Well it was an interesting day, I spent the last three days furiously writing up my exercises for my learning log and getting the web site ship shape. I designed a new pagelayout for the front of the the  learning log to make everything easier to use  and follow. I also spent a lot of time writing everything I have Done up.

So this morning I woke up and carried on sorting the photos for the lasa exercise in part one of the art of photography, knowing that two very important andepic things were going to happent today, the first was scheduled for ten am, actually they both were but we moved one, the first was taking my youngest daughter to get her GCSE results a very difficult thing, thankfully she did exceptionally well and got her place for A levels confirmed.

My second big event for the day was a scheduled conversation with Sharon Boothroyd, this was my first telephone conversation with her, although we have been exchanging emails this was my first chance to get some real feed back and get a good idea of the personality of my mentor for this degree course.

Having set a specific time planned ahead and set up several alarms and reminders in my plethora of electronic devices we experienced the truth of the quote first reported to have been said by Helmuth Karl Bernhard Graf von Moltkeread the elder a German Field Marshall at the beginning of the first world war, that “no plan survives contact with the enemy” When my youngest daughter informed me that I had to take her to pick up her GCSE results at ten o’clock the same time as the phone call anyway we re arranged and I finally managed to get on the phone to Sharon while she was out in the middle of town.

To my mind the call went well and fulfilled it’s purpose excellently, as I guess everyone does I had been worried that I might have gone at the course work with completely the wrong end of the stick and it was a relief to hear her say that things were looking good on the blog and  I seemed to be doing the right things, I shared the ideas I am working on for my first assignment and it was a relief that they seemed to resonate with the purpose of the assignment. The key lessons I got from this meeting were to put more commentary into the blog about the things I am discovering, the ways I am challenging “The Rules” and the books I’m reading, I will also be putting commentary in about trips and photography excursions. I learned that it is good to challenge ask why and be critical about my own work. One thing that hit a chord was that I have often remarked that I might go back and re shoot an exercise, Sharon’s opinion is that this was not necessary as it is our mistakes that give us the biggest lessons and it was more powerful to publish the stuff that did not work and demonstrate that I know it’s flaws understand why it’s flawed and learn from that so that my future work is improved. I did think that if I went through this entire degree without making a mistake or doing something badly I would probably not learn much and the whole experience would be less interesting.

I also picked up again the need to reflect on the art side of photography as the OCA have a strong leaning toward developing photography as an art form rather than a technical process, and it was important to look at the work of others and push myself to find other photographers to admire (or not) and to get to more exhibitions of others work.

To this end I am going to try to search out the work of others and put together a group of people who’s work I admire, most of the people I liked when I studied photography are dead and it would be nice to add a few living to the list.

All in all I really enjoyed my first tutor session and am really looking forward to working with Sharon over the next few years to get my degree. Sharon has made me think about lots of things and I am fired up and off to conquer the world or at least my camera

I have been distracted this week by focus, several things sent me in to a voyage of discovery and I thought I would share my findings and the circumstances that sent me to find them.

Firstly over the last month or two most of the pictures I have submitted to my better photo courses have carried the comment that they are not quite tack sharp, I have to be honest this has driven me round the bend, Kerry Drager is the worst (and the best) at telling me this, that’s not a dig at Kerry but rather the reason I love his classes so much, he tells me straight and has an eye for these things, often I have read the comment and thought he was seeing things but on every inspection he was bang on the money. The first discovery I made happened about two to three months ago when I was trying to figure out how an autofocus system doesn’t!

I came across lots of reviews and forum comments that suggested my old Canon EF Ultrasonic 28 to 200 was a badly built lens that suffered from poor quality:

Like this for instance: Canon EF 28-200mm f/3.5-5.6 USM Lens Review

I took it to the local camera shop who looked at it and found it also had a tightening in the middle of its zoom range that didn’t help. Thy offered to get it serviced for me but since I had just invested in a new Canon 7D I thought it deserved a new main telephoto lens, I went to the local camera shop who sold me after much uming and ering a Tamron 18 to 270 f3.5-6.3 Di II V PZD. This lens was supposed to be a great quality lens but cheaper than the canon equivalent.

