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segal3

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Posts posted by segal3


  1. When I saw the section about Yap, I looked for your name in the photo credits but your name didnt show up so I didnt read the article...

     

    I've got it in front of me right now.

     

    The pictures

     

    1st page: photo of mandarin goby: photo credit Tim Rock

     

    2nd page: B&W shot of the of 3 manta's.  2 coming from the left that are slightly above the camera, one coming from the right that is slightly below the camera.  the tail of a 4th manta is just above the manta below the camera.:  No photo credit

     

    3rd page:  picture of 3 sharks and a bunch of large striped damsels.  Strong cyan colour cast.  Slow shutter speed shows up on the damsils.:  No photo credit

     

    4th page:  skunk clownfish in anemone with diver obsured sunball in background.  No photo credit.

     

    You're kidding about that right? All the photo credits are listed near the spine...

     

    2nd page: Mantas credited to Tim Rock.

    3rd page: Shark credited to Jim Watt.

    4th page: Land scenic credited to Tim Rock. Skunk clownfish in anemone credited to Mike Veitch. Congrats Mike.

     

    ~Matt Segal


  2. By the way,- I read about a trick to attrack sharks with a waterbottle. Does anybody know how to do that? I think they take a small PET bottle partly filled with water and shake or rub it. How does it work?

     

    The crackling sound mimics the sound of the shrimp in the reef. Sharks are attracted to the noise.

     

    ~Matt Segal


  3. Just to resolve this - I took a look at the RAW file, and discovered that Michael has been the victim of Adobe Photoshop's and Bridge's 'Auto' adjustments feature, pushing the exposure almost +3 stops. The original photo was underexposed...a nice capture though.

     

    ~Matt Segal


  4. In terms of corrections...they both look over-processed, perhaps as a result of trying to push exposure latitude a little too far in RAW. ISO800 on the 20D is much cleaner than that, and if you really needed the extra light, would have been a far better solution...

     

    ~Matt Segal


  5. I always try to look for ways to change or improve upon certain objects, in an effort to make things more convenient or to save money. Prior to leaving for my trip to Mexico, I had my Ikelite 20D housing sent in to Ikelite for a few modifications…

     

    Before: original.jpg

     

    After: modified1.jpg

     

    Aside from the obvious usefulness of the 90-degree right angle bulkhead to alleviate sync-cord bending that replaced the previously agonized over straight strobe bulkhead (and I expect that Ikelite may be flooded with retrofit orders for this design), the other noticeable change is the addition of a second strobe bulkhead.

     

    If you have a dSLR, you know how long the batteries can last - a long time. For awhile now, I thought it’d be great to be able to download pictures...without having to open the main housing seal. A little research, and I found that USB carries four wires: ground, +voltage, +data, and –data. After a few emails to Ikelite, the housing was shipped over and went under the drill. With some creative wiring, soldering, and insulating, the bastard child of a USB cable and a sync-cord was born:

     

    modified2.jpg

     

    Along the course of this work, I found that on removing the shielding of the USB cable, odd things can happen if one isn't careful. I went through a stage of "USB device unrecognized", "not responding", etc before I was able to finalize what had to be isolated - this is made more difficult by the fact that all the wires *still* have to travel along the same core. A final solution involved tin foil restoring the USB shielding with additional plastic insulation. Some trial and error involved...

     

    modified3.jpg

     

    Internally, everything had to match up so that I didn't have to worry about destroying my camera and/or computer :D. Multiple checks with a multimeter for connectivity and wire attachments were necessary. In this case, check ten times, solder once. :D After that, a little maneuvering of the wires inside the housing, and it was set. I sealed the housing, turned on the camera, and plugged in both the sync-cord and USB cable. Windows beeped, and started downloading images off the camera. Success :D

     

    It's still rough-cut right now, but fully functional. I am now able to download photos over a USB2 connection, merely by plugging in a sync-cable socket. This is so much more useful on a dive boat, when opening up after every dive really becomes a hassle. When I get the energy, I'll probably clean it up a little as I figure out how everything is holding up. A special thanks to Ikelite, for being open to such radical ideas and for performing the bulkhead changes and installs in such an expedited manner, especially with the all of the craziness during the July 4th weekend. Again, hope this was informative and possibly inspiring. I'm always interested in comments...

