K&F Concept is a new channel partner, and I wanna show you exactly why I've decided to partner with them…
K&F Concept reached out to me to ask if I'd like to review some of their filters. We got to chatting, and they sent me a pile of stuff to evaluate, and I was so impressed after running all my tests, that now they're a channel partner. I'm going to share my exhaustive neutral density test results, my brutal Armor UV filter test results, and some fun stuff through some of their effects filters.
So, let’s start with what are, for me, the most useful filters – the neutral density. And, just in case you're not familiar with what neutral density is, or what it’s for; here's a 60 second explanation. An ND filter — “neutral density” is essentially a dark grey piece of glass that reduces the amount of light coming into the lens. Kind of like sunglasses. There are two standard types; fixed ND, which is a single piece of glass at a fixed reduction, so for example a one stop, two stop, four stop reduction, and variable NDs, or VND for short, which are two pieces of glass that when rotated, vary how much light gets through. Variable NDs are more convenient, because you essentially get a bunch of filters in one, however you often sacrifice a bit of quality, usually in the form of added color cast, or loss of sharpness or contrast. Fixed NDs are higher quality because they are one piece of glass designed to do just one thing, but obviously, their less convenient.
ND filters are used for slightly different reasons in still photography and in video. In still photography, they're generally used to create artificially long exposures, to significantly blur movement, like you've seen in countless misty waterfall photos, while in video, they're primarily used so the filmmaker can shoot at a chosen I.S.O., shutter speed, and aperture, where they need something else to control how much light is coming through the lens. An ND filter in video may allow you to shoot, say, wide open on a sunny day, which might otherwise be impossible without one. I'm simplifying, but that's the general idea. Then there are variations to the filters; fixed ND filters can come as graduated NDs, meaning the filter is darker on one edge than the other, which can be convenient for, say, darkening a bright sky without darkening ground below… and you can get combination VND plus a CPL, or circular polarizer, or even a black mist, all in a single filter. Fixed NDs can also come as a 4x5 inch rectangular piece of glass to be used in a matte box instead circular filters to be put directly on your lens. And finally, for a little more education, while the reduction of light an ND filter provides is measured in stops, the rating of an ND filter is marked in an ND number, which is actually the bottom part of the fraction of light transmission. A one stop reduction in light is one-half the light, so one over two. A one-stop ND filter is an ND2. Two stops reduction is half again, so now that's one quarter the light, or one over four, so a two-stop ND is an ND4. This continues on and on, with the ND number doubling each time… ND2, ND4, ND8, 16, 32, 64, and so-on. That was probably more information than 60 seconds, but hopefully that was useful.
I have three types of ND filters to look at today; two standard variable ND filters; I've got an ND 2-32 which is one to five stop reduction, and and ND 2-400, which is one to about 8.6 stops, generally considered to be nine stops. Then I also have ND 2-32 with CPL; the Circular Polarizer. And finally, I have three 4x5 filters in ND 4, 8 and 16, which are two, three and four stops ND. The important tests here are on the bench, to answer these two critical questions: Is there a color cast from the ND, and assuming that there is, is it correctable with an in-camera custom white balance, and is that color cast consistent across the variable range? And question number two; do the filters create any noticeable reduction of sharpness or contrast?
These tests are kinda boring so I'm not going to make a twenty minute long video just on test results. I'll explain the highlights, then post screenshots of these results in the PhotoJoseph member discord server, which you can gain access to by clicking the Join button, next to the Subscribe button, down below. Of course feel free to pause this video and grab screenshots yourself if you want to.
Let me explain the test methodology. Using a LUMIX S5II with the LUMIX S Pro 50mm f/1.4 lens set at f/2.8, I photographed an X-Rite white balance card, an X-Rite color checker card, and a piece of wood to compare details. Honestly the wood thing may not be the best idea I've ever had, but it's what I did, and, it works. So the baseline that every filter is compared to is these three baseline photos made without any filter on the lens. I set a default custom white balance, obviously without the filter, to ensure a perfectly neutral comparison. When you see “default white balance” on the screen, that means the photo was taken with that original custom white balance. Through each filter, I shot with the default white balance, to see what color shift may have been added by the filter, and then I did a new custom white balance with that filter, to see if any added color cast could be removed with a simple custom white balance. To adjust exposure for all the test photos, as I added and adjusted filters, I only changed the shutter speed, which means every photo will NOT appear to be the exact same exposure, since an identical exposure to the baseline would often fall between available shutter speeds. However since we're measuring color, not brightness, minor exposure shifts have no bearing on the color measurements. And finally, all photos are straight out of camera JPEGs, with no additional processing.
