most of time I use this combination with UV/IR cut filer and paper hood
and Cosina made 28/35mm small finder (the lens was M-mounted by MS)
The mod cost me 55,000Yen @2008-Oct, so it was approximately $500.
(The lens was $400 @2008 from KEH without a finder for this modification.)

M-mount info > https://pbase.com/kkawakami/lens_mods_g_biogon_21mm_to_m