I’ve modelled a single lantern pretty simply, it’s one of those with a flame and goes floating off in to the sky. It consists of a flame, paper around it and a frame. It looks like this.
the flame is an emission shader. The paper is a diffuse shader mixed with an translucent shader.
However when I make this a particle and put it in the scene it looks completely different.
Crank your samples up, see if that fixes it. I think you’re still on 10 samples, I’ve had diffuse/trans/emission lampshades that don’t show their true colors until a few hundred samples.
Increase the emission value to something very high. Go way higher until it begins to wash out the entire scene. Then start lowering it until it’s something you want. The brighter the better when it comes to cycles.
Yeah, try cranking the strength insanely high, see what you get.
It’s also possible you have something like a solidify modifier, which is disabled in preview but enbaled in render. Solidify on a semi-transparent material will make it much much more opaque. Beyond that, post the the packed blend to pastelal or dropbox.
You might also try “overdriving” the color on the translucent shader. The regular color input wont allow RGB values greater than 1, but if you use combine RGB node you can, and running color through a gamma or brightness contrast also seems to do this. It may break some of the realism in how the light interaction is simulated, but the effect is much weaker light sources will show through the material. (It ends up boosting the light amount as it passes through. And it can get weird with multiple light sources.) This is also a handy trick when you have light sources passing through glass, as the glass shader is very light absorbing by default.
Random thought: particles often default to a tiny scale (.01 or something), so that might be affecting things. Have you tried modelling the lantern 1:1 so you can set your particle size to 1?