Shutter Speed

Of the three attributes of the camera used to obtain a correct exposure, shutter speed is perhaps the one that can really catch you out.  In this respect if you remember the F-Stop and ISO are the other attributes that play a role in getting the right exposure.

The function of setting the shutter speed is to: freeze moving objects, accentuate the movement of an object, give more time for the light to hit the sensor or allow less time for the light to hit the sensor.

I have taken a couple of shots below, which although they do not quite freeze the movement it does give you an idea of what the shutter speed will do.

The image above was taken using the following settings: F4.5, 1/60sec and ISO 800.  I shot this without flash and took a meter reading of the ambient light to obtain the correct exposure.  So what does this mean, well at 1/60sec you can see that the rotor blades are moving as they are blurred.  I bumped up the ISO (sensitivity of the sensor) and opened up the F-stop(hole) to let more light in.  The camera was on a tripod and I used a remote shutter release to take the picture.

 

In this image the settings were: F2.8, 1/160sec and ISO 800.  I compensated the increased shutter speed by opening up the aperture to 2.8, allowing more light in.  Although I have not frozen the movement you can see more clearly the rotor blades.   In order to capture the blades clearly (apart from not spinning them in the first place) I could introduce more light by either using flash or increase the ISO thereby making the sensor more sensitive.  I would then be able to increase the shutter speed to freeze the blades.

Things to think about when doing this: you may not see this clearly but the first image will have a greater depth of field, more of it is in focus because the aperture is smaller.  You will have to trade off between depth of field and shutter speed in this case but you can also trade off between graining or noise (quality of the image) by adjusting ISO settings, higher being less quality.  It all depends upon what it is you are trying to capture.

The last thing to keep in mind is that as you get to 1/60sec and below then you might experience camera shake.  You can overcome this by using a tripod and remote shutter release or resting the camera on something and using the timer feature that most cameras have.  Some lenses have image stabilisers and if you have a steady hand then maybe you can get away with hand holding the camera at slower speeds.  I used to be happy to hold the camera at 1/5sec but that was bracing myself against a wall or some other solid object.

Studio - In The Chair

Following on from my earlier post Studio Shoot and Photoshop, I thought I would add the following images that were taken as part of the same shoot.

In essence I wanted to try out a number of poses from a recent book that I bought (Photographing Models:1000 Poses A Practical Sourcebook For Aspiring And Professional Photographers by Eliot Siegel).  One of those that I saw used a classic looking chair.

I set up the lighting for high key which involved having a white background and floor covering, with two lights fixed onto the back wall and two further lights set up on the model.  The settings for the lights at the back was F22, meaning that the power was turned up to allow a correct exposure at F22 on a speed of 1/125 sec and ISO 200.  The settings for the lights on the model was F11 to allow a correct exposure at a speed of 1/125 and ISO 200.  The camera was set initially to the settings matching the lights on the model.  What this means is that the wall would end up over exposed and this is because the hole/aperture setting is smaller for the lights on the wall meaning more light is required to get the correct exposure and the camera setting is to allow only enough light in to correctly expose at F11 which is a larger hole.  The effect is that it bleaches out the white wall at the back. 

It is difficult to try and demonstrate the effect.  Another way to think about it is that the two wall lights are independent from the two model lights and to get a similar, if exaggerated effect outdoors, it to compare a sunlit patch of ground with a patch in shade.  If you take a picture of the two patches of light you will find that either the shadow will be under exposed or the sunlit patch will be over exposed.  Outdoors we use fill in flash to get rid of the shadow or a diffuser to tone down the sunlight.  More blogs to come in later! Anyway getting back to the shadow and sunlit patches, the wall lights are the sunlit part and the model lights are the shadow, it is the same effect caused deliberately in the studio.

Quite an explanation for that so I best move on to the photos.  There were a number of images which I quite liked from this shoot for different reasons.  All of them had to be cleaned up as the high key effect was not sufficient to leave the photos as they turned out.  My aim was to show the curves and shape of the model.  Although the camera was set to F11 at 1/125/sec and ISO 200 I adjusted the F-Stop to either 14 or 16 for most of the shots.  What I maybe should have also done is adjusted the lights at the back to ensure that the wall remained bleached out.

