Lens Convergence?

[Sirius Glass]

That lens IME does not have a large enough image circle to properly shoot architeture.

I will keep that in mind and look for another 90mm lens. Thanks

[Darin Boville]

I've been struggling with this lately...
http://www.largeformatphotography.in...ad.php?t=78766

A level helps get you in the ballpark, but adjusting the back, with the gridded screen, is the final say.
Being low to a building makes things more difficult to square up as well.

Just to underline this further. There are times when the camera may be perfectly level but, due top the topography, things look a tad slanted. You may want to "correct" for this and tilt the camera left or right. The screen is all tat matters in the end, unless you are doing some sort of scientific survey...

--Darin