I've seen acceptable work done on wildlife with stacked
teleconverters - 2x2X. Acceptable on the grounds that the photograph
you got is almost always better than the one you didn't. It was a
marginal practice with film but with digital and with film scanning,
manipulation makes it more useable.
It's also good to practice with such a rig before shelling out for an
expensive long lens. Despite the clumsiness and the dim viewfinder
image, it's just plain fun and if you can get an image this way,
you'll have no problems with a true long lens. It's a way to learn
telephoto technique. Have a go! (I've tried it years ago to 'catch'
students smoking at school but the Principal was too worried about
'privacy' issues to use the images! Had fun tho'). Whatever you get,
you'll probably have fun.
Recently I was photographing an eagle disemboweling a wallaby on a
beach (as you do) when a Sea Eagle flew over. I got a snap shot but
it was good enough to see that it didn't have a fish in its claws but
a baby turtle. Not a good image but I got a kick out of it.
And one rule that hasn't been mentioned I think is that while
teleconverters degrade image quality, not all 2X units are equal.
Prefer 7 element over 4 element units in low cost models and
'matched' converters when available, such as the Tamron SP Adaptall
units. There are also the name brand and Tamron or Sigma pro-grade
units for digital AF but they are pricey. Very!
Andrew Fildes
afildes@xxxxxxxxxxxxx
On 03/03/2007, at 10:34 AM, Chuck Norcutt wrote:
> In general, adding any other optical element to a lens (including a
> filter) will cause some degree of image degradation. The only
> question
> is: How bad is it? You've already gotten a couple of answers
> indicating that two 2X's is probably not a worthwhile thing to do
> and I
> would agree. It's rare that you even find someone using a 3X... at
> least satisfactorily. For best results limit yourself to a 2X and
> even
> that must be of excellent quality and limited to attaching to
> lenses in
> the telephoto range.
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