Exercise: Your tollerance for noise

The term ‘noise’ in the way we are using it here originally came from the world of radio… more specifically old fashioned High Frequency radio use.  The transmitted signal would be received but those long wavelengths were also coming from lots of other sources; car engines, refrigerators, overhead power cables, the atmosphere, thunderstorms and even outer space… indeed almost any electrical effect, natural or man made.  If these other sources were strong enough they would swamp the transmission and the strains of the BBC World Service would fade into the hiss.

The effect of image noise is similar but a better analogy is to remember our days of using wet film.  In order to shoot in low light we used fast film that had large crystals of the light sensitive silver halide in the film emulation, big enough to react quickly to the low light levels.  The disadvantage was that these fast films produced grainy, blurred negatives.  When we wind up the ISO setting of our digital cameras we get a similar effect, albeit for a different reason.

When we increase the ISO setting of our cameras we are asking the electronics to amplify the light signals received by the sensor so that we can get a viewable image.  This amplification (increase in sensitivity) has a down side.  The millions of light sensitive pixels on our sensors cannot all be made perfectly.  Some will react  to light a little more than its neighbour and some a little less.  As we amplify the output of the sensor these differences become more apparent and errors appear.  We see this as noise.

An acceptable level of noise will depend on our personal tolerance to imperfections.  As a general rule however, if the level of noise exceeds the level of detail in the image it will probably be unacceptable and visa versa.

This exercise asks us to shoot an identical image throughout the ISO range of our cameras, varying the speed to obtain the same EV (Exposure Value) but going no lower than ½ sec to avoid introducing long exposure noise.  Below are my images with areas of the ceiling, the dark doorway and the bust details magnified.  The images were shot in RAW but haven’t received any additional processing, just a basic conversion to JPG.

1/2 sec, f22, ISO 100

At ISO 100 the ceiling looks smooth, the dark areas unblemished and the detail is clear.

1/5 sec, f20, ISO 200

1/10 sec, f20, ISO 400

By ISO 400 a small amount of noise is appearing in the smooth ceiling area but not enough to affect the natural texture, indeed without the ISO 100 shot to compare it might well have gone unnoticed.  The door and bust details are generally unaffected.

1/20, f20, ISO 800

1/40, f20, ISO 1600

For a lot of cameras, ISO 1600 would be almost unusable but I am fortunate to be using the Canon 5DII and even at this level the noise isn’t too noticeable, until you examine the smooth ceiling which is now quite obviously suffering from a rash of speckles.

1/80, f20, ISO 3200

By ISO 3200 the ceiling is developing it’s own patterns caused by the noise that has appeared.  The frame of the door has also become quite speckled, however the texture and colours mixed in with the bust do a good job at disguising the effect.

1/160, f20, ISO 6400

ISO 6400 is the practical maximum of my camera.  It does have specialist levels of H1  (ISO 12800) and H2 (ISO 25600) but these should be used in conjunction with the High ISO speed noise reduction C.Fn settings which would skew the findings of this exercise.  At ISO 6400 noise is apparent in most areas of the image and it gives the entire image a mottled, rough textured finish.  The overall image is still quite acceptable at a reduced size but close up it definitely suffers.

High ISO settings will always degrade an image to one degree or another, particularly in areas of smooth texture that will become artificially grainy.  However, if the situation demands a speed or aperture setting that forces the use of high settings then it is the lesser of the evils.  In some situations, the grainy quality introduced by a high ISO can help to create a period feel to an image but usually when combined with a form of monochrome to complete the illusion.

The images above had only the most basic RAW to JPG conversion but with a little effort even a high ISO image can be corrected to become quite acceptable.  Below are two magnified images taken from the set above, one is from the ISO 100 photo and one from the ISO 6400 one.

The advantage of using good RAW processing software can’t be overemphasised when dealing with high ISO images.  If you haven’t quite worked it out yet… the top one is the ISO 6400 one.

Exercise: Highlight clipping

This is a scene of high contrast and I have photographed it from the point just below which the camera indicates hightlight clipping.  From this light level I then replicated the shot through +1 to -3 EV giving me five shots.  Detail from each shot, an area of colour and an area of near white is shown below for comparison.

