You missed one - C1151 (top left) is a MiG-21PF. Check the spine radio communication antenna, centerline Pitot tube, narrow spine, no GSh-23 cannon, forward opening canopy.
Also, I do see two 21MFs (inner left and right wingmen) but no 21bis.
March 28, 2013
A unique formation - all MiG-21 variants in IAF service. Leading the formation is CU2796, a MiG-21 Bison. Behind him is C2218, a MiG-21bis, and below is C1576, a MiG-21MF. The last frame is a MiG-21UM. Taken during the opening flypast of Exercise Iron Fist 2013 at the Pokhran Range.