Depth of field for portraits

or, “A Little Learning is a Dangerous Thing” I needed to work out suitable apertures to make the environmental portraits for ‘Derby at Work’. (Environmental portrait? A portrait of someone in their usual environment; and for the project I have in mind, it needs so show some detail of that environment, not just hint that it’s a pub or a factory.) The studio portraitist doesn’t have this problem – there is no background to worry about. He or she can simply stop the lens down to f/8 for optimum sharpness, turn up the lights and shoot away.

The obvious way to get some rules of thumb would be to do some experiments, but I decided to prepare for them using a depth of field calculator. I learned something, but not what I was hoping for. Most depth of field calculators get it back to front. You tell them the subject distance and they tell you the depth of field. My requirement is to tell the calculator the subject and the lens and get an appropriate aperture. So I made a spreadsheet for the following arrangements of a person in a picture:

Tight headshot – I assumed (wrongly as it turns out) that I wanted 120mm depth of field from the eye to the back of the ear Head and shoulders – assume 200mm in front of the eye for a rather ample figure Half length – 300mm to accommodate a forward elbow Seated – 800mm to cover the shoes Full length – 300mm for a forward elbow again
I ran the calculations for four common enough focal lengths: 35, 50, 85 and 105mm.
So what did I learn?

1) Focal length made little difference! For the head and shoulders, with the subject distance was 500mm with a 35mm lens and 1500mm with a 105; but to get the 200mm depth of field the aperture was the same. This – if it is the case in practice – makes life easier.

2) The calculated figures – which I’ve doubled checked against an online calculator – give a spectacularly wrong (or at least impractical) answer – f/45 in the case of the headshot; f/11 for the seated portrait. Why?

First I’ve been overgenerous with the assumptions about how much depth of field a portrait needs. Eyes – or at least the eye closest to the camera needs to be pin-sharp; whether earrings need to be just that sharp is debatable. However even if we relax the 120mm to 25mm for the length of a nose the answer is still f/13 for a headshot.

Moreover, there’s perhaps something about the aesthetics of a portrait that means that it actually helps to have the eyes (or the closer eye) sharp and have the sharpness drop off from there. In fact if you stop down far enough to get the front-to-back sharpness in a portrait I suspect you’ll just get more sharpness in the background than you want. The two photos below taken in the Sarry Heid (a noteworthy Glasgow pub) were taken at f/4.8 and f/2.8 respectively.
I’d say that for a portrait f/2.8 is all that’s needed, but perhaps for documentary purposes you might prefer f/4.8. But not f/45! So I’m starting to think of the effect of aperture for my work not as something that controls depth of field, but which controls the degree of out of focus in the background.

No doubt a depth of field calculator is useful for landscape or macro photography, but a snare and a delusion for portraits!
In case you’re interested, here are the calculated aperture – it makes little practical difference which lens you use to aperture needed to achieve a particular  depth of field.
 Screenshot 2014-11-13 19.11.39

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RAW shooting for the musically inclined

A musical friend, let’s call her “Second Violin” recently asked for some advice on processing a photo and as she’s not keen on shooting RAW images I used a musical analogy to explain why and when she should consider it. She found it helpful, so if you’re musically minded this may help you too. (A quick word on RAW images. Nearly all digital photos are taken in ‘jpg’ format – this is a compressed file which saves space and also provides a punchier image straight out of the camera. A RAW file is much bigger, less punchy, but more tolerant of you getting the exposure wrong and able to be tweaked much more to produce a finer image – if you have the time, skills and inclination).

“Taken in b/w. How would you have edited this – more contrast?” was her question.


Derby Hippodrome

I reminded Second Violin of the story of the English cyclist who stops and asks a local the best way to Tipperary. The Irishman replies “if I wanted to get to Tipperary I wouldn’t start from here”. And so by analogy, if I had wanted to interpret this creatively I wouldn’t have started from a black and white jpg.

