Digital BW, The Print

Just my $.02 worth, as someone who likes to shoot B&W IR landscapes with 
a Better Light scan back and a large format camera.

I'm quite fond of shooting infrared, partly (mostly?) because it's 
really easy to do with a a Better Light scan back. The Better Light has 
no built-in IR filter, so you normally need to use an IR high-pass 
filter in front of or behind the lens for visible light work. I like to 
swap this for a (visible light opaque) IR low pass filter, which makes 
it possible to shoot very high quality IR.

The first thing I'll say is that I've not really seen any problems with 
any of the glass I own with regard to IR -- whilst it would be difficult 
to get a sharp result shooting IR and colour *at the same time*, using 
an IR low pass filter and refocussing gives pin-sharp results. There 
*is* a focus shift, however, which can be troublesome at times, but the 
focus meter capability of the back makes it possible to tweak the focus 
and get it right even though it's impossible to actually focus 
conventionally (i.e. no visible light to focus with). I've had the 
sharpest results with my 150mm Fujinon and my 90mm Super Angulon, but 
then, they are my sharpest lenses anyway (not that my 47mm Super Angulon 
XL or my 210mm Caltar are exactly blurred either, mind you). As regards 
f stops, the usual 'stop down at least 2 stops from wide open, but don't 
go too far or you'll get diffraction losses' advice works for IR just 
fine, and (I suspect) even more so, because the longer wavelengths 
involved will be affected more by smaller apertures, at least in theory. 
I've heard people say that IR gives dreamy, slightly blurred images 
inherently -- from experience, I can say for certain that this isn't 
fundamental to IR because I've had some truly pin-sharp results. It 
probably *is* inherent in some IR shooting techniques, particularly IR 
film, however. There's a bigish print on my office wall of Split Rock at 
Joshua Tree National Monument where pretty much every grain in the 
house-sized rock is clearly visible.

My workflow is pretty simple: take the filter off, set the lens wide 
open, focus and set shifts, swings and tilts conventionally (I use a 
reflex finder as a matter of preference), insert the back, stop down, 
put the filter in place, put the back in, refocus, shoot.

To return to the original point, rather than IR for a moment, depth of 
field can certainly be an issue with large format cameras shooting 
landscapes. The best sharpness is generally found at around 2 to 4 stops 
narrower than wide open for most LF lenses, but this rarely gives you 
depth of field that would have, for example, a meadow of flowers in 
focus from a couple of metres to the horizon. This is particularly 
noticeable with a 'standard' lens or short telephoto (150mm or 210mm 
with a Better Light, a bit longer than that for 4x5 film due to the 
slight crop factor), though it's still noticeable with a 90mm. 
Ultrawides like the crazy 47mm Super Angulon I use sometimes do 
obviously help, but you don't always want to shoot with something that 
extreme. I've had very good results from using a 90mm Super Angulon with 
a small amount of tilt to rotate the plane of focus  -- this is the 
*real* secret of pin-sharp large format landscapes. Stopping down to 
f/64 will indeed give far more depth of field, but it does very 
noticeable soften the image. It's not so noticeable with film, but it's 
*very* noticeable with a modern digital sensor, so tilts and swings are 
where it's at in practical terms unfortunately. (And I mean 
*unfortunately* -- getting them right is difficult and time consuming)

[s]