     

    ~Matt Segal


  6. I guess the only thing is that you have to make sure the camera is always pointed directly into the current, otherwise you have a sail instead of a wing and that's a whole different game.

     

    Not necessarily the camera, but the arms/corecell with the least cross-sectional area...the housing is already creating so much obstructional drag that the floats are simply filling in more of that dead space if there is a sideways current...

     

    ~Matt Segal


  7. corecellmounted.jpg

     

    Imagine my 20D housing there mounted on the rail (it's in to Ikelite right now for some...modifications :) more on that later) and you'll have an idea of the full setup.

     

    In salt water, when using the 10-22mm lens with the regular 6" Ikelite dome, the setup is completely neutral (or at least so imperceptibly negative that it would take more than a few seconds to start descending). When using the 100mm macro, the setup is just slightly negative, but nothing like it is without the core-cell foam added on. A good friend's calculations showed this to be nearly 1lb 5oz of positive lift.

     

    Attachment of the core-cell to the ULCS arms is easy - I simply drilled two holes in each block (there are three 6"x1"x1/2" sections on each side of each arm), and then ran zip cords through the assembly, using the end of a cutoff zip cord to tighten the blocks against the arm.

     

    More drag, you ask? Well, some of you know I've been majoring in Aerospace Engineering, and this is something I've been meaning to scan for the board for awhile:

     

    wiredrag.jpg

     

    Notice that the airfoil...with it's *much* greater thickness, and length, has the drag of that small diameter wire. Look at it a different, and much more striking way. That tiny wire, as small as it is, has all the drag of that huge airfoil shape (note that the Wright Flyer is shown here because it was astonishing that a plane with such a huge number of wire wing supports, and the drag attached to each of those wires, was able to make it off the ground).

     

    Drag is a force that delays or slows the forward movement of an object through a fluid when the flow direction is opposite to the direction of motion of the object. It is the friction of the fluid as it meets and passes over and about an object and its components. The more surface area exposed to rushing fluid, the greater the drag. An object's streamlined shape helps it pass through the fluid more easily. It's caused by the resistance of the fluid to move. Water is a fluid and it has mass and inertia.

     

    This issue of drag is not just limited to the air, but also underwater. As a result, if the foam is lined up with the arm itself (and the cross-section is not presented to the flow of water), the drag is practically no different from the strobe arm alone. I used this setup in the Solomons, and did not notice any additional problems, even in some significant current. If anything, the setup was easier to use because of the reduced weight.

     

    pic4-9.gif

     

    The best solution would be to form-sand 'fronts' and 'backs' of core-cell to glue onto the attached pieces of core-cell to form a foil. This would yield less drag (with all core-cell attached) than the strobe arms alone...another project to work on...

     

    Hope this has been educational :)

     

    ~Matt Segal


  8. Hey John - Tried doing a quick search, but not sure of your problem...you might try DPReview and see what a forum search gives you there...good luck working it out...

     

    Leaving for Fiji on the Naia in 2 days!

     

    Hey, if you could, say hi to Josh and Liz for me (they work on the boat)...they were on the Bilikiki during my Solomons trip...enjoy Fiji.

     

    ~Matt Segal


  9. _MG_5590_14.jpg

     

    Well, after long and hard thinking about whether or not to hold a few images off for contests, I figured 'whatever' and put up the gallery of my recent trip to the Solomon Islands. I hope you enjoy viewing the photos as much as I enjoyed taking them...

     

    http://www.carbonos.com/gallery/list.php?exhibition=19

     

    Any comments, criticism, or questions are always appreciated (especially for any of you thinking about a Solomons trip in the near future...I should be writing a trip report when I get some time). Enjoy...

     

    ~Matt Segal


  10. Anyone else get that feeling?

     

    The link Todd gave seems consistent with my shots taken with the 10-22@10mm...it's just very wide, but nothing of extreme distortion that would be associated with a FE lens...

     

    ~Matt Segal

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