lay (ran out of room

) multipule instruments, especially, respond)
I've mentioned I'm helping at a Jr.High camp, and I noticed the one Fr. Horn player was having a bit of trouble. I had pretty much finished my work with the trumpets throughout the week and they are doing fine, but the poor horn player was a little lost. So, I looked at the music, helped with rythms, and, once figuring out the key difference (F to Bb is - 1b and down three notes), with the notes (the first time I had transposed from F to Bb).
My questions (for those who play multiple instruments):
1 What is your frame of mind when you transpose from one key to another while playing trumpet? Esp weird keys like F to Bb, or bass cleff C to Bb treble (up an octave).
2 What is it when you play on a different instrument? Are you, in your mind, transposing from, say, BC baritone to trumpet when playing baritone, or adopting a completely new mindset? If so, what?
I sing and play piano, but that isn't exactly the same thing. You can trick your mind into hearing higher and just focusing on your 'new' do and go from there.

I would love to hear your different thoughts. I just like hearing how different people feel and seeing the highs and lows of each.