My problems were over or so I thought, my photos continued to get not quite sharp comments from Kerry, REALLY? maybe his eyes are not what they were, no such luck as usual Kerry was spot on the money, so what could be wrong, I did the one thing I don’t think anyone who spent a lot of money on a camera body should ever do! I googgled “Canon EOS 7D Focus problems”, OH MY GOD! The forums are alive with chatter on this; mostly hear say and lots of ignorance I discovered.

So do I have the one flawed body that Canon Make???? Well if you own a canon EOS 7D calm down you don’t!

It’s perfectly capable of producing Tack Sharp images to equal any Nikon body, this is where it gets hard and where the skill arrives, there are so many factors that effect this problem and many of them relate to workflow.

First of all I was using the standard ONE SHOT AF setting with the 19 point auto AF selection enabled that should work for all situations right? Wrong! It will focus on an object or series of objects that are closest to the camera not necessarily the object that is your main subject.

Lesson 1 Take control you decide where to place the focus after deciding to take Charlotte Lowrie’s Better photo Class on the 7D (Highly recommended by the way) the first week’s lesson got me looking at the Auto Focus System and adjusting it for the shot I am taking to ensure that the focus sensor is the one over the subject (I won’t try to teach the how of that go take Charlottes class if you need to know). So now I am actually focussing on the right thing that’s good

I took a photo of a tractor wheel, it was one of the picture that set me on this quest, I thought that Lesson 1 would fix that problem, oh no! When I looked at it there was not a single place on the picture that was sharp it was all fuzzy. Now how can a camera with one of the most complex auto focus systems on the market fail to focus on any point in the frame maybe the EOS 7D really does have a focus problem WRONG!!!, looking at the data I took the shot hand held with a shutter speed of 1/40sec at f6.3 ISO 100 and a focal; length of 219 mm, anyone spot the problem? Shutter speed, you ant hand hold 1/40 of a second at 216mm without the shacking of your hands sending the image fuzzy, so the old age rule has always been shutter speed should be the reciprocal of the length of the lens to hand hold that 1/216 sec or in this case 1/270 sec minimum as I am reliably told by Kerry that the rule is for telephotos to use the longest focal length for all shots with a zoom lens to compensate for the weight of the thing.

Lesson 2 USE a tripod and if you can’t get the shutter speed up to allow for a hand held response, don’t forget you can raise the ISO if you can’t get the shutter speed you need but watch out that you balance this with the digital noise you get from higher iso numbers.

Lesson 3 Set up your camera and test it. I found that you can adjust the micro focus of your lens on the EOS 7D and I found a great sight that tells you how PUT IT HERE I did this and found my Tamron lens was slightly out so worth doing.

Next I was given a link to a forum where there was a raging discussion about getting a sharp focus on a product shoot at f22, now I use f22 quite a lot in the belief that I will get great depth of field like this, and there was some comment that at f22 most lenses go a little soft, not sure if that is even slightly true but some physics was quoted which in an internet forum almost always means its rubbish, however I did find this site which may help to offset this conundrum you can decide for yourself I have included a range of test shots with all parameters fixed except aperture to show my 7D with mu Tamron Zoom set to a focal length of 39 mm focused using the Manual Single point AF with the centre sensor active in ONE SHOT AF with the sensor over the centreline of the chart you can see the results for yourself and decide if there is a focus problem or not.

39mm Focal Length at f/4.5

39mm Focal Length at f/8

39mm Focal Length at f/11

39mm Focal Length at f/22

39mm Focal Length at f/29

Links you may Find Helpful:
A blog on the Nikon D70 the chart above came from here

Ugly Hedgehog.com: The forum discussion on focusing at f22 thanks to Jan

10 -12 photographs
Next, do the same kind of thing while following the movement with the camera. Take the camera off the tripod for this (or loosen the tripod head), and simply swing it so that the moving subject stays in the middle of the frame. This comes naturally as a technique to most people, and is known as panning. Again, compare the results of different shutter speeds. 1/60 sec or 1/30 sec will give a fairly sharp image of the subject, while the background will be streaked. This is an easy way of freezing the essential movement in photography.
Having assessed your results in a technical way, sit back and choose the one from each of the two series that you actually like the best. Is it the sharpest version? Or do you think that some slight blurring gives more of a sense of speed? Sometimes the amount of sharp detail that you get in a photograph is less important than the overall impression. Write down your thoughts in your learning log referring to the prints by the numbers you have given them. File the prints, and order the digital files in a folder (or place the negatives or slides in a file, if you used film).

