Opacity VS Flow

[Syd]

This is a question that has vexed me for some time now. When using the brush settings what is the difference between Opacity and Flow? I have yet to see the difference when I swop them around and suspect that they might only apply to a Graphics Tablet. For instance if I use an Opacity of 100 and a Flow of 50 is it the same as using a Flow of 100 and an Opacity of 50? It looks the same to me but I could be wrong.

An equally intriguing, and not unrelated question, is the relationship between Opacity and Fill with regards to Layers. Once again, they seem to have the same effect.

Sincerely Syd

[mistermonday]

Syd,
First on opacty vs fill, use the rectangular marquee to create a square / rect box over a white layer and fill it with a color like blue. Bring up the Layer styles palette and add a black drop shadow. If you lower the layer opacity, the colored shape and its drop shadow fade in synch with each other. However if you just lower the %fill, you will fade out only the shape but maintain the layer style. So Fill allows you to preserve all of your layer style effects while adjusting the opacity of the layer contents. There are many occasions when this feature is essential.

On brush opacity vs flow, the flow controls the rate at which the color flows from the brush and therefore the brush dynamics. For example choose a blue brush 30 pixels, 100% hard edge. On a white layer, select Opacity 10%, Flow 100% and brush for a couple of inches. See the resultant color and smoothness. Now reverse the values of the opacity and flow and see the difference. Opacity controls the amount or intensity of the color. Flow controls its dispersion. These things combined give you a tremendous level of control in your application of brushes.

Regards,
Murray

[Syd]

Murray, thanks for a wonderfully clear explanation. I tried it immediately and it behaved exactly as you said it would. I have been wanting to ask this question for a while but it seemed so elementary. The difference is very significant. I set them both at their extremes i.e. 100 and 1. With the low opacity and the high flow the stroke was wider but fainter. When I reversed it the stroke was narrower but darker.

I wll have to try the layer example later.

Thanks once again.

Sincerely Syd