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herbko

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Everything posted by herbko

  1. Nice reports. Really looking forward to the photo galleries.
  2. Not really recent. I was still shooting with the Olympus 5050. Photo by Todd Mintz
  3. Nice collection. I really liked the macro shots with pairs of critters.
  4. Who's Larry? I always enjoy these fall color pics. It looks quite different here in California.
  5. Thanks James. I was looking for one of these. Herb
  6. For a modeling light, the CRI is not a big deal. Actually I sometimes wish for one with red LEDs which would be less disruptive to the critters. I tried using a red filter on a white LED light and found almost no red light coming out. That was what got me starting looking into the output spectra of these LEDs.
  7. Having the TTL exposure compensation knob on the outside can be handy. Although if you really need to use that frequently, there's not much point to having the TTL in the first place.
  8. Has there been other work on making videos with a white LED as a light source or are we breaking new grounds here? I would be concerned with the spectral output of the white LED. Here's a reference to the devices I'm familiar with. http://en.wikipedia.org/wiki/Image:White_LED.png Maybe the L&M ones are something different. If the spectrum of the LED is like the one in the above reference, you'll only get to use a small percentage of the light by the time you filtered and white balanced for a day light spectrum.
  9. If nothing else the 21MP will make the Dx crop or digital zoom feature that Nikon will put in more useful. The advantages of the 12MP are cost and speed and most importantly better signal-to-noise and dynamic range. The cost in the required larger storage is negligible. If speed is not a factor to you then the only trade-off is the lost of about 1/2 stop in signal-to-noise and dynamic range. You lose about a factor of 2 in signal-to-noise in making the photosites 1/2 as big. However, if you down sample back to the lower resolution you'll get 1/2 of that the back. So for a given print resolution doubling the number of photosites will only cost 1/2 stop in noise and dynamic range.
  10. I haven't seen a formal standard, but measuring the angle at which the light falls off by one stop would go a long ways to characterizing the strobes.
  11. Watt-sec is a measure of the electrical input. We're interested in the light output. The efficiency in converting electrical energy to light can vary by more than a factor of 2 for incandescent sources and is very sensitive to filament temperature which also determines the color of the light output. Lower temperature, redder sources are much less efficient. See for example: http://en.wikipedia.org/wiki/Luminous_efficacy
  12. I don't think a modular digital camera ever made any sense. There has to be lots of design compromises to make it work, and I doubt any camera maker wants to be held back by an old set of controls when they may have new features like live view to implement. Except for a tiny number of underwater photographers, it probably does not even make economic sense for the user. He's probably better off selling the old one on ebay and buy the new one than to paid the cost of upgrading sensor, processor, and memory.
  13. Sorry to hear that. I hope you have it backed up. Any ideas how the vandals got your password?
  14. Find a container slightly bigger than your camera setup. Put camera in container. Put container on scale. Fill with water until overflow and note the weight. Take the camera out. Fill with water until overflow and note the weight again. The difference in the two measurements is how much your camera is negative. EDIT: I just read the rest of the thread more carefully and noticed Steve had a similar idea. This way you don't need to make any volume measurement. You only have to read the scale. You can get .1 lb precision with a $30 scale. http://www.amazon.com/Weight-Watchers-Glas...049&sr=8-22
  15. That's great. Thanks Jean. I knew all the harassment would pay off eventually.
  16. How about instead of building housings, specialize in ports. Be the Sigma and Tamron analog in the underwater housing market. I think there's a sizable demand for ports not offered by the all the housing makers. I would buy a smaller dome and smaller macro port for my Aquatica housing if such were available. You can do what the lens makers do and sell your ports in all the popular housings or make adapters for the other housing to fit your mount.
  17. I doubt that you'll be able fit any other camera in a UK-Germany 300D housing. All the newer Rebels are smaller, and everything else is bigger. If are still satisfied with the features of the 300D the easy answer is to buy another used one. It probably cost less to buy a functioning one on ebay than to have the old one repaired. If you want to upgrade, you'll need a new housing.
  18. One way to compare the strobes is to look at the bang you get for the weight in air of the strobe. I think higher GN/weight is better and it's better to make buoyancy adjustments in places other than the strobe. Of course you have to take into consideration the width of the beam and it's uniformity. It does seem clear from theory and practice that you paid at least a factor of 2 in output power/weight for the redder color output of the Ike strobes.
  19. Good information. It looks like it's true that the Z-240 is significantly brighter than the DS-125 at least at the center. The weight information is very welcomed. Although, it's an important consideration, there are advantages to small strobes. Smaller size sometimes give you more freedom in strobe placement. If you asked me the question: where would you add volume to your setup to make it more buoyant, I probably would not choose to increase the size of my strobes.
  20. Beautiful shots David. I like the one with the turtle in the middle of the sunball best, nice rays.
  21. Beautiful shots. Definitely much better than your average ID shots. I especially like the free swimming seahorse.
  22. The 5D is significantly better at sunball shots than the old 300D. I don't know how it compares to the 20D or 40D.
  23. You can use 4 Z-240. I've see someone dive with 4 Inon strobes. It's not that unwieldy.
  24. The Z240 and DS125 have very different output color. I think that explains the difference in efficiency. They are both incandescent sources which means that the one operating at higher temperature, bluer light, will be more efficient in converting electrical power to light. See for example http://en.wikipedia.org/wiki/Luminous_efficacy
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