1/50sec

At 1/50 of a second the horse and the background are pretty much frozen by the shutter speed, but we do start to see an effect here that was discovered from the early studys by Eadweard James Muybridge into horse locomotion that the hooves of a horse move at dramatically higher speeds than the rest of the leg as they flick them, in this photograph you can see that the hooves are slightly blurred compared to the rest of the horse. In the last two shots this is exaggerated and finally frozen at 1/800 sec

1/40 sec

At 1/40 sec the motion of panning the camera is holding some of the horse in focus while the background is beginning to blur this is a relatively fast shutter speed for this effect to work

1/30 sec

At 1/30 sec we start to see a more pronounced effect as we start to leave the safe speeds for hand holding a camera

1/25 sec

At 120 of a second we are starting to get a sense of motion

1/20 sec

At 1/20 sec I think it is really starting to work there is enough balance between blur and sharpness to make the image work, notice this image captures the horse with all 4 feet off the ground

1/15 sec

At 1/15 sec again its working bur we are starting to get to the point where most of the photograph is blurring it’s not quite to a point where none of it is recognisable yet

1/13 sec

At 1/13 the image background is a blur but enough of the horse is in focus for us to identify with the image as a horse.

1/10 sec

Starting to get some real blur at 1/10 sec at this sort of speed the differing movement speeds of different parts of the horse begin to show up, you notice the added impression of speed generated by the blur on the rear legs

1/8 sec

At 1/8 sec you can see the photographer’s natural instinct to follow the eye or head as this is the part that has remained most in focus during the pan

1/6 sec

At 1/6 sec it is hard to tell which parts of the horse are which the tail is almost indistinguishable from the rear leg.

1/5 sec

at 1/5 sec we are getting double images and a lot of blur this is starting to not look as good to me

1/4 sec

It’s funny how this happens but mostly by luck all the parts of the horse come together here at the slower shutter speed and the image works better than the ones with the slightly faster shutter speed I like this image.

1/800 sec

I had to go to a shutter speed of 1/800 sec to finally freeze the hooves showing just how fast this horse flicks the tips of his hooves. This horse was only in a canter for these photographs imagine the speed if it had been galloping, It would be interesting to see if a much higher shutter speed would be needed to freeze a galloping hoof

1/160 sec

Just to prove a point this was shot at 1/160 sec and the horse and background are relatively sharp but notice the speed of the front right leg which is not frozen at this relatively fast shutter speed.

CONCLUSION

I think I prefer the shots at 1/25 and 1/20 sec they convey a sense of movement and are exciting to look at. over both of the exercises on photographing motion I think I have prefered images that have some blur and motion conveyed in them to stark sharp shots frozen at really high shutter speeds.

Lessons Learned

Continuing on from the discussion in the previous exercise if our example is no longer a rock or a building but now a person waving an arm. In this example the photons continue to bounce off our subject and enter the camera lens, if we have a fast enough shutter speed the photons only bounce onto the sensor from one position of the arm and appear to freeze the action, see the last image of Colin cantering around the ring above, however if the shutter is too slow the photons collected by the lens will have bounced off the arm while it was in more than one position giving multiple exposures for the arm on the film, the result will be a blur of motion. Like the images taken a 1/4 and 1/5 second above.

Now from an aesthetic point of view it get complicated now as this is not necessarily a bad thing and neither scenario is right or wrong depending of what you are trying to achieve with the image, if we wish to take an image of Colin that shows our audience that he is a magnificent and fast beast then the slow shutter speed will convey a greater idea of the speed and motion if we want to demonstrate that a horse does indeed take all four feet off the ground in mid gallop then the faster shutter speed is the answer.

