Shooting directly up

[jcc]

This is exactly what camera makers reflex viewing hoods do. The hoods have advantages over DIY mirrors. They attach directly to the camera's back with no tinkering, thinking or fabrication needed and they keep the dark in.

They're talking about attaching the mirror in front of the lens though, not behind the focusing screen. Nonetheless, I like the reflex viewer idea better.

I tried shooting "up" with a Sinar P2 once. Will never try it again without spiking the tripod legs in the ground or something. The F2 is quite a bit lighter though, but still make sure it's well supported from tipping over.

[Daniel Stone]

Here's another thought:

Put a slightly (longer) lens on, then drop the height of the tripod/camera setup, so you can focus/compose on the ground glass when LAYING ON THE GROUND(using a tarp or blanket underneath you of course, unless getting dirty is your thing)

I worked on a job a few years ago here in LA, we needed to shoot a stairwell looking UP(straight up). The photographer did exactly that: laid on the ground and "zoomed" in with a longer lens to get the composition required for the shot. Worked well, and allowed him to "lay down on the job"

Not everyone might think that this is easy, and TBH, it isn't. But it's an option if you can make it work. HAVING A STRONG TRIPOD/TRIPOD HEAD(thinking a #5 Gitzo/gitzo head) would probably be best in this instance.

-Dan

p.s. use a level on the standards to gauge "level, or put it across the threads of the lens barrel, and likewise the ground glass/film plane.

[lfpf]

what about a front-surface mirror on it's own stand(say, with a ballhead attached to the back of the mirror)? Camera remains pointed horizontal, just use a large enough mirror at a 45˚ angle so you can see "up"?

I've purchased a few process lenses in the past that came with mirror box attachments

+1,
1st surface mirror works very well and is convenient for up/dn/L/R.
Attachment to same camera tripod or drop-bed strut makes alignment easy, closer-->smaller mirror
Your mirror box sounds like quite the unit.
Cleaning 1st surface mirrors is thorough, quick and easy with First Contact Cleaning Solution.