Fast Glass
I have an indoor event coming up that I will be photographing and every time I have an event I always consider how I might shoot it.
In the 4/3 lens lineup the zoom lenses are very fast but mayby not quite fast enough. I am considering picking up a Sigma 30mm f1.4 prime to use.
As luck would have it, I have been able to borrow one of these lenses for a few days and Have been putting it thru the paces to see if it is for me.
I have always been very happy with the Olympus Zuiko Digital Lenses as their build quality and optical properties are outstanding. While they are great, they don't make any lens faster than F2.0 - and that is the 50mm Macro and the 150mm.
At the event I going to shoot I will have reasonable Access and be able to get fairly close to what is going on and the 30mm will be a useful length.
So, firstly, My initial thoughts on the Lens. It is bigger and heavier than I expected it to be. It feels qute good on my Camera.
My first test shots were simply using normal indoor lighting inside. The Lens is quite fast at locking focus - but it seems to need a bit more contrast at the focal point than the Oly ZD lenses. It will focus fairly close - about 1 foot away.
Now, being f1.4 the depth of field shooting wide open is VERY narrow and something that I'll need to carefully consider. My favourite website dofmaster proved invaluable in determining just how small the DOF is.
My first chance I had, I went outside and selected some small flowers on a tree that was around 50cm away from me and ran the lens thru it's paces.
I set the Camera up at 400 ISO and started at F1.4 and took a shot at each Aperture value right up to f7.1.
I put together a simple chart of the shutter speed at each aperture setting as if I am going to use this lens I need to know it's (and my) capabilities.
- f1.4 - 1/160sec
- f1.6 - 1/125sec
- f1.8 - 1/80sec
- f2.0 - 1/60sec
- f2.2 - 1/50sec
- f2.5 - 1/40sec
- f2.8 - 1/30sec
- f3.2 - 1/25sec
- f3.5 - 1/20sec
- f4.0 - 1/13sec
- f4.5 - 1/10sec
- f5.0 - 1/8sec
- f5.6 - 1/6sec
- f6.3 - 1/4sec
- f7.1 - 1/4sec
Now, a few things to note out of this list - My current Zooms at 30mm is around f3.0 - which is quite slow!
Ok, a few pictures - in order, they are f1.4, f2.8, f3.5 and f5.0
I did no PP on these images except to resize them for display.
As you can see, the F1.4 image the DOF is very small - and I totally missed getting the flower in focus - I have around 2cm DOF. Now, the f2.8 shot I have around 2.5cm that will be in focus and the f5.0 shot has around 4cm DOF.
I know I was pretty close - closer than I would be using this lens. I am estimating that I will be shooting at a distance of between 1.5metres and 6metres. A few quick calculations shows me that at 1.5m the DOF will be about 15cm and at 6metres I will have 2.5m DOF at F2.0
Now, My current lenses will only let me shoot at around f3.2, and all things being equal, the difference between f3.2 and f2.0 means I would be able to shoot more than twice as fast.
As the event will involve a reasonable amount of action - I know I will need to get the shutter speed up to around 1/100 to 1/160sec to capture the action.
I have another couple of days to further test this lens and so far, it looks like 1 that I would like to add to my kit in the near future.
Now, the test subject that I chose is not brilliant, but I chose it for a couple of reasons - it has some fine detail in it and it has very harsh lighting of the subject and background.
Even wide open the Image quality cannot be faulted - there are no signs of Vignetting at the edges or Chromatic abberation (purple fringing). The Out of Focus parts of the image do not detract from the subject. I am fairly confident that if I choose this lens it will be very useful in shooting in low light - and will be able to provide me with the Image Quality that I am seeking.