I assumed that the brief was to photograph the skyline: and suggested that I would have exposed for the sky rather than the building. Give it two or three stops less, a bit like this:
Leeuwarden (1)


As it is, with no sky detail and shot on jpg, the question (how would I process this?) makes me feel like a conductor who has been asked to conduct a village orchestra as a favour to Second Violin. The work will be broadcast on Radio 3 tomorrow. He turns up at the agreed time and finds that his Second Violin has decided that she will replace the violins, flutes and piccolos with a triangle. And she has sawn the top two octaves off the piano.

I’m going to explain this with a histogram – no, please stay with me! The histogram that your camera or your editing software shows illustrates the how much of the picture is covered by dark tones, mid tones and highlight tones, laid out, just like a piano keyboard with the dark (bass) notes at the left and the highlight (treble) notes at the right. Or if you prefer, like a graphic equaliser. That peak is the white, detail-less sky; in the analogy, the triangle!


In contrast, the histogram below is from the Leeuwarden photo – it shows a full range of notes in the treble as well as the bass – anything off to the right only dogs can hear.

Screenshot 2014-11-13 09.03.31

Second Violin has also painted the poor conductor into a corner by taking this in black and white. Why? Well, if I start with a full orchestra I can inject some tone colour by emphasising the bass bombardon, a contrabass oboe, kettledrums or whatever. But while the left hand side of the histogram on the left contains the full range of notes, I have no (tone) colour, only one instrument, say a double bass. Plunk, plunk, plunk. Eh? I’m suggesting that if you want a black and white photo you should take it in colour?
Yes. Have a look at the histogram below:
Screenshot 2014-11-13 09.15.21
This is ‘Leeuwarden’ before it was converted to black and white – the three ‘instruments’ – bass bombardon etc (all right, red, green and blue) have slightly different profiles or tone colours. And that’s ever so helpful because the conductor can manipulate them separately depending on whether he wants a rasping parp or a noise like an elephant trumpeting. And the photographer likewise can change the brightness of things of different colours. In the original of Leeuwarden, the building at the bottom was a pretty dull grey, but by lifting the reds (or telling the tubas to give it some welly) it stands out better. A red filter (applied digitally) is the most useful one in my experience – it will lift red brick and darken blue skies (although it will do nothing for grey ones!). A red filter will also lighten skin and so if you make a portrait of a person standing in front of a background of a similar shade of grey it will make the person stand out. It will also reduce the contrast in skin tones, tactfully hiding skin ‘blemishes’ if that’s what the person portrayed wants.
So finally, the promised discussion of why and when you might want to shoot RAW, as promised. Firstly, a RAW file would allow some recovery of sky detail. In the analogy, if you’d recorded the performance on a reel-to-reel tape (or high quality digital recorder) the boffins at Radio 3 might have been able to salvage some treble detail electronically. However jpeg is the equivalent of recording this on a C-60 cassette from Poundland using Grandma’s cassette tape recorder which last had the heads cleaned in 1965. There is no detail there to recover! RAW won’t put the two full octaves back on the piano, but it might give you half an octave. Secondly, a RAW capture will contain colour info even if you set the preview to black and white (which is what I do).
If I haven’t convinced you to capture in RAW, could I suggest that if we’d had more time we’d have done a few takes of the recording and picked the best which is, by analogy, bracketing. Take a few more shots, some over-exposed, some under and pick the best. But the Scouts are in the hall at 5pm so we have to be clear by then. No retake. Nor for this photo, so how could we process it? Second Violin suggested a bit more contrast – that will certainly improve things. More radically, the musical performance could be rescued by dubbing in a vocalist later – nice range of tones and effects. By analogy, print in a more interesting sky by combining two photos. I wouldn’t have the technical skill to do it, (and if you’re not up for shooting RAW neither, I suspect, do you!) but a legitimate artistic choice nonetheless.
Another possibility would be to find out what the orchestra you have could perform. Tear up the score for the Dance of the Sugar-Plum Fairy and do some Mahler or even get them to improvise the sounds emanating from a drug-dealer’s BMW with mirror windows. Which is to say, photographically, apply some radical filtering – heavy use of the effects pedals. Solarisation for example:
Maybe not what you planned but I think more interesting than the rather flat original.
Have I convinced you? At least I hope, my musical reader, you now have a better idea of what RAW could do for you. You don’t need to use it every time, but perhaps use RAW where the photo is unrepeatable or where the histogram is clipping at both ends even with the best exposure settings you can manage. Your camera will probably let you capture both a RAW and a jpeg for each exposure. You can always delete the RAWs if you don’t need them.
A final thought then. Is processing “manipulation” of an image? You could say that, but I’d suggest that what you capture in the camera is the score, the final image is the performance, your interpretation of it. Imagine if all music were performed by feeding the score as a MIDI file into a synthesiser. Shudder!

