I use Canon 5D Mark ii and the longest lens I have is 70-200. Most of the time I take photographs near Istanbul Ataturk airport, however I could not find a spot close enough due to the fact that security is really itchy around the airport. Nowadays the best place I found to take photographs is a park 800 meters south of the 18-36 runway.
Unfortunately, the aircraft taking of usually takes off much earlier so they are quite up in the air for me to take their photograph with 70-200. Since I dont have the funds to buy a 400 mm or upper lens I bought the 2x extender for the Canon. Last saturday when I went to take photographs with the extender for the first time, I was shocked to see the lack of sharpness in the images. I was expecting a bit of bluriness but just enogh to correct with the photoshop. However the images were really smudgy.
I did my best to correct the images, while transfering from RAW I began to sharpen and I used the unsharp mask at CS5 and sent one photograph to the screeners here at the airliners. Of course it got bounced by the screeners with a nice personal note of " vignetting,looks like oversharpened blurry original".
When I just use 70-200, from cropping and maximizing the image I get the same bluriness as I am using the extender.
At the moment I can't find a spot closer to the airport so the extender was my only hope, if you guys have any suggestions for sharpening or have a better way of using the extender please let me know,