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Bob_W

Member Since 20 Jun 2007
Offline Last Active Today, 03:47 AM
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Posts I've Made

In Topic: Help with strobe settings

21 July 2016 - 07:21 AM

 

How does that work? Doesn't that mean that the camera is controlling the flash intensity and duration, even though you're in Manual mode? I infer that there is a separate camera setting that controls whether the camera flash is in Manual mode or automatic? So, if the camera is in M but the flash is still in A, then despite your manual settings for A, S, and ISO, the camera will still light the flash if it thinks it needs to?

 

I had assumed that putting the camera in M would mean that the flash was also in M mode and you would have to manually set it if you wanted it to go off when you snap a picture.

 

Note: I'm talking about the camera's built-in flash because I think with a fiber optic cable, the camera's built-in flash controls the external strobe as well, right? Assuming the external strobe is in TTL mode, that is. So, whatever the answer is here, it's the same answer whether you are using an external strobe (in TTL) or not, right?

 

That depends!. There are 3 different things involved in the process, each controlled separately:

1) the camera - f/stop, shutter speed, ISO in manual mode. Variations of control in the other modes..

2) the built in flash - depending on your camera, it may be able to be set to only fire when needed, fire full all the time, only fire fractional power, etc.

3) the external strobe - it can be set to TTL where the on/off mimics what the camera flash is doing as seen through the fiber optic cable. The strobe has no idea what's going on, it's just doing what it's told. You can use the the rotary dial to tweak the light from the strobe. Or it can be set to manual mode, where the light from the camera through the fiber optic cable is just a trigger for the strobe. It then fires based on the settings on the rotary dial. If your camera uses a pre-flash to make it's adjustments, you have to use the 2 lightning bolt setting on the strobe so it knows to ignore the 1st flash. Otherwise the strobe will fire on the pre-flash and won't be able to recycle quickly enough to fire when the shutter opens. conversely, if your camera doesn't use a pre-flash, and you tell the strobe it does, the strobe will ignore the flash and wait for the 2nd, which never comes. Ideally, when using the strobe in manual mode, you should set the camera flash (if capable) to fire all the time at it's minimal power setting. That way, you get enough light through the fiber optic cable to fire the strobe, but conserve battery power that would otherwise be wasted firing the camera flash at a high power.

 

Bob W


In Topic: To Filter or Not To Filter

08 July 2016 - 07:07 AM

Take a look at the page at the link below. It should help you understand how a filter can help.

http://www.magic-filters.com/need.html

 

Bob W


In Topic: Help with strobe settings

08 July 2016 - 06:56 AM

Here are links to 2 write ups for setting up the Canon G16 for underwater use.

http://reefphoto.com/kb.php?id=59

http://www.bluewater...uide-underwater

 

There are 2 different manual modes to consider: 1 for the camera; 2 for the strobe. For the camera, in manual, you select the f/stop and shutter speed. For the strobe, you select the amount of light, from min to full. They are independent settings but do effect one another. You can use M on the camera and TTL for the strobe. Set the camera to M, f/16 and 1/160. Set the left dial on the strobe to TTL and the right dial to 0 (mid position). Take a shot. You can then fine tune you image by adjusting any 1 of the settings. (You could also make adjustments using the ISO setting, but save that for later) If you want to use the strobe in manual, set the left dial to the double lightning bolt position. Your G16 uses a pre-flash. Set the right dial to 1/4 - 1/2. Take a shot. Fine tune by adjusting the right dial to get more or less light. For larger subjects, or further away, set the right dial to full.

 

Bob W


In Topic: My New Book: Underwater Photography Masterclass

27 June 2016 - 05:33 AM

For everybody waiting to get a copy of Alex's book, you can order it from Amazon.co.uk and get it in 1 - 2 weeks. You don't have to wait for Amazon US to get their act together. The cost, including shipping, is $32.80 (USD). If Amazon US ever gets around to shipping it, the cost will be $30.80 (USD), including shipping. For $2.00, why wait??? Get it today!!!

 

I pre-ordered  the book from Amazon US back in March. I'm still waiting on that order. In the meantime, I got a copy from Amazon UK.

 

Don't wait.....Get yours!!!

 

Bob W


In Topic: Two noob questions - wet lenses and lighting

02 May 2016 - 04:06 PM

The typical duration of a strobe is 1/1000th of a second. Typical shutter speeds run from 1/60th to 1/250th. If you are using light(s), there is more of a chance that a moving subject will blur, unless you use a faster speed. The sequence is the shutter opens, the strobe fires (freezing the action), then the shutter closes.

 

Bob W