+1 EV

EV 0 (exposure just below the white clipping point)

EV -1

EV -2

EV -3

Looking at the magnified areas above we can note the following.

At +1 EV the white areas of stone are completely lacking in detail such that different areas of stone blend together as if they were one.  Except where shadow indicates breaks, it is impossible to tell the edges of the stone.  Clicking on the +1 EV image to expand it, lines of green fringing can be seen around the block (top left corner) and red fringing on the shadow it creates.  The colour sections shows a little desaturation as it is washed out by the overexposure.

Examining the other images the amount of detail that becomes obvious on the white increases as photos are stopped down but by the time they get to EV-3 things are getting so dark that the detail is becoming lost in the gloom. The coloured fringing is generally present throughout but by -3 EV the green has almost disappeared however the red is still present.  The colour saturation increases until the lack of exposure at -2EV and beyond makes it too dark to be obvious.

As is suggested, on this blowup I used the Recovery option in Lightroom to regain some of the detail from the +1 EV image.  Certainly, this option has done a lot to recover the information from the clipped areas; the edges are more obvious and much more texture is visible.  There were no discernible strange effects from putting the slider to maximum.

Finally, I used all of the available options in Lightroom to adjust this +1 EV image in an attempt to recover the maximum amount of information from the RAW photo.

Exercise: Sensor linear capture

One of the most appealing aspects of wet film is it’s natural response to light, in that it tends to mimic the capability of our eyes.  Not so the digital sensor.  Our eyes have the ability to compress the extremes of light and dark into a larger dynamic range than is available to the digital sensor.  This allows our eyes to cope with a wide range of light levels but to achieve the same with a digital camera we have to resort to electronic manipulation.

In the great majority of cases, our cameras process the raw digital interpretation of a scene before we are presented with it.  This ensures that the result is much more to our liking than the basic data would have appeared.  Of course it is possible to process this raw data ourselves using suitable software in such programmes such as Photoshop or Lightroom.

To examine how the raw data would be presented without processing this exercise asks us to open a picture and adjust it’s curves to simulate the raw data.

This is the original picture with it’s histogram attached.

With the curves of this picture adjusted like so…

the picture looks more like it would have done without any processing.

With the two images together I now return the dark one (left) back to resemble the normal one (right) by moving the curve up and left.

The result of this adjustment is to lift the dark areas of the image but the side effect is the noise that was previously hidden in the shadows had appeared.  Below is a comparison with the original image.

The noise is quite evident when viewed above with a section of the original image.

For all practical purposes, the processing done by the camera to create a good looking image is beyond the understanding of most photographers.  Even when converting a RAW image file to save as a TIF or JPG, the photographer is mainly tweaking a pre set series of values that have been chosen by the software designer.  However, having access to the RAW file allows us much greater artistic freedom.  Though we must endeavour to remember the limitations of the digital sensor, particularly when eyeing up a scene of high contrast and large dynamic range.  What our eye sees is not necessarily what the camera will be able to record!

Addendum:  The course notes relating to this exercise would seem to be in error.  They state that ‘for the linear image the histogram shows the tones to be squashed strongly to the right’, whereas in fact they are moved to the left as can be seen above.  In addition, the notes add that the linear image ‘has most of the levels available to represent the tones devoted to the brightest parts of the image’ whilst it can clearly be seen that the linear image has more dark tones.

Fujifilm X10

I will soon be headed off on a visit to Australia to see my aged father and I always cringe at the thought of trying to pack for a long visit whilst trying to include my camera gear.  Which body and lenses, will I need filters, what flash, which tripod.  Inevitably I end up with way too much and arguing with the check-in staff that my 10 Ton kit bag is hand luggage.  This time I am trying a different tack.  I have invested in the Fuji X10 and will limit myself to that, a couple of data cards and batteries with charger and perhaps an external flash.

The X10 is the latest in a series of modern ‘range finder’ camera’s that hark back to the days when photographers wanted a sophisticated camera but not an SLR.  Leica seem to have kicked this trend off with a revival of some of their iconic cameras, now digital.  Fujifilm have jumped onto the bandwagon and their latest is the single lens version of their expensive X100.

