Unknown shadow cast in my photos !!

[Hitham]

See if it works better at 1/30 and worse at faster than 1/60.

faster than 1\60th means i'll have to turn flash off.. and then i wont see the shadow cast for sure

 

[tursiops]

faster than 1\60th means i'll have to turn flash off.. and then i wont see the shadow cast for sure

No, leave the flash on. See of the shadow changes size...covers more of the picture.

 

[Hitham]

No, leave the flash on. See of the shadow changes size...covers more of the picture.

as i mentioned before i can't go above 1\60 cuz its the max flash sync speed (the camera wont allow me).. beside i dont believe its sync prob since it happens only underwater and not every photo

 

[KeithG]

as i mentioned before i can't go above 1\60 cuz its the max flash sync speed (the camera wont allow me).. beside i dont believe its sync prob since it happens only underwater and not every photo

by "only under water" do you really mean "only when the camera is in the housing" or you do mean "only when the camera is in the housing and the housing is underwater"?

If it is housing related, then try to recreate it on dry land.

I agree with storker - this is more than a little strange.

 

[Hitham]

by "only under water" do you really mean "only when the camera is in the housing" or you do mean "only when the camera is in the housing and the housing is underwater"?

If it is housing related, then try to recreate it on dry land.

I agree with storker - this is more than a little strange.

I never use the j4 outside the housing.. so its the 2nd
tried to recreate it on land and couldn't.. actually i've been using this system for a while freediving but haven't noticed the shadow cast until i started scuba recently

 

[Hitham]

once i fit the lens the port is rubber sealed.. but i was doing some testing trying to recreate the prob.. and i did !!
since my camera syncspeed is low 1\60, when i need to cut out ambient light underwater i have to rise the aperture lets say f14 while most ppl use shutter speed to do that.. i did that on white wall and bamm the shadow cast is there.. confirmed that by returning to my photos exif.. after lowering shutter speed to 1\50th the cast disappeared even at f16...
still dunno what causing the cast but i can live somehow with lowering the shutter speed and hope i'll still keep getting sharp images

 

[tursiops]

That's what I was trying to get you to do by using different shutter speeds. Your camera is not syncing correctly at 1/60, it is a bit too fast. Stick with 1/50 and you'll be fine.

 

[Hitham]

That's what I was trying to get you to do by using different shutter speeds. Your camera is not syncing correctly at 1/60, it is a bit too fast. Stick with 1/50 and you'll be fine.

yes your suggestion of using lower shutter was the key.. i just didn't think the aperture could affect the syncspeed
appreciate the help

 

[tursiops]

The aperture does not affect the sync. You can use any aperture with any shutter speed and only the lightness/darkness of the resulting image changes.

 

[Hitham]

The aperture does not affect the sync. You can use any aperture with any shutter speed and only the lightness/darkness of the resulting image changes.

i would never get the cast below f8 with 1\60th after stepping down to f10 or more it starts to appear