First; here's the baseline white balance card with no filter, and the custom, now named “default” white balance. You can see on the RGB histogram that red, green and blue are perfectly in alignment. The first filter tested was the ND 2-32, at its lowest setting of ND2, so minus one stop. I will say that for each of these variable ND filters, ND2 was more like a stop and a half reduction, not just one stop. Just so you know. Again we're still shooting with the default white balance, so we can see that there is a slight shift towards red with the VND in place. As we change the VND, to three and then five stops reduced, we see what appears to be a consistent offset. Next I created a custom white balance with the filter in place, which does reset white perfectly, and we can see that throughout the range, the RGB histograms remain in alignment.
This tells us that our white balance will remain true all the way through the range. So this is all very good. It's expected that there will be a slight color shift with a VND. Lots of manufacturers claim “no color shift”, but I've yet to see that. And it really doesn’t matter… If I'm in a controlled environment, I will always do a custom white balance through the ND filter, and if I'm shooting run-and-gun in auto white balance, then the camera will be measuring white balance through the filter, so it should return back to neutral. It’s fine.
This filter does have hard stops, and a nice easy to grab grip, so it’s really comfortable to use. The hard stops prevent you from overclocking the filter, which would result in cross hatching on your image. It's smooth to rotate; not too stiff and not too loose.
Next up is the ND 2-32 CPL. It actually has a little bit less of a shift than the standard ND 2-32, and again, this can be easily compensated for with a custom white balance. Notice as we get up to ND32, there is a slight increase in the blue channel, but given that this is a polarizer filter which can enhance the blues in the sky and water, that's not very surprising.
This filter also has hard stops, and a double handle. To adjust the polarizer, you grab this outer ring, then to adjust the ND, you move the handles. These ND filters all come in this nice leather case as well, with a draw ribbon to pull the filter out without getting your grubby fingers all over the glass.
Next up is the ND 2-400, which I've gotta say is a HUGE range. Typically VND filters that go this high will start much higher; you're more likely to have a pair of filters, like a VND 4-32 and then a 32-512. So to go from ND 2-400 in a single filter is quite a feat. Honestly, I didn't have a lot of faith in this filter before I tested it. It does have a noticeable color cast just looking through it, so I wanted to see what it’d do. Once I put it on the bench, I was impressed.
First, back to the default white balance — the color shift is noticeable. The reduction in the blue channel make the image yellow, and this continues through the range. So the important question is, of course, “can that color shift be eliminated?”. And it turns out… it can! Here's a custom white balance at ND2, ND32, and ND400.
Now, one big difference on this filter is that it does NOT have the hard stops, which means if you go too far, you'll see this in your image. This image you're looking at now is highly exaggerated; I cranked it up in the computer so you could very clearly see what I'm talking about, but that X pattern will appear if you rotate too far. Also the ramping from ND2 to ND32 goes from here… to here on the filter… then the final jump from ND32 to ND400 happens in this very little range. That means it can be challenging to get a precise exposure at the high range as even the most subtle of movements will change the image quite a bit, however, the fact remains that it is possible. You do get an one to nine stop variable ND range in a single filter. That's pretty great.
OK, so far we've looked at an overall color cast, fixable by a white balance adjustment. But does that really tell the whole story? I also wanted to know if we would see variances in specific colors throughout the range, so to test that, I shot this color chart, and compared the images on a vectorscope. As before, we start without the filter, and our default white balance. Here you can see the native rendering of colors in the LUMIX camera set to the flat color profile which ensured that the black and white levels on the card stayed in range. The fact that the center of the branches are dead center on the vectorscope indicate that our white balance is accurate, and you can see where the color spikes for each lower and higher saturated color tiles reach out to. They're all very close to their technical lines; blue reaching slightly towards cyan, green reaching slightly towards yellow, and so-on. Again, this is the native LUMIX look that you get with that chosen flat profile.
