The final post in the series…
Compact mirror less cameras such as Micro 4/3 are slightly different from this. Most seem to be good performers from wide open, hit their best performance when stopped down by one stop and then gradually tail off as diffraction kicks in. The cameras do however have a huge advantage in terms of their smaller sensor size increasing the depth of field. A typical Micro 4/3 camera has a sensor with a 2x magnification. This also means my depth of field is also effectively doubled. I know that at f/7.1 on a 14mm lens (28mm equivalent) I can achieve a full depth of field. My LX5 has an even smaller sensor so by the time I have stopped down to f/3.5 at 24mm equivalent focal length I can achieve sharp focus from 1m to infinity.
So how do you use this advantage?
Firstly understand how your lenses perform at each of the apertures. When are they at their sharpest and when do they suffer from problems such as diffraction. This gives you your ideal range which you should try to keep within.
Now select the focal length of the lens you will use. This has a big impact on depth of field with longer lenses having less depth of field than wide angles. I suggest selecting the focal length first as I see this as a more important consideration in composition than depth of field.
Once you have composed your image consider how much depth of field you need to achieve. A number of important factors come into play here:
- The focal length of the lens as wider lenses give a greater depth of field than telephoto lenses at the same aperture
- How far you are from the closest point you want in focus. The nearer this is to the camera the less the depth of field.
- The size of your sensor as small sensors give a greater depth of field at the same aperture than larger sensors
- Where your point of focus is. The depth of field at a given aperture extends roughly 1/3 in front of the point of focus and 2/3 beyond.
The reason I was able to shoot my New York Skyline image at f/2.8 is that my point of focus was at infinity and I was shooting at the wide angle end of my lens. These points alone were enough to give me the depth of field required. Once you have mastered the points above you suddenly realise the common wisdom of stopping your lens down to its smallest aperture often isn’t correct and won’t give you the optimal image.
Copyright: Robin Whalley, 2011
Continued from previous blog…
So, looking at the use of aperture to control depth of field is actually a very effective tool for doing this and depth of field is a key creative decision you need to make when capturing your images. Let’s say you want to create a portrait but the background is distracting. The solution is to open the aperture wide to throw the background out of focus and isolate the subject. If you are shooting landscapes and want to achieve the maximum depth of field so that everything from the foreground to the distant background is sharp, you would select a small aperture. Sure there are other factors at work here which can emphasise the impact of the aperture but they do just that, emphasise the effect. The priority should still be to select the right aperture for the image.
Now let’s consider some of the problems that come with the aperture control and lenses. The first occurs when we stop the lens down to its smallest aperture. This often results in diffraction and potentially distortion. I once had a wide angle Pentax lens that when stopped down to its smallest aperture would bend and distort images in the corner. Diffraction is a little different and will result in soft and slightly out of focus images. Again I remember when I was first starting in photography and I had a cheap wide angle Tokina lens that suffered badly from diffraction. Not understanding this I would stop down the lens to f/22 and the results were always poor.
At the opposite end we can open up our aperture as wide as possible. Most lenses however don’t go very wide with a maximum aperture in the range of f/3.5 to f/5.6 (particularly true of zooms). At their widest aperture most lenses are also soft, especially in the corners. Many also suffer from uneven lighting and tend to vignette due to light fall off in the corners – not always something you want. Higher quality lenses from top manufacturers such as Zeiss and Leica tend to be the exceptions and will still perform well when wide open or stopped down. Unfortunately they are also expensive.
This then leaves most of us with an area of optimum lens performance which is usually 1-2 stops above wide open for usually 1-2 stops. With a typically zoom lens on an SLR this is probably in the range of f/8.0 to f/12.0. Does that sound familiar?
To be continued.
Last Thursday night I was presenting at Bolton Camera Club. It was a good evening with lots of discussion, especially when I pulled out the sample prints I had taken. A lot of the members looking at the prints made from my LX5 compact Camera were surprised by the not only the quality and detail displayed but the “relatively wide” aperture I had selected. The image above was shot at f/8.0 yet it’s sharp from front to back. My New York Skyline shown in an earlier post was shot at f/2.8 and everything is in focus, even viewed close up printed at A3+. The member of Bolton Camera Club are not however alone in this surprise as it’s something I experience often when talking to club members from all over.
