Large/adheres flight specs backpack

I'm gonna be flying from Singapore to the US (LA) this August and need a big backpack that adheres to airline safety/carry on measurements. I haven't traveled in a long time (not to the US, at least) and the last time I did to the US was way before we had all these weird security measures, measurements, rules and restrictions. My initial plan was to carry one notebook bag and one dedicated camera bag with me, but I'm told that economy class travelers are only allowed one carry-on with some measurements around the 21x16x9 inch range and weighing less than 20 lbs.

The single bag for flight carry-on that I need is able to hold:

• A 17 inch laptop (HP Elitebook 8730w)
  
• A 12 inch ultra-portable laptop
  
• An EOS 7D with 24-70 mm f2.8
  
• A spare set of clothes
  
• A couple of important paper documents and passport
  
• Preferably with some additional 'wiggle' room for any additional important things I might need

International flights allow 2 checked luggages and 1 personal and 1 carry on. you should check your airline for details.

I carried a large instrument + a lowepro CompuRover AW (Gripped 40D, 70-200, 50mm, 17-55IS, 10-22, + flashes + 2 netbooks + PSP) to Taiwan from US with no problems.

its not about the security measures - its about the person manning the ticket counter (avoid showing them your carry-ons) and then getting past the xray/security crew (which just means your bag needs to fit thru the template of the xray scanner)

I find that once you get to security its not such a big deal what you have with you cause you have to take out your laptops and then put your shoes and jackets and all that crap in bins, and there is no way for security personnel to keep track of who put what on the belt.

Personally I have flown with a Think Tank Airport Antidote backpack for almost 3 years now. It has flown a lot of miles (internationally and domestically) and done the job well. I prefer this style of backpack because it is very sleek and does not look bulky, even if it is well over weight. The way stuff "looks" is what attracts airport security or airline employees attention as opposed to actual dimensions and weight in my experience.

Think Tank has a whole line of "Airport" backpacks that are a range of sizes... www.thinktankphoto.com