Consequences about flash position

[juzug]

Hello,

I have wondered, what are the reasons (and pros/cons) for flash positions in different cameras, mainly in pocket cameras. Usually it is said, that the further the flash is from optics the better. What are the reasons behind that? If I buy camera, where flash and optics are close together, what kind of problems should I expect? How about benefits?

Currently I think that benefit from longer distance is less red eyes (is there some fact or tests, which supports this..?). But drawback is wrong flash position in macro-shooting.

 

[slowhands214238]

The book...Light, Science and Magic
could provide much of the information you seek.

Distance from optics AND distance from subject should both be considered, as well as positioning and relative size... for red eye, macro, and many other reasons.

 

[BAK]

Farther apart is better. It has to do with the angle at which the light hits the back of the eye and the angle that it is
seen" by the lens.

Farther apart, and there is less chance the brightly lit back of the eye will show up in the photo.

That's proven by using an external flash, farther away from the lens.

Second: position of the flash affects where shadows fall behind / beside a subject. Best place for an oncamera flash, mostoften,is a few inches above thelens, so shadows fall behind the shoulders of people in the shot.

This is why wedding photographers use brackets that turn,solight is still above the lens when camera is turned sideways.

BAK

 

[juzug]

Thanks for the answers (probably I should find the book mentioned in first answer).

I should probably clarify the question a little. The principle about the red eyes and shadows are more or less clear for me - thanks for clarification anyway. But the point is that does it matter within the limitations of pocket cameras?

Of course it depends on the situation, but in general does 1-3 inches matter at all. I.e. do I notice the difference in practice, if I have similar camera with "flash and lens together" or "flash and lens far from each other" (usually around 2 inches on side).

I know, that the question is little bit "academic" But still somehow valid for camera comparisons.

 

[John Deerfield]

I know, that the question is little bit "academic"

I would say it is more like irrelevant.

But still somehow valid for camera comparisons.

You are trying to determine if the flash position on a point & shoot camera makes it a better choice than another point & shoot camera? See my first point. If would be more beneficial to consider point and shoot cameras that have a hot shoe for shoe mount flash. A shoe mount flash with a rotating flash head can make a difference. Otherwise, I believe there are far,far too many other things to understand about photography that will have a decided impact on your image than whether you P&S has a flash 2" closer to the lens than your friends P&S.

 

[juzug]

Like I said, the question is little bit academic (also irrelevant for normal use cases). I am not going to make my camera decisions based on this question. I just want to increase my knowledge about this topic. So let's take this again:

It would be nice to hear from studies, theories or just opinions, if the flash position has any visible effect to image quality within pocket camera limitations. Especially, when the distance is usually in horizontal direction. IF not, where could be the threshold, when you start to benefit from the distance.

 

[Quantum Help]

There is a law of physics, which is: " the angle of reflectance is equal to the angle of incidence ". That means that the light being emitted and reflected is equal to the angle it goes in at. Using a P&S camera, the light is going almost directly in, thereby reflecting directly out. It is the light hitting and reflecting off the blood vessels in the eyeball and being magnified by the lens of the eye that causes the effect of "red eye". If the light source is at a greater angle, say 3 inches away from the lens, the angle is greater and the reflection will be lesser.

A lot of serious " macro " photographers do not use a point & shoot, nor an on camera flash. They use off camera flash, so that they can control the light and give the object they are photographing more "dimension " rather then the flat light produced by having a built in flash used.