I gave no particular direction about the clothing, but occasionally I would adjust the scarf, I like the combination of black and red against the white background.  In terms of camera angles and poses I got the model to look down over her right arm and to cross her legs as I did a low level shot.  I just like this image as it is a formal appearance but yet a thoughtful look.

 

With this image I turned the chair 90 degrees and got the model to look towards the camera, the hand struck me as being a bit 'lost' on the end and I took a further picture with it lying flat although I didn't process it as she was looking forwards with that image.

 

For this image I again adjusted the angle of the chair and then I stood on another chair to get a downward shot with the arms crossing over.  In a lot of cases I waited until I saw the shot before getting her to pose.  She would often keep changing her position without being asked, but this sometimes resulted in me liking a position and then capturing it.

 

I then set about doing some close in shots.

 



ISO - Film Speed or Sensor Sensitivity

The ISO is supposed to stand for the International Standards Organisation but this covers more than just photography so it is rather meaningless in this context.  The ISO number ranges from 100 up to 6400 and sometimes higher on some cameras.  On my Canon D50 I have 100 up to 3200 then H1 and H2 (which I am presuming double each time).

The ISO number is one of the three variables to obtaining the correct exposure, the others being aperture and shutter speed.  So when adjusting the ISO you must remember to alter either the aperture or the shutter speed or both.

What is the effect of a low ISO such as 100?  Well this means the sensor is less sensitive to light, meaning you need more of it.  Also it will give richer colours.  An ISO of 3200 will be much more sensitive to light (5x) and will produce less rich colours.  When we had film this difference was referred to as graining, the graining increased in size when increasing the ISO number.  With digital cameras it is referred to as noise but has a similar if less noticeable effect.  In simple terms you will get better quality with a lower ISO.

For most of us you would not notice much of a difference unless you zoom in on the image some considerable distance.  The images below show the difference in quality shooting with different ISO settings.

 

This image was shot with the settings: F2.8 1/3sec ISO 100.  You will notice that the colour is stronger in this image.

 

This image was shot with the settings F2.8, 1/100sec and ISO 3200.  There is more noise or less quality with this shot.  I adjusted the shutter speed to compensate.

Just for scale the full sized image would normally be 168 x 112cms or 66 x 44 inches and is shown below.

So after all of that what is the main uses in digital photography.  Well for me it is to increase or reduce the sensitivity of the sensor to control the light.  In general terms though the advice is that you should not shoot above 400 to maintain quality of the image.  I now shoot at ISO 200 and I used to shoot at ISO 400.

Social Documentary - Photographing The Memorial

The Memorial that I wished to take a picture of is set in a corner of the main square.  My intention was to do a slow shutter speed with An stood in the foreground.  This was a challenging task for the following reasons:

• To get a slow shutter speed and catch the movement of people I needed:
• Low light conditions therefore it had to be shot either very early or very late in the day. 
• I needed people to walk past to generate the movement, they were surprisingly considerate when they did go by and tried to avoid the camera!
• I wanted to get An in the foreground and make some impact on the picture.
• I had to frame it so that there was no distractions such as lamp posts or other things.
• I had to avoid harsh shadows as this would result in under or over exposure of the shot.
• My lens was limited to F22 at its shortest focal length and therefore I had to think of other techniques to deal with the light.

I took the pictures at around 08.53 which is not a great time but then I needed people too and thankfully there was a market which opened at 08.30.  The light meter indicated that I would need F29 for a correct exposure in the shade, this was 2/3rds less than my lens would allow.  There was also a bright sunlit part of the memorial which was changing as clouds went by.  I could not meter for this and so that part could well be over exposed.

The solutions I used were:

• I set up the camera across the street on the tripod.
• I used my remote trigger to take the picture, avoiding camera shake.
• I set the ISO to 100 to make the camera less sensitive to light, although this would not have a great impact.
• I fixed a Neutral Density filter to my camera.  This is a piece of glass that is tinted to reduce the amount of light entering the camera.  In this case is was an ND8 which is supposed to take 3 F-stops of light out.  This would mean that I should be able to drop from F29 to F14.  After taking some test shots I dropped to F8 almost 4 stops down.  The main reason was to try and balance between the shadow and the brightly lit areas.
• I could have adjusted the ISO back up to 200 if I needed more depth of field (more of the picture in focus), this would have allowed me to close the F-stop to 11 if required. 

