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About Willy

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    Hermit Crab
  1. Thanks David and Carol for your detailed replies. Good point about the ease of bayonet mounts, especially for a less experienced diver. Yes, the A570 takes AA batteries, just like the strobe, which is a convenience when traveling and you can standardize on one kind of rechargable. And yes, I can believe the D200 would produce great shots! Some day... One of the reasons I am favoring the A570 is it's manual exposure controls. Do you feel this is more important than having a wider zoom (28mm, for example) or a larger, higher resolution LCD for focusing or lower noise at higher ISO's? BTW, what ISO do you guys use, say for reefs at 40-60 ft and then for wrecks up to 130ft? Is it so important with an adequate strobe? Carol, do you have a photo showing how bad the CA can be?
  2. I have a Nikon D200, but unfortunately can't dive often enough to justify the cost of a nice UW case with ports. As a more affordable alternative I've been researching P&S cameras, especially with the Inon system. Wondered if anyone has any exerience with this. I can get a Canon A570 for about $200, plus the UW case for $180 - manual controls for aperture, shutter speed, and ISO (uncommon in an inexpensive P&S) - custom white balance - optical image stabilization (useful for the slow shutter speeds needed in balanced lighting) - 2.5" LCD - 7 megapixels Inon 105 degree wide angle lens is $280 Inon macro lens is $125 Inon bayonet lens mounting bracket is $60 Inon D2000 flash plus arm is around $600 - clever TTL flash control with P&S cameras - looks very compact This looks like a nice system on paper: - total system price of $1500, which is less than just a case for a d-SLR - ability to interchange wide angle and macro lenses underwater - available fish eye lens for $350, also interchangeable underwater Anyone's thoughts or actual use?
  3. Thanks Luiz, nice explanation in that link. You're right, I'm really talking about using this lens as a close-up and not a macro. Now, if I were to use this lens with a macro port instead of a dome, would it's reproduction ratio be increased by the change in refractive index (ie, 1.33) so that it would have the equivalent angle of view of a 73mm (1.33x55) lens? And would this increase the max reproduction ratio to 1:2.4 (3.2/1.33)? Finally, I'm a bit confused about how the close-up diopters on a zoom effect the angle of view with dome ports. From your link... "[With zoom lenses] the port cannot be set-up for true wide-angle work, because the lens entrance pupil moves with the zoom control. The solution is simply to cancel the de-magnifying effect of the port by adding an approximately equal and opposite magnifying lens." Now, if adding + diopters "cancels the de-magnifying effect of the port," do you no longer get the benefit of the port maintaining the same angle of view UW as above water? Thanks for you help. Off to Thanksgiving turkey.
  4. A beginner question about the Nikon 18-55 DX... On land this lens focuses to 11.4" to give a 1:3.2 reproduction ratio. Would this hold true UW using a port? That is, could this lens be a reasonable macro? Any idea how far the front of the port would be from the subject? Along these lines, with the DX sensor, does a 1:3.2 ratio mean that the field of view is 3.2 x the width and length of the sensor (ie, 23.6mm x 15.8mm)? By my calculations, an object 3 inches long would fill the frame. Thanks.
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