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bobf

Member Since 30 Jan 2003
Offline Last Active Jun 13 2012 08:44 AM
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Posts I've Made

In Topic: Additional Buoyancy for ULCS float arms

16 December 2008 - 05:43 AM

Research Core Cell. Doesn't break down when chafed as easily as Divinycell does.

Core Cell A500 weighs 5 pounds per cubic foot resulting in @ 57 pounds of buoyancy created per cubic foot in salt water. It does not compress at recreational dive limits.

In Topic: How to aim strobe?

14 August 2008 - 07:47 AM

strobes are designed to emit a certain beam pattern. understanding this beam pattern may help in strobe placement~aiming options. for instance, a DS 125 spreads a 100 beam pattern with diffuser installed.

if you take some construction paper, scissors, and a protractor to create a shape similar to the beam that your particular strobe throws, it may lead to a better understanding in strobe aiming options while minimizing the capturing of backscatter.

hth,
b

In Topic: The new Wise Man... Henry!

11 August 2008 - 09:19 AM

Congratulations Sarah and James!

In Topic: I adapted an Ikelite strobe land use.

05 August 2008 - 10:00 AM

What settings are you using?

I have the same set up, although I have just have the standard short PC cord, and I'm had holding the camera, not connecting it to a PC.

No matter what I try, I can't get the strobe to fire.

I've used a bunch of different shutter speeds and every setting on the strobe.


First, test the sync cord. Use the metal end of a plastic headed push pin (or facsimile) to cross between the outer ring and the center pin on the pc connector. Once contact is complete, your strobe should fire.

That said, I do recall experiencing a similar situation......so I went back into my notes and found an email that i sent to a friend......in it i stated to him:

When I was in M mode, live view activated, strobe would not trip. When I set the dial to Av, live view would automatically deactivate (never occurred to me that there might be a link). All I knew was that strobes began tripping once I switched from M to Av........and as long as when I switched back to M without any other mods( live view stayed off)........strobes continued to fire........


Therefore.........if activated, try shutting live view off during actual image capture. (i use live view magnification ........5x or 10x.........to confirm manual focus (manual focus allows me to dictate what is in focus).........but after focus confirmation, shut live view off and return to relying upon the viewfinder.

see page 106 of the 40D manual for more info on the use of non canon strobes........also at the bottom of page 113 the manual discusses other scenarios on the use of non canon strobes.........

hth,
b

In Topic: 40D and 2nd Curtain Sync

16 May 2008 - 05:09 PM

A few posts back I reported that author David D. Busch (Canon EOS 40D guide to digital slr photography) stated that when 2nd curtain sync is selected :

"the flash will still fire as soon as the shutter opens, and then triggers a second flash at the end of the exposure.........."


Ryan however reported in a follow up post that this first flash was actually a preflash, occurring prior to the shutter opening.

I was able to contact David Busch and he agreed with Ryan. Mr. Busch went on to state that his sentence should have read:

"the flash will still fire as soon as the shutter release button is depressed fully (but before the shutter begins to open), so that exposure can be calculated. Then, a second flash is triggered at the end of the exposure..."