You're not going to get a lot of optical vignetting (cos^4 falloff) from a 120 mm lens on 4x5. You'll probably get substantial image degradation towards the corners with a lens around 120 mm made for a 6x6 or 6x7 camera.
Your best best at 4-5 feet would be a shorter lens made for a 6x6 camera. And it won't give you exactly what you want.
How about two series 5 or series 6 close up lenses. If mounted concave to concave a plus 3 and a plus 4 would be a plus 7, about 143mm. Put a thin brass stop inside, about a 17 mm hole should give you f8.5 with plenty of fall off. Don't know what to do about a shutter.
1) a lens designed for smaller format (6x6 cm or 2x3 in), e.g. lenses for 2x3 Speed Graphics (or Century Graphics), like the 101/4.5 Ektar or Optar, or similar, or a lens scavenged from a medium format (6x6 or 6x9) folder. However, in this case you're limited to focal lengths ranging from about 80mm (6x6 format) to about 105mm (2x3 format).
2) some DIY lens hacking - mix and match various lens cells in an existing shutter - or use close-up (diopter) lenses, as already mentioned. You could try one of the lenses mentioned under 1) above, and try removing/swapping lens elements with other lenses, close-up diopters, etc.
Most of the lenses in shutter in the focal lengths you mention (120-135mm) will cover 4x5 without serious vignetting - at least not as pronounced as in a Holga. The Kodak Ektar 127 that Andrew mentioned does not really vignette on 4x5: well, it actually does when you try movements, but only on the side which ran out of coverage (not what you want).
Now that I think of it, there might be a third solution: you could try 135mm lens from a Mamiya TLR, but I'm not sure about its coverage and vignette characteristics (if any) when used on 4x5 format.
If you're willing to forego the shutter, your options increase with many older barrel lenses you might try.
I have actually mounted the Agfa Solinar 105mm from my Record III on a 5x4. This is a tessar-type lens and normal for 6x9cm. It illuminates 5x4, but gets soft outside of the intended 6x9 frame. It does not vignette at the corners - you would have to put it on a 5x7 to see the corners really darken. The Synchor-Compur shutter has the close to circular iris mentioned originally, though the lens also mounts in a standard Copal 0 shutter.
I suspect that any lens designed as 'normal' i.e. a focal length close to the diagonal of the format won't work for corner vignetting at the focal lengths you want. You probably need a projection lens of some sort.
Grabbed a cheap 135 Mamiya TLR lens on eBay tonight - we'll see what that does in a few days. I have the 127/4.7 Ektar and that does indeed cover 4x5, at least any closer than infinity. Checked a 101 Raptar which seems to cover too well also. Will test other options as time allows. Even 6x9 lenses would fill the narrow dimension of the 4x5 frame though, I think.
Thanks for suggestions.
Last edited by Ben Altman; 12-16-2012 at 10:31 PM. Click to view previous post history.
Update - the Mamiya 135 TLR lens comes close to what I want if I use it wide open. A bit more coverage than I want but it does fall off towards the sides. Corners are dark but a bit more abrupt than I'd like. Not bad, though. May try some mechanical vignetting too. It's hard to get something as bad as a Holga lens... Thanks Denis for the suggestion.