Flash study. . . Conclusion ???

[aparmley]

OK guys - I need some help here.

I'm going to throw everything I thought I knew about flash out the window and start over. . .

I need a little help in the mean time. On Easter Sunday the sun was out and it made getting even exposures very difficult. I knew this is an ideal flash situation but my lack of true flash understanding made me keep it in the bag.

I kidnapped the Travelocity gnome and his trusty companion and used him as the subject today.

All images with flash used it in high sync mode. My past understanding was that flash can not be used above the high sync shutter speed - I'm pretty sure thats wrong now but can't say I graps why exactly. . .

First images - trying to stay below flash sync speed in AV mode:



I didn't care for these results so much. . . I really wanted to shoot with a larger aperture. but I had to open it up because of the brightness of the scene.

So I switch to manual mode. For shits and giggles I came up to 2.8 - adjusted my exposure so I would not over expose the highlights. then I turn the flash on - using the omnibounce diffuser this time - and I was suprised. At 1/1600s it did exactly what I wanted it to do. . . ???



Whats the High speed flash sync ceiling of 1/250 or 1/500 in some cases for then? totally confused. . .

I am now trying to understand why I saw the results I did. I was opertating under the assumption that I had to keep my shutter speeds down around 1/500 to get my flash to work properly. . . So - in fill situations I always had to use smaller apertures and I really didn't care for that too much so I never really used it. . .

I think its clear that I never really fully explored flash before and what ever knowledge I thought I had before has been blown out of the water.

Please feel free to chime in and let me know what I am failing to grasp. . .

Thanks

[cdifoto]

You can sync above 1/250th with any flash that has high speed sync compatibility. The 430EX, 580EX, 550EX, and Sigma EF-500 Super (not the ST) can all do this. You lose range though and the higher the shutter speed, the more severe the loss of range is.

Any other flash can sync at 1/250th on the XT (or is it 1/200th? I forget) and this includes studio strobes.

[aparmley]

You can sync above 1/250th with any flash that has high speed sync compatibility. The 430EX, 580EX, 550EX, and Sigma EF-500 Super (not the ST) can all do this. You lose range though and the higher the shutter speed, the more severe the loss of range is.

Any other flash can sync at 1/250th on the XT (or is it 1/200th? I forget) and this includes studio strobes.

I did not know that. I thought in order use a faster shutter speed you have to change the flash to high sync mode and that allowed you to use 1/250 - 1/500. Man what the hell was I thinking? GXX Damnit Christian!

Well none the less I am totally "wrapped" about this - I am going to exploring this further. . . BTW - That last image, 1/1600 + flash - I was blown away with the results. . . Image quality wise - thats what I think I should see! "Light" something else I need to explore further and expand my knowledge, because they weren't kidding - its all about light!

[cdifoto]

I did not know that. I thought in order use a faster shutter speed you have to change the flash to high sync mode and that allowed you to use 1/250 - 1/500. Man what the hell was I thinking? GXX Damnit Christian!

Well none the less I am totally "wrapped" about this - I am going to exploring this further. . . BTW - That last image, 1/1600 + flash - I was blown away with the results. . . Image quality wise - thats what I think I should see! "Light" something else I need to explore further and expand my knowledge, because they weren't kidding - its all about light!

High speed sync lets you use anything above the camera's default sync speed, at the loss of range. For the XT it's 1/200th. For the 1 series I think it's 1/250th...although I could be wrong on that too. Point is, it's camera specific and not flash specific. The flash specific part is whether or not high speed sync is available.

[aparmley]

Ok. so I am going to walk through the logic here.

I placed my flash on high sync mode. This allowed me to use however fast a shutter speed I want - ofcourse at the loss of range - light travels at a finite speed, if I stop the travel of light quicker it will not travel as far - makes sense.

I shot in manual mode - Why? Well here I wanted to expose my photo so that the highlights were not blown. in last set of images, the hand rail on the deck was blown at 2.8 until I reach 1/1600s. In the image on the left, you see the result, hand rail not blown - Gnomey underexposed. With high sync mode selected on my flash - it filled Gnomey and his ride with enough flash to even out the exposure.

Here is something I need to keep repeating to myself:
Shutter speed has notthing to do with flash exposure. Shutter speeds only have to do with ambient light exposure - ie the light on the hand rail required 1/1600s to expose properly - hence my exposure.

Taken from the EOS Flash Bible - I guess I missed that part

" This mode is useful for shooting with fill flash outdoors with wide apertures. Normally you can’t shoot outdoors and use fill flash unless you stop down the lens or use very slow film. However, changing film is a nuisance and stopping down the lens increases the depth of field. If you’re shooting a portrait, say, you probably want to blur the background and the only way to do this is to shoot with a wider aperture. But the wider aperture lets in more light, and you can’t compensate by increasing the shutter speed if you then bump up against the camera’s X-sync limit.

FP mode flash solves this problem by letting the shutter speed exceed the X-sync limit and reach the camera’s maximum shutter speed (usually 1/2000 or 1/4000 sec) instead. The primary drawback is that pulsing the light causes a reduction in overall light output and thus range ... Of course, if you’re using FP mode simply for a little fill flash (rather than relying on it to illuminate your subject) then this loss of range shouldn’t be a huge problem."

Ok I feel like I made a big leap forward here today with understanding flash and I'm happy to now know for a fact I can use my flash out doors to fill indepented of my shutterspeed. . . Thats good to know. . . I should have learned this a while ago but at least now I know.

[ktixx]

anybody know a good link for a tutorial on using manual flash? Speicifically dealing with guide numbers, etc?

[aparmley]

anybody know a good link for a tutorial on using manual flash? Speicifically dealing with guide numbers, etc?

The two most useful links I've been given are the following:

http://photonotes.org/articles/eos-flash/
http://www.planetneil.com/faq/flash-techniques.html

[Bluedog]

And to think lots of people will tell you this piece of Tupperware is useless outdoors for fill-flash. I'd like to see you post the Omni Bounce results over at POTN.

[aparmley]

And to think lots of people will tell you this piece of Tupperware is useless outdoors for fill-flash. I'd like to see you post the Omni Bounce results over at POTN.

I started my session with out it and threw it on and was happy with the results!

POTN member don't like the omni bounce outdoors for fill ? the last three weddings I went to all three of the WP used them. . . at least one of them has to know something I should think. . .

I should do a comparison of no flash, fill flash and omni bounce fill flash and post it over there huh??? LOL sounds like a hum-dinger of a good time. . . I'll do something tomorrow.

[cwphoto]

anybody know a good link for a tutorial on using manual flash? Speicifically dealing with guide numbers, etc?

Manual flash is pretty easy. At full power you simply divide the aperture value into the GN for correct subject distance. This will expose the subject correctly using flash only and you will need to take ambience into account.