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Lower part of image too dark (sometimes) when using flashes


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#1 Gazpacho

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Posted 01 January 2012 - 02:31 AM

Hi folks and happy new year to everybody.

Id appreciate your advice on my following problem:
Sometimes, but not always, the lower part of my images is too dark when using strobes (lower part of image not being lit by flash lights). I post an example of my problem, taken at a night dive. Sorry, its not a good picture, but illustrates my problem.
Im shooting a Nikon D 90 in a Hugyfot housing without TTL converter. Ive got 2 INON Z 240 stobes, connected electrically. Usually I shoot completely on manual settings (camera and strobes) and use diffusers on the strobes. My guess would be that this a a sync problem with the shutter, but I have not yet been able to find out systematically.
Any experts out there who can help? Would be very much appreciated.

Greetings from Switzerland,
Gazpacho

Problem_peq.jpg

#2 johnjvv

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Posted 01 January 2012 - 02:41 AM

Hi folks and happy new year to everybody.

Id appreciate your advice on my following problem:
Sometimes, but not always, the lower part of my images is too dark when using strobes (lower part of image not being lit by flash lights). I post an example of my problem, taken at a night dive. Sorry, its not a good picture, but illustrates my problem.
Im shooting a Nikon D 90 in a Hugyfot housing without TTL converter. Ive got 2 INON Z 240 stobes, connected electrically. Usually I shoot completely on manual settings (camera and strobes) and use diffusers on the strobes. My guess would be that this a a sync problem with the shutter, but I have not yet been able to find out systematically.
Any experts out there who can help? Would be very much appreciated.

Greetings from Switzerland,
Gazpacho

Problem_peq.jpg


What shutter speed are you using? It could be the curtain closing at the same time as the strobe firing. I think the max shutter speed you can use with strobes on a D90 is 1/200.

#3 Gazpacho

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Posted 01 January 2012 - 03:12 AM

What shutter speed are you using? It could be the curtain closing at the same time as the strobe firing. I think the max shutter speed you can use with strobes on a D90 is 1/200.


Hi Johnjvv,

I just reviewed the parameters of the pictures and think you are right. The shutter speed of the posted image was 1/400. On other images I had 1/320, and the dark part was smaller (curtain not that much closed, makes sense to me). On images with shutter speeds 1/200 or longer, the problem does not seem to exist.
Im impressed by your profound knowledge and speed of response. I had not been aware of this problem. Thanks a lot!
Where did you get the technical information (1/200 for a D90) from?

Unfortunately, in the menu of my camera you can only define a LONGEST shutter opening when using a strobe. According to this problem, you should also be able to define a SHORTEST opening, and the problem would not occur. But as I shoot on manual settings anyway, now that I am aware of this, problem should be avoidable.

Pictures (without technical problems) of my latest trip to Cocos Island can be seen here: http://www.flickr.co...57628567090599/

Thanks again.

#4 johnjvv

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Posted 01 January 2012 - 06:03 AM

No worries...I knew it as I previously discussed fastest shutter speeds using a D90 with a friend when he mentioned that he found it easier to get a black background out of the camera with a D70 as the shutter speed could be set higher. So I tested what the maximum shutter speed was and the outcome looked similar to your picture when higher than 1/200.

I would not describe my knowledge as profound :) yet glad to be able to help in this instance!!

Cheers

#5 DiverPam

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Posted 01 January 2012 - 02:25 PM

I have D90 as well. Look in the technical specifications section at the end of the manual that came with the camera and you will find it. Also - when I got my D90 a couple of years ago - I bought the book Nikon D90 for Dummies - don't laugh - the lady who wrote it really has some great tips / short cuts / and other stuff that is hard to find in the manual.

Good luck with everything - DiverPam

Edited by DiverPam, 01 January 2012 - 02:26 PM.

Nikon D90 in Aquatica Housing, Tokina 10-17mm, 60mm macro, 105mm macro, Sigma 17-70mm, + Ikelite DS 161 and DS-125 strobe combo  www.flickr.com/photos/pammurph/

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#6 divengolf

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Posted 01 January 2012 - 05:23 PM

There was a real good article on front/rear curtains and flash synch speed for UW photogs a couple years ago. I cannot find it right now, but it may have been on WP or on the dive photo guide. I've got both a D70 and a D90. The synch speed of the D70 is faster at 1/500. The D90 is around 1/200 as previously stated.

If someone knows where the article is, it was very well written and informative on this topic.