This exercise demonstrates some further factors, the art of panning allows us to shift the blur but moving the camera with the subject we lessen the blur caused by that motion and transfer this blur to the stationary background thus creating an aesthetically pleasing image that cry’s out motion and speed and if done properly will not make the audience cry “Out OF Focus”

10 -12 photographs
You need the camera to be fixed in front of something that moves several times or continuously across your view. Water flowing over some rocks is one possibility, or a friend riding a bicycle a number of times in front of the camera. The subject and setting of the image above is a good example. Try and think of something by yourself but make sure that the setting – and in particular, the background – is simple and plain.
Set the camera on a tripod, if you have one, so that the flow of movement is across the view. If the subject is someone walking or riding, their image should fit just within the viewfinder frame. Make a series of exposures, from the fastest shutter speed on your camera to a very slow one, such as one second. Adjust the aperture each time, or have the camera set so that it automatically adjusts the aperture (see its instruction manual) so that the exposure stays the same, as in the last exercise. Keep a note of the shutter speed used for each frame. Compare the finished images and mark each one with the shutter speed that you used. Find the slowest shutter speed at which the movement is sharply frozen. With some kinds of movement, like a person walking or cycling, there will be different rates of movement at the same time: the bicycle, say, will be moving at one speed, while the legs may be moving faster. You should be able to see this, too. Make notes about each print in your learning log.

This exercise required me to take a series of images of a moving object at differing shutter speeds, I went to quite a few different venues before selecting the images I used for this exercise, I had taken and was set on using a series from my trip to Purford lock of the water flooding into the lock as it was operated by the people with their long boats, it was a chance trip to Bird World with my oldest daughter that gave me the final inspiration for this fountain which has a much more consistent shape for comparison with this exercise.

My first image was taken at 1/250 sec which is mostly fast enough to freeze the motion of the water:

The Final image was taken at 1/4 sec shutter speed you can dramatically see the difference between the two ends of the exercise the water is in motion and has blurred to a soft white foamy appearance while the surroundings remain in focus, this image gives much more of an impression of motion you can no longer pick out the individual droplets of water.

Looking at an image that is in the middle of the range at 1/50 sec shutter speed you can see a combination of both traits it is possible to pick out the droplets of water but they are blurred with motion this image gives an impression of rapid motion of the water while retaining some of the definition and shape of the individual parts of the water:

The next nine images show the rest of the sequence 1/160 sec, 1/125, 1/100

1/80sec, 1/40sec, 1/20sec

1/30sec, 1/10sec, 1/6sec

Looking at each image I think I prefer a slower shutter speed the higher speed shots look a little false as the human eye when looking at a fountain like this does not freeze the action in this way so I think som blur is preferable I think the 1/50sec shot looks more the way I remember the scene so more life-like, but artistically I love the more unnatural angel hair like quality of the slower shots.

In conclusion

If I were to pick a shot for realism it would be the 1/50sec but my personal favourite is 1/4 sec as I love both the shape and the soft nature of the water.

Exercise 4 Shutter Speeds Gallery

Clearly Shutter speed is a key consideration in the set up and composition of an image. at its basest level shutter speed controls the time window in which the  camera captures the photons bouncing off our subject, if our subject is stationary such as a rock or building the more photons that are reflected into the camera the more the image is exposed so too slow a shutter speed would make too much light enter the camera and thus over expose the image the reverse is true for too fast an exposure that would result in a dark or under exposed image, This has to balance withe the elements of the last exercise the aperture which opens and closes the lens allowing more light or less light to flow in to the camera, much as a bigger pipe used at the same pressure as a smaller pipe would take less time to fill a swimming pool with water. In our still example of the rock or building our concern is for a correct exposure in the amount of light, as we will see in the next exercise this is not our only concern there is a case where the correct amount of light where the shutter speed and aperture balance do not necessarily make a harmonious image. This is where we add motion to the mix.