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Starting again

A very helpful review of my work by Claire Kern at the Third Floor Gallery prompted me to get my arse back into gear. Having lost confidence in being able to shoot anything meaningful and lost interest in photographing things that aren’t, there I was with a DSLR and a bag of gear wondering how to carry out The Plan. Yes, at least there is A Plan.


The Plan is ambitious – to document Derby at work. Maybe some street style. A focus on older crafts, skills, workplaces. I want to do urban exploration while the people are still there, while the workplace is still functioning. Like this photograph of a bell tuner in a bell foundry
 Bell Tuner
 which is admittedly in Whitechapel, London, but you get the picture.

Places in Derby that appeal:
- the pub
- a traditional bakery
- the markets
- a clothing factory in the Indian quarter.


I need some contacts to get me in the door and I’m away. Or would be I had any confidence that in return for half an hour of somebody’s time I will be able to give them a correctly exposed, sharp photograph of themself that they can show to family and friends to communicate what they do. That they might pin to the wall at least for a few weeks. What’s stopping me?


Let’s start with technique. I’ve now got a full-frame DSLR that will produce sharp black and white photographs at ISO1100 with a 35mm lens with an exposure of 1/90s at f/2.8. Or at least, which has done once:
Can I consistently get sharpness at 1/90? How slow could I go? Could I get adequate depth of field at f/2? How far can I go past ISO1100? At higher ISOs I seem to lose sharpness – but is that a focussing problem in low light or is it noise? Only a good bit of experimenting will show. Fortunately I have a willing victim model.


Why black and white, by the way? It can stand higher ISO because grain looks ok, colour noise doesn’t. Colour balance is hard work – my first experiments were in a pub where the economical landlord has installed energy-efficient lighting which is to say every bulb has a different colour temperature and of course they’re all fighting with daylight. Drinking is mainly done at night, but the cellar work, cooking and cleaning is done in the day:
Yes I considered the Martin Parr ‘puff of flash’ technique – but that’s just one more variable to juggle. Yes, I have seen photographs taken down a Derbyshire fluorspar mine with healthy skin tones and barely-noticeable noise, but I can’t do that. Yet. Black and white suits the subject I think and can better hide background distractions.


So, I have the kit and I have one tame workplace. The next steps are:
- experiments to see how far I can push the exposure and achieve sufficient depth of field
- photographing in a small kitchen – how do you photograph a cook who spends her day with her back to you?
- have a look at what others have done – David Hurn, Martin Parr, Chris Killip, Walker Evans, Blazej Maczak  – who else?

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Photography for Free

This isn’t so much a blog post as a summary of my talk on 20th March 2014 to TOGSQuad, a new-ish Derby photography group founded by Victoria Wilcox, the Picture Editor at the Derby Telegraph. The group has photographers at all levels of ability and here I aim to be an antidote to the notion that spending hard-earned money on fancy equipment is a sensible way to make better pictures.  So here are the images and captions, and below is a summary of the points made:

Post processing isn’t inherently unnatural or dishonest
In the good old days of film you had to choose a the contrast level and the exposure in the darkroom. It was also normal to crop and to dodge and burn to deal with highlights and shadows. You still do. You may find Photoshop intimidating (it’s beyond me), but iPhoto on the Mac, the camera manufacturer’s software of Picasa (Mac and PC), and Snapseed (iOS and Android) will provide a simple and free introduction.