Selecting the right aperture for a scene is something we tend to do automatically once we have been in photography for a while. Unfortunately the aperture selection in lightweight cameras might not be quite as you expect it and you could end up making choices that have a negative impact on your photographs. If you stop and think, there are only a couple of reasons why you might want to control your aperture:
- To control your depth of field
- To control your shutter speed (increase or decrease)
Now I’m going to be controversial and say the only reason you should be changing your aperture is the first one. The second option, to control your shutter speed is in fact a trade off from controlling your depth of field. If you disagree good (you have your own opinion) but stay with me and understand my argument. It might just change your perspective on photography.
So let’s deal with the “misconception” of using aperture to control shutter speed and why I argue against this. My reason is that it’s actually a relatively ineffective when used in this way. If you want to change the shutter speed for creative reasons (which should be your first priority) it will be because your current speed if either too slow to freeze action or it’s too fast to introduce creative blur and motion.
Let’s say I want to freeze motion so I open up my aperture as wide as I can. This will increase the shutter speed but at the expense of reducing the depth of field in the image, something I might not want. Often such a reduction in depth of field will affect the aesthetics of the image and will change it completely. A better option is to increase the ISO setting as this is more effective. It will introduce noise but you can always address noise if it becomes too great in other ways. Another solution which is often overlooked is to use flash to help freeze motion. In the end you might need to adjust the aperture as well as these solutions but this needs to be a deliberate decision and you need to be aware of the impact on your image as well as the drawbacks.
Now if you want to slow the shutter speed you might try to stop down the lens to as small an aperture as you can. This will however introduce diffraction as we will cover later as well as affecting the aesthetics of the image. Rather than this approach try reducing the ISO you are using. Again, this might not have sufficient effect or you might already be shooting at the slowest ISO your camera can support. The best option however is to use a Neutral Density (ND) filter placed over the lens. These come in various strengths up to 10 stops and are incredibly useful. An alternative option might be to use a polarising filter which usually takes out 3 stops of light.
To be continued.
Nokia PureView 808 41mp First Impressions Review.
Just been reading this review of the new 41mpixel camera phone. The results look impressive and specs amazing. Could this be the mega pixel wars starting up again?
I remember when I first purchased my Canon 5D MKII. One of the drivers behind this decision was to have a 21MPixel sensor. This was partly due to the main stock library I supplied only accepting 50Mb files and the pixel count on the 5D making this easy to achieve without interpolation. The other factor was that I wanted to be able to print large; 30 inch, perhaps even 40 inch images with good quality. When I recently purchased my GX1 I was also keen to ensure it would allow me to print large.
The GX1 is a 16Mpixel camera but it’s only the 4×3 format that gives an image this size. The 3×2 (similar format to my 5D) gives a smaller size and the 16×9 a smaller image still. To put this into context the 4×3 image would produce a 45Mb TIFF image, which is just short of the size required by the stock library but it’s not too far off and easily achieved with some interpolation. Print size was however the more important to me and out the camera the image is around 15” on its longest side when printed at 300dpi.
Now you are possibly reading this and thinking that the resolution is more than enough to create a 30” print given the viewing distance should be at least 3 feet and I would agree with you. I am however quite fussy (as are most photographers) and I want to look more closely at areas of my photographs and feel happy and confident that the image stands close scrutiny. Now you might think I am ignoring lens quality (which is true) but I know the 14-45 standard lens I use is more than capable of resolving sharp detail. No, what matters to me is the question am I satisfied when I look at the image closely when I print at 30 or even 40 inches.
To test this I resized my starting image (above) to 30 and 40 inches at 300 dpi using Genuine Fractals. I then extracted A4 sized sections from each image, sharpened and printed these on A4 Gloss paper ready to examine the results. If you want to know why I picked this image it’s because it has lots of fine detail. The glass as you can see from the images below has lots of fine straight, parallel lines on it that will show up any problems.
