A basic flash question

Swartzy

When I had my Canon AE-1...I had 2 different flash components. One was a Vivitar bounce flash, the other a Canon Speedlight. I forget the model numbers. In any case my question is this:

What advantage is using a speedlight mounted on the shoe versus the pop up flash installed on the camera itself? Both are aimed directly at the subject and have variable settings including that of internal camera settings. It seems to me that if one were to use an alternative flash, it would be off to the side, or used as a bounce that the light wouldn't be harsh on the subject. Can any of you enlighten (no pun intended) me? I've wondered about this for years.

Thanks in advance.

gluwater

I'm definitely no expert on flash but here are my thoughts. If at all possible you should have the flash off camera but you already knew that. The speedlights are much higher powered than the on camera flash. Some if not all can use high speed sync which lets you go above a 1/250th shutter speed, which is useful for fill flash in daylight when your shutter speed will definitely be higher than 1/250th. You can point the flash towards the ceiling to bounce it at your subject to diffuse the flash, or you can use a diffuser. These are just a couple reasons for using a speedlight, I'll sure others will chime in with better reasons.

Scott_Quier

The following was taken directly (no editing, no cropping, written by 'CurtisN') from here

REASON #1: REDEYE
We’ve all seen pictures of people whose eyes have that diabolical red glow. It can ruin an otherwise very good shot. It is caused by light reflecting off the retina in the back of the eye. This phenomenon is worst when the subject’s pupils are dilated (indoors), and when there is a narrow angle between the light source (flash), eye, and lens. Geometrically, the two factors which affect this angle are the distance between the flash and the lens, and the distance between the camera and the subject’s eyes. One way to avoid this problem is to move the flash further from the lens. The more distance there is between the flash and the lens, the further away the camera can be from human subjects without causing red eyes. Typically, a hotshoe-mounted flash unit will be twice as far from the lens as a “pop-up” unit. A flash bracket can be utilized to make this distance even greater.