to the back of the head, this is achieved by opening the aperture on the lens to one of the lowest f numbers, only by experimenting with the camera / lens combination will a photographer be able to know what works best for them. With my previous full frame Sony, and 85mm lens f/1.8 gave a far shallower depth of field, and so I favoured an aperture setting of f/2 to f/4.
This image of Rachel from a recent photoshoot with my micro four thirds system camera using a 25mm prime lens (50mm FF) has a field of view of 38 degrees, and at f/1.8 the depth of field is 0.06m, enough to keep the nose, and both eyes sharp, with the ears just beginning to soften, the background is suitably blurred, keeping the emphasis on the face.
In portraiture the focus point will usually be set on the eyes, and I would typically use f/1.8 – f/2.8 aperture in an outdoor situation. Indoors, or in a studio depending on the lighting and distance from the subject, an aperture of f1.8 – f/8 could be employed to give the correct depth of field, and exposure.
Interestingly we find that the depth of field will double for every two stops that the lens aperture is stopped down, hence with the micro four thirds 25mm prime lens:
At f/2.8 depth of field = 0.015m.
At f/4 depth of field = 0.02m.
At f/5.6 depth of field = 0.03m.
At f/8 depth of field = 0.04m.
The images of the TV remote show the quite dramatic difference with the first image taken at f/2, and the second image taken at f/8.
In shooting landscapes, the photographer will be looking to have a greater depth of field, ensuring that the scene is sharp from the foreground to the furthest distance away, use a mid-range aperture usually f/5.6 – f/11 depending on the sensor size, and lens used, because most lenses are sharper in the mid-range, often called the "sweet spot". Another tip is to focus a third of the way into the scene, this is a rough rule of thumb to ensure sharpness throughout the scene. In this example image of a tree in a glade, my zoom lens was set at a focal length of 18mm (36mm FF), and aperture of f/5.6, focusing on the tree, which is about a third of the way into the scene, gave a depth of field from 2.06m to infinity ensuring the whole scene was pin sharp throughout.
For shooting macro insect photography, the photographer is often tempted to push the front element of the lens as close as possible to the creature, but the closer the lens is to a subject the shallower the depth of field, so move back, it is far easier to crop into an image than try to rescue an unsharp image, and we have all been there!!
So, this morning I would encourage you to get the camera out, dust it off, and try different camera, and lens combinations, experiment with different apertures, and find what suits you in the various scenarios.
Rachel
Photo By: Derek Smith
TV Remote f/2
Photo By: Derek Smith
TV Remote f/8
Photo By: Derek Smith
A Woodland Glade
Photo By: Derek Smith
Louth Photographic Society
Last night our members enjoyed a visit to the Swaby valley nature reserve. We crossed over two fields from South Thoresby, then followed the course of the Swaby Beck chalk stream through the valley, the public footpath was bounded by dense vegetation that hindered our progress at times. There was plenty to see around the reserve, myriad butterflies flitted around in a very lively manner, making for difficult photography, I spotted several small grasshoppers, and soldier beetles in the long grass, I tried to photograph a ladybird, but it was gone by the time I focussed on the creature. It was a very enjoyable evening, with good friendly company, and our camera skills were needed for the macro photography, these are a few of my photos from the evening.
