Skystef's aviation page

 

home  |  e-mail    


 

Contrail pictures

 

Contrail spotting or taking pictures of planes with contrails, which is a Cirrus like trail consisting of water vapor, can be quite fun. Of course you need the right equipment. During 2005 & 2006, I used a Canon EOS 300D/30D digital camera with a 50-500 mm Sigma lens. But I wanted more so from 2007 onwards, I switched to a Synta SkyWatcher Dobson reflector telescope with a focal length of 1200 mm, mostly in combination with a 2x converter or a so called barlow lens. The amount of mm on the telelens gives the same magnification when an equal amount of mm on the telescope is to be found. Thus, switching to a telescope, gave roughly 5x more magnification (500 mm versus 2400 mm) and it really helps in getting more details out of these far distant airplanes.     

 

Here are some tricks & hints for obtaining good photographs with a zoom telelens.

No surprise in saying that the full zoom is needed, in my case this was 500 mm which is equivalent to 800 mm on an analogue camera. Best is to use a monopod, or better even a tripod, and sit on a chair to get a stable image. Descent shots are made when you precisely follow the aircraft, and may further improve when the aircraft almost passes the zenith, meaning the distance you and the aircraft is as close as possible. For the aircraft self: best shots are made when taken slightly in front with the sun in your back. For the contrail self: taking pictures towards the sun can produce also very nice results. Wide bodies tend to give better results than narrow bodies and this is the logic conclusion of the fact that the plane is larger. Don't be disappointed when checking the photos of smaller aircraft as these are even beyond the limits of a 500 mm zoom lens. Summer skies are less interesting than winter skies. In the summer a lot of heat waves will produce atmospheric distortions giving blurry pictures. Also the high angle of the sun may give poor contrasting pictures. But even in this season it is possible to obtain good quality pictures, namely in the morning or the evening. The blue winter skies are the most interesting as few or no radiation does occur, and the low angle of the sun may produce nice sunlit pictures. Also the coldness does produce contrails at lower levels, thus the plane is closer to your lens. Of course sometimes the everlasting grey skies can spoil things for weeks, but usually there a couple of crystal clear days in the winter season which makes photographing contrails a pleasure.

 

Here are some tricks & hints for obtaining good photographs with a reflector telescope.

Pictures of its setup to be found here.

First of all you need some additional equipment to get the cam connected to the scope. Indispensable is a so called "T-ring", which is different for each cam.  When using a 2" barlow lens, also a 2" T-thread camera nosepiece is needed. The use of a telescope is basicly the same as with a telelens, but due to the weight the tube is already resting in a mount. A so called "Dobson mount" poses no problem to follow manually the planes position.

Using a scope and getting descent pictures is a matter of building up some experience. Step 1 is to find the contrail via the small viewfinder attached on the scope, then go a.s.a.p. to the position of the viewfinder of the cam and try to get the contrail in view, if not repeat that step. If found, step 2 is to follow towards the plane with the left hand on the edge of the scopes tube, right hand on the cams button. When the plane is found (takes usually a few seconds) the final step is keep on tracking and make a dozen or so pictures. This movement is always rather shaky, so not every picture is sharp, just take the best out of the bunch.

There are five reasons why pictures may turn out rather blurry. 1 When transporting a scope, the optical elements are sometimes not in the right angle to the light path, so you may need to collimate it and this is done with a small screw driver. 2 When the temperature of the prime mirror differs from surrounding air (in the tube), it usually creates a disturbance in the air just above the mirror. In most cases the mirror is warmer and the advise is to wait until the temperature of the mirror has reached the same value as of the environment. The larger the difference in temperature, the longer it takes until this equilibrium has been reached (may take up to more than an hour). A ventilator near the mirror can cool down the mirror much faster or clear the small disturbance layer.  3 Sun rays hitting directly the tube of the scope do produce thermal currents inside the tube. The advise is avoid direct sunlight by placing it in the shadow (or use a parasol). 4 To find an airplane, the first step is seek it via the finderscope, then in the viewfinder of your cam, follow it and start to make some pictures. This movement is mostly rather shaky, leading to a blurry output. Best thing to do is to use high shutter speeds, so 1/400 seconds or higher is preferable. To obtain these high shutter speeds and depending on the amount of available light (f.e. scope's focal ratio) you must adjust the ISO value of your cam. But an ISO above 500 gives rather grainy pictures due to the larger pixel size, so values between 100-500 are preferable. Searching a good combination between an acceptable shutter speed and ISO is a matter of try and error.  5 Atmospheric turbulences are the main reason for blurry pictures: especially when using a converter (barlow lens) for stronger magnifications, these distortions are very pronounced. The advise is to wait until they are gone, so usually the period towards sunset or just after sunrise is preferable.

Below are some pictures. All but a few have been taken with the scope and they are refreshed on a regular basis between October and March, prime time for best quality photographs. Registrations via SBS-1 equipment. All pics taken at Kampenhout, 5km NE of Brussels Airport. On the upper air map of EBBU, my location is near BUB (Brussels).

Pictures Skystef.

 


Four engined airliners

Three engined airliners

Two engined airliners

Special contrails