Fairly new to FCP 4. Was wondering if anyone can explain the difference between an additive dissolve and a non-additive dissolve. I can't seem to tell the difference.

Additive Dissolve combines the luminance points (values) of the two clips and it brightens them up to the midpoint of the dissolve. Most of the time where the two brightest areas of the the two images cross will become white.

You might use this for short "Flash" type transitions.


You have to watch out for this dissolve 'cause it might take you up past broadcast safe limits at the brightest point.

So do you suggest using the regular cross dissolve? I've also played around with manually lowing the opacity of one clip before the transition to the next w/ key points. But thats seems tedious for an entire project.

it really depends on what you want.... problem with lowering or increasing the starting or ending point of a transition is that it usually ends up suddenly appearing or disappearing. You can adjust different thing in the transition...


What are you looking to do? There are cross disolves, dip to color dissolves...


what sort of thing are you trying to achieve?

Just looking to add transitions that are the least obvious on screen. I'm putting together a doc and don't want my audience to be aware of the editing - I guess seamless is the word I'm looking for.

well other then cuts, you can do very short duration dissolves which are basically like "soft" cuts.

Very fast "flash" transitions aren't as distracting as you might think but it depends on the content and situation.


I think the thing you need to do is experiment. that's the great thing about NLE, you can do it one way, undo it and try another way over and over again.

Keep in mind that it's not just the type of cuts you make, it's where you place the cuts that make edits unobtrusive.

Take a close look at the way most documentaries are edited. Most are just straight cuts. But careful timing of the cuts can make it seem fluid and seamless. And overlapping an audio track can help carry one cut over into the next.

Dean Sensui
Base Two Productions