Canon g9 - macro settings, where to put the strobe

[Bombarie]

Hi All -

Bought the Canon housing this weekend for my G9 and got a Z240 to go with it (the idea is to be able to upgrade in a year or so, hence the fancy flash). My main interest is macro. Have been toying with it on dry land this weekend (it will get this week) and would be grateful for your advice on the following:

1. Focus. I noticed that, in the dark living room using the aim light of the Z240, the autofocus of the G9 is left literally in the dark - it has no clue what it is doing. If this observation is correct, would you agree that the better approach is to put the camera on manual focus, put it on a distance of say 10cm, and program that in the C1 function (which I want to use as my macro setting)? I can then focus underwater by moving the camera in / out (the MF function requires the dual squeeze of the buttons which, I believe without having trying it, is going to be less than perfect). How do you go about this?

2. Settings. I did my tests with the G9 at ISO 80, 1/125s and 5.6 - all in manual mode, programmed to C1 (with underwater wb, too). That looked alright enough - what's the basic setting you would use for macro?

3. Aim of the strobe. I suspect that aiming the strobe is going to be the hardest work. What is the trick - use the aim light to "light up" the subject, or is the idea to aim in front / back / side of the subject? Again, your thoughts are appreciated. Do you put the strobe at 45 degrees "Northwest" of the camera and aim the flash only, or do you "circle" the subject?

4. When using the strobe in Manual, what power to apply - on dry land the second lowest output was enough, what's the loss underwater?

I realize that all this is trail and error -- but like to come prepared so any thoughts, thanks!

Arie

 

[gert7to3]

Bobof posted a link on strobe positioning a while ago:

http://www.kelpfish.net/strobe.swf

With your camera, I think that manual control of shutter speed and aperture will be helpful. I don't think you want to use manual focus control. Control the color of your background with shutter speed (eg: faster shutter speeds underexpose the background, producing a darker richer color); control your depth of field with the aperture; control your exposure with the strobe.

The focus light in your strobe will likely direct too much light between your lens and subject. This is because the focus light is centered within the strobe light's beam. You want to use more of the edge of your strobe light beam, letting as little of it as possible hit the water column in front of your lens.

For macro photography, with a stopped down lens, you will probably need to move your strobe closer. You will also need to think about how your strobe will illuminate the subject. Usually positioning the strobe above, but a little to the side works well.

Check the sticky threads in the Tips and Techniques forum for further discussion.

 

[Scott D Johnson]

Could you please tell me what a stop down lens is? could you tell me how the aperture works?How high can you go on the shutter speed and does the depth change on how you set your shutter speed?I have never used a underwater camera.I just perchested a G-9 cannon,3944.51 substrobe DS-50 Digit,Ikelite housing with ttl.I have takin lots of photos but never mess with settings.I could use all the advice your willing to give.

Thanks Scott

 

[Larry C]

Could you please tell me what a stop down lens is? could you tell me how the aperture works?How high can you go on the shutter speed and does the depth change on how you set your shutter speed?I have never used a underwater camera.I just perchested a G-9 cannon,3944.51 substrobe DS-50 Digit,Ikelite housing with ttl.I have takin lots of photos but never mess with settings.I could use all the advice your willing to give.

Thanks Scott

To stop down the lens, you raise the f-stop. Usually the highest f-stop (smallest aperture) on most point and shoot cameras is f8. As the f number gets higher, the aperture-the hole that light goes through after passing through the lens-gets smaller. If you're shooting "wide open", that would mean your aperture is the lowest f-number. Usually that's f2.8 on point and shoot cameras. At this aperture, you let the most light in, so if you were shooting in a darker environment it would allow a faster shutter speed for the same exposure. This is why a lens with a smaller available f-number is called a "fast" lens. When you make the aperture larger, you limit your depth of field. This is the range of distance in front of and behind your subject that will remain in focus. Shutter speed doesn't affect DOF, but prevents blur from shooting a handheld camera while moving underwater. Your fastest shutter speed underwater will depend on the power of your strobe and your distance from the subject. Some people shoot as fast as 1/500, which will give you a black background and make your subject stand out. More common is about 1/125 @ f8 for close-up (macro)subjects, and slower shutter and larger aperture for wide shots where you want to see background detail. You might try using the auto exposure settings or "S" or "A" settings and see what the camera gave you on your best pictures. Then use those as base settings for manual exposures.

 

[Scott D Johnson]

Thanks Larry you helped a bunch.
Somebody in a nother post said that they had bleary pictures with the ISO on they had to shut it off. Could you explain why? This was on a G-9 Connon.

Thanks again Scott