Blog Post

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            depth of field =        0.010m.
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.

Have fun, stay safe, enjoy your hobby.  

Louth Photographic Society

by Derek Smith 14 November 2024
One of our members, Dave Turner, an accomplished landscape photographer, took us on a pictorial journey down the east coast of England, from Northumberland, through Yorkshire, Lincolnshire, and finally Norfolk. I was especially taken with some of the images shot from different viewpoints, Lindisfarne castle viewed from the seaward side, Dunstanburgh Castle viewed across some vicious large beach boulders, and the Longstone Lighthouse viewed from the rocky foreshore. Of course, on the east coast of England some of the sunrises can be spectacular, as several of the displayed images showed. Small fishing communities such as Runswick Bay, and Staithes demonstrated how characterful the Yorkshire coast can be. In Lincolnshire, we viewed seal pups at Donna Nook, motorcycle sand racing at Mablethorpe, and the promenade at Cleethorpes. Our pictorial journey ended in Cromer with views of the pier. A big thank you to Dave for presenting a stunning collection of images, and it was interesting to learn some of his techniques in capturing these scenes. Thanks also to Dave Mann for the refreshments.
by Derek Smith 13 November 2024
Arriving at Lincoln for our direct LNER Azuma service to London Kings Cross, I was surprised to find a Network Rail leaf treatment train, topped, and tailed by a pair of very dirty Class 66 locomotives, idling with it’s typical Class 66 rhythmic whistling sound, at the usual departure platform for our LNER service. The leaf clearing train consists of 5 tank wagons, and a compressor mounted on a flat bed wagon, this train travels along the track pressure washing the leaves, and leaf residue from the rails ensuring better grip for all rail traffic during the winter months. The following morning in London, my partner and family took me on a surprise visit to Battersea Power station, we had boarded the Underground Northern Line to Battersea Power Station Station on the recently opened Northern Line extension, not knowing where I was being led, I dutifully followed the family into the refurbished power station, this cavernous space has now been converted into a shopping centre. I was last here in 1968 to visit the working power station as a part of my electricians training course, and it’s very definitely changed since then. Led to the upper level of the shopping centre, I found that my birthday treat was a ride up a lift installed in one of the iconic power station chimneys. From the queue 20 people are moved forward to an exhibit area, then through a slowly opening door into an audio-visual show detailing some of the history of the power station, apparently the power station wasn’t bombed during the Second World War, as the chimneys were used as a navigation point by the Luftwaffe. After the audio-visual show, the group climbed 39 steps to the circular lift which elevated the group to the top of the chimney, the lift rises above the rim of the chimney, and glazed windows offer a 360 degree panoramic view over the London skyline. The windows had some raindrops on slightly obscuring the view, but that enabled me to capture this Monét style image. We completed the day with a lunchtime meal and travelled back to our base in Stratford using a fast Uber Boat catamaran down the river Thames to North Greenwich Pier for the Jubilee Line to Stratford.
by Graham Harrison 12 November 2024
Good Morning All Last week at the club we had a fascinating evening with Alan Harniess coming along to the club whilst visiting family in Louth. Alan showed us his two projects that he had completed photographing strangers he met in the street or pubs around the Birmingham area. There is a blog on our website explaining more. This week, Wednesday 13th, one of our members Dave Turner will be showing photographs from along England's East Coast. Don't forget to enter the PDI of the year if you have not already, the deadline is 6pm this Wednesday. Regards Graham
by Derek Smith 7 November 2024
Our speaker last night was Alan Harniess, he spoke about his Flickr project “100 Strangers”, the intention was to photograph 100 Strangers around his home town of Birmingham. He often found it daunting to walk up to complete strangers in the street, and ask to take a photograph of them, often he retreated to a local public house for refreshment, and sometimes found subjects in there. Alan's collection of images that he showed represented a complete cross section of British society, young, old, beautiful, care worn, characterful, and ethnically diverse. Alan’s work was inspired by the eminent portrait photographer, Jane Bown, and he had one of her photographic books on display. After the break Alan showed images from his next project, “One Family”, he spoke about his dismay about negative media commentary on ethnicity, when his experience of talking, and watching people living their lives painted a completely different picture, people just living life, and making friends whilst being indifferent to colour, race, or religion. Alan’s collection of images with mixed race couples, or friends demonstrated the diversity of current British society. Thanks Alan for a fascinating talk, with some amazing imagery, perhaps his talk will inspire members to begin a project of their own.
by Harry Kerman 4 November 2024
Graham Harrison, Dave Turner and I attended the LPA PDI Inter club Competition yesterday, 3rd November. It was well attended by the 12 LPA clubs that entered the competition. The judge was Steffan Nicholson from Newark, who apparently stepped in at the last minute as the original judge had Covid. Steffan though very critical, was very fair in his comments. However, he did make many assumptions concerning some of the images. There were some very good images from the clubs and the standard was high. The judge held 15 images back from the 108 entrants and of those he gave three 20’s. Dave Turner was one of the 15 and scored 18 points for his image, Louth’s highest scorer. Well done, Dave. The eventual outcome was Grimsby taking the honours with Axholme 2nd and Cleethorpes 3rd. We came 7th which unfortunately was not as high as last year. Diane Seddon from Cleethorpes took the individual trophy with a stunning image called The Travelling Man, it depicted a man on a bench in the pouring rain. Well, that’s it for another year, let’s hope next year we can again be in the top four, illustrated here is one of Dave Turners earlier images, Kings Cross - Going Down
