I have a D90 kit and I carry it in a Tamrac Express 6. The Explorer 2 is 1/2" wider and 1 1/4" deeper. They’re both about the same height.
The height is tall enough for carrying the camera with the 18-105 with its hood installed. That’s great for me because I leave the camera turned on in the bag. I can just pull it out and shoot...it’s always ready to go. I also have a 70-300, and it will fit in the bag but essentially, the camera is standing on the 70-300...it goes all the way to the bottom! I’d say the bag doesn’t really need to be any higher unless you’ve got a high-end big glass.
The D90 is a tall camera and the 3 3/4" depth of my Express 6 is tight. I had bought the bag for a Pentax K-x (was perfect for that) but then returned the K-x for a D90 and decided to keep the bag. It does work, but yeah...the 5” depth of the Explorer 2 might be littler bulkier than my Express 6 but will make getting the camera in and out of the bag easier.
The width is where you’re going to have a problem. You didn’t say what kind of lens you’re getting, but if it’s any sort of AF-S zoom then you’ll need a wider bag. I could not get the camera (with a lens attached) and the 18-105 and 70-300 in my bag at the same time...it wasn’t even close. Flashes are fairly large as well. Judging by the fact that the Explorer 2 is only 1/2" wider than my Express 6, I’d say that there is no way you’re getting an 18-105, flash, and another zoom lens in there. You might be able to squeeze in a 35mm f/1.8 or a smaller prime, but I’m not even sure of that.
If you want to carry all that I would say that the Express 7 is a perfect bag. It’s not as deep as the Explorer 2, so less bulky, but it’s 11 inches wide...nearly 2 inches more than an Explorer 2.
The Velocity 7x suffers the same problem…it’s not nearly wide enough. With its depth you can keep a small prime in the main compartment.
I’m actually glad that I didn’t get a bag large enough for my 70-300 zoom. It’s a heavy lens, and the D90 ain’t no lightweight itself. The combo makes for a very heavy bag. What I did instead is to get a Tamrac large lens case (MX5378) which is designed for the MAS system, and is a perfect fit for the 70-300. I just put it on my pants belt and it’s perfect. The lens stays there, out of the way and it’s easier to carry and to switch lenses on the move. And when I don’t need the 70-300 I just leave it home and I have a nice small camera bag instead of a big one that’s half empty. But that works for me because I walk around with the camera here in New York City.
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