I spent a long time buying a filter because on the one hand I didn't know if I needed something like this and on the other hand because I had already tested a 0815 filter with miserable results and the costs for such a part are not insignificant. The question now was whether I should get several filters or a variable filter. In view of the price, the question ultimately became irrelevant. The first tests were able to dispel concerns that the image quality suffers, as with the filter mentioned at the beginning. The images are slightly blurry, but really only marginally. The weakest position extends the exposure time by a little more than 2. In my experiment (Nikon D7200, Sigma 18-35, K&F variable ND filter 77mm ND2-ND400 with adapter ring) I set the aperture to 2 in sunshine. 8 raised to expose well at 1/8000 without a filter. With the filter screwed on in the "MIN" position, the shutter speed went up to 1/3200. I turned the filter from mark to mark and came up with the following shutter speeds calculated by the camera: 1/3200, 1/3200, 1/2500, 1/2500, 1/2000, 1/1250, 1/800, 1/400, 1/125, 1/20(X-Cross, but underexposed). As you can see, hardly anything happens at first and the markings also do not allow any ND value order to be determined, which according to the logic of the first point is 2, the second 4 and the third 8.... So it's time to try it out. In the "MAX" position (1/20) the images are unusable because of the X-Cross, but this is really only the case in the absolute max position, and between the penultimate with 1/125 and Max intermediate positions are also possible where I got useful up to 1/30. So a usable ND value of 266 is calculated. This value is now completely sufficient for filming, because who says that I can't set the shutter speed higher than 1/60, which was the rule of thumb in the early days of analogue filming. Enough theory, I think the filter is an absolutely good investment.
Unscrewing is completely problem-free and if there was a color cast, it was due to the camera (Nikon D7200).
I've uploaded a few pics:
1.) 100% topless bottom view with filter at 5th position (1/2000)
2.) MIN - position
3.) Last usable position
4.) Filter to with X-Cross where the camera with the exposure of my camera (Nikon D7200) failed and I had to raise 2 values ​​in post-processing to be able to recognize something.

Pretty happy with this filter. The magnetic aspect makes it a breeze to put on and take off. No cross-thread filters or fiddling. The CLP works well and does what it's supposed to do. Reduces glare and enhances blue skies. A CPL is one of those filters I never go without, especially for landscape photography. The filter is well made and finely finished.

This "K&F Concept 77mm True Color Variable Fader" is quite a well designed and constructed filter. It is a "twofer" in so far as it combines both a Neutral Density (ND) and a Circular Polarizing (CPL) filters into one easy to use screw-on device. The build quality is impressive, as have been the majority of K&F filters I've ordered over the last two year. Further, the filter comes packed in a leather case with a pull-out tab to slide the filter out for use.

If forced to find a fault it would only be that I wished the filter went further in its light reducing abillities. Having said that about its ND2 to 32 range, I must also heap praise on the filter for the orange finger putters which allow you to move the filter in gradual amounts instead of only being able to set the filter on full stops. Thus the combination of the CPL function (which cuts out reflections from water or stray light from unwanted directions) together with the ND function (which diminishes the amount of light entering onto the camera's sensor thereby allowing longer exposures) provides the ability to get smooth shots of such things as moving water without suffereing any glare from reflections.

The K&F brand of filters, as a whole and specifically this "K&F Concept 77mm True Color Variable Fader," are well made photographic filters that are true to size and perform their intended effect well. Comparing this filter to similar filters from other makers leaves me with the definite thought that for the cost, fit and effect the K&F filters perform quite well. This filter, specifically, is an impressive filter at a reasonable price and I think it is, if not a spectacular build, definitively better than the average. As such I think that the "K&F Concept 77mm True Color Variable Fader" is unquestionably a strong 4 star product which deserves a place at or near the top of anyone's comparison shopping list.

(Please see below for my rating criteria):

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Disclosure:

As noted by Amazon, I am part of the Vine Program which means that I acquire products at no cost in return for a truthful rating. However, although Vine Members pay nothing up front to get these free products they are considered by the Internal Revenue Service as taxable income at the full retail price at the time we get them and we, therefore, must pay taxes on these items.

On a more personal note I often read reviews for products I am considering buying and rely on those reviews that are detailed and come off as honest and full reviews on the product. I therefore try my best to give a true and honest review based on my own experiences with the product.

My Rating Scale:

1 star. This is the absolute lowest I can go and is a definite recommendation against being purchased.
2 stars. Less than average - having issues that I try to delineate in my review. I personally would not pay for this item.
3 stars. Average - neither great nor terrible. It will do the job it is supposed to do but without any obvious good or bad issues.I might or might not buy this item depending on the severity of my need or want.
4 stars. While the product is better than average it is not an excellent product. I would probably buy this product.
5 stars. Enough above average that it exceeds my expectations of how the product would and should perform. A product getting this rating is highly recommended.

Further middle ratings: The above explanation is the base of the recommendations I give in a review. Some ratings are further rated as soft (1/2 star below), solid (the star rating given) or strong (1/2 star above)

Great little filter made specifically for Cinematic effect.
I'm a professional photographer. I had written a rather lengthy 5 star review, but it was rejected for reasons I am not aware of. I recommend this filter if you are looking to soften the visual impact of your photos and video.

The filter works very well on my Sony Alpha 7 III with a Tamron 24mm F / 2.8. There is no cross formation or other unsightly effects. The workmanship feels good and comes in a practical plastic case. As always, the shipping was great with Amazon. I can definitely recommend the 67mm version of the filter. BUT, the filter may not take into account that well in other sizes.

The filter has the size of 10x10cm, weighs 47.5 gr and is 2mm thick, so it matches the filter holder from the same company. Made of anti-reflective glass, it allows to eliminate the noise caused by artificial lights (that is, the yellow part that appears below in the photos of the Milky Way, due to the city's artificial lights). The difference without the filter is noticeable, although a good post-production process will keep the artificial light while the filter is fully cut. With long exposures for the Milky Way, the amount of light captured by the sensor decreases slightly, but the raw power is rich in information and makes it possible to recover the Milky Way and the whole starry sky. It's possible to overcome this (i.e. capture more light) by using a tracker star or taking multiple shots (in my case, without a tracker star, with an f2.8 to 11mm, the max time to not getting the movement of stars is 30seconds). Even in the city it does its job eliminating that yellowish gradient in the sky and bringing out the beauty of the night lights.

Everything perfect

It's an amazing tripod for most types of photography. It is beautiful to look at, especially with the candy apple red metal fittings and is solidly built. No cheap plastic or fake metal here. I bought this specifically for the cross beam feature to hold my rather heavy D7000 and 105mm Micro Nikkor while doing macro photography. The only minor frustration was finding the cross column (it wasn't detailed in the instructions) but I realized after watching a video online that it was neatly hidden in the center column. Everything about this tripod, even the nice padded carrying case exudes an air of quality (don't forget to fold the legs up to fit in the bag!). VS' is my second K&F product - my first was a flash - and I can't say enough about the quality of their products and attention to detail. Certain brands inherited from the world of photography could certainly learn from this innovative company!