This isn’t a replacement for an SLR… but it is much more than a point a press!  Firstly, with only 12 megapixels (and only 6 in some modes) the file size isn’t going to impress most people but that is what you have to expect with only a 2/3 size sensor.  At full resolution the limitations of a little sensor are evident… its a bit noisy and not very sharp but then I am used to my Canon 5DII.  These limitations don’t worry me in the least as I have no intention of making monster sized prints.  The X10’s performance improves considerably in the EXR setting which can be selected to give additional resolution, dynamic range, high ISO/low noise or automatically do its own thing.  The drawback is that now the sensor effectively becomes only 6 megapixels as the other 6 million are off doing clever things to sort out the photo.  The lens has a handy manual zoom and opens up to a great f2.0 at 28mm to a useful f2.5 at 112mm.  At the other end of the aperture range as f11 seems to be the best it can do… however, from what I know of compact camera systems, getting large depths of field is not an issue.

The camera LCD is large, bright and clear and thankfully the menus are easy to navigate.  Without that handy LCD panel on the top of the camera that I am so used to I find myself referring to the back a fair amount.  I am not really a fan of shooting with a live view so, although limited, the optical viewfinder is great.  What it lacks is any data whatsoever… its just for looking through and although it does zoom with the lens it covers only 85% of the image so you get a little extra on the sides and chunk below the bottom.  That’s easy to cope with in landscape but a bit harder in portrait.  When you zoom back the lens also appears in the viewfinder but I didn’t find this a problem.  What I would have liked is a central dot to help me find the autofocus point and although I can see the focus ‘OK’ light out of the corner of my eye, it would have been great to have put it into the viewfinder.  The auto focus is quick and reliable which is a good job as the manual focus is slow and difficult… nay, impossible to use!

What I love are the controls.  Most of us could just pick this up and use it off the bat.  The front has a simple Auto Focus selector, the top has a mode selector with all the recognisable functions like Program, Aperture and Shutter priority and fully Manual. It has a couple of Custom setup selections for your favourite combinations and the usual point and press settings for when you hand it to someone else to take a shot for you.  The shutter release has a screw thread for a lovely old fashioned cable release and an easy to use exposure compensation knob that allows ±2 stops.  There are also dedicated White Balance, Focus and Exposure lock, RAW shot selection and an extra function button that I have set to control the ISO.  Its a very hands-on camera.  To finish off this lovely set of buttons there is a full hot shoe for an external flash.

The camera is dinky… almost too small for my big hands but not so small that you are going to forget which pocket you crammed it into.  Mind you, why you would want to put it away I have no idea!  The leather case is extra but worth it as the X10 has a magnesium frame and is quite weighty for its size and needs a little protection from knocks.  A couple of interesting design points is the ON selection which is made by twisting the zoom from OFF to the 28mm point.  This isn’t a problem and the camera fires up nice and quickly but a couple of times I have zoomed the wrong way and turned it off by accident… grrrr.  The other little problem might be battery life.  It isn’t great especially if you use the back display all the time but I have found it Ok so far.

A couple of unexpected extras are the film simulation selections where I can set the camera to replicate several film types with my beloved Velvia amongst them.  The camera can also soot in RAW which is a great option for one in its price range and it will even have a go at HD movies.  For picture quality I have taken a few and put them below… if you click on them they get a bit bigger.

Normal Program shot at full resolution.

Normal Program shot at full resolution.

EXR shot which uses 6 megapixels, set to High Dynamic range setting.

EXR shot which uses 6 megapixels set to Resolution Priority mode.

To sum up… although the price of this camera has dropped considerably, at around £400 it isn’t a cheap option.  Neither is it the sort of camera that will produce truly professional results.  What it can do is provide the sort of lovely ‘day out with the family’ images that a photographic enthusiast wants.  It has all the bells and whistles that any good SLR has, allowing full freedom to set up just about any kind of shot that you want.  What it can’t produce is the quality and resolution of an expensive SLR.  However, it is very retro stylish, fun to use and certainly isn’t going to get dusty in a corner like my last attempt at getting an everyday camera.

