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03-19-2009, 11:01 AM   #46
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Almost forgot--mating displays and nesting behaviors may be times when birds let down their guard. Don't interupt or disturb them. They may allow you extra leeway for shooting. Note that the blurred bird in flight is an American Dipper aka Ouzel flying into its moss nest in the upper right. A couple of these shots are actually digi--yellowheaded blackbird, hun and cranes mating dance. Again, all with the 600/4.

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03-23-2009, 01:00 PM   #47
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QuoteOriginally posted by Marc Sabatella Quote
BTW, you are right about that; please accept my apology.
We should have approached this discussion like this regarding field of view:

FOV = 2 arctan (x / (2 f))

where x is the diagonal measure and f is the focal length.

And referred to optical magnification via the lens and digital magnification via the sensor. It is often over looked that film can be "processed" as well either at the enlarger in the dark room or during scanning of the negative/positive film which can be analogous to the digital mag in digital bodies.

That would have avoided one of us arguing a quarter has a heads and the other arguing it has a tails.

Edit: we didn't do a good job acknowledging that wildlife photography uses different strategies and techniques than landscape or architectural photography. In fact, the techniques are sometimes "opposites" of each other.
03-23-2009, 01:29 PM   #48
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QuoteOriginally posted by jbrowning Quote
So what do you do when the Sigma 50-500mm lens just isn't log enough to get some shots of wildlife (tele-converter is not the answer, to me it makes the shot soft). I know that no matter what I do there will be something that this new lens or scope can't get either. So my options that is see right now is to sell this lens and get a longer lens or sell this lens and use the money to get a spotting scope and adapter for my K20D.

So my question are what would a scope give/not give me that a reg camera lens will give me?
Jim, first I would heartily second your notion, not to use a tc with the Bigma. It simply gets too slow to work with a tc - and that is even not taking IQ into account.

There are several options you can choose:
- use a spotting scope with provisions to attch a camera. Pentax makes nice Apo scopes, but there are countless others out there. The real drawback of this option is, that they do not have an diaphragm. So you can't close an aperture to increase the tiny DOF or in really brigh conditions. That should be taken into consideration.

- you could still buy the FA 600/4 from Pentax Japan new. Something like the most expensive solution, I guess.

- you can buy an old Pentax 500/4.5 and add the Pentax 1.7 AF-converter, to have AF under brighter conditions or simply a Pentax 1.4x-L converter, if you don't need AF. This lens produces some CA and is slowlyer to use than the Bigma, but still a very good choice in terms of bang for the bucks.

The real drawback is, that it is very hard to get really sharp shots under the conditions, you present in your photos here, as over longer distances, the atmospheric turbulences ruin most shots. You need even more patience, than with the Bigma and very short exposure times, to "freeze" the turbulences.


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