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buddy

Member Since 20 Jan 2004
Offline Last Active Today, 07:59 AM
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Topics I've Started

exposure impact on ISO variation

11 July 2014 - 05:03 PM

maybe not such a trivial question, but I am unsure about the following:

 

it is common knowledge especially in underwater shooting (all manual, no such thing like TTL) that the flash exposure at a given flash strengths is controlled by the aperture and thus affecting the foreground, while the ambient light (background, environment) is controlled by the shutter speed.

 

If I have a setting to start e.g. f8 and 1/125 sec at ISO 100 and by this my foreground is well exposed but the background is too dark, then I could go to 1/60 sec. If for some reasons I do not want to change the shutter speed but want to increase the ISO from 100 to 200 would that change my ambient exposure of the background AND also my flash exposure of the foreground? Or only the background by 1 full stop? or both by half a stop?

 

It is clear to me that exposing without flash a f8 1/125s at ISO 100 configuration would yield the same as f11 1/125s at ISO 200 or f8 1/250s at ISO 200 (that is a 1 stop difference each). This is not regarding DOF by the changing aperture or freezing effects by the changing shutter speed, just for the exposure value.

 

But how is it with the flash?

 

 

other example:

let's assume I have a good exposure for background and foreground with settings like f8 1/125s at ISO 200 with a half power of the flash. What is the aperture and shutter speed if ISO is changed to 100 (same flash power) which gives me the same overall exposure than in the beginning?

 

thanks for enlightenment! 


Nikon D4s and Subal ND4

30 June 2014 - 06:50 AM

By the way....

 

Nikon D4s fits perfectly into existing Subal ND4 housing (the housing for the older Nikon D4), needs no upgrade. I have tried it!

 

cheers!


Subal PS-30

30 June 2014 - 06:45 AM

anybody have experience with Subal's 30 degrees Prisma viewfinder (PS-30) especially for video work? 

 

http://www.subal.com...viewfinder.aspx

 

I am looking for alternatives to external monitors in order to slim down the rig and/or to limit its extensions and buoyancy.

 

thanks for infos!

 


FS: Atomos Ninja2 and Underwater Housing DNC-N

07 June 2014 - 02:38 PM

I am selling my relative new combo of a Atomos Ninja2 external 10Bit 4:2:2 recorder and video monitor with the dedicated Underwater Housing DNC-N from Dive and See (bought it in 2013). The recorder and the housing is in mink condition, never flooded and used only around 5 times. The bulkhead diameter is M14 and usable for Subal housings and others with same diameters (other bulkhead diameters can be bought separately from the manufacturer).

 

Item specs and content all as per the manufacturer listing:

 

http://diveandsee.co...ater-monitors/1

 

Additionally DNC-N comes with 2 internal hdmi right angle cables and monitor shade.

 

Atomos Ninja 2 comes with full package including the original carry-on box. 2 batteries, charger, 2 disk holders, disk reader. Additionally, I am giving in for free 1 short HDMI cable, a 500 GB fast SSD from OCZ and a 250 GB WD Scorpio Black HDD (value approx. $500). The recorder is equipped with Apple ProRes and Avid DNxHD up to 220 Mbits.

 

Although the video quality of the external recording is impressive I am selling these items now. The huge data handling in post did not match with my workflow. I will record video from my DSLR internally in the future abeith in lower quality and with less comfort (i.e. without external monitor and therefore no focus peaking, zebra and falls color etc). 

 

 

Today's new sales price of the combo is around $2'300, I am asking for $1'400 plus shipping (worldwide shipping with decent cost is available).

 

PM or email me on info@jvpictures.com.

 

 

 


Nikon 14-24 f2.8 on FF

21 February 2014 - 01:11 AM

I am using the Nikon 16-35 on FX with a large Dome port now (Subal DP-230). Albeith this is a good and handy lens for underwater usage, I'm still looking at the 14-24 f2.8 for its better IQ especially at the wide end. And yes, I am aware that this lens is some 325 grams heavier than the 16-35.

 

Going soon to Cocos for large pelagics and eventually will switch to the 14-24.

 

Is there anybody with same or similar configuration having real underwater experience with this lens? I did a search here but did not really find much...

thanks

 

Juerg