I live on 5 acres and am surrounded by lots of wildlife, particularly wallabies and parrots of various descriptions. Often my Canon 100-400 on a cropped format camera such as the 50D (640 equivalent 35mm) is not long enough, but ISO and shutter speed can be a problem with the lens fully extended at 400mm. With a lens fully extended at an equivalent 1560mm in 35mm terms, I can hardly imagine the problems.
To answer my own question, even with a still image, an effective focal length of 1560mm seems daunting as regards the high shutter speeds and high ISO required for a sharp image, if the camera is hand-held.
But is this the case? With video there is the unavoidable wobble without a good tripod and fluid head. However, with a still image, a 1920x1080 pixel crop should still be quite sharp if the full image was sharp to begin with.
Cropping images to the 16:9 aspect ratio, then downsizing for display on my HDTV is something I do quite frequently. If noise is apparent in the full image, it's only marginally reduced by downsampling. If noise is pretty bad in the full image, it's still pretty bad after downsampling, so we shouldn't exaggerate the noise-reducing benefits of downsampling.
Out of curiosity, I wondered what the Extra Tele-Converter multiplier is on my Canon 50D.
The full 50D image is 4752 pixels by 3168 pixels. Since it seems to be the convention to take the longest dimension when comparing the crop factors of two sensors with different aspect ratios, I've divided 4752 by 1920 and arrived at an ETC crop factor of x2.475.
Not quite as good as the x2.6 of the GH2, but I have the benefit of a 400mm lens in the Canon 100-400 IS zoom. So, for example, the 50D has a x1.6 crop factor in relation to full frame 35mm and a further x2.475 crop factor in relation to a 1920x1080 pixel crop of the full image.
400x1.6x2.475= 1584. That pretty close to the GH2 in ETC mode, in 35mm terms. How would a 1920x1080 crop of a 50D image, with no downsampling, look on my 65"plasma HDTV? Pretty good, I think. Provided the cropped part is in focus and not too much in the shade where noise might begin to rear its ugly head.
I searched for a few recent examples of shots of wildlife on my 5-acre property, which might lend themselves to a 1920x1080 pixel cropping. (Hoping Michael doen't have a limit on the number of wallaby shots
).
The first one was taken at 390mm, ISO 400, F11 and 1/400th, hand-held with ISO on. I deliberately chose F11, although not the sharpest aperture with this lens, in order to get both mother wallaby and teenager wallaby in reasonable focus.
Can you see the fly on the wallaby's lower cheek? This crop looks quite 'up to standard' on my 65" plasma. Not bad for a 1544mm lens (effective, of course).