I'm not going to show you all the shots with the default white balance; we already know that each filter needs to have a new custom white balance to look its best, but I do want to show you just one of them, so you can see what the vectorscope looks like if white balance is off. I think you just might find this interesting. Again, here's the no-filter default white balance, and now here's ND400, also with the default white balance. Look at how the center of the color spikes is offset from the middle. That's a clear indicator that white balance is off! Anyway, moving on, as we go through the custom white balanced ND 2-32, 2-32CPL and 2-400, we can see that they are quite consistent. The only one with a noticeable jump is the ND2-32 at maximum; the white balance does shift off just a bit.
The last batch to test is the 4x5 filters, but let's be honest, we're all bored to death with tests. I’ll just tell you that the initial color shift is less than you get with the VND filters, but that these do still benefit from a custom white balance. The last thing I do want to show you though is the sharpness test.
Here's four shots of this chunk of wood, at 100% and then at 200%. There is no noticeable difference; the glass is clean, doesn't reduce contrast, and doesn't reduce sharpness.
Now let's have some fun. The most entertaining filter in the package they sent is also the most unassuming. I mean, after all, how much fun is a UV filter? Turns out, if it’s the Armor filter, and you're deliberately trying to scratch it, or burn it, or break it, it’s actually quite a bit of fun! The Armor filter is dual layered so that even if it does break, it's supposed to keep the fragments from getting to your lens. But it's really hard to break. So, we needed to test all this.
First, a few solid love taps. Just a few thwaps with a screwdriver handle. Nothing too bad, but I certainly wouldn’t be doing this to my camera lens, but this is NOTHING for this filter. I had the idea of filming a sparkler with a macro lens, protected by the Armor filter. These tiny little hot sparks can't possibly be good for the coatings on our expensive lenses, so you'd never shoot something like this unprotected. As these shots go back and forth between the footage through the camera with the filter, and the BTS of the sparkler hitting the filter, you can see the sparks bouncing off the glass. So cool. After a dozen sparklers or so, the only evidence of my misdeeds was a smoked over filter. But, a quick wipe, and this thing was good as new.
The next test was my son's idea, and it was a great idea… but the pigeons wouldn't cooperate. I can't decide if these birds were too dumb to notice the food that wasn't on the ground, or too smart to eat something from my camera box. But unfortunately, after half an hour of trying to attract these feathered fiends, I gave up. Dumb birds ruining my shot.
Next was rocks! A little slow motion skidding into first base, smashing pebbles all over the lens. Again. And again. And again. And since that clearly wasn't enough, I threw some rocks at it, too. Came out clean!
I wanted to blow up a firecracker in front of the filter, but unfortunately, firecrackers are only legal where I live for one week around New Years, so I couldn’t get one to do the test. Maybe at the end of the year I’ll do that.
Alright, enough messing around. I was really determined to break this thing. So, out came the hammer. I started with some softer taps, but I started hitting this thing pretty hard, pretty quickly. I put these screws on the work bench so they could bounce around, and you could get a feeling of how hard I was hitting this thing. And this is a REALLY solid workbench. I just kept going and going until finally… there we go. OK, now that I finally broke this thing, I needed to check the claims that the shattered fragments would be held in place. And here you can clearly see that they are. Even the backside of this is quite smooth. There’s a couple of cracks coming through, but all the little fragments were held in place as it was supposed to. Nearly every break you see is on the front side of the filter, and not on the back. That’s impressive.
In fact this filter is so strong, and so scratch resistant, that I'd be tempted to ditch lens caps entirely. It was really an impressive filter. I'm kinda sad now that I did that to it. But, I did it, so you don't have to!!
Time for the last filters. K&F Concept also makes a bunch of Effects filters. Not the most practical of course, but they’re fun! There's the kaleidoscope filter, which is kinda funky and cool. There’s a star filter that comes in a pack of three, with four, six, and eight points, and you can see that I’m using one of those here… and there’s a shimmer filter, that adds a little softness, or a little bit of glow, which I’m actually also using here… and if I turn this up, you can see the effect that that has. Pretty cool!
So I'll be talking about these filters more in future videos. In fact, if there's a specific filter you want to know more about, let me know and I can ask K&F Concept to send one over so that I can test it out, or play with it, in one of the ads for you guys. Thanks a bunch for watching, and we’ll see you in the next video!
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