Hi
Hope someone can help me with this. Some of my exposures have come out with very large dark patches on and I’m not sure what’s happened here. I never opened the camera mid roll.
Examples:
There are also these weird feint lines on some of the images if you see going across the picture. Any ideas on what this is? You’ll have to open the image up full screen to see them. Other than that this exposure came out ok.
Camera I’m using is rolleiflex SL35E with 50mm planar rollei-HFT lens.
Dark patches can form when two loops of film stick together in the spool during development preventing developer from reaching the emulsion. This local underdevelopment causes thin patches on the negative which appear dark when printed.
Fine parallel scratches are usually caused by grit or dirt on the film pressure plate or too forceful loading of the film onto the spool when developing. Squeegeeing wet film with too much pressure or with a dirty squeegee can also cause scratches.
The lines could either be dirt in the camera that scratches over the film.
Or too much pressure before hanging it up to dry.
Do you develop it by your own?
If so, don’t use a film squeezer! Use your wet fingers once and afterwords I could highly recommend “Kimwipes Kimtech” tissues to reduce the water spots.
They don’t leave dust or particles on the film. 
Hi getting a lab to develop it which makes me think it’s something to do with my camera?
Inspect your negatives on a light table with an 8X loupe magnifier. Also hold them sideways towards a light source on both sides and look for fine scratches.
Using a very diffused light source can help hide scratches. So can a bit of “nose grease,” although you need to clean it off thoroughly with a commercial film cleaner after camera scanning. (I use Photosol PEC-12.)
You would be surprised how many labs scratch film! I worked in the lab industry for decades. We had two roller transport processors I would never allow to touch my film. The other six processors were leader-belt or dip-and-dunk type, which minimize film contact during processing. When I was an AV producer for the same company, I sent my film out to a local lab. After a couple of years, they hired a new processor operator who would not clean the rollers of their Hope roller transport machine. The result was a lot of scratched slides. That was the point at which I learned to process E6 films myself.