by Graham Harrison 4 November 2024
Good Morning All Last week at the club we had members giving 15-minute mini lectures on club outings as well as other subjects. There is a report on our website, but it was a very good evening ending in Richard Hildred showing Bromoil prints. This week, Wednesday 6th November Alan Harness will be speaking and showing PDI's, Alan is travelling quite a way to speak to us so hopefully as many members as possible will be there on the night. If you have not entered the PDI of the year, send your entry to Harry as soon as you can please. Today at 1pm we are as a club taking part in the LPA club PDI competition at Nettleham, hopefully we will have a few members attend the competition. Regards Graham
by Derek Smith 31 October 2024
At our meeting last night, members of the Society gave a series of “mini lectures”. The topic for the evening was intended to showcase images from the summer Society outings to the nature reserves at Donna Nook, Chambers Wood, and Kirkby Gravel Pits. Unfortunately, owing to the paucity of wildlife this year at the various nature reserves the wildlife images were short on the ground, members stepped up and produced some exceptional images from over this summer. Dave Turner produced some beautiful monochrome images of grasses, and thistles from Chambers Wood. Tony Gaskins stunned with one of his trademark long exposure seascape images, followed up by atmospheric images of his trip to the isle of Harris, and a beautiful image of a Gannet inflight at Bempton Cliffs. Paul Twomey produced some excellent considered images from a visit to the National Trust properties at Quarry Bank, and Lyme Park in Cheshire. Graham Harrison as the Society President had attended all three outings found the greatest concentration of wildlife at Kirkby Gravel Pits, and this stunning image of mating damsel flies is testament to that. Chris Birchmore treated members to a selection of his images of local churches from the Open Church week, as well as photos from the Heckington Show, and steam road engines at the Driffield Showground. Last, but not least, Richard Hildred passed around some of the prints from the Bromoil Circle box, this heritage photographic print technique creates some exquisite artistic prints. It was fascinating to see the diverse skills of members of the Society, a big thanks to members who participated in the lectures making for a wonderful evening. Thanks also to Dave Mann who tirelessly provides refreshments for our evening meetings.
by Paul Malley 29 October 2024
One of the many things that life has taught me, is to be very wary of Politician's promises; alongside this is a growing skepticism in the ability of Weather Forecasters. Knowing October, I was expecting a cool, perhaps damp day but no indication of the fog at the Coast (according to our esteemed TV forecaster). Heading south over the Wolds and then past Alford the mist was bad, turning into nasty fog patches. Chapel St Leonards, as my destination, was pretty much a white-out in parts. Yet again, I do what most photographers do and adapt as best as possible to the situation. I had committed myself to a walk along the sea front, but in setting off, with the muted colours and absence of people, I thought a moody Black & White set may present itself. I enjoy attempting to visualise a B&W scene, then trying to produce my thought on the monitor with the software. I'm nowhere near as proficient as some, but the fun is in the trying. Armed with the Canon EOS 5D iv and the 24-105 f4 L IS series lens, I shot in Manual mode, setting1/250sec and using the aperture range of f8-f10, letting the camera traverse the ISO scale in Auto ISO. I find Auto ISO a real bonus as I can establish both the depth of field I want, and the time the shutter stays open (despite the light level), to let me hand hold, having confidence that the exposure is maintained as I want, through the Auto ISO. Another clever feature (useful when mist and fog are involved) is the Canon's functionality to alter the EV in Manual mode by reassigning a Fn button, rather than compromising a change in set aperture or shutter speed. I spent about an hour walking round, hardly any people around other than a few hardy walkers taking the air and a lovely lady with a Greyhound. Any day with a camera in hand is a good day, it was also pretty much free until we called in at the Garden Centre on the way home, but that's another story... Don't be put off by the weather, where possible embrace it, there's an image out there somewhere. The visit in the mist showed me low contrast levels, muted colours and how it's nice not to be trapped by people in every scene.
by Graham Harrison 27 October 2024
Good Morning All We were away last week staying at Loftus which is about 15 miles north of Whitby. We had some very good weather which was lucky for this time of the year and visited many places on the North Yorkshire coast as well as inland. Last week at the club you watched part two of the N&EMPF Exhibition DVD, I hope you all enjoyed looking at some of the best club photography in the East Midlands. There is a report on our website blog. This coming week, Wednesday 30th, we are holding a series of mini lectures (15 mins) with photo's from this years outings, please let me know ASAP if you would like to take part. Harry is still taking entries for the PDI of the year (PDIOTY). Regards Graham
by Derek Smith 24 October 2024
At our meeting last night we held a showing of the N&EMPF Exhibition Print DVD, as always the standard of entries was of an extremely high standard. The images demonstrated the pinnacle of photographic excellence amazing wildlife images of birds, insects, and I loved the pride of lions gazing at a herd of antelope. The stunning night time images of heritage steam locomotives were very atmospheric. As usual images of sports featured highly, but there seemed to be fewer landscape images this year. For me as a portrait photographer, I was particularly interested in several of the images shown, and wondered if I have sufficient talent to enter next year, this image of a “Beach Maiden” is possibly headed in the right direction. It was a very interesting evening.
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