Is your camera good enough?

  • Probably – look at the Flickr Camera Finder – find your own camera – and see what others are achieving with it.
  • Are you making the most of it? Do you know how the features work? Have you gone through the menus?
  • And practice, practice practice! Do you know which way the dial moves to open the aperture or do you fiddle? If you use auto exposure can you deal with tricky lighting quickly?

Learn from your rejects
Some typical faults:

  • Dull, boring pictures
  • Tilted
  • Chopping off legs and arms
  • Funny faces
  • Smiles
  • Intrusions
  • Not close enough
  • Negative space
  • Technical fault (focus, movement)
  • Backs
  • Overlaps
  • Burned out sky
  • Timing
  • Verticals
  • Distracting background

Less that 5% of my rejects would be fixed with a better camera.

Analyse your rejects and apply suitable remedies, for example:

  • Get closer
  • Select moment
  • Change position
  • Shoot square
  • Engage, direct the subject
  • Further away
  • Up the ISO and if need be
  • … hide noise in B&W
  • Find out how the camera works!
  • Practice, practice, practice
  • Check in camera
  • Get up / down
  • Get closer

Always carry a camera:
Lots of fun things happen every day in the street. It doesn’t need to be a fancy camera – you may not want to cart a bulky DSLR round all the time. Magic juxtapositions don’t just happen. You need to find element 1 and wait for element 2 to appear.
Keep your eyes open, look up and learn to see what the camera will see, not what you see.

Light is magic and free:
Low light is generally more interesting. With high, soft light black and white may work better. Know how the sun moves with time (left to right in the Northern hemisphere, 15 degrees per hour) and the seasons. If you want, play with The Photographer’s Ephemeris to see how a favourite place will be lit. When you see lovely light, keep the camera in your hand. Shooting by candle-light is possible – crank up the ISO.

What do YOU want to say?
Once you’ve mastered the camera’s operation, lighting and composition then what’s your project? What I did on my holidays? Life in multicultural Derby? A year in the garden? Something that will give you, say, a dozen images to show.

And finally – Artists Statements:
I don’t understand them either. Make your own at

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Somebody mentioned they were going to photograph a wedding for a friend. Not formally, but all the same I’m sure they want to do a good job. So on the basis of having photographed two weddings, one in 1978 using a Zenit E and one this year on digital, I’ve set down my thoughts, not so much on how to do it, but more on the things to think about. I’m going to assume a white wedding here as that’s almost the hardest. And while I’m going to point out the pitfalls, if you’re doing this as a favour for someone, don’t worry I’m sure they’ll be delighted with the results and doubly delighted at not being ripped off by some of the comedians who are charging six hundred quid for a day’s shoddy work and not so much as a crop in post.

Why do people get married around midday – the light’s awful. Bright sun from above casts horrible shadows. And that’s not the worst of it – in such lighting the contrast between the detail in the bride’s dress and the groom’s suit is far more than the nominal eight stops that a jpg can record or a monitor or a print can display. OK, the following example was shot on contrasty slide film in 1978, but digital will struggle too.

Bishopbriggs146 (1)

It looked even worse when printed

If on the other hand you set the exposure to cope with the shadow side of the faces, the detail in the dress be burned out and it will look like a Bri-nylon short. The bride will not thank you.

What can you do about it? Obviously the best thing is to persuade people to get married at a more photogenic time of day – in high summer say 05:00 or 21:00. Failing that, you’re going to have to do battle with the light. The professional or well-heeled amateur will use fill-in flash to brighten the dark areas and bring the contrast under control. You can’t do this with a pop-up flashgun – it needs to be a big, separate job costing £100-£300 which I’m assuming you don’t have. So you need to be clever.

