Normally when we think of Variable ND filters, we think about a circular filter. One that gives us the ability to change the exposure simply by rotating the front element. Something like this K&F concept one I recently reviewed here.
But what if you wanted both the convenience of a Variable ND filter AND the ability to use graduated or other filters. This would give you far more control over the scene that you are going to capture?
Well! Haida has released a brand new filter the ‘Insert Variable ND filter‘.
Inside the box, Haida treats you to a lovely metal filter box. It does a great job of keeping the filter safe. Inside that box, you’ll find the Insert Variable ND.
Unlike a traditional Variable ND filter, the new Haida Insert Variable ND is a single 100mm square polarizing filter. It’s kinda obvious fro the photo above. You use it with “other” CPL filters to create the variable ND effect.
While this filter should work on different filter systems as long as they have a rear CPL filter, it was specifically designed to be used with Haida’s own M10 filter kit which comes with a drop in CPL filter while a 0.9ND CPL and 1.8ND CPL are also available to offer even more flexibility.
To use the filter you simply place it in the front of the M10 kit. A CPL filter is in the back; and to change exposure, you rotate the little CPL dial to achieve the desired results.
From my testing turning the CPL dial no longer has any effect on the reflections on the image. It simply darkens the exposure. You can rotate the front filter to control reflection, as you can see in this demonstration.
Having separate control over exposure and reflections adds more creative options. Combine that with the extra flexibility a square holder kit provides, and you’ll give photographers/videographers incredible control over the final output.
Changing the CPL filter in the M10 kit is also rather easy. You just grab the red clips at the top, push them in and pull the filter out. Then you drop in the new filter in, making it simple to go from one strength of Variable ND to another. Here is a quick demo for that:
The whole point in this Insert Variable ND filter is to easily adjust the exposure between a few stop-ranges. Let me quickly go over just what you get with each drop in CPL combination.
- Insert Variable ND + CPL = ND2-16 (1-4 stops)
- Insert Variable ND + 0.9ND + CPL = ND8-32 (3-5 stops)
- Insert Variable ND + 1.9ND + CPL = ND64-500 (6-9 stops)
Now there is no hard stop with this combination, so you can actually go past the recommended maximum. You start to degrade image quality doing so, by how much depends on the scene or lens used.
All this ease of use wouldn’t really be worth it, though, if the image quality wasn’t up to scratch. I did a few tests to try and stress the filters.
To test the sharpness of the filters, I wanted to use a long focal length. In the past, I’ve had filters that were great on the wide side, but got soft past 100mm. I grabbed my Sigma sdQ which uses the 19.8mp Foveon 1.5x crop chip that can at time resolve more than a 36mp FF Bayer and the 70-200 f2.8 Sport.
I set the lens to 135mm at f6.3, this should let me focus purely on any changes the filters are having to the images. I then took a shot without the filter and here is the overall scene.
And now a series of crops with the CPL and Insert Variable ND at various different exposure settings. I’m going from one to four stops, and even going past the maximum settings to nine stops. See, there’s nothing to limit how far you can rotate the CPL filter. It’s a shame since this is a standard feature with most circle variable ND’s.
As you can see, there’s not really much in it at all. Using the filters adds a slight warming effect of around +14 temp and -3 tint to the image. The critical element – sharpness – remains almost unaffected. Pushing way past the recommended limit to nice stops does add a bit more color cast with a slight purple hue and a little less contrast. Sharpness is still good though!
Let’s try the 0.9ND + CPL drop-in filter
As you can see this combo gives almost identical results to the normal CPL filter supplied with the Haida M10 kit. This is great news and a good sign of the filter quality. I have had filters before that had different color casts with different strengths of ND effect, even when they were part of the same line.
Variable ND with the CPL
Here’s a view of the overall scene using the Insert Variable ND with the CPL.
The filter looks great between its recommended minimum and maximum settings. Honestly, at 135mm, the image starts to degrade only at nine stops of ND. Wider lenses will degrade quicker though. But even then, results can be in a pinch, as you can see with this quick edit.
Next up I wanted to test for Infrared pollution. Lots of ND filters these days also block infrared light. It’s not something that’s normally part of Variable ND filters and some people recommend not using them on cameras with weak hot mirrors and use regular ND’s instead. The reason for this is that blacks can start to turn slightly red when you reduce only the visible light.
For this test, I took my Sigma sdQ-H and did three shots: One without any filters; One with the Insert Variable ND and CPL; and another with the internal IR-cut filter (Hot-Mirror) removed. I used a special filter from Kolari Vision to show what parts of the scene would be most affected by IR light, so we know where to check for the infrared pollution.
Even going two stops past the recommended limit for the Insert Variable ND + CPL combo at 35mm (45mm equivalent) the image has an even light reduction. With a corrected white balance any Infrared pollution is minimum.
Lastly, I wanted to look for the dreaded X pattern that variable ND filters can cause. This is why recent circular variable ND’s come with limiters – to stop you from rotating the filter after a certain point. Although this combination has no such feature so you can easily go past the recommended amount.
To do this I grabbed the Sigma fp and the new 24-70 f2.8 DG DN Art and set the camera to 24mm and pointed the camera the sky.
At 24mm (full-frame) with four stops of ND, we start getting some vignetting at the top left and bottom right corners. You can rotate that pattern by moving the front filter. If you go way past the recommended maximum exposure you can clearly see the X shape appear at seven stops. The effect will vary from lens to lens and there are two ways to avoid the pattern: Using longer focal lengths and using a stronger drop in CPL to reach that ND level.
In real-life use, though, when shooting landscapes, I don’t feel that X is going to be much of an issue if at all. I shot this photo with the same combination as the tests above. While I don’t know the exact strength of the ND effect (there’s no way to tell without having a base exposure), I was a good bit past the maximum setting.
One drawback I did find is that it’s hard to tell how much ND effect you are actually using. Without any physical markings or rotation limitations, it’s easy to go past the recommended maximum ND effect. Still, photography isn’t about camera settings, it’s about capturing light. The control and freedom to shape the scene are worth more than knowing exactly how much ND you apply.
I’m very pleased with the Insert Variable ND filter. Particularly the image quality and for around $85 it offers great value over buying several standard ND filters. If your main focus is using wide angles with a strong ND effect then a fixed ND filter would offer better image quality. You should not be surprised by this, and its the tradeoff you get when you need a more versatile tool.
The Insert Variable ND filter, like Haidas other filters, also comes with a scratch and waterproof coating. While I’m not going to test the scratch part, I did want to play around with some splash photography. It was fun to see the water just slide off the filter. It makes it much easier to keep the filter clean too, which is a nice bonus.
For anyone wondering, yes! You could use the Insert Variable ND with other holders with rear adjustable CPL filters if that’s what you have. Although I do find using the filter with Haida’s own M10 holder with its quick-change CPL makes for an enjoyable photographic experience.
You can see more about Haida’s M10 kit here from our very own John Aldred.