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Feedback on KnF Concept variable filter ND8-128

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djfoxy View Drop Down
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Post Options Post Options   Quote djfoxy Quote  Post ReplyReply Direct Link To This Post Topic: Feedback on KnF Concept variable filter ND8-128
    Posted: 24 November 2019 at 19:40
Hello,

I wanted a filter for my minolta 28-135 72mm filter thread.

I already own and positevely reviewed a K&F concept 77mm ND variable filter recently, so got a new K&F Concept variable filter ND8-128 (3 to 7 stops) in 72mm this time.

The build quality is as expected and as good as my previous 77mm ND variable and the packaging is the very same with a nice case.

Concerning the use of the filter, I have noted the same pattern as with the 77mm: Once in place, it is not possible for me to set the cap of my lens on top of it because the thread becomes more like 74mm.
To address this issue I'd like to see KnF concept providing a cap with the filter.


So I gave a quick test run to this filter at the park earlier in the month and I concluded that more than the posibility offered to shoot longer exposure with the filter, the real advantage has shown up to me when I turned to video mode.

This range of stops (3 to 7) is clearly ideal to shoot video.


Concerning the quality results of the images, like for the 77mm I used before, I didn't see any color cast of any kind. Nor vignetting problems.

Here below are a some samples of the shots (A99m2 with minolta 28-135)



Wishing you a nice day.


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longer exposure:



fall colors:



proxy shot:


Edited by djfoxy - 26 November 2019 at 12:16
 



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Fred_S View Drop Down
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Post Options Post Options   Quote Fred_S Quote  Post ReplyReply Direct Link To This Post Posted: 25 November 2019 at 18:40
Thanks for sharing these examples. At what ND values did you make these?

Did you notice any difference over range (from 3 to 7 stops)?
That is sometimes mentioned as disadvantage of these variable ND filters, where the higher numbers give more color cast for example.
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djfoxy View Drop Down
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Post Options Post Options   Quote djfoxy Quote  Post ReplyReply Direct Link To This Post Posted: 25 November 2019 at 18:58
Originally posted by Fred_S Fred_S wrote:

Thanks for sharing these examples. At what ND values did you make these?

Did you notice any difference over range (from 3 to 7 stops)?
That is sometimes mentioned as disadvantage of these variable ND filters, where the higher numbers give more color cast for example.


I think I had shot anything between 3 and 7 stops but I can't be sure if it was with this pics exactly.
If you want more samples I'll put them in my incoming video review no prob.

Indeed it is often a disavantadge on the previous ND variable filters I used: I have a KnF variable I used in Shanaghai in 2012. And the yellow color cast is just awfully insane on this thing. I had like a quarter of the image totally yellow and the rest of the frame under exposed no color cast ....
What they propose now is just night and day from what they had.

I have taken a KnF variable ND2-32 in 77mm during last summer and was gladly surprised by the results: images stay sharp, didn't have any color cast, just a little bit of vignetting at the highest value. but on this last topic, nothing comparable to my DORR fixed ND1000 though.

As a result I decided to give a try to this ND8-128in 72mm this month. The top values are higher so honestly I expected it to be a bit behind the ND2-32.
But in the end, not at all it gave me the same results. sharp all the range, no color cast on the range and a little bit of vignetting at the highest value.

So really my conclusion is that definitely KnF has improved its stuff. Yes the price is a bit higher than before but for the properties of the glass and the result you get that's still a no brainer to me.
I'd love to try a Haida 100mm to compare side by side with a KnF 100mm: The prices are different so it would be interesting to understand where is situated that money right :)


EDIT: Here is the link to my review of the ND2-32 .

KnF Concept variable filter ND2-32 77mm

You will see there a direct side by side comparison with my fixed ND1000 concerning the vignetting

Edited by djfoxy - 25 November 2019 at 19:17
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Fred_S View Drop Down
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Post Options Post Options   Quote Fred_S Quote  Post ReplyReply Direct Link To This Post Posted: 25 November 2019 at 19:31
Thanks for this useful info!
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