From: Exercise 1 Focal Length and Angle of View

I posed my self the following:

NOTE: I need to do some reasearch into my camera to establish the sensor size and the relationship to the focal length.

QUESTION: What is the standard focal length mathematically and how do I calculate it?

The first thing I have discovered is that My Canon EOS 7D has a 18MP APS-C CMOS sensor which is not full frame.

FULL FRAME WHAT IS THAT?

A full-frame digital SLR is a digital single-lens reflex camera (DSLR) fitted with an image sensor that is the same size as a 35 mm (36×24 mm) film frame (Source) (Source 2 Canon White Paper)

From the course we determined that a normal or standard focal length is one that gives an image in the viewfinder equivalent to the view seen by the human eye

I found this definition

Focal Length

The technical definition of a standard lens is one whose focal length roughly matches the diagonal or the film or image sensor. For a standard full-frame 35mm camera this gives a focal length of around 43mm.

In reality, the actual focal lengths chosen by manufacturers tend to be slightly longer than this. For a 35mm sensor, 50mm is the most common standard lens, although some companies do sell lenses which are closer to 43mm focal length.

I found this here at photography mad: which also states:

Crop Factor

Because the “ideal” focal length depends on the sensor size, cameras which are less than full-frame will require lenses with shorter focal lengths. For example, a camera with a 1.5x “crop factor” will require a lens which is 1.5 times shorter than the standard 50mm, which works out at 33mm. A number of manufacturers produce 35mm standard lenses to meet this requirement.

On Digital Picture .com I found a useful table and an explanation of crop factors which suggests my camera has a crop factor of 1.6 my maths tells me that a standard focal length for my camera should be 50 / 1.6 which rounds down to a 31 mm lens.

Next question is why does the camera show 50 mm on the zoom scale when the image looks normal? It appears from this Canon article that the focal length is correct or true as it says at the bottom of the article:

It is important to realise that there is no change to the actual focal length of the lens when it is used on cameras with different sensor sizes. Focal length is a characteristic of the lens and cannot be altered simply by moving it to a different camera.

As my lens is an EF lens and is intended to be used on full frame Canons such as the 1D or the 5D, it would be rather odd for them to have marked it with the equivalent focal length, so I assume that the magnification is the same but the angle of view is not, thus I see an image that is equivalent in magnification but more cropped than a 35mm frame.

I wondered why any of this mattered at all if the result was much the same then it occurred to me that this would not be an issue for telephoto users but would be a problem for wide-angle users as the standard 28mm wide-angle lens would not show as much of the scene. It seems that canon has remedied the problem by producing lenses such as the EF-S 10-22mm which has framing equivalent to a 16-35mm zoom on a full frame.

I think the reason that this question originally stuck out for me is that my normal working lens is a Canon EF 28-200mm USM lens and by my recollections of the old days of my Pentax SP2 and my Canon A1 28mm would have given a very wide effect that this lens does not seem to replicate, I know why now and have ordered a canon EF-S 10-22mm so life should be perfect now.

Exercise 3: Focus at different apertures – cameras with a
manual option

3 photographs – prints needed to note results
For this exercise, find a similar subject to the previous exercise. One that will show the results very clearly is a row of things seen from an angle: railings, parked cars, terraced houses, for example. Stand at an angle to this row and, if you have a tripod, set the camera on it so that each photograph will be framed identically. Focus on an obvious point somewhere near the middle, and make a note in your field notebook of this focus point.
Take the first picture with the lens at its widest aperture. Take the second with the lens stopped down to the mid-point of its scale of numbers. Take the third with the lens at its smallest aperture. You will, naturally, need to adjust the shutter speed so that the exposure stays the same, or have the camera set so that it automatically adjusts the shutter speed for a constant exposure (see its instruction manual). Remember that there is a reciprocal relationship between shutter speed and aperture. Just as shutter speeds are graduated in steps that double or halve the time (and so the exposure), the main steps in the aperture control are separated by the same amount. Each stop down from the widest aperture halves the area of the circular opening. This means that, in practice, one stop down to a slower speed accompanied by one stop down to a smaller aperture makes no change to the exposure.
Have a print made from each of the photographs; number them and compare them. There should be an obvious difference between at least the first and the third. With a pencil or marker, draw on each print what you see as the limits of sharpness. This will give you a more precise picture of the depth of field at different apertures. You can see that each pencil band is arranged around the point on which you focused. Keep these and other prints in, or with, your learning log for future reference.

