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buddy

Member Since 20 Jan 2004
Offline Last Active Jul 29 2014 07:59 AM
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Posts I've Made

In Topic: exposure impact on ISO variation

11 July 2014 - 08:08 PM

I understand it now in the following way:

 

either change the aperture (by 1 stop in the example) and leaving shutter speed and flash output unchanged

 

or

 

leave aperture unchanged but change flash power output and shutter speed both by 1 stop

 

Why do I ask this?

 

I have had an interesting discussion recently with Kurt Amsler (a well known underwater photographer) and he told me about today's new concepts regarding the virtual no noise sensor cameras at higher ISOs like ISO 400 (I have a D4s now).

 

Think about the following scenario:

 

You shoot a dynamic scene (let's say fast moving sharks) in relative deep water with dim ambient lighting conditions. You shoot at f8 and 1/125 sec, 2 flash guns at half power each. The image on the LCD looks ok on the exposure of the shark (foreground) but is too dark on the background, almost black and thus rather underexposed (let's say by -1 stop). But we want blueish water !

 

Now, instead of lengthening the shutter speed to 1/60sec you can do as alternative: change ISO from 100 to 400 (2 stops) plus lowering the flash output to 1/8 power and thus reducing backscatter and decreasing flash recycle time, leaving the aperture unchanged (relative closed at f8) thus conserving DOF (nobody shoots today with f2.8 - 4.0 anymore!), shorten the shutter speed to 1/250sec and thus freezing the action of the moving subjects even more...

 

Off course, that works only with a camera which can handle ISO 400 on a neglectable noise level.

 

Wonderful world, isn't it ?

 

Anybody else to chime in?

 

 

 

 

 

 

 

 

 

 

 


In Topic: exposure impact on ISO variation

11 July 2014 - 06:25 PM

and what about the shutter speed for the ambient? did you forget about that?

 

Also by 1 stop if changing the ISO 1 stop? or half a stop in aperture plus half a stop in shutter when ISO is changing by 1 stop?

BTW, some flash lights do pretty well with 1/8, 1/4, 1/2 and full power e.g. Subtronics.

thanks


In Topic: FS: Atomos Ninja2 and Underwater Housing DNC-N

10 July 2014 - 07:00 AM

anybody?

 

drop sales price to $1'200!


In Topic: Macro Gear at Cocos Is.????

26 June 2014 - 03:38 AM

totally similar, went to Cocos in 2013 and going again in this August. Do not bring macro stuff, no macro sites there and no night diving for macro is available from underseahunter. only for big fish: hammerheads, grey reef sharks, tiger sharks etc.


In Topic: Nikon 105vr manual vs auto focus

24 March 2014 - 12:13 AM

As others said AF with the AF-ON technique is a standard today in macro photography. But manual focusing in addition to the AF is for some situation superior. I have the Subal 105 manual focus flat port which has a built-in crone for manual focusing on the Nikkor 105.

The manual method lets you focus exactly on a specific part of the object e.g. the eye of the critter without shifting the camera (focus and recompose) or selecting different focus points in the viewfinder. But this also has some disadvantages, e.g. you must use both hands (left hand to manual focus and right hand to release the shutter).

Manual focusing also requires a bright viewfinder of the camera (with a fast 2.8 lens as the 105) and preferably a housing viewfinder (45 degree viewfinder from Subal and others or GS180).

With AF and assuming your rig is well balanced (neutral buoyancy and also not forward or backward leaning) you can use one hand (the right hand) only for focusing pressing the AF-ON with your thumb and release the shutter with your finger while holding on to something (but not a coral!) and thus stabilizing your position with the left hand. I also like to use one of these "Lembeh sticks" for stabilizing.