Tag Archives: propellor

Prop Vortices on a Damp Morning

A small twin is not going to get a lot of attention from the local photographers at Paine Field on a busy day with lots of traffic.  However, it was still relatively early in the day and the air still had a fair bit of moisture in it.  I took a guess that this might result in some prop vortices so decided to shoot it anyway.  Sure enough, some swirls of moisture showed themselves.  Not a dramatic look to them but still what I was after and there wasn’t anything else to do anyway!

If You Want Shocks, You Don’t Need Fast Jets

Every once in a while, when photographing a fast jet at transonic speeds, you might get something in the background that allows the diffraction caused by the formation of shockwaves to be visualized.  I have posted about that here.  I was in Vancouver and shooting the floatplanes taking off from the harbor (since it is a Canadian harbor, perhaps I should write harbour).  As I was looking through the images zoomed in to check on sharpness, I realized that there was a visual effect of a similar nature.  (If you think this is a Schlieren effect, it is not.  That is a technique that involves a certain type of lighting to show the density differences but should not be applied to every time you see it in the wild.)

I don’t know whether what is showing up is the result of shocks forming on the props as they spin rapidly or just the tip vortices causing a similar effect.  You can often see diffraction in trailing vortices.  Whatever the reason, as you look above the aircraft at the patterns of structures on the shoreline beyond, you can clearly see some interesting effects.  Since the props are spinning fast and there is an overlap of the wakes from each pass of a blade, the shapes are rather complex.  Now I know that this is a thing, I might be tempted to take a longer lens and see what I can get in more detail of this interesting visual effect.

Blur That Prop!

wpid7596-C59F7698.jpgAsk any aviation photographer about camera settings and they will quickly turn to shutter speed for prop aircraft.  The goal is a nicely blurred prop and no frozen blades.  This requires a slow shutter speed and this can have downsides.  If you are using a long lens, getting a sharp shot of a moving target with a low shutter speed can be tricky.  A bit of spray and pray with the shutter button can be required.  Interestingly, if you are closer to the aircraft and using a shorter focal length, things are not necessarily better.  When you are close in, the different parts of the airframe are actually moving at different speeds and angular rates to you so one part might be sharp when another isn’t.  Sometimes this looks okay but often it just looks crap.

I have become less focused on gaining the great blur for ground shots.  Air to air it is something a lot more worthwhile since the other plane is not moving relative to you – well, hopefully not that much.  Therefore, you can experiment going slower with hopefully some good results.  Similarly, when I am shooting helicopters close in and hovering, I will give it a go too.

wpid7594-C59F7690.jpgRecently, I was at the Waukegan show and I decided that, since what I was shooting was not something that I had to get (either I would have other chances or I wasn’t so bothered anyway), I would play with some really low speeds.  I ended up shooting at 1/80th of a second which, on a 500mm lens is a stretch.  Needless to say, you are not going to see the failures.  When I have played like this before, I have had times when not one of the shots was of any use.  However, this time I did get a few lucky results – yes, they were luck.  You can have great panning technique (which is not always true for me) but the math is not in your favor when doing this.  Therefore, I shall be happy with the results this time around.  I won’t be doing this all of the time but playing around is an important thing to do when you have the chance.  Just don’t do it when you really want to have a shot you can keep.