Variable ND Filters? - DPChallenge Forums

Canon RF 28-70mm f/2.0 L USM

01/07/2026 10:49:33 AM · #1

As I upgrade some of my gear, I am in need of some new filters. I am curious if anyone here has experience with any of these variable ND filters? I am looking at the K&F Concept ND2-ND400 (1-9 stops) on Amazon. I don't use ND filters that often but I'm considering the convenience of not having to stack filters when I might want to achieve a specific shutter speed. The price is definitely right at $35 so I'm wondering if there is some sort of unacceptable side effects of this filter....

KristjanUnnar

Canon EOS R3

01/07/2026 11:22:41 AM · #2

I don't have experience with this particular filter but the cheap price raises a little bit of a red flag for me. Cheap variable ND's tend to have one or two deal-breaking problems, mainly color-shift (especially during long exposures) and the so-called "X-pattern" where the overlapping polarizers create a nasty effect you can't fix in post. I guess the price is low enough that it won't hurt testing it out :)

I can however recommend the NiSi True-Color VND's, they feature the least color shift I've ever seen in variable ND's, they are hugely popular with the filmmaking crowd for their quality, I have one of those in the 82mm size for my Canon RF 15-35mm and I can verify that they are truly great.

glad2badad

Apple iPhone 16 Pro

Lensbaby Sweet 35 Optic

01/07/2026 11:26:43 AM · #3

If you're trying to work out exposure calculations you'll want hard stops on the variable filter, instead of one that just rotates freely.

Fujifilm XF 10-24mm f/4 R IOS

01/07/2026 11:30:56 AM · #4

Originally posted by KristjanUnnar:

Thanks. That is exactly the kind of feedback I am looking for. I'll scrap the cheap one and look forward from there. When the price is too good to be true, it's usually too good to be true :)

markwiley

Fujifilm X-Pro2

01/07/2026 11:33:20 AM · #5

I have little experience. I had a cheap variable ND filter a few years ago (I forget the brand). I think it was 8 stops. It was passable through the low end of the range, but it was uneven/unusable in the higher range. I would be careful.

kanaj

Canon EOS M200

Canon EF-M 55-200mm f/4.5-6.3 IS STM

01/07/2026 11:42:20 AM · #6

I'm definitely commenting out of my league on this, as I'm still a neophyte to filters generally and can barely describe what any of them do. But for what it's worth, I've been using one of K&F Concepts budget variable ND filters for my Canon M200 because it's the only way I've so far been able to do any kind of daytime long-exposure photography with any success. I have noticed some minor color shifts or introduction of floating abstractions when using it, but nothing that (so far) I have had trouble compensating for in post. I think if I was more accomplished a photographer, I might be irritated with it, but as a casual shooter who is better with his software than with his camera, I find it to punch above its weight for my needs.

I'd say that about K&F Concepts products generally. They seem targeted at the "enthusiast" market that I'm in more than the serious professional crowd I imagine veterans like you guys shoot within. For me, they represent genuine upgrades. For others, I'm sure they would be compromising retrogrades except for niche use cases.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

01/07/2026 01:11:21 PM · #7

Originally posted by kanaj:

I think I'm gonna go ahead and buy one based on your comments. I'm only outta 35 bucks if it's crap. I'll test it and post results. That would be a good chance for me to geek out with some camera gear.

My problem is that I have a bag of filters that are all too big for the gear I'm using now. I abandoned the world of SLR gear after I stopped doing the journalism/sports side gig. I don't think these adjustable filters even existed when I was shooting daily. Looks like I'm shooting with a Sony version of your Canon. Your lens takes 49mm filters, which is kinda nice. My kit 16-50 uses 40.5mm but my 55-210 uses 49mm. I think I'm just gonna buy a 40.5 to 49mm step up ring so I can share filters across those two lenses.

GeneralE

Canon PowerShot S3 IS

01/07/2026 01:33:13 PM · #8

I only have a graduated (not variable) ND filter, but FWIW I was able to achieve a 2-second daytime exposure by stacking two polarizers -- rotating them with respect to each other seemed to vary the amount of blockage, as well as amount of color-shifting.

$35 seems a modest investment to experiment with and see if the technique is useful enough to justify upgrading in the future (sure is easy to spend other people's money!)