I decided to buy a FD 300mm F4 plus FD 2x-A extender and FD to Ef adapter to use for birds-wildlife video on my 70D by obvious reasons, price and because my final product is footage 1920x1080. I had a similar (L series) 40 years ago with which I made a coffee table book on birds and later I used it on Betacam and DVcam camcorders. There is no way to shoot wildlife video with long lenses but by manual focusing and IS off.
My question is simple: is it really 300x1.6 factor = 480mm or longer. My doubt is because if I shoot with a 18-250mm EF lens at 250 mm (same 1.6 factor) the sise of the frame looks much more smaller when compared with the 300mm. I does not look like the 50mm diff in focal length it should be between both lenses.
How can I measure with certainty the real focal length on the assembly 300mmm-FD to EF adapter. I gess there should be a table where at a certain distance to the focal plane it should give a certain size.
Thanks
Carlo
My question is simple: is it really 300x1.6 factor = 480mm or longer. My doubt is because if I shoot with a 18-250mm EF lens at 250 mm (same 1.6 factor) the sise of the frame looks much more smaller when compared with the 300mm. I does not look like the 50mm diff in focal length it should be between both lenses.
How can I measure with certainty the real focal length on the assembly 300mmm-FD to EF adapter. I gess there should be a table where at a certain distance to the focal plane it should give a certain size.
Thanks
Carlo
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