silly question - black background

hi there, firstly please forgive me if this is a silly question. I know hardly anything about photography but am trying to learn as much as i can in preparation for my trip to the maldives in December.

I have read that in order to get a black background whilst taking macro shots, you need to hold the camera straight ahead (rather than tilting up or downwards). However, if I am using a strobe wont that light up the whole area and the aperture determine my depth of field??? sorry to all you experts this probably is a stupid question but I am puzzled. its been difficult practicing in the garden, I know the results are totally different underwater!!!!

Anyway thanks for any advice, it will be much appreciated.

By the way, I am posting under my husbands login so he will be quite embarressed that I have asked this question!!

Cheers.

lou

Lou,

Don't be embarrassed - it's a question we've all had to deal with. Getting a black background (i.e., making the WATER in the background look black) is simply a matter of NOT exposing the photo (with shutter speed and aperture but IGNORING the effect of the strobe) for the ambient light. If your photo would be significantly underexposed (i.e., black) without using a strobe, then when you DO use a strobe, it will only light up the things within its reach, and everything else will be black. The reason you shoot horizontally to get a black background is so there isn't anything behind your subject near enough to be illuminated by the strobe.

Hope that helps!

To avoid lighting up the background, just change the orientation of your strobes (e.g. slightly upward, or sharply angled from the sides, etc.)

The black background is generally (?) not an intentional effect, it comes from the use of a small aperture (to maximise DOF) in combination with a fast shutter speed to freeze the action when using a long lens.

If you intentionally want to achieve this effect, set the shutter speed on your camera to its highest sync speed, set your aperture in the region of F22, and set your strobe power to expoose the foreground subject properly...

thanks guys that makes a lot of sense now. i cant wait to get in the water in december now (although dont think i will be brave enough to post my pictures on here just yet.....

although dont think i will be brave enough to post my pictures on here just yet.....

Best way to learn, though. If something went wrong and you don't know why, just post away and others will help you understand...

Best way to learn, though. If something went wrong and you don't know why, just post away and others will help you understand...

I agree with Matt. Don't ever feel shy to post a pic or ask a question. Its the best way to learn