Beyond the BackyardCircle B Bar ReservePhotography Tips

Bald Eagles and Teleconverter Magnification

I’ve often wondered how the image quality would be if Dyeyo and I were to stack our teleconverters. I got the opportunity to do an experiment yesterday at the Circle B Bar Reserve. We had seen an adult Bald Eagle flying over the marsh several times, and it finally settled in a treetop all the way across the marsh. I used Live View to refine the focus on my tripod-mounted Canon 7D with 400mm lens. Then I added my 1.4x teleconverter, then I added Dyeyo’s as well. Here’s the result (all cropped, but to the same scale):

Bald Eagle (400mm lens alone, effective 640mm)

Bald Eagle (400mm lens alone, effective 640mm)

Bald Eagle (400mm lens + 1.4x teleconverter, effective 896mm)

Bald Eagle (400mm lens + 1.4x teleconverter, effective 896mm)

Bald Eagle (400mm lens + 2 stacked 1.4x teleconverters, effective 1254mm)

Bald Eagle (400mm lens + 2 stacked 1.4x teleconverters, effective 1254mm)

I was pleasantly surprised by the image quality. Now if only I could turn my 400 f/5.6 lens into a 400 f/2.8 lens so that I could retain autofocus while magnifying…oh well… :)