Assignment 1 completed

My Assignment 1 for DPP is now complete and can be found here http://nicksoca.webs.com/photography1/Digitalphotopractice/workflow/workflow.htm

I have been working fairly constantly for a couple of weeks now, trying to get my work for Assignment 1 finished off.  It hasn’t been a difficult assignment since it gave a free rein on the choice of subject and a relaxed number of shots that needed producing (between 6 and 12).  What I found, however, was that since I have a reasonably well established workflow that conforms fairly well to the suggested methods I didn’t have that much to alter from my usual habits.  As a result I found the two workflow exercises and the assignment a little repetitive.

However, the opportunity to make more use of Lightroom 3, a new software addition, was a real bonus and the work that I have produced gave me lots of practice and learning opportunities.  I have found the change from a complete Category orientated system that I had with IDimager to the folder based system that Lightroom uses required more discipline when uploading my photos than I was used to.  As a result my folder system probably isn’t too logical and I must work to improve that.

My selection of photos for this assignment was based around the 3 locations that I shot and I found that, being New York, I had a bias towards vertical shots of foreground lights with exaggerated skyscrapers towering upwards in the background.  To get the variety I wanted I discarded some quite reasonable shots but overall I am pleased with the final set.  Someone commented that I had created a ‘happy, sparkly’ view of Christmas and that it might have been more interesting with a comparison between the bright lights and a more sombre social commentary on the down side the holidays.  I have to agree that social commentary is always more thought provoking and ultimately more meaningful but to be fair, this was a themed shoot, done in a short space for a work-flow assignment… well OK, no excuse really!  I could probably have kept some of the shots a little less like a chocolate box lid but hey, I like them!

The shots below are some of my discards from the 27 that I selected for close consideration.  They weren’t included for a variety of reasons.  I didn’t want too many exaggerated views of tall buildings no matter how impressive they look.  I had several views of the same location, window or building and obviously only needed a few.  Some just didn’t seem to celebrate Christmas very well, Time Square being one.  Still, several of them will make good stock images for my Alamy account.

Shooting Assignment 1

December has been a hard month!  I have done 6 long haul flights and 2 training days in the simulator.  I seem to be in a constant haze of jet lag and fatigue.  With only around 14 days in the UK, most of which were spent trying to recover from the previous trip, I did well to have Christmas day at home,,, albeit I was in bed by 8 pm to rest for the next day’s flight.  Whilst most of the UK had a holiday between Christmas and New Year I went to America and back twice!  Unfortunately, although I have done my best to shoot whilst away, I haven’t had much time to process my stuff once I got home.

My most successful achievement was to get my shots for Assignment 1 in the bag.  Because several of my trips were to New York I had decided to try to photograph the city by night, concentrating on a Christmas theme.  I took my images over 3 nights, working at a different location each time… I didn’t have the luxury of spending more than a couple of hours at each location because the layover was short and I needed to get some rest before getting back to the airport.

Manhattan was like a rugby scrum.  I have rarely seen so many people out on the streets, particularly once the sales had started.  I won’t try to describe the frustration of trying to guard a tripod in a river of people who wouldn’t hesitate to trample mothers and children to get to those Nike Airs at 50% off!  Still, I have managed to cut my efforts down to 12 shots and apart for weeding out a couple of the weaker efforts I think I they will do.

My troubles handling a Canon 5DII with battery pack on a tripod and another few lenses about my person whilst negotiating the streets makes me think that there must be an easier way.  I am being lured by the Fujifilm X10 as the discrete street photographer’s weapon of choice.

This neat camera is styled after the old 35mm range-finder cameras that were so common in my father’s era and is one that any competent photographer would love.  I say that because many of the controls are manual switches and dials rather than menu options accessed through the back screen.  The lens opens to a wide f 2.0 and although the zoom isn’t everything I might want at 28-112mm it will do fine for my family holidays and quietly walking the cities of the world.  I’ll let you know how I get on.

In the mean time… welcome to 2012 and have a great New Year.