Your Canon is a low noise camera so the quick fix is:
Increase ISO to 400/640 ISO. Choose a wider aperture (lower or lowest number) say go from f8 to f4.5 - or preferrably f2.8 if you have a fast lens. Set shutter speed to something you can comfortably hold - say a 1/40th of a second with flash on rear sync. This remedies most situations for still objects providing a fairly good foreground/background exposure.
In short: increase ISO setting (but not to the point where noise is excessive), open up the aperture, set shutter to 1/60th or 1/40th for stationary subjects and rear sync on the flash/camera.
If you get blurry pictures it boils down to:
Not enough light, forces camera to open up the shutter for longer period = shaky. Solution: increase light or use flash.
Wrong aperture: don't choose f11(higher value = smaller hole = longer exposure) unless you really need the extra depth of field (stopping down the lens increases depth of field but each f-stop pays a penalty of one stop on the shutterspeed setting). f11 and 1/8th of a second (blur guarantee) equals f4 and 1/60th of a second. F-stops are for example f2.8/4/5.6/8/11 where each increment increases or halves the light: 2.8 and 1/60th equals 4 and 1/30th equals 5.6 and 1/15th etc. Shutterspeeds follow the aperture and vice versa.
If you use flash you also need to balance it off with the ambient exposure to get a natural result. You can set the camera to rear (second curtain) sync so the flash pops at the end of the exposure. Note that if light levels are low the exposure gets longer and if it is too dark you are better off with the quick fix above.
Also, if you are shooting close up on ISO 800 the flash might not be able to suppress itself enough on a wide aperture so you might need to stop down close up or suffer overexposure. The built in flash in generally weak and close up the lens usually casts a unsightly shadow over the subject.
Check flash settings. Best is to bounce the flash on a white card for a more even illumination. However with a light tent and good illumination you might not need flash at all - just need to white balance correctly. But choose aperture carefully: if your subject is flat you don't need to stop down that much on the aperture - just choose the angle carefully. At closer range the depth of field is smaller and for each stopping down on the aperture the depth of field increases by a ratio of 1:3 from the field of focus towards you and 2:3 from the point of focus towards infinity. A wide angle will give you better depth of field but can provide more distortion where as a telephoto lens has narrower depth of field and stopping down a telephotolens close up doesn't do as much as one might want.
If shutterspeeds are low: tripod yes. If you haven't a cable release use the self timer.
I could write more but I need to eat some and then I am off to... ...a photoshoot. I have written small articles on setting things up for digital cameras but only in my native tongue.
Bill; the problem with the built in flash is that it sits close to the camera body and therefore casts a shadow over the subject.
To minimize the shadow you could use the quick fix in my previous post - it produces a softer flash output as you set the camera to allow more room for ambient light. If you get an ugly shadow on the subject try and elevate yourself slightly as this will produce a lower shadow. Also, if you are taking a portrait of someone and must use flash (or an item - like a Festool box) remember to tilt the camera to the correct side when shooting vertical shots:
If you are on the left side of the subject (or if the subject is looking to YOUR left) tilt the camera to the left so the flash is on the left side as well. The try and shoot at a very slight angle from above. If the subject is close to a wall try and get it out from the wall a wee bit. By doing this you allow for the shadow to drop beneath the subject and become less apparent.
If you tilt the camera the wrong way you get a ugly nose shadow and a strong shadow from the subject, on the wall.
If the subject is facing the other way - tilt the camera the other way. Once you've got the hang of it it becomes second nature.
If shooting your work shop use a wideangle lens, set the ISO slightly higher than normal (normal is as LOW as possible) use a wide aperture (low number) as depth of field is generally good enough, place focus where it needs to be choose rear sync on flash. If uncertain place focus at the closest (to the camera) interesting object and let the depth of field do the rest by stopping down some more on the aperture or just fade naturally. If you have an external flash you can angle it up against the ceiling and set the flash manually to the widest setting to allow a more even spread. Note that a white ceiling is preferrable as a dark ceiling will just consume the light and a coloured ceiling will colour the picture... ...If ceiling is dark, too high or green/blue/red you can use a piece of white cardboard at 45 degree angle and bounce the flash on. Or get one of the nice diffusers (which are meant to be tilted as well).
Reflections are trickier but in general they are much nicer with bounced flash.
Now I really gotta go!
