Originally posted by wehavenowaves! so my friend let me borrow her dad yashica 635 tlr (rolleiflex copy) and i took a few rolls. two of them came out with nice results (kodak t-max 400 and acros 100) but the ilford hp5 plus 400 has these strange vertical "splotches". any ideas what it might be? the film was not expired. bad scan???
I suspect insufficient agitation. The general agitation recommendation is 30 seconds initially, then 10 seconds per minute. Without agitation the developer becomes locally exhausted and perhaps even stratified or layered, the emulsion thus isn't developed evenly. Are you developing with replenishment, or "one-shot?" With D-76, for instance the stock solution can either be replenished, or diluted 1 to 1 and discarded after use. Many of us prefer one-shot, since developer is relatively cheap.
An advantage of 1 to 1 is that the developing time is longer, so small errors in timing make little or no difference.
The Yashica is a nice box, isn't it? Is this the one with a 35mm adaptor? If so, did you use it? I don't really see how that could make a difference, but... other members may find the information useful. Although if the adaptor is the problem it should affect all rolls, not just one.