Would like to add my review of Haida filters here 
Haida is a relative newcomer to the world of neutral density (ND) filters, but they have been receiving rather rave reviews on several forums and in a UK photography magazine. They caught my eye when I noticed that a photographer friend of mine was using them, and upon further research, the images I was seeing really impressed me. For a very reasonable price, I thought Id give them a try.
Ive always been very interested in long exposure photography, and Ive had and used quite a number of brands and types of filters over the years. I started out with the Cokin P Series in 2008, moving on to the B+W ND110 in 2010 and finally, after switching to fullframe this year, I started using a combination of Lee and Formatt Hitech slot in filters. The Cokin P filters were relatively affordable, but unfortunately had a very strong magenta cast that was rather unacceptable to me. The B+W 10 stop had a slight yellowish cast, but was neutral enough for my taste, and I would have continued using it had I not switched to using the Nikon 14-24 a behemoth of a lens that doesnt accept normal filters. I eventually acquired the Lee SW150 holder, and have been using the 150mm Lee filters together with a 10 stop made by Hitech (the Prostop IRND 3.0), as Lee unfortunately does not make a Big Stopper for this filter size.
I was planning on getting Haida screw in filters to use with my Nikon 24-85 VR (when I bought the filters, 100mm slot-in filters were not available, and as far as I know, Haida does not currently make 150mm filters). Although that lens has a 72mm front thread, I decided to get 77mm filters and use them with a step up ring, as I do have some other lenses that I might occasionally use the filters with, and I generally try to standardize my filter sizes.
Build Quality and Handling
In addition to my B+W 10 stop, I also have B+W UV filters on almost all my lenses. So while for the price, I was not really expecting the same nicely finished brass that B+W filters have, I was still interested to see how far off Haida filters were.
The filters are definitely not in the same league as B+W in terms of build quality, and I have noticed a tendency for the filters to get stuck they get stuck to the front thread of the lens, to each other when Im stacking them, and to the step up ring as well. While I wouldnt go as far as to say that they always get stuck, they do get stuck often enough for it to be mildly irritating. This issue of getting stuck never really occurred with my B+W filters, even when stacking or using them with step up rings.
As compared to B+W filters, Haida filters are also quite obviously lighter, and not as nicely finished. However, I acknowledge that it is unfair to compare the aluminum ringed Haida filters to the brass B+Ws, and also, the Haidas are much cheaper.
Stackability
The ability to stack at least two filters without significant vignetting is very important to me, as I need more than 10 stops of ND filters in my long exposure photography. The only way to achieve this is to stack, and one of the reasons I was particularly interested in Haida filters was because they were slim while maintaining a filter thread on the front, which is essential for stacking.
As you can see, the Haida filters the Slim version at least is quite a bit slimmer than the standard B+W.
At the moment, the widest focal length Ill be using these filters with is 24mm on fullframe. I am also currently using 77mm filters on a 72mm lens (the Nikon 24-85 VR)
At 24mm, as expected, a single filter poses no issue with regards to vignetting. I suspect this will be the same even on wider focal lengths.
However, when I stack two filters at 24mm, there is some very pronounced vignetting at the corners. I was a little surprised at this, especially as I had hoped that using a larger filter size would combat this problem.
It must be said that the vignetting quickly disappeared when I applied lens correction to the image, and that it isnt extreme to the point that some quick cloning wouldnt be able to fix it, but should an image have important information in the extreme corners, the vignetting produced by stacking two filters would probably be an issue. Image below shows the same photograph, post-lens correction.
Haida is a relative newcomer to the world of neutral density (ND) filters, but they have been receiving rather rave reviews on several forums and in a UK photography magazine. They caught my eye when I noticed that a photographer friend of mine was using them, and upon further research, the images I was seeing really impressed me. For a very reasonable price, I thought Id give them a try.
Ive always been very interested in long exposure photography, and Ive had and used quite a number of brands and types of filters over the years. I started out with the Cokin P Series in 2008, moving on to the B+W ND110 in 2010 and finally, after switching to fullframe this year, I started using a combination of Lee and Formatt Hitech slot in filters. The Cokin P filters were relatively affordable, but unfortunately had a very strong magenta cast that was rather unacceptable to me. The B+W 10 stop had a slight yellowish cast, but was neutral enough for my taste, and I would have continued using it had I not switched to using the Nikon 14-24 a behemoth of a lens that doesnt accept normal filters. I eventually acquired the Lee SW150 holder, and have been using the 150mm Lee filters together with a 10 stop made by Hitech (the Prostop IRND 3.0), as Lee unfortunately does not make a Big Stopper for this filter size.
I was planning on getting Haida screw in filters to use with my Nikon 24-85 VR (when I bought the filters, 100mm slot-in filters were not available, and as far as I know, Haida does not currently make 150mm filters). Although that lens has a 72mm front thread, I decided to get 77mm filters and use them with a step up ring, as I do have some other lenses that I might occasionally use the filters with, and I generally try to standardize my filter sizes.
Build Quality and Handling
In addition to my B+W 10 stop, I also have B+W UV filters on almost all my lenses. So while for the price, I was not really expecting the same nicely finished brass that B+W filters have, I was still interested to see how far off Haida filters were.
The filters are definitely not in the same league as B+W in terms of build quality, and I have noticed a tendency for the filters to get stuck they get stuck to the front thread of the lens, to each other when Im stacking them, and to the step up ring as well. While I wouldnt go as far as to say that they always get stuck, they do get stuck often enough for it to be mildly irritating. This issue of getting stuck never really occurred with my B+W filters, even when stacking or using them with step up rings.
As compared to B+W filters, Haida filters are also quite obviously lighter, and not as nicely finished. However, I acknowledge that it is unfair to compare the aluminum ringed Haida filters to the brass B+Ws, and also, the Haidas are much cheaper.
Stackability
The ability to stack at least two filters without significant vignetting is very important to me, as I need more than 10 stops of ND filters in my long exposure photography. The only way to achieve this is to stack, and one of the reasons I was particularly interested in Haida filters was because they were slim while maintaining a filter thread on the front, which is essential for stacking.
As you can see, the Haida filters the Slim version at least is quite a bit slimmer than the standard B+W.
At the moment, the widest focal length Ill be using these filters with is 24mm on fullframe. I am also currently using 77mm filters on a 72mm lens (the Nikon 24-85 VR)
At 24mm, as expected, a single filter poses no issue with regards to vignetting. I suspect this will be the same even on wider focal lengths.
However, when I stack two filters at 24mm, there is some very pronounced vignetting at the corners. I was a little surprised at this, especially as I had hoped that using a larger filter size would combat this problem.
It must be said that the vignetting quickly disappeared when I applied lens correction to the image, and that it isnt extreme to the point that some quick cloning wouldnt be able to fix it, but should an image have important information in the extreme corners, the vignetting produced by stacking two filters would probably be an issue. Image below shows the same photograph, post-lens correction.