Good Morning All Last week's outing was re-scheduled due to a clash with a certain world cup match, the good news was a victory for England, however we intend to still hold the outing on Wednesday 22 nd July. I did go to the Festival of Flight at the Shuttleworth collection, Old Warden last weekend. It was too windy for some of the old Biplanes, but we were treated to a four-and-a-half-hour display featuring many planes that I had never seen fly before. The De Havilland Comet was built to compete in the 1934 race from Britain to Australia, only three were built and it's good to see it flying, the aircraft design was quite advanced for 1934. This week, Wednesday 8th July, we have another camera club outing to the Swaby Valley, meeting at 6pm. Swaby is just off the A16 heading from Louth to Skegness. Regards Graham
Last night’s Louth Photographic Societies outing to Kirkby gravel pits nature reserve was cancelled as some members preferred to watch some sporting gentleman by the name of Harry Kane. (Congratulations to the England team) The reserve is small, and simply laid out, a public footpath leads along a tree lined avenue to the river Bain at the back of the reserve. Historic sand and gravel extraction has left a large lake in the centre of the reserve, several ducks and waterfowl inhabit the lake and there is a bird hide on the shoreline. Returning to the road, there is a path running parallel to the road bounded by a hedge, insects of various types can be found in this area, damselflies, butterflies, and hover-flies are often prolific. Our outing to Kirkby Gravel pits is now scheduled for Wednesday 22nd July. Parking is on the verge by the roadside. Kirkby Gravel pits are fairly close to where I live, and it’s reserve that I often visit, these are some photos from a visit in July last year.
Good morning, All, Last week at the club we had our monthly print competition, Trees and Open. There was a very good entry with a high standard of photography on show. Tony Gaskins was first in the Open and I managed a first in the trees, all the results are on our website and there is also a blog on the evening. This week, Wednesday 1st July, we are having an outing to Kirkby Gravel Pits, if we meet at 6.30 at the reserve, though you can arrive earlier as there are usually dragonflies etc around the entrance. If we walk straight ahead first, then anyone who arrives late can find us. I have struggled to find a map, but you can see the location on the Lincolnshire wildlife Trust website. Kirkby Grave Pits is also a good reserve for birds. Tattershall Road 1 mile south of Kirkby-on-Bain Woodhall Spa Nearest postcode LN10 6YN. Please note - postcodes are for the nearest registered address as we are unable to get postcodes for nature reserves.
A print competition was held last night with the categories of "Trees" as the subject, and "Open". Our judge for the evening was Gail Wrigg from Barton who did an expert job. The first category to be judged was the "Open" with the high standard of prints making the choice of top placement difficult, and Gail held back 9 prints for further evaluation. There were some chuckles from members around one of Richard Hildred's prints of wooden electricity poles titled "In my previous life I used to be one of them" an "in" joke from Richard, which totally baffled Gail. After the break Gail judged the "Trees" category, with 7 prints held back this time for awarding of higher marks, the beautiful colours of some trees, especially the autumnal images contrasting with the stunning monochrome infrared prints from Richard Hildred. It was a great evening, with excellent prints on display, and the website Competition page has been updated with the full results.
Good Morning All Last week we visited the nature reserves at Fir Hill quarry and Muckton wood. I have written a blog report on the evening which is on our website. You can always try something a little different like I did using camera movement. This week, Wednesday 24th June, a print competition will be held, with the categories of "Trees" and "Open" and is to be judged by Gail Wrigg. The following week we have an outing to Kirkby Gravel pits. If you want advice on camera settings etc the outings are the perfect opportunity to ask other members while we all have our cameras. Regards Graham
Each year Louth Photographic Society begins a new project, one photo taken each month on a specific subject, that's 12 photos presented on "Project Night" in January. Last year the subject was "Prime Time" one photo each month taken with the same fixed focal length lens. This year the subject is water, the subject sounds easy enough, and I've completed 5 photos already, but I'm struggling a little with a photo for June. I'm currently on holiday in Corfu, an island surrounded by water which should be easy, but I'm yet to find the "definitive" photo for the project. These are my photos so far this month: Best regards Derek
Good Evening All
Summer is here at last, maybe?
Last night a few of our members had an outing to Old Bolingbroke village. Initially visiting the Lincolnshire Wildlife Reserve of Sow Dale, off Spilsby Hill at the village entrance, I was a little hesitant at first at entering the reserve because of the grazing cattle. When the cattle herd moved up the hill we climbed over the stile and entered the reserve, as we began to take some photos around the reserve though, the herd returned, but seemed quite docile. Later in the evening we moved on to Bolingbroke castle, and took several photos of the castle, fauna, and flora. It was a lovely evening, good to get out with cameras, and socialise with others.
