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BottomTime

Member Since 18 Jan 2008
Offline Last Active Mar 03 2014 08:39 AM
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Posts I've Made

In Topic: Strobe with the deepest depth rating

24 February 2014 - 06:59 PM

No contest, the seacam offshore series of strobes have the deepest depth rating at 200m. However, for the cost of a pair of seacam seaflash 150O's, you're probably better off taking a pair of Inons down and risking the occasional loss of a strobe.

In Topic: Scuba luv

13 February 2014 - 09:52 PM

And I do believe that this shot ( http://igviewer.com/...5969248_9432083 ) is Uwe Schmolke's winning shot from the recent Beneath the Sea imaging contest.

In Topic: Bottom of image underexposed when using TTL

07 February 2014 - 09:13 AM

If I'm right, then you should still be able to use TTL, but at lower sync speeds as jlyle said. I would try a TTL shot at 1s. If your still seeing the bar at the bottom of the image then there is something wrong and my theory is bunk. It'll take a little experimentation to figure out what your max sync speed is with FO TTL.

This is something that will vary from camera to camera. My nikon D70 had a preflash/main flash delay that was so long it allowed my wife to blink with 100% accuracy when I used a speed light in TTL mode. I'm guessing that your YS-D1's would have worked with the D70 just fine right up to it's maximum sync speed of 1/500s.

 

 

Dont all slr shutters curtains move sideways rather then horizontal?

I don't know what is most common, but Nikon dSLR's uses focal plane shutters that travel vertically and descend to expose and cover the image sensor. There are FP shutters that travel horizontally but I don't know if any are currently being used in a modern digital camera.


In Topic: Bottom of image underexposed when using TTL

06 February 2014 - 02:27 PM

I've heard of people having similar problems using wireless triggers.

 

When Heinrich Weinkamp was still making TTL converters, he used to provide a (fairly comprehensive) table of strobe timings that listed the minimum time required between a pre-flash and the main flash. Inon strobes were generally in the 2000 microsecond range while my memory was that the Sea & Sea strobes were considerably longer (I think the YS-110a was ~18000 microseconds).

 

HW provided a second list with the minimum timing requirement of the camera. The timing for the nikon's are faster than most and the D300 was around 8000 microseconds. You're D800 will be atleast as fast as that and will do it's thing without regard for strobes that can't keep up. I suspect that in your case, the rear curtain has started to close before the minimum timing for the strobe has elapsed (10000 microseconds is 1/100s).

 

In the case of using manual powers, then the strobe ignores the preflash and the minimum timing between the pre-flash and the main flash is no longer relevant.

 

This is all speculation freshly squeezed from my butt cheeks though. An Oscilloscope would probably be able to tell you exactly what is going on.


In Topic: Housed nikon flash?

06 February 2014 - 01:46 PM

I was once thinking of moving to housed speed lights as well so I’ll offer a couple of additional things to consider.

 

- At 2.3s for full recycle, they are slow.

- They are low power compared to most underwater strobes. I’d put them in the same range as a YS-110/DS125.

- Auto FP mode reduces power further. Strobe power becomes linked to shutter speed so a faster shutter speed results in additional power losses.

- You can’t use Auto FP with more than one strobe (not entirely true).

- Personally, I found the light quality to be bit harsh when I looked at images taken by others with these types of strobe. This could be a function of the user though.

 

On the flip side:

- They have a focusable reflector which could potentially be used creatively to focus light where you want it (provided you don’t drop the built in diffuser panel). The fringe benefit is that the strobe has a higher GN as a result.

- Full blown iTTL control (for one strobe).

- Infinitely controllable strobe power. Full power to 1/128 in 1/3 stop increments.

 

There are cases where the Auto FP will be a creative tool (See Dr. Alexander Mustard’s Anthias shot in this thread) but if you’re hoping to use it to shoot wide angle shots in shallow water on a bright sunny day while aiming directly into the sun, I think you will be disappointed.