I recently got a 10-stop ND filer (B&W #110) after my previous experience with doing a 10 stop filter DIY have been rather disappointing. During my first test shots with my new filter I was even more disappointed. The pictures I took had some weird horizontal lines across all the pictures:
I cleaned the filter, the lens and the camera sensor. I checked the filter but could not find any issue either. Finally I found the explanation in an internet forum. The problem is a light leak caused by the view finder. This means that light falls through the view finder somehow onto the sensor. The solution is easy, just cover the view finder during the exposure and the weird lines are gone:
Overall I’m quite satisfied with the B&W #110 filter. As reported by some other users the is has slight warming effect on the colors, which I personally like. Here is the final version image after I converted it onto black&white:
A 10-stop filter is essentially like really strong sun glasses. Actually, and literally, it has the darkness of welding glass. Therefore various place suggest to replace a rather expensive ND-filter with just welding glass. This is what I did. I ordered a strength 10 welding glass an step-up filter ring and glued both together with super glue. The welding glass had a really string green tint and caused the pictures to be somewhat soft. But more importantly the biggest issue with my DIY ND filter was to use super glue. The vapors of the super glue are pretty aggressive and started to attach the plastic of my lens front and to crystallize on the front element of my lens (similar to the finger print recovery scene in Beverly Hills Cop). Lessons learned. You get what you pay for (optically) and do not use super glue on anything that get attach to you camera or lens.