First, know you enemy. Case the joint at about the same time of day as the wedding. See where the light will be. Pick a spot for the formal photos that doesn’t have a distracting background and where the light will be a bit diffuse – perhaps through trees. Diffuse mind, not deep shade. If you can’t get to the venue then try a solar calculator like The Photographer’s Ephemeris to see where the sun is going to be (a bit geeky, should be fine for blokes under fifty). The Adobe Air version is free for Mac or PC, there’s a charge for the iOS or Android version.

You can diffuse the light yourself for portraits, or rather your lovely assistant can by holding a diffuser between the happy couple and the sun. That’s probably the limit for a simple hand-held diffuser. A similar bit of kit is the reflector which your lovely assistant can use to bounce back into the shadows. Look on eBay for ‘photo reflector’ or tap up one of your photographic mates.

And finally on exposure, keep an eye on the histograms. Set the camera display to ‘flash’ burned out highlights. Don’t lose highlight detail although if you shoot RAW+jpg there’s more that can be done to rescue you.

Shoot RAW+jpg

Straight out of the camera jpg will be better and will do for most of the shots. However if you get a priceless shot that isn’t quite exposed right or with wonky colour balance a TOGSQuad chum or other photographic friend will rescue you. Yes you will probably need a second memory card. There’s no benefit in using uncompressed RAW, use lossless compression (probably the default. If you have the choice 12-bit is fine, you don’t need 14-bit.

The Lovely Assistant

You are taking a lovely assistant, aren’t you? Not just to hold the diffuser / reflector, but also to carry a back-up camera. A compact will do fine and of course be bagging all the good candid shots while you sweat blood over the formal ones.

Candid (1)

They’ll like the candids more than the formal shots. Tough.

On that subject, the lovely assistant will also tick off the shots the bride asked for when you ran through it in advance. If she wants a picture of her with Aunt Dolly and Aunt Daisy DO IT. If Aunt Daisy and Aunt Edna must never appear in the same frame because of what Aunt Dolly’s cook told Aunt Edna’s parlourmaid find out. Family feuds matter.

The lovely assistant will also arrange people for the formal shots while you are tearing our hair out trying to work your new camera. And when you have the brilliant idea of posing the bride in a tree, the lovely assistant will bring the white towel or sheet to protect the dress from dirt.


List the shots in advance

Oh, I’ve already done that.

Don’t upset the Vicar
No, really. If they say ‘no photographs during the service’ they mean it. If the vicar stops the service to tell you off the bride will be unhappy. And it does happen.


You have been warned

You’re going to have a lot of photos. Pick the best plus the essentials from the list and sort them out from the ‘also rans’. People might want to see 50 photos; they don’t want to sit through the 200-2000 you might shoot. Put them in a separate folder.

You now have a workable number of photos if you are going to be doing any tweaking. On that subject establish the extent to which the bride wants her complexion softening. If she has a plook on her neb (a spot on her nose) she may want it airbrushing out. She may not. Don’t waste your time making a forty year old look fourteen if that’s not what she wants.


So the Just Do Its

- speak to the bride and get a list of must-have shots

- sus the light in advance

- sus where you’re going to do the posed shots

- watch the highlights and shoot RAW+jpg

- most importantly, take a lovely assistant and if you don’t have one it’s a jolly good chance to ask

- and remember, they will be delighted anyway!

Good luck!

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How to fix a Nikon GPS cable

If you’ve got one of these you’ll soon find (at least my son and I did) that the cable design is woeful – it’s far too long and catches on stuff and bends. What’s worse is that the strain relief is far too rigid and it just snaps rather than bending. (I’m specifically talking about the CA10 that joins the GPS to a 10-pin camera like the 300, the principle holds good for others I suspect).