Now it was a question of catching a few people as they went by.  There were a number of shots taken to try and get the right picture.  The final shot we took was pretty much the one I wanted, see below:

Problems with this image:

• The framing is not great, with the tree and the orange pole.
• An is too small in the foreground.
• There is a crane I don't like in the background.
• The memorial itself is a little too small for my liking.
• The red post box on the left is distracting too.

I turned to Photoshop for the solutions and did the following changes:

• I did adjust the light as it was a little too dark and as it happened a cloud managed to take the shadows away at just the right time.  You can still see the cast of the memorial on the wall but I was ok with this.
• I selected An and cut and paste her into a new layer in Photoshop.  This was a fiddly job to do.
• I then enlarged An to fill more of the foreground.
• I cropped as much as I could to take out the orange pole and the other distractions.
• I then created another layer to mask the rest of the orange pole at the top of the image.  I did this by cutting and pasting a section of the wall into a new layer and then sliding it into place to cover the orange pole.
• I then selected the crane, in two parts into their own layers and then erased it.
• For effect I thought it would have more of an impact if An appeared ghostly and thus I selected the layer that she was on and used the eraser tool set at 18% opacity resulting in the picture as it is.
• I then flattened the layers onto one image and then cleaned up by applying a stroke black line border and then by re-sizing the canvas to make a border.

The finished image is below:

It was a lot of work and if you look closely you may well be able to see where I have made my adjustments, but then it was a learning experience.  It is the first time I have used my neutral density filters since buying them almost 8 years ago!  Also I learnt an awful lot by padding my way through Photoshop. I do need to go back and take a picture of Arthur's name, which appears on the left hand side of the memorial.  I will be using another Photoshop technique which I discovered recently, allowing you to pick a spotlight and position it onto the photograph.

I never used to believe in post photo editing but then in some cases you can achieve a dramatic effect by using the software that is impossible in the camera.  Also it clearly managed to save my image from the rather bog standard shot that I began with.

The F-Stop or Aperture

After chatting to a friend today he suggested it might be useful to describe some of the technical aspects of the camera and its settings.  So here is the first of a few blogs on what the different settings do.

In the studio my routine camera setting is usually on the Manual mode, F-Stop 11, ISO 200 and speed 1/125Sec. 

Manual and other modes allow different levels of control over the settings in the camera, which allows everyone from the happy snapper to the professional to set the camera according to their knowledge and skills.  As you get better you will experiment with the other settings and eventually become comfortable with manual.  In layman's terms you cannot go wrong in fully automatic (usually a green rectangle on the dial on the top of the camera body), but then it can be a total disaster on manual if you do not set the rest of the camera up correctly.  I will talk more about modes in a later blog.

The ISO number ranges from 100 up to 3200 or higher on some expensive cameras.  The number refers to film or sensor speed.  What it means is that the lower the number the less sensitive it is to light, the higher the number the more sensitive to light.  Again I will come back to ISO later on in more detail.

The 1/125sec is the shutter speed.  This can be varied from bulb setting which means you hold the shutter open to 1/8000sec.  A speed of 1/60sec is enough to take a photo of a person and avoid camera shake or blurring.  The shutter speed can be set low to allow lots of light in or high to freeze movement or where there is too much light.  Again I will go into more detail later on.

Now the main purpose of this blog the F-Stop or aperture setting, in this case F11.  The F-Stop number refers to the size of the hole that allows light to pass through the lens and onto the sensor.  Bizarrely, the smaller the number the bigger the hole and the more light that will hit the sensor. 

If you look at the lens you have it will have written on it the maximum size of the hole.  On my standard 17-70mm lens it has F2.8-4.5.  This means that when the lens is at 17mm the aperture will be 2.8 but as you zoom in the aperture will close up to 4.5.  This is to do with the characteristics of the lens and its manufacture.  The more expensive lenses have this maximum aperture throughout the zoom range.  The minimum aperture or smallest hole size varies depending upon the lens you have, the lens above has a minimum aperture of F36 when fully zoomed out to F22 when set to 17mm.

So what does this mean?  Well the three characteristics of ISO, Shutter speed and aperture are combined to obtain the correct exposure.  If you adjust the aperture or hole size then you must adjust one or both of the other two to obtain a correct exposure.

