The other day I was working through a huge backlog of lenses to test (aftermath of the airshow season), and I was getting a bit bored, and I realised that I had a 500mm f/4 and a bunch of Extenders, so... time for a bit of experimentation and fun.
To set the scene, here's what our garden looks like. You can see the bird feeders hanging from the pear tree, at the back of the garden on the left. When I'm inside the house (lurking in the shadows!) with the patio door open, they're about 15-20 metres away.
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First off, let's try a 1.4x Extender.
#1. Goldfinches, 700mm, f/5.6, uncropped.
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Now let's try a 2x Extender, which means manual focussing.
#2. Greater Spotted Woodpecker, 1000mm, f/8, uncropped.
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#2. Greater Spotted Woodpecker, 1000mm, f/8, uncropped.
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The second woodpecker shot illustrates one of the problems I had; with small apertures, the shutter speeds were on the slow side and when the bird moved its head (as woodpeckers do!) I got some motion blur. The tail feathers are nice and sharp though.
#4. Goldfinch, 1000mm, f/8, uncropped.
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I think that one came out quite well.
Now for some real fun - a pair of 2x Extenders.
#5. Greenfinch, 2000mm, f/16, uncropped.
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You can see that the image quality is starting to degrade, and focus precision and motion blur are real issues.
#6. Goldfinch, 2000mm, f/16, uncropped.
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I never imagined I would ever be taking a photo from within my house where a Goldfinch filled the frame! Again, the IQ is starting to degrade, but I think if I'd taken the exercise a bit more seriously I could have got somewhat better results.
And finally, here's a repeat of one of the previous Goldfinches.
#7. Goldfinch, 1000mm, f/8, cropped to simulate 2000mm.
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The image quality here is noticeably better than on the previous photo, when I was using the full 2000mm. But it would be interesting to make the comparison again if and when I can squeeze a bit more IQ out of the 2000mm setup.....