Camera end on its last legs


This is the GPS unit end under stress

A quick Google finds somebody offering the cable for GBP260, Grays have them for about GBP50. Mine lasted a fortnight in India. Yes you can get a replacement from the shop under warranty but they’re not going to do that every two weeks for the next few years.The solution is simple if you have access to someone with an electronics lab – you need to put some flexible rubber sleeving over the transitions to better take spread the stress. Here are a couple of ends – one almost gone, another brand new so treated. You can guess it’s better to fix the cable when it’s new or as soon as possible.

Hellerman 4

Repaired ends – top one was ready to fail, lower one protected before it got the chance.

So how do you get those rubber supports on? You need the fiendishly-cunning Hellerman three-pronged pliers:

Hellerman 1

You slip the sleeve over the prongs and expand it so:

Hellerman 3

then slip the smaller end of the cable through. Slacken off the pliers and withdraw them from the sleeve.It takes a certain amount of force and dexterity and be careful not to impale yourself on the prongs, but it does the job. If you haven’t got a chum who can lend you the tool and a few sleeves the tool costs only GBP35 so would be worth it if you plan to use the GP-1 a lot.

Finally, as you can see I’ve used a combination of medium and large sleeves to taper the strain relief.

My first and last article on DIY!













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Strobism – not as easy as it looks

It all seemed so easy. That nice David Hobby (Strobist)’s videos show him wandering round Howard County, Maryland lighting anything and everything with a handful – at most – of Nikon strobes (or flashguns as we say here in Britain). So when I had a minor op on my hands and was provided with a couple of splints to keep my palms flat during the night it reminded me of the appliances the Victorians used to stop boys, ahem, ‘touching themselves’. A photograph of my hands encased in these things and entitled ‘Tales from a Victorian orphanage’ seemed like an idea. Had I known what lay before me… Anyway here’s the photo.

Tales from a Victorian orphanage

Tales from a Victorian orphanage

and yes I know that the Victorians painted institutions green not orange and didn’t have Velcro. But it all started as a five minute project to provide some amusement on Facebook. Two people and three and a half hours later…

Let’s start with what went right. I used a Manfrotto 055XPROB tripod on which the centre column can be bent out sideways so the tripod is of to my left out of the way. A 10-24mm zoom on a Nikon D300s was pulled back to 10mm to allow me to be behind the camera and stick my hands up in front. My wife focussed using live view and pressed the shutter. It might have been better to have used a Triggertrap to fire the shutter and used the multipoint AF rather than the rather slow contrast detection AF in live view – lots of wasted shots.

Now the strobes. Five! The problem was trying to light the stairwell. The SB-900 upstairs couldn’t see the master downstairs. So the master on the camera is zoomed out and pointed at a flash just out of sight half way up the stairs and at zero power – it in turn relays the signals to the one on the landing. There’s a brolly behind me and another flash clipped to the cord of the pendant lamp by the kitchen door on the right. The time was spent iterating that setup. Oh and the splints came out too bright so I tried using a polariser to turn them down. Did it work? I don’t know, I was past caring. But it did mean two of the flashes were on full power just to get f/5.6 (and I only went to f/5.6 because the focus was so chronic. Perhaps a brighter way to tackle it would have been to have exposed the house using ambient and to have gelled the flash to match the compact fluorescents and then shot at 1/30. We live and learn.

But at least I’ve justified that fifth strobe to SWMBO. And when I go and try to shoot an interior I won’t make nearly such a fool of myself in front of the client trying to light it!

If you’re wondering about the medical side, Dupuytrens Contracture is when cords grow in your hands and pull it into a claw. Mind had progressed to the point where I could only just get my hand around a pint pot, so time to get it sorted. The operation consists of a local anaesthetic which has to be partial as you need to scream if they hit a nerve. Then the surgeon simply inserts a syringe needle and breaks the cord with a series of punctures. Sounds horrid – it wasn’t. Here in Derby (UK) it’s done as a one stop shop – you’re in and out in half an hour. Making the splints takes longer. And I was using my hands fully as soon as I got home. Three cheers for the NHS!

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