Chair and chair frame

A chair comprising:

• a frame configured to expand radially outward and collapse radially inward relative to a central longitudinal axis between a folded position and an open position, the frame comprising:
• two front legs each configured to be independently adjustable between a plurality of different lengths to extend a length of each of the two front legs independently and obliquely relative to a level plane, wherein each of the two front legs comprises a leg member and a foot held at a corresponding end portion of the leg member, the foot being mounted to the leg member at a joint comprising a ball joint, a clevis, or a spherical rod end, the joint allowing rotation about at least two perpendicular axes to enable the foot to conform to uneven terrain;
• and
• two rear legs each having a fixed length, wherein each of the two rear legs comprises a leg member and a foot held at a corresponding end portion of the leg member, the foot being mounted to the leg member at a joint comprising the ball joint, the clevis, or the spherical rod end, the joint allowing the rotation about the at least two perpendicular axes to enable the foot to conform to the uneven terrain;
• and
• a seat bottom secured by the frame and configured to be selectively adjustable between at least two different angles relative to the level plane in conjunction with independently adjusting the length of the two front legs, wherein at least one of the at least two different angles of the seat bottom extends obliquely relative to the level plane.