There are other effects to adjusting the aperture depending upon what it is you are trying to do.  A small aperture of say F22 will result in what is called a large depth of field - the amount of the picture in front and behind the subject which is in focus.  If you want to capture the foreground and background with your subject you will need to set a small aperture/hole (high number).

Alternatively if you set a large aperture of say F2.8 then only the subject will be in focus and you will have a small depth of field.  Now the added complication here is that the depth of field will also vary depending upon how close the camera is to the subject.

So, summarising, a small hold (F22) in general terms will let less light in and result in more of the picture being in focus.  A large hole (F2.8) in general terms will let more light in and result in less of the picture being in focus.  There are two main uses, letting light in when there is not much about and arranging the amount of the photograph that is in focus.

Just a little more detail and then I will finish off.  The F-stops are 1.0, 1.8, 2.0, 2.8, 4.0, 5.6, 8.0, 11, 16, 22, 32, 44 etc.  You will notice that they double every other time, each of these is called a full F-stop.  The F-stops have a linear relationship each one allows twice as much light in as the previous.  So F22 allows twice as much light in as F32.  To add to the complexity or really just to have a finer level of control, most cameras have 1/3 of a stop increments between full stops.  So the sequence between F22 and F32 is 22, 25, 29, 32.

The last line on this is to remember that it is a balance between the three attributes of Aperture, ISO and shutter speed.  It is a lot to think about and therefore it is best to look at the camera mode and use each one depending upon which of these attributes you wish to control, until you master each element.  The camera will always try and compensate or indicate when you have exceeded the limits, except of course in Manual!  You can still take an incorrectly exposed picture in all but fully automatic, if you do not heed the camera's warning (usually a blinking indicator that can be seen when looking through the viewfinder).

I will post some pictures to demonstrate what I have written, it will just take me a bit longer to get that sorted!

As promised a couple of photos to demonstrate the F-Stop and its effect.

This was taken at F22 (small hole), 5 second exposure at ISO 400.  Notice that almost everything is in focus.  The focal point or subject was the word Cochrane on the left.  This is referred to as a large depth of field.

This image was taken at F2.8 (large hole), 1/15 second at ISO 400.  Notice how the right hand side of the image is now out of focus.  The focal point was the same.  This is referred to as a small depth of field.

I adjusted the shutter speed when compensating for the aperture setting.  As I closed the aperture I lengthened the time that the sensor was exposed to the light.  The camera was quite close to the subject here, the further away you are the less the effect.  As you get further away the depth of field to the front and rear of the focal point gets greater.

Studio Shoot and Photoshop

As part of my portfolio project to shoot portrait shots I set up the living room for high key photography.  This involved rigging a backdrop of white material that extended down over the floor.  I had four lights set up two at the back on the white screen set for F22 @ 1/125 sec and ISO 200.  The front two lights were set at F11 @ 1/125 sec and ISO 200.  I adjusted this down by closing up 2/3rdson the camera to F14.  I had An lie on the floor and therefore the over-exposed background was a bit of a wasted effort.  The original image is shown below:

Editing in Photoshop I selected the subject using the lasso and magic wand, I feathered the selection, inverted the selection, then selected the brush tool with a large setting.  I then brushed over with white across the image to clear the background.  I then re-sized the image to 8 x 12 inches @ 300dpi, applied a stroke and then re-sized the canvas by adding 6 and 4 inches to the long and short edges respectively.  The resulting image is shown below.

Messing around I then applied an effect, which was called Glowing Edges and sits in the Stylize option under the filters tab.  Which I thought looks ok, the image is below:

 



The most difficulty I had here is getting the subject to relax and be comfortable in front of the camera.  The inspiration for the pose came from a recent book I have bought called Photographing Models:1000 Poses A Practical Sourcebook For Aspiring And Professional Photographers by Eliot Siegel.  It is a useful book which gives good advice for lighting and other aspects of preparation as well as the different poses.  In a lot of cases the set up only requires one or two lights, which is quite handy.

I did take other shots during this shoot which I will post in due course.  For me this was about learning what sort of poses I liked, but remembering that it could be that it is better to ask what the model likes.  It was handy to show her the book and she could flick through and suggest poses.