Change Lens, camera or what to read?

alowe

I'd really appreciate help/advice please. I have a canon 550d with a 18-135mm (f3.5-5.6) and a 50mm (f1.8). I'm trying to take nice portrait of my kids with using a white background that I'm over-exposing with one flash, and another flash at 45degrees in front. Light is fine, however I think my settings are a bit off. I have got some beautiful pics, but more often than not, something is slightly out of focus. This especially happens when I'm trying to get the 3 together - its like the main focus is on one, and the others blurry - but what I've found is that if I change one thing (such as the f value to lets say above 11 to capture more definition), then another value is wrong, i.e. the speed of the shutter open is too long for them moving.

I feel like I need a shutter speed of about 100-150, and ideally an f stop of f16 and an iso of 100/200. (this is probably completely wrong).

What I'm wondering is ... in order to get those crisp shots should I get a better lens? Would my money be better spent getting a better camera? Or can I get what I want with what I have, but I should read this particular blog/book, etc.

My out-door pics seem to turn out great - perfectly clear and sharp - its just the ones I'm doing indoors with flash.

All advice greatly received :-)

DaireQuinlan

You're metering for ambient, but you're using your flash to illuminate. Just, in manual, set your shutter speed to 1/100 or whatever, f/16, and rely on your camera to TTL meter the flash properly if it's capable of doing that. Otherwise you'll have to fiddle around with manually setting the flash power until you get it right.

Alternatively your camera probably has some flash program mode which will keep the shutter speed high even though it'd otherwise be way under. Read your manual, there's probably some section on shooting with flash.

cnocbui

I know next to nothing about your particular equipment, but I would think you want to avoid too small an aperture. At f16 you would be getting a bit diffraction limited so won't be getting the maximum resolution from the lens. http://dpnow.com/7644.html

I would use the 50mm f1.8 and use the max flash sync speed of 200 and adjust the aperture to suit - and try manual focusing.

Farmlife

For 3 people standing beside each other F8 should be well enough dept of field, with a shutter speed of 160 and your flashes set to half power and play with your ISO, dont worry about bringing the ISO up to a 800-1000. Make sure your focusing is set to "AI" as kids moving about could mess up "one shot focus"

mikka631

What to read - Understanding Exposure and Understanding Shutter Speed both by Bryan Peterson.

alowe

Thanks everyone for advice. Am going to hopefully setup again in the next few days and re-try.

still feel and urge to buy something though ....