Four images taken at a fixed focal length with the focal plane adjusted to the middle soldier

TOP LEFT: f/5.6 1/30sec  Focal length 90mm ISO400 this has the smallest depth of field and really only allows the middle soldier to be in focus which does not really work as we cannot see much of him.

TOP RIGHT: f/11 1/6sec Focal length 90mm ISO400 In this image we can see the depth of field increase leaving the front and rear slightly out of focus.

BOTTOM LEFT: f/22 0.6sec Focal length 90mm ISO400 In this image the whole line of soldiers are in focus although the first and last soldier are not quite pin sharp

BOTTOM RIGHT: f/32 1.3sec Focal length 90mm ISO400 Some lenses seem to support this extremely small aperture and whilst it seems to bring all the soldiers into focus if you look to the edges of the frame and compare it with the f22 shot you will see a degradation in sharpness caused by the small aperture as a rule I try not to use this 100mm Macro lens above about f22 where it remains sharp.

Exercise 3 demonstrated the importance of depth of field and its relationship to aperture, it is important to select the right depth of field for your subject. For instance a closeup of a flower would probably benefit from a shallow depth of field so that the distracting elements behind the flower are not distracting by being in focus.

A panoramic city scape photo however would benefit from a wider depth of field in order to bring all of the compositional elements of the picture into focus.

The lessons that can be drawn from this exercise build on my coments for the previous exercise that used a fixed aperture, this execise adds a further dimension to the focus part of our workflow. This dimension is the one of different depths of field, in the last exercise the apature was fixed at its widest and thus at its smallest depth of field. In this exercise we were asked to focus on the centre of the composition and slowly change the apature as we took shots. The effect of this was to increase the depth of field in increments. The dilemer now is not just where should the focal plane be set but how much depth of field should be included in the composition. There is no correct answer to this itb will depend on the intent of teh photographer. The whole mood and meaning of a photo can change based on the placement of the focal plane and the amount of depth of field. this two is a vital consideration in my composition workflow

Exercise 2: Exercise: Focus with a set aperture – cameras with a manual option

2 – 3 photographs
Find a scene which has depth — a wood full of trees, for example, a row of cars seen from an acute angle, or a crowded
market. From the same place take two or three pictures, each focused on something at a different distance. (For this to work, the
lens aperture must be wide – at its lowest f-stop number.) When the photographs are processed, compare them. Notice first how the sharp
focus draws the attention, and also how a sharp subject stands out very clearly against the out-of-focus surroundings. Which version do you prefer? Enter in your learning log, as clearly as possible, why you prefer one photograph over another.

For this exercise we were asked to find a subject where a number of elements moved away diagonally from the viewfinder. I decided to take these shots of a row of toy soldiers.

For the fist image I focused on the front soldier.

The next image focused on the second soldier but the depth of field from a fully open aperture bought some of the front and third soldier into focus

The third image moved the focal plane back to the third soldier loosing focus on the first but gaining some focus on parts of the fourth soldier

The fourth predictably took the focus back one soldier and as we can see the depth of field was about one soldier plus or minus about half a soldier meaning if I focused on the space between two they may both be in focus.

Due to the uniform size of the soldiers the results have become quite predictable we can see from the sequence so far that we have about two soldiers in-depth of field at f5.6 the widest aperture at this focal length. As the bases of these soldiers are 20mm square It suggests that at this aperture and focal length the depth of field is about 40 mm.

We have reached the back soldier the focus is actually on the one before last but the depth of field has started to bring parts of the last soldier into focus

The Final image leaves the last soldier in focus with the depth of field bringing parts of the second to last soldier into focus

If I had to select an image I think it would be the second one because it has a nice group of soldiers in focus in the foreground and compositionally I want to see the first soldier in sharp focus. This unfortunately has not really happened here and I would probably re shot this to capture a sharp focal plane that concentrated on the first soldier but allowed some of the second soldier to come into focus.