Image sample when viewed at 100%.
So the results? I’m not happy with the 40 inch print when viewed closely but it will be fine at normal viewing distance. The 30 inch print as show by the sample below is however is very good and you need to look very closely indeed to see the problem areas.
Image sample from 30 inch print scanned at 75ppi.
I do however know that I could achieve a good 40 inch print as I would simply reduce the resolution of the 30 inch print to 200dpi rather than 300dpi. I am also questioning the results of the Genuine Fractals software as I find it produces quite blocky results and this is what I can see in the 40inch print, but that’s another issue for another day.
Have I proved anything? Only that I am now satisfied that the GX1 is a really credible performer and fast becoming my camera of choice.
In a previous blog (Don’t Let Noise Kill Your Images) I wrote about the steps you could take to minimise noise in your images. It’s long been recognised that cameras with small sensors have higher levels of noise than they would if they had a larger sensor as a result of packing more pixels into less space. Whilst there have been great advances in this area, it can still be a problem.
If I look at the images produced by my GX1 (16Mpixels) and compare these to images shot on my GF1 (12Mpixels) both of which have the same sized sensor, I can see real improvements in the GX1 both at base and higher ISO levels. I would say that I am examining the images in great detail for any trace of noise in case you think these cameras are poor performers. To give you something to compare against, when I do this for check with my 5D MkII I can also pick out noise at ISO100 in dark areas and in the Blue channel. So what do you do if you find you can’t avoid capturing noisy images?
In the past I have used a noise reduction tool called Neat Image but to be honest it’s quite a lengthy process to get good results and whilst it has a batch mode, I prefer to fine tune the software to each image (hardly a lightweight processing workflow). This weekend however I decided to download a trial of DeNoise from Topaz Labs and the Noise reduction plug in from PhotoWiz (I already use Contrast Master, B&W Styler and Focal Blade plug-in and rate these highly). The results were a bit of a surprise.
I found both solutions did a better job than Neat Image however the PhotoWiz product took some time to process my sample image, something I want to avoid. Comparing this with the performance of Topaz Labs DeNoise solution I found a huge difference. DeNoise was incredibly fast to process my image but it also gave the cleanest and most lifelike results. Finding the right level of reduction was as simple as moving one slider but it was then possible to further fine tune the results. It gave me lots of control in an interface that was very easy and fast to use.
I want to experiment further before purchasing, but early results look very promising.
The Lightweight Portfolio Challenge
New York, March 2011
Copyright: Robin Whalley 2011
I was recently reading about Haiku which is a form of Japanese poetry. The objective is to describe an idea in just 17 syllables in three lines (there is a bit more to it but this is the key point for me). As you can imagine, this is a huge undertaking if you are to convey the idea effectively with accuracy, beauty and completeness. It got me wondering if there were any parallels that we could draw as Lightweight photographers.
The idea I came up with is the Lightweight Portfolio Challenge.
The idea is simple; you have to create a portfolio of 5 images that completely express a subject or an idea:
- The portfolio must contain 5 images
- The images must explore the idea as fully and completely as possible
- All the images in the portfolio should work together with no image standing out from the others
You might also want to consider setting yourself some additional rules around this to make it Lightweight and prevent it from expanding into a huge task:
- Are you going to set a timeframe on how long you have to complete this exercise e.g. 1 month from the start?
- Will you include images from your archives or must the work be new?
- Consider restricting yourself to just one camera or even just one lens.
- Only have one of these projects on the go at any one time. It’s much better to have the focus.
Initially you might want to try to create such a body of work from images you already have. This will help you understand just how difficult the exercise can be. Once you are happy with this approach you can move on to shoot new material.
Now, once you are proficient in producing these mini portfolios consider broadening either the theme you are trying to represent in 5 images. What would you say if I asked you to produce such a set of 5 images which were to represent your work for the current year and that it would be only these 5 images that you could publish or share?
How about the 5 images that would represent your life’s work and would be how you want to be remembered as a Photographer?
Copyright: Robin Whalley 2012 www.thelightweightphotographer.com
See more of my work at www.lenscraft.co.uk