Ann has a good point. These lenses are not very contrasty so to bump up the contast somewhat, you'll need to add more development. Lots of times, I use 400 speed film and process with my other 120 film. Sunny days/400speed file/D76/11-12 minutes. Or sometimes PMK usual development for your other films.
Here's a photo shot in bright light. 400 speed film. I processed with my other rolls of 400 speed film (shot with a normal camera) in D76. Looks a little flat, I had to bump up the contrast a bit. But if I did the roll by itself, I would have given it like 10-20% more processing.