I should begin by stating the following entry is my own experience, opinions and should be vetted by outside resources prior towards making your own opinions/decisions. This blog post should be digested as an opinion editorial piece only.
In 2012, I first came across the Cokin Pure Harmonie filter at the PDN Photo Expo, in New York. I was completely blown away, by it's thickness (or lack of thickness); and knowing the quality of the Cokin brand, I was jumping at the bit to get my hands on this filter.
In 2013, I purchased a 77mm, 72mm and two 58mm Cokin Pure Harmonie filters from B&H. My experience with the Pure Harmonie started turning south the moment I attached the first 58mm filter to my Zeiss 50mm 1.4 Planar lens. I discovered the Zeiss lens cap wouldn't stay on with the Pure Harmonie filter. Why? Simply not enough threads on the filter for the cap to connect with. The filter was removed; and replaced with the Zeiss' previous B+W filter.
The lens caps stayed on better with the 77mm and 72mm filters on my Canon 200mm 2.8L and 24-105mm 4L lenses.
Last Friday (April 4, 2014), wanting to clean the 24-105mm. I noticed the glass rotating when I began cleaned the lens with lens tissue and my finger. My pressure was gentle. Somehow the Cokin Pure Harmonie's glass dropped. I was able to clearly hear a tinging when I gently rotated the lens. I believed the glass was trapped between the filter ring and the front lens area. I contacted Cokin via their website, asking for assistance. As the date this entry was written, I've not heard back from them.
My immediate concern was the lens' front element. Was this piece of glass touching or scratching the lens element? I didn't know for sure. I was unable to unscrew the filter. The tinging had caused much concern. I went to B&H, seeking a filter wrench. No luck. I knew Unique Photo in New Jersey had them. They were out of stock. However one of the employees helped me remove the Pure Harmonie filter by snipping the filter's filter ring. It was done so carefully and patiently. A number of things could have happened. What didn't happen was the filter's glass coming in apparent contact with the lens' front element.
I was extraordinarily lucky.
I've removed all of the Cokin Pure Harmonie filters from my lenses. Please be aware of my issue, if you have these filters.
This blog entry was written a short while after the Cokin Pure Harmonie Filter failed. I had wanted to give the folks at Cokin an opportunity to take care of the situation. They responded to me a week after the incident occurred, on April 4th, 2014. I was told someone from the American branch of the company would be contacting me. He did, a short time after Cokin Corporate contacted me. He was apologetic, but unmoving (in my opinion). He stated if there was damage brought to my Canon L Series lens, Cokin would not compensate me.
I told him, I removed all of the Cokin Pure Harmonie filters from my lenses. And I would not want to obtain a replacement (especially because he wanted the failed filter. And the failed filter was discarded).