Pgytech ND Filters - Corners Blacked

[LeslieS]

Hi everyone, I wonder if anyone noticed this before. So I bought Pgytech filters (16/64/128/256) and noticed that I have a problem with blur mostly on lower left corner, but as I went further to investigate, I've also noticed, that the un-shilded glass opening has inner and outer circle, which is visible to the eye if you look close trough it, and move it left-right a little. So when I'm using this filters I have a problem focusing left part of the picture, being particularly terrible when light is coming from the rear left. I think it's confusing the sensor, or maybe filter itself causes blurriness in certain angles... The thing that I thing confirms this circle reaching into the sensor area is blackened corners I've noticed home in the editor after shooting a timelapse (attached picture). Do you think this should justify return of this item? Lost a month of recordings, coming home into disappointments...

 

[FLDave]

How does this compare to a picture with no filter? Do you really need an extra piece of glass on the camera lens?

 

[LeslieS]

I haven't noticed any focusing problems recording in conditions that didn't require ND filters. I mostly record videos, so I actually need them almost always, as I don't want crisp like recordings, even in this daytime time-lapse case I was aiming for more smoothness, so yes, ND is a must for me. I'm more into if this darkened corners are what's causing blurring or confusing the focus...

 

[FLDave]

That seems to mean a different brand of ND filter is the way to go.

 

[Felix le Chat]

Tried K&F CONCEPTS filters on a whim, now I won't use anything else. Transmission of light and clarity are really good given that they work out cheaper (at the moment) than any of the established brands.

 

[RogerDH]

If the blurred corner also appears in shots without the filter, a common cause for one side or corner to be out of focus is that the optical axis of the lens is not quite perpendicular to the sensor -- a manufacturing defect. I believe I've read on this board of at least one Mini 3 that DJI replaced for that.

 

[Ridefreak]

It's called Vignetting and not unusual with some ND filters.

 

[LeslieS]

In the end the drone was indeed replaced under warranty, due to described blurriness on the left side of the lens (it had a real problem especially on infinity focus setting), but the vignette effect on all four corners was caused by filters. I bought a new set of Neewer variables and have no such problems anymore. Now as far as clarity I'm still not fully satisfied, so I might try those K&F's mentioned few posts before. Thank you all for the help and valuable info.