WHAT LENS DO I NEED FOR A 4FTX5FT (Image circle of 68 inches or bigger)

[jnantz]

this would work perfectly "on the cheap"

You use a simple meniscus 2000mm lens from Surplus Shed (stock # L8093, $4.00), mount it in a tube, and stop it down to f/128 or smaller and have something better than a pinhole.
Or a pair of 4000mm lenses (L4639), mount them in a tube, symmetrically about a central stop, and have a periskop (symmetrical doublet lens).
Making the huge bellows would be an interesting challenge, wouldn't it? I'm pretty certain that the exposure time would be minutes, not fractions of a second, so a shutter could be a lens cap.

[Dan Fromm]

I would look into commissioning Reinhold to build one. I think someone linked to his website early in the thread but the OP might have passed over it because the lenses he offers by default aren't big enough. I bet he could make one though, perhaps even with a more-complex design (rectilinear or double-gauss) than his default meniscus lenses.

Does he buy blanks and grind them into lenses or does he buy the lenses?

[polyglot]

Does he buy blanks and grind them into lenses or does he buy the lenses?

I think he's buying cheap/surplus elements and gluing them into PVC tubes. One or two elements per lens maybe.

[goamules]

In that case, I would just buy a surplus shed meniscus and build it myself.

[Darin Boville]

Just the other day someone thought Leigh was a woman.

That was me. Turns out that *all* of the people here I thought to be female are male.

--Darin

[Simon Liddiard]

That was me. Turns out that *all* of the people here I thought to be female are male.

--Darin

That is somewhat depressing!

[StoneNYC]

That is somewhat depressing!

There's at least one girl, a girl in New York who started a large-format Facebook group and invited bunch of the guys that are in this New England area to it, though there hasn't been a get together yet. I'm fairly certain she's very young, and seems very very nice.