The results of an I‐ and Z‐band survey and infrared follow‐up of 1.1 deg2 of the Pleiades open cluster complete to I≈ 21.4 (Ic∼ 22) are presented. A total of 23 candidate cluster members has been unearthed, 15 of which are previously unpublished. Assuming canonical cluster age and distance, and using the latest theoretical models, we determine that the cluster mass function continues to rise down to a mass of 0.03 M⊙, following a power law with α= 0.8. By considering several potential sources of uncertainty we show that this result is robust and we compare it with the results from other work on young clusters.

We present the results of a comprehensive I‐ and Z‐band photometric survey of 10.5 deg2 of the Hyades to search for low‐mass stellar and substellar members. The survey, which is ≳95 per cent photometrically complete to , has unearthed a total of 20 candidates, 14 of which are previously uncatalogued. Despite follow‐up observations indicating that nine display spectral energy distributions consistent with cluster membership, a detailed astrometric study of all 20 reveals that only one, the previously known stellar member RHy297, displays a proper motion typical of a Hyad. We discuss our failure to detect further low‐mass members in terms of the shape of the present‐day mass function of the Hyades and find that dynamical evolution has probably led to their preferential evaporation from the cluster.

We present both synthetic and observed I‐Z colours for a sample of spectroscopically classified M and L dwarfs drawn primarily from recent wide‐field infrared surveys. Our synthetic photometry does not reproduce the strong decrease in the IHarris‐ZRGO natural colour beyond M9 to a minimum around L2.5 reported by Steele & Howells. However, it does support the result that the IHarris‐ZRGO colour does not increase with spectral type between L0–L2.5. Instead, the IHarris‐ZRGO, iWFC‐ZWFC, iSDSS‐zSDSS and IC‐ZRGO colours are shown to remain more or less constant before increasing once again for types later than L3–L4. These results, which are supported by both previously published observations and new photometry obtained with the Isaac Newton Telescope (INT) and the Wide Field Camera (WFC), have implications for the interpretation of the recently publicly released Wide Field Survey Programme data covering the Pleiades cluster and surveys for late‐type M and L dwarfs in general.