I do not really like the images that have the focal plane in the centre or the rear as the subject demands that with soldiers seemingly marching toward you it should be the front rank in focus and the rear ones gradually dissolving focus.

If I had taken a different subject like a fence etc the story may have been different depending on the motivation of the subject. I do not think there is a right or wrong answer to this and the answer would depend on the purpose of the image and the artistic taste of the viewer.

When I set this up  I stuck all of the soldiers to a line of masking tape so that they would stay in place and not move and spoil the composition, I decided to set them up at about 45 degrees to the camera so that there was a clear movement away from the camera that would allow this exercise to demonstrate its point.

I set the soldiers up in a light tent with a black background and two fixed lights with daylight bulbs, the typical sort used for product type shots, because of the white nylon of the tent the bulbs cast a very even soft light on the subject. I have found that the closer you place a light the bigger a source it is and the softer it is on the image, this was a revalation I picked up taking a short course in photographic studio lighting, I also learned that putting a difuser in front of the light made the whole difuser the source and hence made it a softer light, the effect of the tent is to give a very soft difuse light which works well in showing the effect of this exercise. The toy soldiers are made from grey plastic and have not been painted, the effect this gives on the black backround is that the images look like they were shot in black and white even though there is clearly other coloured light at work in these images.

Over all I am pleased with the results of this execise which clearly show that the lens has a small depth of field at the widest aperture and demonstrates that there are important decisions to be made about the positioning of the focal plane when composing an image. I have discovered in the time since taking these images how important this lesson is in the development of a workflow and in getting a composition that works. Misplacing the focal plane can give the impression that the image is out of focus or not sharp. It leads the eye to a specific place in the image which if set incorrectly can unbalance or even alter the intent of the original image.

This idea of getting the origin of the focus is a really important part of my developing workflow for taking images, one that constantly catches me out when balancing it against everything else that needs consideration in the construction of an image. for more of my thoughts on focus and the problems I had see my post called Focus aVoyage of Discovery

For exercise 1 I took a walk along the Basingstoke canal to the lock that is between North Town and Ash Vale. Initially I went behind the house to the river there but because of the time of year there is so much new greenery sprouting that there really was not enough room to do this test and the pictures looked rather dull.  I thought the Lock gates would make a nice subject for this test.

Equipment: I used my Canon EOS 7D fitted with an EF 28 to 200 mm f5.6 Zoom lens.

I set the zoom to the point where the image looked the same to my open eye as it did through the viewfinder, this lead me to my first discovery. I was expecting the standard focal length to be different to the 50mm that was the norm on 35mm cameras because I had read that the sensor size of the camera would change this ratio and it only worked on so-called full frame sensor cameras. However the lens was at 50mm on the dial and the meta data on the file confirms this. I will now have to go ahead and investigate this further to fully understand this relationship.

Here is the Image at 50mm Focal Length (Standard):

f/5.6 1/160sec ISO200 50mm

Next I zoomed the lens to its minimum focal length of 28mm and took the second image

Here is the Image at 28mm Focal Length (Wide Angle):

f/5.6 1/160sec ISO200 28mm

Next I zoomed the lens to its maximum focal length of 200mm and took the third image

Here is the Image at 200mm Focal Length (Telephoto):

f/5.6 1/80sec ISO200 200mm

It is clear from this experiment that the shorter the focal length the wider the angle of view i.e. smaller the image and therefore more of the scene fills the image.

When extending the focal length the image gets larger and appears closer therefore les of the scene fills the image.

I printed out the images and returned to the scene, I found that the standard image i could just about get to match the size of the scene by holding it at the extent of my reach. I found that I had to get about an inch from the paper in the case of the 28mm print and that I would need to have taken an assistant to make the telephoto one work as it was far beyond the reach of my arm.

NOTE: I need to do some reasearch into my camera to establish the sensor size and the relationship to the focal length.

QUESTION: What is the standard focal length mathematically and how do I calculate it?